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Sample records for supersonically cooled molecular

  1. Study of active cooling for supersonic transports

    Science.gov (United States)

    Brewer, G. D.; Morris, R. E.

    1975-01-01

    The potential benefits of using the fuel heat sink of hydrogen fueled supersonic transports for cooling large portions of the aircraft wing and fuselage are examined. The heat transfer would be accomplished by using an intermediate fluid such as an ethylene glycol-water solution. Some of the advantages of the system are: (1) reduced costs by using aluminum in place of titanium, (2) reduced cabin heat loads, and (3) more favorable environmental conditions for the aircraft systems. A liquid hydrogen fueled, Mach 2.7 supersonic transport aircraft design was used for the reference uncooled vehicle. The cooled aircraft designs were analyzed to determine their heat sink capability, the extent and location of feasible cooled surfaces, and the coolant passage size and spacing.

  2. Numerical Analysis of Supersonic Film Cooling in Supersonic Flow in Hypersonic Inlet with Isolator

    Directory of Open Access Journals (Sweden)

    Silong Zhang

    2014-02-01

    Full Text Available Supersonic film cooling is an efficient method to cool the engine with extremely high heat load. In order to study supersonic film cooling in a real advanced engine, a two-dimensional model of the hypersonic inlet in a scramjet engine with supersonic film cooling in the isolator is built and validated through experimental data. The simulation results show that the cooling effect under different coolant injection angles does not show clear differences; a small injection angle can ensure both the cooling effect and good aerodynamic performances (e.g., flow coefficient of the hypersonic inlet. Under selected coolant injection angle and inlet Mach number, the cooling efficiency increases along with the injection Mach number of the coolant flow, only causing a little total pressure loss in the isolator. Along with the increase of the inlet Mach number of the hypersonic inlet, the cooling efficiency does not present a monotonic change because of the complex shock waves. However, the wall temperature shows a monotonic increase when the inlet Mach number increases. The mass flow rate of coolant flow should be increased to cool the engine more efficiently according to the mass flow rate of the main stream when the inlet Mach number increases.

  3. An Introduction to the Supersonic Molecular Beam Injection

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Recently a new fuelling method with supersonic molecular beam injection (MBI) has been developed and used in the tokamaks experiments successfully. It is economical to develop and maintain. The advantages of supersonic MBI compared with the conventional of gas-puffing method are as follows: deep deposition of fuel, better fuelling efficiency, reduced recycling and pure plasma. Particle and energy confinement can be improved and density limit extended. This review described the Laval nozzle molecular beam and a simple collective model for the injection of a supersonic MBI into the tokamak plasma.

  4. Laser Cooling of Molecular Anions

    CERN Document Server

    Yzombard, Pauline; Gerber, Sebastian; Doser, Michael; Comparat, Daniel

    2015-01-01

    We propose a scheme for laser cooling of negatively charged molecules. We briefly summarise the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C$\\_2^-$, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photo-detachment process is present, as well as Doppler laser cooling of trapped C$\\_2^-$, are also simulated. This cooling scheme has an impact on the study of cold molecules, molecular anions, charged particle sources and antimatter physics.

  5. Laser cooling of molecular anions.

    Science.gov (United States)

    Yzombard, Pauline; Hamamda, Mehdi; Gerber, Sebastian; Doser, Michael; Comparat, Daniel

    2015-05-29

    We propose a scheme for laser cooling of negatively charged molecules. We briefly summarize the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C_{2}^{-}, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photodetachment process is present, as well as Doppler laser cooling of trapped C_{2}^{-}, are also simulated. This cooling scheme has an impact on the study of cold molecules, molecular anions, charged particle sources, and antimatter physics.

  6. Analyzing the structure of the optical path difference of the supersonic film cooling

    Science.gov (United States)

    Ding, Haolin; Yi, Shihe; Fu, Jia; He, Lin

    2016-10-01

    While high-speed aircraft are flying in the atmosphere, its optical-hood is subjected to severe aerodynamic heating. Supersonic film cooling method can effectively isolate external heating, but the flow structures formed by the supersonic film cooling can cause the beam degradation and affect the imaging quality. To research the aero-optics of supersonic film cooling, an experimental model was adopted in this paper, its mainstream Mach number 3.4, designed jet Mach number 2.5, measured jet Mach number 2.45. High-resolution images of flow were acquired by the nano-based planar laser scattering (NPLS) technique, by reconstructing the density field of supersonic film cooling, and then, the optical path difference (OPD) were acquired by the ray-tracing method. Depending on the comparison between K-H vortex and OPD distribution, the valleys of OPD correspond to the vortex `rollers' and the peaks to the `braids'. However, the corresponding relationship becomes quite irregular for the flow field with developed vortices, and cannot be summarized in this manner. And then, the OPD were analyzed by correlation function and structure function, show that, there is a relationship between the shape of OPD correlation function and the vortex structure, the correlation function type changed with the development of the vortex. The correctness that the mixing layer makes a main contribution to the aero-optics of supersonic film cooling was verified, and the structure function of aero-optical distortion has a power relationship that is similar to that of atmospheric optics. At last, the power spectrum corresponding to the typical region of supersonic film cooling were acquired by improved periodgram.

  7. Super-Sonic Turbulence in the Perseus Molecular Cloud

    CERN Document Server

    Padoan, P; Billawala, Y N; Juvela, M; Nordlund, A A; Padoan, Paolo; Bally, John; Billawala, Youssef; Juvela, Mika; Nordlund, AAke

    1999-01-01

    We compare the statistical properties of J=1-0 13CO spectra observed in the Perseus Molecular Cloud with synthetic J=1-0 13CO spectra, computed solving the non-LTE radiative transfer problem for a model cloud obtained as solutions of the three dimensional magneto-hydrodynamic (MHD) equations. The model cloud is a randomly forced super-Alfvenic and highly super-sonic turbulent isothermal flow. The purpose of the present work is to test if idealized turbulent flows, without self-gravity, stellar radiation, stellar outflows, or any other effect of star formation, are inconsistent or not with statistical properties of star forming molecular clouds. We present several statistical results that demonstrate remarkable similarity between real data and the synthetic cloud. Statistical properties of molecular clouds like Perseus are appropriately described by random super-sonic and super-Alfvenic MHD flows. Although the description of gravity and stellar radiation are essential to understand the formation of single prot...

  8. Numerical Simulation of Reactive Flows in Overexpanded Supersonic Nozzle with Film Cooling

    Directory of Open Access Journals (Sweden)

    Mohamed Sellam

    2015-01-01

    Full Text Available Reignition phenomena occurring in a supersonic nozzle flow may present a crucial safety issue for rocket propulsion systems. These phenomena concern mainly rocket engines which use H2 gas (GH2 in the film cooling device, particularly when the nozzle operates under over expanded flow conditions at sea level or at low altitudes. Consequently, the induced wall thermal loads can lead to the nozzle geometry alteration, which in turn, leads to the appearance of strong side loads that may be detrimental to the rocket engine structural integrity. It is therefore necessary to understand both aerodynamic and chemical mechanisms that are at the origin of these processes. This paper is a numerical contribution which reports results from CFD analysis carried out for supersonic reactive flows in a planar nozzle cooled with GH2 film. Like the experimental observations, CFD simulations showed their ability to highlight these phenomena for the same nozzle flow conditions. Induced thermal load are also analyzed in terms of cooling efficiency and the results already give an idea on their magnitude. It was also shown that slightly increasing the film injection pressure can avoid the reignition phenomena by moving the separation shock towards the nozzle exit section.

  9. Cooling Effect of Water Injection on a High-Temperature Supersonic Jet

    Directory of Open Access Journals (Sweden)

    Jing Li

    2015-11-01

    Full Text Available The high temperature and high pressure supersonic jet is one of the key problems in the design of solid rocket motors. To reduce the jet temperature and noise, cooling water is typically injected into the exhaust plume. Numerical simulations for the gas-liquid multiphase flow field with mixture multiphase model were developed and a series of experiments were carried out. By introducing the energy source terms caused by the vaporization of liquid water into the energy equation, a coupling solution was developed to calculate the multiphase flow field. The temperature data predictions agreed well with the experimental results. When water was injected into the plume, the high temperature core region area was reduced, and the temperature on the head face was much lower than that without water. The relationship between the reduction of temperature on the bottom plate and the momentum ratio is developed, which can be used to predict the cooling effect of water injection in many cases.

  10. Computational and experimental study on supersonic film cooling for liquid rocket nozzle applications

    Directory of Open Access Journals (Sweden)

    Vijayakumar Vishnu

    2015-01-01

    Full Text Available An experimental and computational investigation of supersonic film cooling (SFC was conducted on a subscale model of a rocket engine nozzle. A computational model of a convergent-divergent nozzle was generated, incorporating a secondary injection module for film cooling in the divergent section. Computational Fluid Dynamic (CFD simulations were run on the model and different injection configurations were analyzed. The CFD simulations also analyzed the parameters that influence film cooling effectiveness. Subsequent to the CFD analysis and literature survey an angled injection configuration was found to be more effective, therefore the hardware was fabricated for the same. The fabricated nozzle was later fixed to an Air-Kerosene combustor and numerous sets of experiments were conducted in order to ascertain the effect on film cooling on the nozzle wall. The film coolant employed was gaseous Nitrogen. The results showed substantial cooling along the walls and a considerable reduction in heat transfer from the combustion gas to the wall of the nozzle. Finally the computational model was validated using the experimental results. There was fairly good agreement between the predicted nozzle wall temperature and the value obtained through experiments.

  11. Evolution from a molecular Rydberg gas to an ultracold plasma in a seeded supersonic expansion of NO

    CERN Document Server

    Morrison, J P; Keller, J S; Grant, E R

    2008-01-01

    We report the spontaneous formation of a plasma from a gas of cold Rydberg molecules. Double-resonant laser excitation promotes nitric oxide, cooled to 1 K in a seeded supersonic molecular beam, to single Rydberg states extending as deep as 80 cm$^{-1}$ below the lowest ionization threshold. The density of excited molecules in the illuminated volume is as high as 1 x 10$^{13}$ cm$^{-3}$. This population evolves to produce prompt free electrons and a durable cold plasma of electrons and intact NO$^{+}$ ions.

  12. Pulsed rotating supersonic source used with merged molecular beams

    CERN Document Server

    Sheffield, L; Krasovitskiy, V; Rathnayaka, K D D; Lyuksyutov, I F; Herschbach, D R

    2012-01-01

    We describe a pulsed rotating supersonic beam source, evolved from an ancestral device [M. Gupta and D. Herschbach, J. Phys. Chem. A 105, 1626 (2001)]. The beam emerges from a nozzle near the tip of a hollow rotor which can be spun at high-speed to shift the molecular velocity distribution downward or upward over a wide range. Here we consider mostly the slowing mode. Introducing a pulsed gas inlet system, cryocooling, and a shutter gate eliminated the main handicap of the original device, in which continuous gas flow imposed high background pressure. The new version provides intense pulses, of duration 0.1-0.6 ms (depending on rotor speed) and containing ~10^12 molecules at lab speeds as low as 35 m/s and ~ 10^15 molecules at 400 m/s. Beams of any molecule available as a gas can be slowed (or speeded); e.g., we have produced slow and fast beams of rare gases, O2, Cl2, NO2, NH3, and SF6. For collision experiments, the ability to scan the beam speed by merely adjusting the rotor is especially advantageous when...

  13. Broadband optical cooling of molecular rotors

    CERN Document Server

    Lien, Chien-Yu; Odom, Brian C

    2014-01-01

    Contrary to intuition, resonant laser excitation of bound electrons can decrease the temperature of a system, with electronic relaxation times as fast as nanoseconds allowing for rapid cooling to far below ambient temperature. Although laser cooling of atoms is routine owing to their relatively simple internal structure, laser cooling of molecular translational speeds, vibrations, or rotations is challenging because a different laser frequency is required to electronically excite each populated vibrational and rotational state. Here, we show that molecules with decoupled vibrational and electronic modes can be rotationally cooled using a single spectrally filtered broadband laser to simultaneously address many rotational states. We optically cool AlH$^+$ ions held in a room-temperature radiofrequency Paul trap to collect 96% of the population in the ground quantum state, corresponding to a rotational temperature of 4 K. In our current implementation, parity-preserving electronic cycling cools to the two lowes...

  14. Molecular dynamics computations of two dimensional supersonic rarefied gas flow past blunt bodies

    Science.gov (United States)

    Greber, Isaac; Wachman, Harold Y.; Woo, Myeung-Jouh

    1991-01-01

    This paper presents results of molecular dynamics computations of supersonic flow past a circular cylinder and past a flat plate perpendicular to a supersonic stream. The results are for Mach numbers of approximately 5 and 10, for several Knudsen numbers and several ratios of surface to free stream temperatures. A special feature of the computations is the use of relatively small numbers of particles in the molecular dynamics simulation, and an examination of the adequacy of using small numbers of particles to obtain physically useful results.

  15. Molecular dynamics computations of two dimensional supersonic rarefied gas flow past blunt bodies

    Science.gov (United States)

    Greber, Isaac; Wachman, Harold Y.; Woo, Myeung-Jouh

    1991-01-01

    This paper presents results of molecular dynamics computations of supersonic flow past a circular cylinder and past a flat plate perpendicular to a supersonic stream. The results are for Mach numbers of approximately 5 and 10, for several Knudsen numbers and several ratios of surface to free stream temperatures. A special feature of the computations is the use of relatively small numbers of particles in the molecular dynamics simulation, and an examination of the adequacy of using small numbers of particles to obtain physically useful results.

  16. Broadband Optical Cooling of Molecular Rotors

    Science.gov (United States)

    Lien, Chien-Yu

    Laser cooling of atoms is a widely utilized technique in scientific research, and has been developed over more than three decades. Recently, optically controlling and manipulating the external and internal degrees of freedom of molecules has aroused wide interest in the physics and chemistry communities. However, owing to the more complicated internal structure of molecules, laser cooling of molecules is still underdeveloped. Here we demonstrate cooling the rotation of trapped molecular ions from room temperature to 4 K. The molecule of interest, AlH+, is co-trapped and sympathetically cooled with Ba+ to milliKelvin temperatures in its translational degree of freedom. The nearly diagonal Franck-Condon-Factors between the electronic X and A states of AlH+ create semi-closed cycling transitions between the vibrational ground states of X and A states. A spectrally filtered femtosecond laser is used to optically pump the population to the two lowest rotational levels, with opposite parities, in as little as 100 mus by driving the A-X transition. In addition, a cooling scheme including vibrational relaxation brings the population to the N=0positive-parity level on the order of 100 ms. The population distribution among the rotational levels is detected by resonance-enhanced multiphoton dissociation (REMPD) and time-of-flight mass-spectrometry (TOFMS). This technique opens new avenues to many further studies such as high-precision molecular quantum logic spectroscopy (mQLS) and fundamental constant measurements.

  17. Classical electron ionization mass spectra in gas chromatography/mass spectrometry with supersonic molecular beams.

    Science.gov (United States)

    Gordin, Alexander; Fialkov, Alexander B; Amirav, Aviv

    2008-09-01

    A major benefit of gas chromatography/mass spectrometry (GC/MS) with a supersonic molecular beam (SMB) interface and its fly-through ion source is the ability to obtain electron ionization of vibrationally cold molecules (cold EI), which show enhanced molecular ions. However, GC/MS with an SMB also has the flexibility to perform 'classical EI' mode of operation which provides mass spectra to mimic those in commercial 70 eV electron ionization MS libraries. Classical EI in SMB is obtained through simple reduction of the helium make-up gas flow rate, which reduces the SMB cooling efficiency; hence the vibrational temperatures of the molecules are similar to those in traditional EI ion sources. In classical EI-SMB mode, the relative abundance of the molecular ion can be tuned and, as a result, excellent identification probabilities and very good matching factors to the NIST MS library are obtained. Classical EI-SMB with the fly-through dual cage ion source has analyte sensitivity similar to that of the standard EI ion source of a basic GC/MS system. The fly-through EI ion source in combination with the SMB interface can serve for cold EI, classical EI-SMB, and cluster chemical ionization (CCI) modes of operation, all easily exchangeable through a simple and quick change (not involving hardware). Furthermore, the fly-through ion source eliminates sample scattering from the walls of the ion source, and thus it offers full sample inertness, tailing-free operation, and no ion-molecule reaction interferences. It is also robust and enables increased column flow rate capability without affecting the sensitivity.

  18. Electron ionization LC-MS with supersonic molecular beams--the new concept, benefits and applications.

    Science.gov (United States)

    Seemann, Boaz; Alon, Tal; Tsizin, Svetlana; Fialkov, Alexander B; Amirav, Aviv

    2015-11-01

    A new type of electron ionization LC-MS with supersonic molecular beams (EI-LC-MS with SMB) is described. This system and its operational methods are based on pneumatic spray formation of the LC liquid flow in a heated spray vaporization chamber, full sample thermal vaporization and subsequent electron ionization of vibrationally cold molecules in supersonic molecular beams. The vaporized sample compounds are transferred into a supersonic nozzle via a flow restrictor capillary. Consequently, while the pneumatic spray is formed and vaporized at above atmospheric pressure the supersonic nozzle backing pressure is about 0.15 Bar for the formation of supersonic molecular beams with vibrationally cold sample molecules without cluster formation with the solvent vapor. The sample compounds are ionized in a fly-though EI ion source as vibrationally cold molecules in the SMB, resulting in 'Cold EI' (EI of vibrationally cold molecules) mass spectra that exhibit the standard EI fragments combined with enhanced molecular ions. We evaluated the EI-LC-MS with SMB system and demonstrated its effectiveness in NIST library sample identification which is complemented with the availability of enhanced molecular ions. The EI-LC-MS with SMB system is characterized by linear response of five orders of magnitude and uniform compound independent response including for non-polar compounds. This feature improves sample quantitation that can be approximated without compound specific calibration. Cold EI, like EI, is free from ion suppression and/or enhancement effects (that plague ESI and/or APCI) which facilitate faster LC separation because full separation is not essential. The absence of ion suppression effects enables the exploration of fast flow injection MS-MS as an alternative to lengthy LC-MS analysis. These features are demonstrated in a few examples, and the analysis of the main ingredients of Cannabis on a few Cannabis flower extracts is demonstrated. Finally, the advantages of

  19. High resolution photoelectron spectroscopy and femtosecond intramolecular dynamics using supersonic molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    Niu, B.

    1992-09-01

    High resolution He I[alpha] photoelectron spectroscopy of formaldehyde and ketene and their deuterated compounds, are reported. The combination of a (H2CO) double-pass high-resolution electron-energy analyzer and effective rotational cooling of the sample by supersonic expansion enable the spectroscopy of these molecular cations. The vibrational autocorrelation functions are calculated from the high-resolution photoelectron spectra, shedding light on the ultrafast intramolecular dynamics of the molecular cations. This study reveals much more vibrational structural detail in the first electronic excited state of H2CO cations. The first electronic excited state of H2CO cations may have nonplanar equilibrium geometry. Strong isotope effects on vibronic (vibrational) coupling are observed in the second electronic excited state of H2CO. Vibrational autocorrelation functions are calculated for all four observed electronic states of H2CO. The correlation function of the first electronic excited state of H2CO shows a slow decay rate on the femtosecond time scale. The ultrafast decay of the H2CO cations in the third electronic excited state implies that dissociation and intramolecular processes are the main decay pathways. The present spectra of the ground states of ketene cations have more fine structure than before. The AIEs of the first and fifth excited states are determined unambiguously more accurately. The doublet-like fine structures present in the lint excited state of ketene implies the excitation of a soft'' mode not observed before. The vibrational autocorrelation functions are calculated for 4 of the 6 observed electronic states. The dynamics of the ground states of the cations are characterized by a wave packet oscillating with small amplitude around the minimum on the upper PES. The decay dynamics of the first and the fifth excited states of ketene are characterized by ultra-fast intramolecular processes like predissociation.

  20. High resolution photoelectron spectroscopy and femtosecond intramolecular dynamics using supersonic molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    Niu, B.

    1992-09-01

    High resolution He I{alpha} photoelectron spectroscopy of formaldehyde and ketene and their deuterated compounds, are reported. The combination of a (H2CO) double-pass high-resolution electron-energy analyzer and effective rotational cooling of the sample by supersonic expansion enable the spectroscopy of these molecular cations. The vibrational autocorrelation functions are calculated from the high-resolution photoelectron spectra, shedding light on the ultrafast intramolecular dynamics of the molecular cations. This study reveals much more vibrational structural detail in the first electronic excited state of H2CO cations. The first electronic excited state of H2CO cations may have nonplanar equilibrium geometry. Strong isotope effects on vibronic (vibrational) coupling are observed in the second electronic excited state of H2CO. Vibrational autocorrelation functions are calculated for all four observed electronic states of H2CO. The correlation function of the first electronic excited state of H2CO shows a slow decay rate on the femtosecond time scale. The ultrafast decay of the H2CO cations in the third electronic excited state implies that dissociation and intramolecular processes are the main decay pathways. The present spectra of the ground states of ketene cations have more fine structure than before. The AIEs of the first and fifth excited states are determined unambiguously more accurately. The doublet-like fine structures present in the lint excited state of ketene implies the excitation of a ``soft`` mode not observed before. The vibrational autocorrelation functions are calculated for 4 of the 6 observed electronic states. The dynamics of the ground states of the cations are characterized by a wave packet oscillating with small amplitude around the minimum on the upper PES. The decay dynamics of the first and the fifth excited states of ketene are characterized by ultra-fast intramolecular processes like predissociation.

  1. Fast, high temperature and thermolabile GC--MS in supersonic molecular beams

    Science.gov (United States)

    Dagan, Shai; Amirav, Aviv

    1994-05-01

    This work describes and evaluates the coupling of a fast gas chromatograph (GC) based on a short column and high carrier gas flow rate to a supersonic molecular beam mass spectrometer (MS). A 50 cm long megabore column serves for fast GC separation and connects the injector to the supersonic nozzle source. Sampling is achieved with a conventional syringe based splitless sample injection. The injector contains no septum and is open to the atmosphere. The linear velocity of the carrier gas is controlled by a by-pass (make-up) gas flow introduced after the column and prior to the supersonic nozzle. The supersonic expansion serves as a jet separator and the skimmed supersonic molecular beam (SMB) is highly enriched with the heavier organic molecules. The supersonic molecular beam constituents are ionized either by electron impact (EI) or hyperthermal surface ionization (HSI) and mass analyzed. A 1 s fast GC--MS of four aromatic molecules in methanol is demonstrated and some fundamental aspects of fast GC--MS with time limit constraints are outlined. The flow control (programming) of the speed of analysis is shown and the analysis of thermolabile and relatively non-volatile molecules is demonstrated and discussed. The tail-free, fast GC--MS of several mixtures is shown and peak tailing of caffeine is compared with that of conventional GC--MS. The improvement of the peak shapes with the SMB--MS is analyzed with the respect to the elimination of thermal vacuum chamber background. The extrapolated minimum detected amount was about 400 ag of anthracence-d10, with an elution time which was shorter than 2s. Repetitive injections could be performed within less than 10 s. The fast GC--MS in SMB seems to be ideal for fast target compound analysis even in real world, complex mixtures. The few seconds GC--MS separation and quantification of lead (as tetraethyllead) in gasoline, caffeine in coffee, and codeine in a drug is demonstrated. Controlled HSI selectivity is demonstrated in

  2. Numerical Investigation of Wall Cooling and Suction Effects on Supersonic Flat-Plate Boundary Layer Transition Using Large Eddy Simulation

    Directory of Open Access Journals (Sweden)

    Suozhu Wang

    2015-02-01

    Full Text Available Reducing friction resistance and aerodynamic heating has important engineering significance to improve the performances of super/hypersonic aircraft, so the purpose of transition control and turbulent drag reduction becomes one of the cutting edges in turbulence research. In order to investigate the influences of wall cooling and suction on the transition process and fully developed turbulence, the large eddy simulation of spatially evolving supersonic boundary layer transition over a flat-plate with freestream Mach number 4.5 at different wall temperature and suction intensity is performed in the present work. It is found that the wall cooling and suction are capable of changing the mean velocity profile within the boundary layer and improving the stability of the flow field, thus delaying the onset of the spatial transition process. The transition control will become more effective as the wall temperature decreases, while there is an optimal wall suction intensity under the given conditions. Moreover, the development of large-scale coherent structures can be suppressed effectively via wall cooling, but wall suction has no influence.

  3. Supersonic molecular beam experiments on surface chemical reactions.

    Science.gov (United States)

    Okada, Michio

    2014-10-01

    The interaction of a molecule and a surface is important in various fields, and in particular in complex systems like biomaterials and their related chemistry. However, the detailed understanding of the elementary steps in the surface chemistry, for example, stereodynamics, is still insufficient even for simple model systems. In this Personal Account, I review our recent studies of chemical reactions on single-crystalline Cu and Si surfaces induced by hyperthermal oxygen molecular beams and by oriented molecular beams, respectively. Studies of oxide formation on Cu induced by hyperthermal molecular beams demonstrate a significant role of the translational energy of the incident molecules. The use of hyperthermal molecular beams enables us to open up new chemical reaction paths specific for the hyperthermal energy region, and to develop new methods for the fabrication of thin films. On the other hand, oriented molecular beams also demonstrate the possibility of understanding surface chemical reactions in detail by varying the orientation of the incident molecules. The steric effects found on Si surfaces hint at new ways of material fabrication on Si surfaces. Controlling the initial conditions of incoming molecules is a powerful tool for finely monitoring the elementary step of the surface chemical reactions and creating new materials on surfaces.

  4. A simple counter-flow cooling system for a supersonic free-jet beam source assembly.

    Science.gov (United States)

    Barr, M; Fahy, A; Martens, J; Dastoor, P C

    2016-05-01

    A simple design for an inexpensive, cooled, free-jet beam source is described. The source assembly features an integrated cooling system as supplied by a counter-flow of chilled nitrogen, and is composed primarily of off-the-shelf tube fittings. The design facilitates rapid implementation and eases subsequent alignment with respect to any downstream beamline aperture. The source assembly outlined cools the full length of the stagnation volume, offering temperature control down to 100 K and long-term temperature stability better than ±1 K.

  5. A simple counter-flow cooling system for a supersonic free-jet beam source assembly

    Energy Technology Data Exchange (ETDEWEB)

    Barr, M.; Fahy, A.; Martens, J.; Dastoor, P. C., E-mail: Paul.Dastoor@newcastle.edu.au [Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308 (Australia)

    2016-05-15

    A simple design for an inexpensive, cooled, free-jet beam source is described. The source assembly features an integrated cooling system as supplied by a counter-flow of chilled nitrogen, and is composed primarily of off-the-shelf tube fittings. The design facilitates rapid implementation and eases subsequent alignment with respect to any downstream beamline aperture. The source assembly outlined cools the full length of the stagnation volume, offering temperature control down to 100 K and long-term temperature stability better than ±1 K.

  6. Cooling in the Central Molecular Zone

    Science.gov (United States)

    Ragan, Sarah

    2015-10-01

    The Central Molecular Zone (CMZ) of the Milky Way contains a huge reservoir of molecular gas, and yet its star formation efficiency appears to be significantly lower than expected from standard star formation relations. This suggests that additional physics must be considered in order to understand the regulation of star formation in the CMZ. We propose GREAT observations of the [OI] and [CII] transitions toward two compact clouds residing in the so-called 100 pc ring surrounding the Galactic Centre. These lines are predicted to be the primary coolants of molecular clouds in this harsh environment. Measuring the strength of the [CII] and [OI] line emission produced by the clouds will therefore allow us to constrain their total cooling rate, while the [OI]/[CII] line ratio and the ratio of both lines relative to the measured FIR emission will allow us to constrain the density and temperature of the clouds, and hence the intensity of the cosmic ray ionization rate in their vicinity. We can test models that predict that the CMZ is a unique environment in which oxygen dominates carbon as a coolant. The superb velocity resolution provided by GREAT will also allow us for the first time to study the kinematics of the warm gas in the clouds, which we expect to fill much of their volume. Finally, by comparing clouds at different locations within the 100 pc ring, we will be able to study whether the age of the clouds increases as we move away from Sgr A*, allowing us to test the idea that the formation of the clouds may have been triggered by the tidal influence of the Milky Way's central black hole and nuclear star cluster. These ground-breaking observations are only possible with SOFIA and offer several different pathways to high-impact science.

  7. A low thermal mass fast gas chromatograph and its implementation in fast gas chromatography mass spectrometry with supersonic molecular beams.

    Science.gov (United States)

    Fialkov, Alexander B; Moragn, Mati; Amirav, Aviv

    2011-12-30

    A new type of low thermal mass (LTM) fast gas chromatograph (GC) was designed and operated in combination with gas chromatography mass spectrometry (GC-MS) with supersonic molecular beams (SMB), including GC-MS-MS with SMB, thereby providing a novel combination with unique capabilities. The LTM fast GC is based on a short capillary column inserted inside a stainless steel tube that is resistively heated. It is located and mounted outside the standard GC oven on its available top detector port, while the capillary column is connected as usual to the standard GC injector and supersonic molecular beam interface transfer line. This new type of fast GC-MS with SMB enables less than 1 min full range temperature programming and cooling down analysis cycle time. The operation of the fast GC-MS with SMB was explored and 1 min full analysis cycle time of a mixture of 16 hydrocarbons in the C(10)H(22) up to C(44)H(90) range was achieved. The use of 35 mL/min high column flow rate enabled the elution of C(44)H(90) in less than 45 s while the SMB interface enabled splitless acceptance of this high flow rate and the provision of dominant molecular ions. A novel compound 9-benzylazidanthracene was analyzed for its purity and a synthetic chemistry process was monitored for the optimization of the chemical reaction yield. Biodiesel was analyzed in jet fuel (by both GC-MS and GC-MS-MS) in under 1 min as 5 ppm fatty acid methyl esters. Authentic iprodion and cypermethrin pesticides were analyzed in grapes extract in both full scan mode and fast GC-MS-MS mode in under 1 min cycle time and explosive mixture including TATP, TNT and RDX was analyzed in under 1 min combined with exhibiting dominant molecular ion for TATP. Fast GC-MS with SMB is based on trading GC separation for speed of analysis while enhancing the separation power of the MS via the enhancement of the molecular ion in the electron ionization of cold molecules in the SMB. This paper further discusses several features of

  8. The influence of Laval nozzle throat size on supersonic molecular beam injection

    Institute of Scientific and Technical Information of China (English)

    Xinkui He; Xianfu Feng; Mingmin Zhong; Fujun Gou; Shuiquan Deng; Yong Zhao

    2014-01-01

    In this study, finite element analysis (FEA) has been used to investigate the effects of different Laval nozzle throat sizes on supersonic molecular beam. The simulations indicate the Mach numbers of the molecular stream peak at different positions along the center axis of the beam, which correspond to local minimums of the molecular densities. With the increase of the throat diam-eter, the first peak of the Mach number increases first and then decreases, while that of the molecular number density increases gradually. Moreover, both first peaks shift pro-gressively away from the throat. At the last part, we discuss the possible applications of our FEA approach to solve some crucial problems met in modern transportations.

  9. The very slow expansion of an ultracold plasma formed in a seeded supersonic molecular beam of NO

    CERN Document Server

    Morrison, J P; Grant, E R

    2008-01-01

    The double-resonant laser excitation of nitric oxide, cooled to 1 K in a seeded supersonic molecular beam, yields a gas of $\\approx10^{12}$ molecules cm$^{-3}$ in a single selected Ryberg state. This population evolves to produce prompt free electrons and a durable cold plasma of electrons and intact NO$^{+}$ ions. This plasma travels with the molecular beam through a field free region to encounter a grid. The atomic weight of the expansion gas controls the beam velocity and hence the flight time from the interaction region to the grid. Monitoring electron production as the plasma traverses this grid measures its longitudinal width as a function of flight time. Comparing these widths to the width of the laser beam that defines the initial size of the illuminated volume allows us to gauge the rate of expansion of the plasma. We find that the plasma created from the evolution of a Rydberg gas of NO expands at a small but measurable rate, and that this rate of expansion accords with the Vlasov equations for an i...

  10. Condensed-Phase Mass Fraction in a Supersonic Molecular Beam Containing Clusters

    Science.gov (United States)

    Knuth, Eldon L.; Toennies, J. Peter

    2008-12-01

    For a supersonic molecular beam containing clusters, a relatively general and simple conservation-of-energy procedure for deducing from time-of-flight measurements the fraction of the beam in the condensed phase is developed. The procedure is applied to measurements for 4He beams formed by expansions which approach the two-phase region either near the critical point or to the liquid side of the critical point. The deduced values of the mass fraction are correlated using a scaling parameter which was used previously for correlating mean values of cluster sizes formed via fragmentation in free-jet expansions of liquid 4He.

  11. Experimental Study on Electrostatic Guiding of Supersonic D2O Molecular Beam with Two Charged Wires

    Institute of Scientific and Technical Information of China (English)

    YIN Ya-Ling; XIA Yong; Chen Hai-Bo; YIN Jian-Ping

    2007-01-01

    We demonstrate the guiding of a supersonic heavy-water(D2O)molecular beam using a hollow electrostatic field generated by the combination of two parallel charged-wires and two grounded metal-plates,and report some new and preliminary experimental results.In the experiment,we detect the guiding signals by using the method of time-of-flight mass spectrum and study the dependence of the relative transmission of the beam guide on the guiding voltage.Our study shows that the relative transmission of the beam guide is increased linearly with increasing guiding voltage Vguid,and the number of the guided D2O molecules is at least increased by 89.4%when the guiding voltage is +20.0kV.Finally,some potential applications of our guiding scheme in the molecule optics are briefly discussed.

  12. Suppression of runaway current generation by supersonic molecular beam injection during disruptions on J-TEXT

    Science.gov (United States)

    Huang, D. W.; Chen, Z. Y.; Tong, R. H.; Yan, W.; Wang, S. Y.; Wei, Y. N.; Ma, T. K.; Dai, A. J.; Wang, X. L.; Jiang, Z. H.; Yang, Z. J.; Zhuang, G.; Pan, Y.; J-TEXT Team

    2017-08-01

    The suppression of disruption-generated runaway electrons (REs) by supersonic molecular beam injection (SMBI) has been investigated on the J-TEXT tokamak. Experimental results demonstrate that the hydrogen injected by SMBI during plasma current flattop phase can provoke magnetic perturbations, which increase RE losses rapidly. The effective radial diffusion coefficient of REs due to SMBI is estimated as D r ≈ 16 m2 s-1. Based on this benefit, the SMBI has been used to explore the suppression of disruption-generated REs. In J-TEXT, RE current is created with rapid argon injection by a massive gas injection valve. It is found that hydrogen SMBI before disruption efficiently suppresses the generation of RE current.

  13. Short-range interactions within molecular complexes formed in supersonic beams: structural effects and chiral discrimination

    Science.gov (United States)

    Latini; Satta; Guidoni; Piccirillo; Speranza

    2000-03-17

    One- and two-color, mass-selected R2PI spectra of the S13-pentanol, were recorded after a supersonic molecular beam expansion. Spectral analysis, coupled with theoretical calculations, indicate that several hydrogen-bonded [R.solv] conformers are present in the beam. The R2PI excitation spectra of [R.solv] are characterized by significant shifts of their band origin relative to that of bare R. The extent and direction of these spectral shifts depend on the structure and configuration of solv and are attributed to different short-range interactions in the ground and excited [R.solv] complexes. Measurement of the binding energies of [R.solv] in their neutral and ionic states points to a subtle balance between attractive (electrostatic and dispersive) and repulsive (steric) forces, which control the spectral features of the complexes and allow enantiomeric discrimination of chiral solv molecules.

  14. Radial molecular abundances and gas cooling in starless cores

    CERN Document Server

    Sipilä, O

    2012-01-01

    Aims: We aim to simulate radial profiles of molecular abundances and the gas temperature in cold and heavily shielded starless cores by combining chemical and radiative transfer models. Methods: A determination of the dust temperature in a modified Bonnor-Ebert sphere is used to calculate initial radial molecular abundance profiles. The abundances of selected cooling molecules corresponding to two different core ages are then extracted to determine the gas temperature at two time steps. The calculation is repeated in an iterative process yielding molecular abundances consistent with the gas temperature. Line emission profiles for selected substances are calculated using simulated abundance profiles. Results: The gas temperature is a function of time; the gas heats up as the core gets older because the cooling molecules are depleted onto grain surfaces. The contributions of the various cooling molecules to the total cooling power change with time. Radial chemical abundance profiles are non-trivial: different s...

  15. Rotational Laser Cooling of Vibrationally and Translationally Cold Molecular Ions

    DEFF Research Database (Denmark)

    Drewsen, Michael

    2011-01-01

    by sympathetic cooling with Doppler laser cooled Mg+ ions. Giving the time for the molecules to equilibrate internally to the room temperature blackbody radiation, the vibrational degree of freedom will freeze out, leaving only the rotational degree of freedom to be cooled. We report here on the implementation...... of a new technique for laser-induced rotational ground-state cooling of vibrationally and translationally cold MgH+ ions [10]. The scheme is based on excitation of a single rovibrational transition [11], and it should be generalizable to any diatomic polar molecular ion, given appropriate mid......-infrared laser sources such as a quantum cascade laser are available. In recent experiments, a nearly 15-fold increase in the rotational ground-state population was obtained, with the resulting ground-state population of 36,7±1,2 %, equivalent to that of a thermal distribution at about 20 K. The obtained cooling...

  16. Production and sympathetic cooling of complex molecular ions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chaobo

    2008-06-24

    This thesis reports on experimental and theoretical studies of the sympathetic cooling of complex molecular ions demonstrating that this general method for cooling atomic and molecular ions is reliable and efficient. For this purpose, complex molecular ions and barium ions have been confined simultaneously in a linear Paul trap. The complex molecular ions are generated in an electrospray ionization system and transferred to the trap via a 2 m long octopole ion guide. These molecular ions are pre-cooled by room temperature helium buffer gas so that they can be captured by the trap. The atomic barium ions are loaded from a barium evaporator oven and are laser-cooled by a 493 nm cooling laser and a 650 nm repumping laser. Due to the mutual Coulomb interaction among these charged particles, the kinetic energy of the complex molecular ions can be reduced significantly. In our experiments we have demonstrated the sympathetic cooling of various molecules (CO{sub 2}, Alexa Fluor 350, glycyrrhetinic acid, cytochrome c) covering a wide mass range from a few tens to 13000 amu. In every case the molecular ions could be cooled down to millikelvin temperatures. Photo-chemical reactions of the {sup 138}Ba{sup +} ions in the ({sup 2}P{sub 1/2}) excited state with gases such as O{sub 2}, CO{sub 2}, or N{sub 2}O, could be observed. If the initial {sup 138}Ba{sup +} ion ensemble is cold, the produced {sup 138}BaO{sup +} ions are cold as well, with a similar temperature as the laser-cooled barium ions (a few tens of millikelvin). The back-reaction of {sup 138}BaO{sup +} ions with neutral CO to {sup 138}Ba{sup +} is possible and was observed in our experiments as well. A powerful molecular dynamics (MD) simulation program has been developed. With this program dynamic properties of ion ensembles, such as sympathetic interactions or heating effects, have been investigated and experimental results have been analyzed to obtain, for example, ion numbers and temperatures. Additionally, the

  17. Rotational Laser Cooling of Vibrationally and Translationally Cold Molecular Ions

    DEFF Research Database (Denmark)

    Drewsen, Michael

    2011-01-01

    [7,8,9]. Furthermore, in order to learn more about the chemistry in interstellar clouds, astrochemists can benefit greatly from direct measurements on cold reactions in laboratories [9]. Working with MgH+ molecular ions in a linear Paul trap, we routinely cool their translational degree of freedom...... of a new technique for laser-induced rotational ground-state cooling of vibrationally and translationally cold MgH+ ions [10]. The scheme is based on excitation of a single rovibrational transition [11], and it should be generalizable to any diatomic polar molecular ion, given appropriate mid...

  18. Pulsed supersonic molecular beam for characterization of chemically active metal-organic complexes at surfaces

    Science.gov (United States)

    Lear, Amanda M.

    Metal-organic coordination networks (MOCNs) at surfaces consist of a complex of organic ligands bound to an atomic metal center. The MOCNs, when chosen appropriately, can form highly-ordered arrays at surfaces. Ultra-high vacuum surface studies allow control of surface composition and provide 2D growth restrictions, which lead to under-coordinated metal centers. These systems provide an opportunity to tailor the chemical function of the metal centers due to the steric restrictions imposed by the surface. Tuning the adsorption/desorption energy at a metal center and developing a cooperative environment for catalysis are the key scientific questions that motivate the construction of a molecular beam surface analysis system. Characterization of the created systems can be performed utilizing a pulsed supersonic molecular beam (PSMB) in unison with a quadrupole mass spectrometer. A PSMB allows for the highly controlled delivery of reactants with well-defined energy to a given platform making it possible to elucidate detailed chemical tuning information. In this thesis, a summary of prior theoretical molecular beam derivations is provided. Design considerations and an overview of the construction procedure for the current molecular beam apparatus, including initial characterization experiments, are presented. By impinging an Ar beam on a Ag(111) surface, the location of the specular angle (˜65°) and rough sample perimeter coordinates were determined. Additionally, surface analysis experiments, mainly Auger Electron Spectroscopy (AES), were performed to investigate the oxidation of epitaxial graphene on the SiC(0001) surface utilizing an oxygen cracking method. The AES experiments are described in detail and highlight the challenges that were faced when several different graphene samples were used for the oxygen adsorption/desorption experiments.

  19. Sympathetic cooling of molecular ion motion to the ground state

    CERN Document Server

    Rugango, Rene; Dixon, Thomas H; Gray, John M; Khanyile, Ncamiso; Shu, Gang; Clark, Robert J; Brown, Kenneth R

    2014-01-01

    We demonstrate sympathetic sideband cooling of a $^{40}$CaH$^{+}$ molecular ion co-trapped with a $^{40}$Ca$^{+}$ atomic ion in a linear Paul trap. Both axial modes of the two-ion chain are simultaneously cooled to near the ground state of motion. The center of mass mode is cooled to an average quanta of harmonic motion $\\overline{n}_{\\mathrm{COM}} = 0.13 \\pm 0.03$, corresponding to a temperature of $12.47 \\pm 0.03 ~\\mu$K. The breathing mode is cooled to $\\overline{n}_{\\mathrm{BM}} = 0.05 \\pm 0.02$, corresponding to a temperature of $15.36 \\pm 0.01~\\mu$K.

  20. Rotational laser cooling of vibrationally and translationally cold molecular ions

    DEFF Research Database (Denmark)

    Staanum, Peter; Højbjerre, Klaus; Skyt, Peter Sandegaard

    2010-01-01

    -molecular reactions with coherent light fields 8, 9 , for quantum-state-selected bi-molecular reactions 10, 11, 12 and for astrochemistry 12 . Here, we demonstrate rotational ground-state cooling of vibrationally and translationally cold MgH+ ions, using a laser-cooling scheme based on excitation of a single...... rovibrational transition 13, 14 . A nearly 15-fold increase in the rotational ground-state population of the X  1Σ+ electronic ground-state potential has been obtained. The resulting ground-state population of 36.7±1.2% is equivalent to that of a thermal distribution at about 20 K. The obtained cooling results...

  1. The gas density measurement of one long distance supersonic molecular beam

    Science.gov (United States)

    Liu, D.; Han, J. F.; Chen, Z. Y.; Bai, L. X.; Zhou, J. X.

    2016-12-01

    The gas density of the supersonic molecular beam (SMB) is a crucial parameter for the fueling or diagnostic process in the tokamak experiments. Using the microphone, one improved method of gas density measurement is proposed, which can greatly improve the measurement capacity by about 3 orders of magnitude by studying the pulsed signal characteristic of the microphone when it is pushed by the SMB. The gas density of the SMB is measured within the axial range of 20-2000 mm, and the axial central density at 2000 mm is about 100 times less than that at 20 mm. It is also found that the radial density distribution follows the Gaussian function in both free expansion (where the SMB can expand freely without any influence from the vacuum chamber) and restricted expansion (where the expansion of the SMB is restricted inside the flight tube of the vacuum system). And the axial central density decreases with the axial distance, which follows the inverse square law in the free expansion, but it deviates from this law in the restricted expansion.

  2. Intense Atomic and Molecular Beams via Neon Buffer Gas Cooling

    CERN Document Server

    Patterson, David; Doyle, John M

    2008-01-01

    We realize a continuous guided beam of cold deuterated ammonia with a flux of 3e11 ND3 molecules/s and a continuous free-space beam of cold potassium with a flux of 1e16 K atoms/s. A novel feature of the buffer gas source used to produce these beams is cold neon, which, due to intermediate Knudsen number beam dynamics, produces a forward velocity and low-energy tail that is comparable to much colder helium-based sources. We expect this source to be trivially generalizable to a very wide range of atomic and molecular species with significant vapor pressure below 1000 K. This source has properties that make it a good starting point for laser cooling of molecules or atoms, cold collision studies, trapping, or nonlinear optics in buffer-gas-cooled atomic or molecular gases.

  3. Adiabatic Cooling for Rovibrational Spectroscopy of Molecular Ions

    DEFF Research Database (Denmark)

    Fisher, Karin

    2017-01-01

    The field of cold molecular ions is a fast growing one, with applications in high resolution spectroscopy and metrology, the search for time variations of fundamental constants, cold chemistry and collisions, and quantum information processing, to name a few. The study of single molecular ions...... is attractive as it enables one to push the limits of spectroscopic accuracy. Non-destructive spectroscopic detection of molecular ions can be achieved by co-trapping with an easier to detect atomic ion. The ion chain has coupled motion, and transitions which change both the internal and motional states...... to the measured heating rates, almost perfectly fitting existing heating rate theory. Further, the same model successfully predicted the heating rates of the in-phase mode of a two-ion crystal, indicating that we can use it to predict the heating rates in experiments on molecule-atom chains. Adiabatic cooling...

  4. Non-adiabatic ab initio molecular dynamics of supersonic beam epitaxy of silicon carbide at room temperature.

    Science.gov (United States)

    Taioli, Simone; Garberoglio, Giovanni; Simonucci, Stefano; a Beccara, Silvio; Aversa, Lucrezia; Nardi, Marco; Verucchi, Roberto; Iannotta, Salvatore; Dapor, Maurizio; Alfè, Dario

    2013-01-28

    In this work, we investigate the processes leading to the room-temperature growth of silicon carbide thin films by supersonic molecular beam epitaxy technique. We present experimental data showing that the collision of fullerene on a silicon surface induces strong chemical-physical perturbations and, for sufficient velocity, disruption of molecular bonds, and cage breaking with formation of nanostructures with different stoichiometric character. We show that in these out-of-equilibrium conditions, it is necessary to go beyond the standard implementations of density functional theory, as ab initio methods based on the Born-Oppenheimer approximation fail to capture the excited-state dynamics. In particular, we analyse the Si-C(60) collision within the non-adiabatic nuclear dynamics framework, where stochastic hops occur between adiabatic surfaces calculated with time-dependent density functional theory. This theoretical description of the C(60) impact on the Si surface is in good agreement with our experimental findings.

  5. A cryogenic buffer gas cooled beam of BaH for molecular laser cooling and ultracold fragmentation

    Science.gov (United States)

    Iwata, Geoffrey; Tarallo, Marco G.; Soerensen, Fabian; Zelevinsky, Tanya

    2015-05-01

    Laser cooled and trapped molecules promise many possibilities to explore a variety of fields such as many-body physics, quantum collisions and dissociation, and precision measurement. We report on an experiment for cooling and trapping barium monohydride (BaH) diatomic molecules. We present a cryogenic buffer gas cooling apparatus for producing a 4 K beam of BaH, and describe the laser cooling schemes necessary to load a molecular magneto-optical trap from that beam. Current progress includes identification of the cooling transitions in the BaH B2 Σ molecules and construction of the molecular beam. The large mass ratio of constituent atoms in BaH makes this system attractive for future studies of ultracold fragmentation, potentially resulting in samples of ultracold hydrogen atoms.

  6. GC determination of N-nitrosamines by supersonic molecular beam MS equipped with triple quadrupole analyzer, GC/SMB/QQQ/MS.

    Science.gov (United States)

    Anna, Voloshenko; Rimma, Shelkov; Lev, Ovadia; Jenny, Gun

    2011-01-31

    The determination of 14 N-nitrosamines by a supersonic molecular beam electron ionization mass spectrometer equipped with triple quadruple analyzer, GC/SMB/EI/QQQ/MS is presented. The supersonic molecular beam electron ionization ion source allows the elucidation of the molecular ion of 13 out of the 14 examined nitrosamines (except for diphenylnitrosamine which was degraded before the analysis). It was possible to use the molecular ions of all the nitrosamines as the parent ions for multiple reactions monitoring mode, which in turn allows significant increase of specificity and lowering of the method limit of detection of the higher molecular weight nitrosamines. The instrumental LOD for different N-nitrosamines was 1-5 pg injection(-1). The proposed method was exemplified by analysis of N-nitrosamines and N-nitrosatables in rubber teats according to the British Standard BS EN 12868:1999. Copyright © 2010. Published by Elsevier B.V.

  7. The first results of divertor discharge and supersonic molecular beam injection on the HL-2A tokamak

    Institute of Scientific and Technical Information of China (English)

    Yao Liang-Hua; Yuan Bau-Shan; Feng Bei-Bin; Chen Cheng-Yuan; Hong Wen-Yu; Li Ying-Liang

    2007-01-01

    HL-2A tokamak is the first tokamak with divertors in China. The plasma boundary and the position of the striking point on the target plates of the HL-2A closed divertor were simulated by the current filament code and they were in agreement with the diagnostic results in the divertor. Supersonic molecular beam injection (SMBI) system was first installed and tested on the HL-2A tokamak in 2004. In the present experiment low pressure SMBI fuelling on the HL-2A and during the period of SMB pulse injection into the HL-2A plasma the power density convected at the target plate surfaces was 0.4 times of that before or after the beam injection. It is a useful fuelling method for decreasing the heat load on the neutralizer plates of the divertor.

  8. Modelling Alkali Line Absorption and Molecular Bands in Cool DAZs

    CERN Document Server

    Homeier, D; Allard, F; Hauschildt, P H; Schweitzer, A; Stancil, P C; Weck, P F; Homeier, Derek; Allard, Nicole F.; Allard, France; Hauschildt, Peter H.; Schweitzer, Andreas; Stancil, Phillip C.; Weck, Philippe F.

    2005-01-01

    Two peculiar stars showing an apparent extremely broadened and strong NaI D absorption have been discovered in surveys for cool white dwarfs by Oppenheimer et al. (2001) and Harris et al. (SDSS, 2003). We discuss the nature of these objects using PHOENIX atmosphere models for metal-poor brown dwarfs/very low mass stars, and new white dwarf LTE and NLTE models for hydrogen- and helium-dominated atmospheres with metals. These include complete molecular formation in chemical equilibrium and a model for the alkali resonance line broadening based on the damping profiles of Allard et al. (2003), as well as new molecular line opacities for metal hydrides. First results of our calculations indicate good agreement with a hydrogen-dominated WD atmosphere with a Na abundance roughly consistent with a state of high accretion. We analyse deviations of the abundances of Na, K, Mg and Ca from the cosmic pattern and comment on implications of these results for standard accretion scenarios.

  9. Efficient sympathetic motional ground-state cooling of a molecular ion

    CERN Document Server

    Wan, Yong; Wolf, Fabian; Schmidt, Piet O

    2015-01-01

    Cold molecular ions are promising candidates in various fields ranging from precision spectroscopy and test of fundamental physics to ultra-cold chemistry. Control of internal and external degrees of freedom is a prerequisite for many of these applications. Motional ground state cooling represents the starting point for quantum logic-assisted internal state preparation, detection, and spectroscopy protocols. Robust and fast cooling is crucial to maximize the fraction of time available for the actual experiment. We optimize the cooling rate of ground state cooling schemes for single $^{25}\\mathrm{Mg}^{+}$ ions and sympathetic ground state cooling of $^{24}\\mathrm{MgH}^{+}$. In particular, we show that robust cooling is achieved by combining pulsed Raman sideband cooling with continuous quench cooling. Furthermore, we experimentally demonstrate an efficient strategy for ground state cooling outside the Lamb-Dicke regime.

  10. Vibrational relaxation and vibrational cooling in low temperature molecular crystals

    Science.gov (United States)

    Hill, Jeffrey R.; Chronister, Eric L.; Chang, Ta-Chau; Kim, Hackjin; Postlewaite, Jay C.; Dlott, Dana D.

    1988-01-01

    The processes of vibrational relaxation (VR) and vibrational cooling (VC) are investigated in low temperature crystals of complex molecules, specifically benzene, naphthalene, anthracene, and durene. In the VR process, a vibration is deexcited, while VC consists of many sequential and parallel VR steps which return the crystal to thermal equilibrium. A theoretical model is developed which relates the VR rate to the excess vibrational energy, the molecular structure, and the crystal structure. Specific relations are derived for the vibrational lifetime T1 in each of three regimes of excess vibrational energy. The regimes are the following: Low frequency regime I where VR occurs by emission of two phonons, intermediate frequency regime II where VR occurs by emission of one phonon and one vibration, and high frequency regime III where VR occurs by evolution into a dense bath of vibrational combinations. The VR rate in each regime depends on a particular multiphonon density of states and a few averaged anharmonic coefficients. The appropriate densities of states are calculated from spectroscopic data, and together with available VR data and new infrared and ps Raman data, the values of the anharmonic coefficients are determined for each material. The relationship between these parameters and the material properties is discussed. We then describe VC in a master equation formalism. The transition rate matrix for naphthalene is found using the empirically determined parameters of the above model, and the time dependent redistribution in each mode is calculated.

  11. A simulation of the collapse and fragmentation of cooling molecular clouds

    Science.gov (United States)

    Monaghan, Joe J.; Lattanzio, John C.

    1991-01-01

    The application of the Smoothed Particle Hydrodynamics method to the fragmentation of rotating cloud and disk systems is described, allowing for molecular cooling due to H2 and CO. A novel approach to solving Poisson's equation for disklike structures which exploits the multigrid algorithm is also described. Numerical studies are presented which investigate the evolution of both rotating clouds and Maclaurin disks, in each case with both an isothermal equation of state and with molecular cooling. The results establish the influence of molecular cooling on the fragmentation of molecular clouds. The isothermal sequences, if they fragment at all, do so into far fewer lumps than the cooling sequences. This is not due to a cooling instability as such, but rather to the reduced thermal support. One of the sequences shows a remarkable similarity to the W49A star-forming region.

  12. Reaction dynamics of Si(001) oxidation at room temperature induced by supersonic O sub 2 molecular beams

    CERN Document Server

    Teraoka, Y

    2002-01-01

    Potential energy barriers for dissociative chemisorption of O sub 2 molecules on clean and H sub 2 O-preadsorbed Si(001) surfaces were verified using supersonic O sub 2 molecular beams and synchrotron radiation photoemission spectroscopy. The saturated oxygen amount on both kinds of Si(001) surfaces were measured as a function of incident energy of O sub 2 molecules. The saturated oxygen amount was dependent in both cases on the incident energy. Especially, two energy thresholds appeared in the H sub 2 O-preadsorbed Si(001) surface oxidation. An Si-2p photoemission spectrum for the oxygen-saturated Si(001) surface formed by O sub 2 gas possessing incident energy below the first threshold on the clean surface revealed the oxygen insertion into backbond sites of Si dimers. The dimer backbonds, however, were not oxidized by O sub 2 irradiation without incident energy larger than 1.0 eV in the H sub 2 O-preadsorbed surface. These facts indicate that a chemisorption reaction path of the oxygen insertion into dimer...

  13. SENSITIVE LIMITS ON THE MOLECULAR GAS CONTENT OF CLUSTER COOLING FLOWS

    NARCIS (Netherlands)

    MCNAMARA, BR; JAFFE, W

    1994-01-01

    We have searched for molecular gas toward six cluster cooling flows in the CO(2-1) line using the James Clerk Maxwell Telescope. The sample includes clusters with estimated total cooling rates Of m(CF) approximately 10-600M. yr-1, at redshifts between z approximately 0.01-0.06. None were detected ei

  14. On the evolution of the phase-space distributions of a non-spherical molecular ultracold plasma in a supersonic beam

    Science.gov (United States)

    Schulz-Weiling, Markus; Sadeghi, Hossein; Hung, Jachin; Grant, Edward

    2016-10-01

    This paper offers a toolbox for characterizing the initial conditions and predicting the evolution of the ultracold plasma that forms after resonant laser preparation of a Rydberg gas entrained in a differentially pumped supersonic molecular beam. The conditions afforded by a skimmed free-jet expansion combined with the geometry of laser excitation, determines the phase-space volume of the excited gas. A hydrodynamic shell model, that accounts for the ellipsoidal spatial distribution of this excitation volume in concert with the deforming effects of dissociative recombination, serves to simulate the ambipolar expansion of this molecular ultracold plasma.

  15. Progress towards the laser cooling of the magnesium fluoride molecular beam

    Science.gov (United States)

    Xia, Yong; Dai, Dapeng; Li, Xingjia; Yin, Yanning; Yin, Jianping

    2015-05-01

    Though the laser cooling techniques that have been tremendously successful in producing ultracold atoms are difficult to apply to molecules, in the past few years, a new approach, laser cooling and trapping of diatomic molecules has become possible. We select magnesium fluoride (MgF) as a prototype molecule for laser cooling experiment. In order to compensate the changes of the Doppler shift during the longitudinal slowing of the molecular beam, we theoretically investigate the possibility of stimulated light force deceleration and cooling of the diatomic magnesium fluoride molecular beam with near-cycling transitions in the bichromatic standing light wave of high intensity which estimated by the two-level optical Bloch equations. We also demonstrate a robust and versatile solution for locking the continuous-wave Ti:sapphire tunable laser for applications in laser cooling of molecules which need linewidth-narrowed and frequency-stabilized lasers.

  16. Cluster Effects during High Pressure Supersonic Molecular Beam Injection into Plasma

    Institute of Scientific and Technical Information of China (English)

    YAOLianghua; FENGBeibin; DONGJiafu; LIWenzhong; FENGZhen; HONGWenyu; LIBo

    2001-01-01

    When we speak of clusters, we have in mind entities which have neither the well-defined compositions, geometries, and strong bonds of conventional molecules northe boundary-independent properties of bulk matter. For example, an aggregate of a few atoms held together by Van der Waals forces constitutes a cluster. But clusters need not be weakly bound, several metal atoms bound together also constitute a cluster. Clusters need not be composed of a single kind of chemical entity, either atomic or molecular,

  17. Continuous all-optical deceleration and single-photon cooling of molecular beams

    CERN Document Server

    Jayich, A M; Hummon, M T; Porto, J V; Campbell, W C

    2013-01-01

    Ultracold molecular gases are promising as an avenue to rich many-body physics, quantum chemistry, quantum information, and precision measurements. This richness, which flows from the complex internal structure of molecules, makes the creation of ultracold molecular gases using traditional methods (laser plus evaporative cooling) a challenge, in particular due to the spontaneous decay of molecules into dark states. We propose a way to circumvent this key bottleneck using an all-optical method for decelerating molecules using stimulated absorption and emission with a single ultrafast laser. We further describe single-photon cooling of the decelerating molecules that exploits their high dark state pumping rates, turning the principal obstacle to molecular laser cooling into an advantage. Cooling and deceleration may be applied simultaneously and continuously to load molecules into a trap. We discuss implementation details including multi-level numerical simulations of strontium monohydride (SrH). These techniqu...

  18. BaH molecular spectroscopy with relevance to laser cooling

    Science.gov (United States)

    Tarallo, M. G.; Iwata, G. Z.; Zelevinsky, T.

    2016-03-01

    We describe a simple experimental apparatus for laser ablation of barium monohydride (BaH) molecules and the study of their rovibrational spectra relevant to direct laser cooling. BaH is a promising candidate for laser cooling and ultracold fragmentation, both of which are precursors to novel experiments in many-body physics and precision measurement. We present a detailed analysis of the properties of ablation plumes that can improve the understanding of surface ablation and deposition technologies. A range of absorption spectroscopy and collisional thermalization regimes has been studied. We directly measured the Franck-Condon factor of the B 2Σ+(v'=0 ) ←X 2Σ+(v''=1 ) cycling transition. Prospects for production of a high luminosity cryogenic BaH beam are outlined.

  19. BaH molecular spectroscopy with relevance to laser cooling

    CERN Document Server

    Tarallo, M G; Zelevinsky, T

    2015-01-01

    We describe a simple experimental apparatus for laser ablation of barium monohydride (BaH) molecules and the study of their rovibrational spectra that are relevant to direct laser cooling. We present a detailed analysis of the properties of ablation plumes that can improve the understanding of surface ablation and deposition technologies. A range of absorption spectroscopy and collisional thermalization regimes has been studied. We directly measured the Franck-Condon factor of the $\\mathrm{B}^2\\Sigma^+(v'=0)\\leftarrow\\mathrm{X}^2\\Sigma^+(v"=1)$ transition. Prospects for production of a high luminosity cryogenic BaH beam are outlined. This molecule is a promising candidate for laser cooling and ultracold fragmentation, both of which are precursors to novel experiments in many-body physics and precision measurement.

  20. Supersonic compressor

    Science.gov (United States)

    Roberts, II, William Byron; Lawlor, Shawn P.; Breidenthal, Robert E.

    2016-04-12

    A supersonic compressor including a rotor to deliver a gas at supersonic conditions to a diffuser. The diffuser includes a plurality of aerodynamic ducts that have converging and diverging portions, for deceleration of gas to subsonic conditions and then for expansion of subsonic gas, to change kinetic energy of the gas to static pressure. The aerodynamic ducts include vortex generating structures for controlling boundary layer, and structures for changing the effective contraction ratio to enable starting even when the aerodynamic ducts are designed for high pressure ratios, and structures for boundary layer control. In an embodiment, aerodynamic ducts are provided having an aspect ratio of in excess of two to one, when viewed in cross-section orthogonal to flow direction at an entrance to the aerodynamic duct.

  1. Different Cooling Rate Dependences of Different Microstructure Units in Aluminium Glass by Molecular Dynamics Simulation

    Institute of Scientific and Technical Information of China (English)

    LIU Chang-Song; ZHU Zhen-Gang; XIA Jun-Chao; SUN De-Yan

    2000-01-01

    Constant-pressure molecular dynamics simulation and the pair analysis technique have been performed to study the microstructural evolution of aluminium during rapid solidification. The microstructure characteristics of icosahedral ordering increase with decrease of the cooling rate, whereas the microstructure unit characteristics of hcp crystalline structure decrease. There are two kinds of microstructure units which are similar to those in the fcc crystal containing interstitialcies. These two kinds of microscopic units are nearly independent of the cooling rate. The microscopic structural unit characteristics of fcc crystalline structure do not depend on the cooling rate either. These results may help us understand the microstructure of glass and its stability.

  2. Continuous all-optical deceleration and single-photon cooling of molecular beams

    Science.gov (United States)

    Jayich, A. M.; Vutha, A. C.; Hummon, M. T.; Porto, J. V.; Campbell, W. C.

    2014-02-01

    Ultracold molecular gases are promising as an avenue to rich many-body physics, quantum chemistry, quantum information, and precision measurements. This richness, which flows from the complex internal structure of molecules, makes the creation of ultracold molecular gases using traditional methods (laser plus evaporative cooling) a challenge, in particular due to the spontaneous decay of molecules into dark states. We propose a way to circumvent this key bottleneck using an all-optical method for decelerating molecules using stimulated absorption and emission with a single ultrafast laser. We further describe single-photon cooling of the decelerating molecules that exploits their high dark state pumping rates, turning the principal obstacle to molecular laser cooling into an advantage. Cooling and deceleration may be applied simultaneously and continuously to load molecules into a trap. We discuss implementation details including multilevel numerical simulations of strontium monohydride. These techniques are applicable to a large number of molecular species and atoms with the only requirement being an electric dipole transition that can be accessed with an ultrafast laser.

  3. Development of a molecular-dynamics-based cluster-heat-capacity model for study of homogeneous condensation in supersonic water-vapor expansions.

    Science.gov (United States)

    Borner, Arnaud; Li, Zheng; Levin, Deborah A

    2013-02-14

    Supersonic expansions to vacuum produce clusters of sufficiently small size that properties such as heat capacities and latent heat of evaporation cannot be described by bulk vapor thermodynamic values. In this work the Monte-Carlo Canonical-Ensemble (MCCE) method was used to provide potential energies and constant-volume heat capacities for small water clusters. The cluster structures obtained using the well-known simple point charge model were found to agree well with earlier simulations using more rigorous potentials. The MCCE results were used as the starting point for molecular dynamics simulations of the evaporation rate as a function of cluster temperature and size which were found to agree with unimolecular dissociation theory and classical nucleation theory. The heat capacities and latent heat obtained from the MCCE simulations were used in direct-simulation Monte-Carlo of two experiments that measured Rayleigh scattering and terminal dimer mole fraction of supersonic water-jet expansions. Water-cluster temperature and size were found to be influenced by the use of kinetic rather than thermodynamic heat-capacity and latent-heat values as well as the nucleation model.

  4. Supersonic Dislocation Bursts in Silicon

    Science.gov (United States)

    Hahn, E. N.; Zhao, S.; Bringa, E. M.; Meyers, M. A.

    2016-06-01

    Dislocations are the primary agents of permanent deformation in crystalline solids. Since the theoretical prediction of supersonic dislocations over half a century ago, there is a dearth of experimental evidence supporting their existence. Here we use non-equilibrium molecular dynamics simulations of shocked silicon to reveal transient supersonic partial dislocation motion at approximately 15 km/s, faster than any previous in-silico observation. Homogeneous dislocation nucleation occurs near the shock front and supersonic dislocation motion lasts just fractions of picoseconds before the dislocations catch the shock front and decelerate back to the elastic wave speed. Applying a modified analytical equation for dislocation evolution we successfully predict a dislocation density of 1.5 × 1012 cm-2 within the shocked volume, in agreement with the present simulations and realistic in regards to prior and on-going recovery experiments in silicon.

  5. Cooling rate dependence of solidification for liquid aluminium: a large-scale molecular dynamics simulation study.

    Science.gov (United States)

    Hou, Z Y; Dong, K J; Tian, Z A; Liu, R S; Wang, Z; Wang, J G

    2016-06-29

    The effect of the cooling rate on the solidification process of liquid aluminium is studied using a large-scale molecular dynamics method. It is found that there are various types of short-range order (SRO) structures in the liquid, among which the icosahedral (ICO)-like structures are dominant. These SRO structures are in dynamic fluctuation and transform each other. The effect of the cooling rate on the microstructure is very weak at high temperatures and in supercooled liquids, and it appears only below the liquid-solid transition temperature. Fast cooling rates favour the formation of amorphous structures with ICO-like features, while slow cooling rates favour the formation of FCC crystalline structures. Furthermore, FCC and HCP structures can coexist in crystalline structures. It is also found that nanocrystalline aluminium can be achieved at appropriate cooling rates, and its formation mechanism is thoroughly investigated by tracing the evolution of nanoclusters. The arrangement of FCC and HCP atoms in the nanograins displays various twinned structures as observed using visualization analysis, which is different from the layering or phase separation structures observed in the solidification of Lennard-Jones fluids and some metal liquids.

  6. Comb-assisted cavity ring-down spectroscopy of a buffer-gas-cooled molecular beam.

    Science.gov (United States)

    Santamaria, Luigi; Sarno, Valentina Di; Natale, Paolo De; Rosa, Maurizio De; Inguscio, Massimo; Mosca, Simona; Ricciardi, Iolanda; Calonico, Davide; Levi, Filippo; Maddaloni, Pasquale

    2016-06-22

    We demonstrate continuous-wave cavity ring-down spectroscopy of a partially hydrodynamic molecular beam emerging from a buffer-gas-cooling source. Specifically, the (ν1 + ν3) vibrational overtone band of acetylene (C2H2) around 1.5 μm is accessed using a narrow-linewidth diode laser stabilized against a GPS-disciplined rubidium clock via an optical frequency comb synthesizer. As an example, the absolute frequency of the R(1) component is measured with a fractional accuracy of ∼1 × 10(-9). Our approach represents the first step towards the extension of more sophisticated cavity-enhanced interrogation schemes, including saturated absorption cavity ring-down or two-photon excitation, to buffer-gas-cooled molecular beams.

  7. Molecular Tracers of Turbulent Shocks in Giant Molecular Clouds

    CERN Document Server

    Pon, A; Kaufman, M J

    2012-01-01

    Giant molecular clouds contain supersonic turbulence and simulations of MHD turbulence show that these supersonic motions decay in roughly a crossing time, which is less than the estimated lifetimes of molecular clouds. Such a situation requires a significant release of energy. We run models of C-type shocks propagating into gas with densities around 10^3 cm^(-3) at velocities of a few km / s, appropriate for the ambient conditions inside of a molecular cloud, to determine which species and transitions dominate the cooling and radiative energy release associated with shock cooling of turbulent molecular clouds. We find that these shocks dissipate their energy primarily through CO rotational transitions and by compressing pre-existing magnetic fields. We present model spectra for these shocks and by combining these models with estimates for the rate of turbulent energy dissipation, we show that shock emission should dominate over emission from unshocked gas for mid to high rotational transitions (J >5) of CO. ...

  8. Simulating Supersonic Turbulence in Galaxy Outflows

    CERN Document Server

    Scannapieco, Evan

    2010-01-01

    We present three-dimensional, adaptive mesh simulations of dwarf galaxy out- flows driven by supersonic turbulence. Here we develop a subgrid model to track not only the thermal and bulk velocities of the gas, but also its turbulent velocities and length scales. This allows us to deposit energy from supernovae directly into supersonic turbulence, which acts on scales much larger than a particle mean free path, but much smaller than resolved large-scale flows. Unlike previous approaches, we are able to simulate a starbursting galaxy modeled after NGC 1569, with realistic radiative cooling throughout the simulation. Pockets of hot, diffuse gas around individual OB associations sweep up thick shells of material that persist for long times due to the cooling instability. The overlapping of high-pressure, rarefied regions leads to a collective central outflow that escapes the galaxy by eating away at the exterior gas through turbulent mixing, rather than gathering it into a thin, unstable shell. Supersonic, turbul...

  9. a Continuous Supersonic Expansion Discharge Nozzle for Rotationally Cold Ions

    Science.gov (United States)

    Kauffman, Carrie A.; Crabtree, Kyle N.; McCall, Benjamin J.

    2009-06-01

    Molecular ions play an important role in chemistry and astronomy. In particular, molecular ions are key reaction intermediates, and in the interstellar medium, where temperatures and densities are low, they dominate the chemistry. Studying these ions spectroscopically in the laboratory poses a difficult challenge due to their reactivity. In our effort to study molecular ions, our research group is building SCRIBES (Sensitive Cooled Resolved Ion BEam Spectroscopy), which combines a cold ion source, mass spectrometry, and cavity ring-down spectroscopy. With this apparatus, we will be able to record rotationally-resolved gas-phase spectra, enabling interstellar searches for these species. The SCRIBES instrument requires a source of rotationally cold ions, and this has been accomplished by coupling a supersonic expansion with an electric discharge. Other groups (e.g. Thaddeus and McCarthy at Harvard, Salama et. al at NASA-Ames) have produced cold ions in a similar fashion, but always with a pulsed discharge source. Due to our need for a continuous ion source for SCRIBES, we have designed a continuous supersonic expansion discharge nozzle. We will discuss the various design factors considered during the construction of our continuous self-aligning cold ion source.

  10. The origin of peculiar molecular bands in cool DQ white dwarfs

    Science.gov (United States)

    Kowalski, P. M.

    2010-09-01

    Aims: The DQ white dwarfs are stars whose atmosphere is enriched with carbon, which for cool stars (Teff fluid-like atmospheres of cool DQ white dwarfs. Methods: In our investigation we use a density functional theory based quantum mechanical approach. Results: The electronic transition energy Te increases monotonically with the helium density (ΔTe (eV)~1.6 ρ (g/cm3)). This causes the Swan absorption to occur at shorter wavelengths compared with unperturbed C2. On the other hand the pressure-induced increase in the vibrational frequency is insufficient to account for the observed Swan bands shifts. Our findings are in line with the shape of the distorted molecular bands observed in DQp stars, but the predicted photospheric density required to reproduce these spectral features is one order of magnitude lower than the one predicted by the current models. This indicates pollution by hydrogen or reflects incomplete knowledge of the properties of fluid-like atmospheres of these stars. Conclusions: Our work shows that at the physical conditions encountered in the fluid-like atmospheres of cool DQ white dwarfs the strong interactions between C2 and helium atoms cause an increase in Te, which should produce a blueward shift of the Swan bands. This is consistent with the observations and indicates that the observed Swan-like molecular bands are most likely the pressure-shifted bands of C2.

  11. Pahs, Ionized Gas, and Molecular Hydrogen in Brightest Cluster Galaxies of Cool Core Clusters of Galaxies

    CERN Document Server

    Donahue, Megan; O'Connell, Robert W; Voit, G Mark; Hoffer, Aaron; McNamara, Brian R; Nulsen, Paul E J

    2011-01-01

    We present measurements of 5-25 {\\mu}m emission features of brightest cluster galaxies (BCGs) with strong optical emission lines in a sample of 9 cool-core clusters of galaxies observed with the Infrared Spectrograph on board the Spitzer Space Telescope. These systems provide a view of dusty molecular gas and star formation, surrounded by dense, X-ray emitting intracluster gas. Past work has shown that BCGs in cool-core clusters may host powerful radio sources, luminous optical emission line systems, and excess UV, while BCGs in other clusters never show this activity. In this sample, we detect polycyclic aromatic hydrocarbons (PAHs), extremely luminous, rotationally-excited molecular hydrogen line emission, forbidden line emission from ionized gas ([Ne II] and [Ne III]), and infrared continuum emission from warm dust and cool stars. We show here that these BCGs exhibit more luminous forbidden neon and H2 rotational line emission than star-forming galaxies with similar total infrared luminosities, as well as ...

  12. Efficient stimulated slowing and cooling of the magnesium fluoride molecular beam

    Science.gov (United States)

    Dai, Dapeng; Xia, Yong; Fang, Yinfei; Xu, Liang; Yin, Yanning; Li, Xingjia; Yang, Xiuxiu; Yin, Jianping

    2015-04-01

    We theoretically investigate the possibility of stimulated light force deceleration and cooling of the diatomic magnesium fluoride molecular beam with near-cycling transitions in the bichromatic standing light wave of high intensity. The weighted degeneracy and force reduction factor are considered due to the behavior of the optical bichromatic force (BCF) in near-cycling transitions with internal degeneracies, and the two-level optical Bloch equations can estimate the actual behavior of the BCF. Our simulation shows that the stimulated force exceeding the spontaneous force by a factor of 2.8 can slow down the molecular beam to several m s-1 within centimeter-scale distance, and this slowing mechanism can eliminate the need of compensation of Doppler shift during the longitudinal deceleration of the molecular beam.

  13. The interaction of C60 on Si(111 7x7 studied by Supersonic Molecular Beams: interplay between precursor kinetic energy and substrate temperature in surface activated processes.

    Directory of Open Access Journals (Sweden)

    Lucrezia eAversa

    2015-06-01

    Full Text Available Buckminsterfullerene (C60 is a molecule fully formed of carbon that can be used, owing to its electronic and mechanical properties, as clean precursor for the growth of carbon-based materials, ranging from -conjugated systems (graphenes to synthesized species, e.g. carbides such as silicon carbide (SiC. To this goal, C60 cage rupture is the main physical process that triggers material growth. Cage breaking can be obtained either thermally by heating up the substrate to high temperatures (630°C, after C60 physisorption, or kinetically by using Supersonic Molecular Beam Epitaxy (SuMBE techniques. In this work, aiming at demonstrating the growth of SiC thin films by C60 supersonic beams, we present the experimental investigation of C60 impacts on Si(111 7x7 kept at 500°C for translational kinetic energies ranging from 18 to 30 eV. The attained kinetically activated synthesis of SiC submonolayer films is probed by in-situ surface electron spectroscopies (XPS and UPS. Furthermore, in these experimental conditions the C60-Si(111 7×7 collision has been studied by computer simulations based on a tight-binding approximation to Density Functional Theory, DFT. Our theoretical and experimental findings point towards a kinetically driven growth of SiC on Si, where C60 precursor kinetic energy plays a crucial role, while temperature is relevant only after cage rupture to enhance Si and carbon reactivity. In particular, we observe a counterintuitive effect in which for low kinetic energy (below 22 eV, C60 bounces back without breaking more effectively at high temperature due to energy transfer from excited phonons. At higher kinetic energy (22 < K < 30 eV, for which cage rupture occurs, temperature enhances reactivity without playing a major role in the cage break. These results are in good agreement with ab-initio molecular dynamics simulations. SuMBE is thus a technique able to drive materials growth at low temperature regime.

  14. Molecular Cooling as a Probe of Star Formation: Spitzer Looking Forward to Herschel

    Science.gov (United States)

    Bergin, Edwin A.; Maret, Sebastien; Yuan, Yuan; Sonnentrucker, Paule; Green, Joel D.; Watson, Dan M.; Harwit, Martin O.; Kristensen, Lars E.; Melnick, Gary J.; Tolls, Volker; Werner, Michael W.; Willacy, Karen

    2009-01-01

    We explore here the question of how cloud physics can be more directly probed when one observes the majority of cooling emissions from molecular gas. For this purpose we use results from a recent Spitzer Space Telescope study of the young cluster of embedded objects in NGC1333. For this study we mapped the emission from eight pure H2 rotational lines, from S(0) to S(7). The H2 emission appears to be associated with the warm gas shocked by the multiple outflows present in the region. The H2 lines are found to contribute to 25 - 50% of the total outflow luminosity, and can be used to more directly ascertain the importance of star formation feedback on the natal cloud. From these lines, we determine the outflow mass loss rate and, indirectly, the stellar infall rate, the outflow momentum and the kinetic energy injected into the cloud over the embedded phase. The latter is found to exceed the binding energy of individual cores, suggesting that outflows could be the main mechanism for cores disruption. Given the recent launch of Herschel and the upcoming operational lifetime of SOFIA we discuss how studies of molecular cooling can take a step beyond understanding thermal balance to exploring the origin, receipt, and transfer of energy in atomic and molecular gas in a wide range of physical situations.

  15. Molecular dissociation and shock-induced cooling in fluid nitrogen at high densities and temperatures

    Science.gov (United States)

    Radousky, H. B.; Nellis, W. J.; Ross, M.; Hamilton, D. C.; Mitchell, A. C.

    1986-01-01

    Radiative temperatures and electrical conductivities were measured for fluid nitrogen compressed dynamically to pressures of 18-90 GPa, temperatures of 4000-14,000 K, and densities of 2-3 g/cu cm. The data show a continuous phase transition above 30 GPa shock pressure and confirm that (delta-P/delta-T)v is less than 0, as indicated previously by Hugoniot equation-of-state experiments. The first observation of shock-induced cooling is also reported. The data are interpreted in terms of molecular dissociation, and the concentration of dissociated molecules is calculated as a function of density and temperature.

  16. Evaporative cooling of microscopic water droplets in vacuo: Molecular dynamics simulations and kinetic gas theory.

    Science.gov (United States)

    Schlesinger, Daniel; Sellberg, Jonas A; Nilsson, Anders; Pettersson, Lars G M

    2016-03-28

    In the present study, we investigate the process of evaporative cooling of nanometer-sized droplets in vacuum using molecular dynamics simulations with the TIP4P/2005 water model. The results are compared to the temperature evolution calculated from the Knudsen theory of evaporation which is derived from kinetic gas theory. The calculated and simulation results are found to be in very good agreement for an evaporation coefficient equal to unity. Our results are of interest to experiments utilizing droplet dispensers as well as to cloud micro-physics.

  17. Molecular Dynamics Simulation Studies on the Cooling Process of Polyvinyl Chloride

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    By means of molecular dynamics simulation, the transition of the conformations of polyvinyl chloride during a cooling process from 600 to 300 K was studied. The results show that the amorphous polyvinyl chloride chain experiences the melting state, elastic state and glass state and the conformations can be characterized by the increases of the trans-state of C-C-C-C and the near gauche-state of C-C-C-Cl with the decrease of temperature. It is found that the transition of the conformations is driven mainly by the Coulomb interaction between chain segments.

  18. Dynamical cooling of galactic discs by molecular cloud collisions - origin of giant clumps in gas-rich galaxy discs

    Science.gov (United States)

    Li, Guang-Xing

    2017-10-01

    Different from Milky Way-like galaxies, discs of gas-rich galaxies are clumpy. It is believed that the clumps form because of gravitational instability. However, a necessary condition for gravitational instability to develop is that the disc must dissipate its kinetic energy effectively, this energy dissipation (also called cooling) is not well understood. We propose that collisions (coagulation) between molecular clouds dissipate the kinetic energy of the discs, which leads to a dynamical cooling. The effectiveness of this dynamical cooling is quantified by the dissipation parameter D, which is the ratio between the free-fall time t_ff≈ 1/ √{G ρ _{disc}} and the cooling time determined by the cloud collision process tcool. This ratio is related to the ratio between the mean surface density of the disc Σdisc and the mean surface density of molecular clouds in the disc Σcloud. When D cloud), cloud collision cooling is inefficient, and fragmentation is suppressed. When D > 1/3 (which roughly corresponds to Σdisc > 1/3Σcloud), cloud-cloud collisions lead to a rapid cooling through which clumps form. On smaller scales, cloud-cloud collisions can drive molecular cloud turbulence. This dynamical cooling process can be taken into account in numerical simulations as a sub-grid model to simulate the global evolution of disc galaxies.

  19. Theory of vibrational cooling in molecular crystals: Application to crystalline naphthalene

    Science.gov (United States)

    Hill, Jeffrey R.; Dlott, Dana D.

    1988-07-01

    The process of vibrational cooling (VC) is theoretically investigated in the molecular crystal naphthalene. Specificially we consider the process where a highly excited vibration cools by emitting lower energy vibrations (vibrational relaxation, or VR) and phonons. We also consider the subsequent cooling of emitted optic phonons by emission of acoustic phonons. Using previously determined vibrational lifetimes [J. R. Hill et al., J. Chem. Phys. 88, 949 (1988)], a consistent transition rate matrix is obtained which describes VR of all vibrations and optic phonons at all temperatures. Then a Master equation is solved numerically to obtain the time dependent vibrational populations of all states following impulse excitation of a high frequency vibration. These results are compared to a previously derived analytic model for VC in molecular crystals [J. R. Hill and D. D. Dlott, J. Chem. Phys. 89, 830 (1988)]. In that theory, which is shown to be in good agreement with the naphthalene calculation, the excess vibrational excitation moves to lower energy states and broadens as time increases. The motion toward lower energy states is described by a temperature independent ``vibrational velocity'' (emitted energy per unit time). In naphthalene, the vibrational velocity is V0 ≊9 cm-1 /ps. The VC process occurs on a time scale as much as an order of magnitude longer than an individual VR step. Although VR is highly temperature dependent, VC is not. The VC calculations are used to predict the decay from the initial state, the time dependent populations of transient vibrational excitations, and the return to the vibrationless ground state. All these quantities are directly related to experimental observables such as incoherent anti-Stokes Raman scattering and hot luminescence.

  20. On supersonic combustion

    Institute of Scientific and Technical Information of China (English)

    袁生学

    1999-01-01

    Some basic concepts and features of supersonic combustion are explained from the view point of macroscopic aerodynamics. Two kinds of interpretations of supersonic combustion are proposed. The difference between supersonic combustion and subsonic combustion is discussed, and the mechanism of supersonic combustion propagation and the limitation of heat addition in supersonic flow are pointed out. The results of the calculation of deflagration in supersonic flow show that the entropy increment and the total pressure loss of the combustion products may decrease with the increase of combustion velocity. It is also demonstrated that the oblique detonation wave angle may not be controlled by the wedge angle under weak underdriven solution conditions and be determined only by combustion velocity. Therefore, the weak underdriven solution may become self-sustaining oblique detonation waves with a constant wave angle.

  1. Supersonic combustion engine testbed, heat lightning

    Science.gov (United States)

    Hoying, D.; Kelble, C.; Langenbahn, A.; Stahl, M.; Tincher, M.; Walsh, M.; Wisler, S.

    1990-01-01

    The design of a supersonic combustion engine testbed (SCET) aircraft is presented. The hypersonic waverider will utilize both supersonic combustion ramjet (SCRAMjet) and turbofan-ramjet engines. The waverider concept, system integration, electrical power, weight analysis, cockpit, landing skids, and configuration modeling are addressed in the configuration considerations. The subsonic, supersonic and hypersonic aerodynamics are presented along with the aerodynamic stability and landing analysis of the aircraft. The propulsion design considerations include: engine selection, turbofan ramjet inlets, SCRAMjet inlets and the SCRAMjet diffuser. The cooling requirements and system are covered along with the topics of materials and the hydrogen fuel tanks and insulation system. A cost analysis is presented and the appendices include: information about the subsonic wind tunnel test, shock expansion calculations, and an aerodynamic heat flux program.

  2. Tesseract supersonic business transport

    Science.gov (United States)

    Reshotko, Eli; Garbinski, Gary; Fellenstein, James; Botting, Mary; Hooper, Joan; Ryan, Michael; Struk, Peter; Taggart, Ben; Taillon, Maggie; Warzynski, Gary

    1992-01-01

    This year, the senior level Aerospace Design class at Case Western Reserve University developed a conceptual design of a supersonic business transport. Due to the growing trade between Asia and the United States, a transpacific range was chosen for the aircraft. A Mach number of 2.2 was chosen, too, because it provides reasonable block times and allows the use of a large range of materials without a need for active cooling. A payload of 2,500 lbs. was assumed corresponding to a complement of nine passengers and crew, plus some light cargo. With these general requirements set, the class was broken down into three groups. The aerodynamics of the aircraft were the responsibility of the first group. The second developed the propulsion system. The efforts of both the aerodynamics and propulsion groups were monitored and reviewed for weight considerations and structural feasibility by the third group. Integration of the design required considerable interaction between the groups in the final stages. The fuselage length of the final conceptual design was 107.0 ft, while the diameter of the fuselage was 7.6 ft. The delta wing design consisted of an aspect ratio of 1.9 with a wing span of 47.75 ft and mid-chord length of 61.0 ft. A SNECMA MCV 99 variable-cycle engine design was chosen for this aircraft.

  3. Tesseract: Supersonic business transport

    Science.gov (United States)

    Reshotko, Eli; Garbinski, Gary

    1992-01-01

    This year, the senior level Aerospace Design class at Case Western Reserve University developed a conceptual design of a supersonic business transport. Due to the growing trade between Asia and the United States, a transpacific range has been chosen for the aircraft. A Mach number of 2.2 was chosen too because it provides reasonable block times and allows the use of a large range of materials without a need for active cooling. A payload of 2500 lbs. has been assumed corresponding to a complement of nine (passengers and crew) plus some light cargo. With these general requirements set, the class was broken down into three groups. The aerodynamics of the aircraft were the responsibility of the first group. The second developed the propulsion system. The efforts of both the aerodynamics and propulsion groups were monitored and reviewed for weight considerations and structural feasibility by the third group. Integration of the design required considerable interaction between the groups in the final stages. The fuselage length of the final conceptual design was 107.0 ft. while the diameter of the fuselage was 7.6 ft. The delta wing design consisted of an aspect ratio of 1.9 with a wing span of 47.75 ft and midcord length of 61.0 ft. A SNEMCA MCV 99 variable-cycle engine design was chosen for this aircraft.

  4. Interaction of a supersonic NO beam with static and resonant RF fields: Simple theoretical model to account for molecular interferences

    Science.gov (United States)

    Ureña, A. González; Caceres, J. O.; Morato, M.

    2006-09-01

    In previous experimental works from this laboratory two unexpected phenomena were reported: (i) a depletion of ca. 40% in the total intensity of a pulsed He seeded NO beam when these molecules passed a homogeneous and a resonant oscillating RF electric field and (ii) a beam splitting of ca. 0.5° when the transverse beam profile is measured, under the same experimental conditions. In this work a model based on molecular beam interferences is introduced which satisfactorily accounts for these two observations. It is shown how the experimental set-up a simple device used as C-field in early molecular beam electric resonance experiments, can be employed as molecular interferometer to investigate matter-wave interferences in beams of polar molecules.

  5. Molecular Dynamics Simulations of Aqueous and Confined Systems Relevant to the Supercritical Water Cooled Nuclear Reactor

    Science.gov (United States)

    Kallikragas, Dimitrios Theofanis

    Supercritical water (SCW) is the intended heat transfer fluid and potential neutron moderator in the proposed GEN-IV Supercritical Water Cooled Reactor (SCWR). The oxidative environment poses challenges in choosing appropriate design materials, and the behaviour of SCW within crevices of the passivation layer is needed for developing a corrosion control strategy to minimize corrosion. Molecular Dynamics simulations have been employed to obtain diffusion coefficients, coordination number and surface density characteristics, of water and chloride in nanometer-spaced iron hydroxide surfaces. Diffusion models for hydrazine are evaluated along with hydration data. Results demonstrate that water is more likely to accumulate on the surface at low density conditions. The effect of confinement on the water structure diminishes as the gap size increases. The diffusion coefficient of chloride decreases with larger surface spacing. Clustering of water at the surface implies that the SCWR will be most susceptible to pitting corrosion and stress corrosion cracking.

  6. Laser cooling of new atomic and molecular species with ultrafast pulses

    OpenAIRE

    Kielpinski, David

    2005-01-01

    We propose a new laser cooling method for atomic species whose level structure makes traditional laser cooling difficult. For instance, laser cooling of hydrogen requires single-frequency vacuum-ultraviolet light, while multielectron atoms need single-frequency light at many widely separated frequencies. These restrictions can be eased by laser cooling on two-photon transitions with ultrafast pulse trains. Laser cooling of hydrogen, antihydrogen, and many other species appears feasible, and e...

  7. Physical fundaments of supersonic molecular beams; Fondamenti fisici dei fasci molecolari supersonici. Parte 7: Il getto libero supersonico

    Energy Technology Data Exchange (ETDEWEB)

    Tomassetti, G. [L' Aquila Univ., L' Aquila (Italy). Dipt. di Fisica; Sanna, G.

    1999-07-01

    The structure of the free jet emitted by a converging nozzle as obtained by the method of characteristics by Ashkenas and Sherman is described in details. In particular the dependence of the field variable by the distance from the nozzle is given. The transition from continuum to molecular free regime is then considered and the sudden freeze approximation is introduced. The processing of monoatomic and polyatomic gasses is also considered. [Italian] Le caratteristiche del campo di flusso in regime continuo di un getto libero supersonico ottenute col metodo delle caratteristiche da Askenas e Sherman sono messe in evidenza. In particolare le relazioni analitiche per i parametri di flusso in funzione della distanza dal nozzle sono riportate. Viene poi considerata la transazione al regime molecolare ed e' introdotta la sudden freeze approximation. Vengono anche considerate le situazioni di non equilibrio tra gradi di liberta' interni ed esterni.

  8. Supersonic free jet, molecular free regime; Fondamenti fisici dei fasci molecolari supersonici. Parte 7. Il getto libero supersonico

    Energy Technology Data Exchange (ETDEWEB)

    Sanna, G. [ENEA, Centro Ricerche Frascati, Rome (Italy). Dipt. Innovazione; Tomassetti, G. [L' Aquila Univ., L' Aquila (Italy). Dipt. di Fisica

    1999-07-01

    The structure of the free jet emitted by a converging nozzle as obtained by the method of characteristics by Ashkenas e Sherman is described in details. In particular the dependence of the field variable by the distance from the nozzle is given. The transition from continuum to molecular free regime is then considered and the sudden freeze approximation is introduced. The processing of monoatomic and polyatomic gasses is also considered. [Italian] Le caratteristiche del campo di flusso in regime continuo di un getto libero supersonico ottenute col metodo delle caratteristiche da Ashekanas e Sherman sono messe in evidenza. In paricolare le relazioni analitiche per i parametri di flusso in funzione della distanza dal nozzle sono riportate. Viene poi considerata la transizione al regime molecolare ed e' introdotta la sudden freeze approximation. Vengono anche considerate le situazioni di non equilibrio tra gradi di liberta' interni ed esterni.

  9. The Cool ISM in S0 Galaxies. I. A Survey of Molecular Gas

    CERN Document Server

    Welch, G A; Welch, Gary A.; Sage, Leslie J.

    2003-01-01

    Lenticular galaxies remain remarkably mysterious as a class. Observations to date have not led to any broad consensus about their origins, properties and evolution, though they are often thought to have formed in one big burst of star formation early in the history of the Universe, and to have evolved relatively passively since then. In that picture, current theory predicts that stellar evolution returns substantial quantities of gas to the interstellar medium; most is ejected from the galaxy, but significant amounts of cool gas might be retained. Past searches for that material, though, have provided unclear results. We present results from a survey of molecular gas in a volume-limited sample of field S0 galaxies, selected from the Nearby Galaxies Catalog. CO emission is detected from 78 percent of the sample galaxies. We find that the molecular gas is almost always located inside the central few kiloparses of a lenticular galaxy, meaning that in general it is more centrally concentrated than in spirals. We ...

  10. Dielectric barrier discharge source for supersonic beams

    Energy Technology Data Exchange (ETDEWEB)

    Luria, K.; Lavie, N.; Even, U. [Sackler School of Chemistry, Tel Aviv University, Tel Aviv 69978 (Israel)

    2009-10-15

    We present a new excitation source for pulsed supersonic beams. The excitation is based on dielectric barrier discharge in the beam. It produces cold beams of metastable atoms, dissociated neutral atoms from molecular precursors, and both positive and negative ions with high efficiency and reliability.

  11. Molecular fountain.

    Energy Technology Data Exchange (ETDEWEB)

    Strecker, Kevin E.; Chandler, David W.

    2009-09-01

    A molecular fountain directs slowly moving molecules against gravity to further slow them to translational energies that they can be trapped and studied. If the molecules are initially slow enough they will return some time later to the position from which they were launched. Because this round trip time can be on the order of a second a single molecule can be observed for times sufficient to perform Hz level spectroscopy. The goal of this LDRD proposal was to construct a novel Molecular Fountain apparatus capable of producing dilute samples of molecules at near zero temperatures in well-defined user-selectable, quantum states. The slowly moving molecules used in this research are produced by the previously developed Kinematic Cooling technique, which uses a crossed atomic and molecular beam apparatus to generate single rotational level molecular samples moving slowly in the laboratory reference frame. The Kinematic Cooling technique produces cold molecules from a supersonic molecular beam via single collisions with a supersonic atomic beam. A single collision of an atom with a molecule occurring at the correct energy and relative velocity can cause a small fraction of the molecules to move very slowly vertically against gravity in the laboratory. These slowly moving molecules are captured by an electrostatic hexapole guiding field that both orients and focuses the molecules. The molecules are focused into the ionization region of a time-of-flight mass spectrometer and are ionized by laser radiation. The new molecular fountain apparatus was built utilizing a new design for molecular beam apparatus that has allowed us to miniaturize the apparatus. This new design minimizes the volumes and surface area of the machine allowing smaller pumps to maintain the necessary background pressures needed for these experiments.

  12. Supersonic unstalled flutter

    Science.gov (United States)

    Adamczyk, J. J.; Goldstein, M. E.; Hartmann, M. J.

    1978-01-01

    Recently two flutter analyses have been developed at NASA Lewis Research Center to predict the onset of supersonic unstalled flutter of a cascade of two-dimensional airfoils. The first of these analyzes the onset of supersonic flutter at low levels of aerodynamic loading (i.e., backpressure), while the second examines the occurrence of supersonic flutter at moderate levels of aerodynamic loading. Both of these analyses are based on the linearized unsteady inviscid equations of gas dynamics to model the flow field surrounding the cascade. The details of the development of the solution to each of these models have been published. The objective of the present paper is to utilize these analyses in a parametric study to show the effects of cascade geometry, inlet Mach number, and backpressure on the onset of single and multi degree of freedom unstalled supersonic flutter. Several of the results from this study are correlated against experimental qualitative observation to validate the models.

  13. Structural evolution of Ti50Cu50 on rapid cooling by molecular dynamics simulation

    Science.gov (United States)

    Pang, J. J.; Tan, M. J.; Liew, K. M.

    2012-03-01

    The structural evolution and atomic structure of the Ti50Cu50 compound have been investigated by means of molecular dynamics simulation using the generalized embedded-atom model (GEAM) potential. Gibbs free energy calculation manifests the large driving force of undercooled Ti50Cu50 for crystallization and thus the poor glass-forming ability. Radial distribution functions (RDFs) within the temperature range from 2000 K to 300 K are analyzed and reveal the increasing degree of short-range order and reducing periodic length between peaks on cooling. Atomic arrangement is characterized by the Voronoi tessellation method, showing that the frequency of icosahedral configurations is most sensitive to temperature and grows upon quenching while that of the others remains relatively stable. The thermal behavior of the structure factors follows the Debye model up to the supercooled liquid temperature. The structural investigation of amorphous Ti50Cu50 demonstrates that there exist a variety of polyhedral configurations in Ti50Cu50 amorphous alloy, where icosahedral and bcc clusters are the major types. Due to the existence of bcc clusters and the other distorted polyhedra other than full icosahedra, the structural analysis reconfirms the inference from the Gibbs free energy calculation.

  14. Two-color resonance photoionization spectrum of nickelocene in a supersonic jet

    Science.gov (United States)

    Ketkov, S. Yu.; Selzle, H. L.; Schlag, E. W.; Titova, S. N.; Kalakutskaya, L. V.

    2004-10-01

    Two-color photoionization of nickelocene molecules cooled in a supersonic jet is performed using a tunable nanosecond pulsed laser. The first stage of the multiphoton excitation is the transition from the highest occupied molecular orbital of nickelocene to the lowest Rydberg level. Conditions are found under which molecular ions (η 5-C5H5)2Ni+ are the only product of the multiphoton ionization in the one-color experiment. Irradiation of an excited molecule by an intense pulse of another laser increases significantly the yield of molecular ions. The dependence of the yield of (η5-C5H5)2Ni+ ions on the frequency of the second laser makes it possible to determine the adiabatic ionization potential of nickelocene as 6.138±0.012eV.

  15. Molecular relaxation in supersonic free jets of N2 and CH4 from stimulated Raman spectroscopy and time-of-flight measurements

    OpenAIRE

    Abad, Laura; Bermejo, Dionisio; Herrero, Víctor J.; Santos, J.; Tanarro, Isabel

    1997-01-01

    The relaxation of the energy stored in the translational and rotational degrees of freedom of N2 and CH4 in the course of free jet expansions has been experimentally studied. Rotational temperatures along the expansion axis were obtained by means of stimulated Raman spectroscopy, and terminal flow velocities and translational temperatures were determined from supersonic beam time-of-flight measurements. From these measurements low-temperature cross sections for rotational relaxation have been...

  16. Supersonic Motions of Galaxies in Clusters

    CERN Document Server

    Faltenbacher, A; Nagai, D; Gottlöber, S; Faltenbacher, Andreas; Kravtsov, Andrey V.; Nagai, Daisuke; Gottloeber, Stefan

    2004-01-01

    We study motions of galaxies in galaxy clusters formed in the concordance LCDM cosmology. We use high-resolution cosmological simulations that follow dynamics of dark matter and gas and include various physical processes critical for galaxy formation: gas cooling, heating and star formation. Analysing motions of galaxies and the properties of intracluster gas in the sample of eight simulated clusters at z=0, we study velocity dispersion profiles of the dark matter, gas, and galaxies. We measure the mean velocity of galaxy motions and gas sound speed as a function of radius and calculate the average Mach number of galaxy motions. The simulations show that galaxies, on average, move supersonically with the average Mach number of ~1.4, approximately independent of the cluster-centric radius. The supersonic motions of galaxies may potentially provide an important source of heating for the intracluster gas by driving weak shocks and via dynamical friction, although these heating processes appear to be inefficient ...

  17. Molecular dynamics study on the solvent dependent heme cooling following ligand photolysis in carbonmonoxy myoglobin.

    Science.gov (United States)

    Zhang, Yong; Fujisaki, Hiroshi; Straub, John E

    2007-03-29

    The time scale and mechanism of vibrational energy relaxation of the heme moiety in myoglobin was studied using molecular dynamics simulation. Five different solvent models, including normal water, heavy water, normal glycerol, deuterated glycerol and a nonpolar solvent, and two forms of the heme, one native and one lacking acidic side chains, were studied. Structural alteration of the protein was observed in native myoglobin glycerol solution and native myoglobin water solution. The single-exponential decay of the excess kinetic energy of the heme following ligand photolysis was observed in all systems studied. The relaxation rate depends on the solvent used. However, this dependence cannot be explained using bulk transport properties of the solvent including macroscopic thermal diffusion. The rate and mechanism of heme cooling depends upon the detailed microscopic interaction between the heme and solvent. Three intermolecular energy transfer mechanisms were considered: (i) energy transfer mediated by hydrogen bonds, (ii) direct vibration-vibration energy transfer via resonant interaction, and (iii) energy transfer via vibration-translation or vibration-rotation interaction, or in other words, thermal collision. The hydrogen bond interaction and vibration-vibration interaction between the heme and solvent molecules dominates the energy transfer in native myoglobin aqueous solution and native myoglobin glycerol solutions. For modified myoglobin, the vibration-vibration interaction is also effective in glycerol solution, different from aqueous solution. Thermal collisions form the dominant energy transfer pathway for modified myoglobin in water solution, and for both native myoglobin and modified myoglobin in a nonpolar environment. For native myoglobin in a nonpolar solvent solution, hydrogen bonds between heme isopropionate side chains and nearby protein residues, absent in the modified myoglobin nonpolar solvent solution, are key interactions influencing the

  18. COOL: A code for Dynamic Monte Carlo Simulation of molecular dynamics

    Science.gov (United States)

    Barletta, Paolo

    2012-02-01

    Cool is a program to simulate evaporative and sympathetic cooling for a mixture of two gases co-trapped in an harmonic potential. The collisions involved are assumed to be exclusively elastic, and losses are due to evaporation from the trap. Each particle is followed individually in its trajectory, consequently properties such as spatial densities or energy distributions can be readily evaluated. The code can be used sequentially, by employing one output as input for another run. The code can be easily generalised to describe more complicated processes, such as the inclusion of inelastic collisions, or the possible presence of more than two species in the trap. New version program summaryProgram title: COOL Catalogue identifier: AEHJ_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHJ_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 1 097 733 No. of bytes in distributed program, including test data, etc.: 18 425 722 Distribution format: tar.gz Programming language: C++ Computer: Desktop Operating system: Linux RAM: 500 Mbytes Classification: 16.7, 23 Catalogue identifier of previous version: AEHJ_v1_0 Journal reference of previous version: Comput. Phys. Comm. 182 (2011) 388 Does the new version supersede the previous version?: Yes Nature of problem: Simulation of the sympathetic process occurring for two molecular gases co-trapped in a deep optical trap. Solution method: The Direct Simulation Monte Carlo method exploits the decoupling, over a short time period, of the inter-particle interaction from the trapping potential. The particle dynamics is thus exclusively driven by the external optical field. The rare inter-particle collisions are considered with an acceptance/rejection mechanism, that is, by comparing a random number to the collisional probability

  19. Supersonic flows over cavities

    Institute of Scientific and Technical Information of China (English)

    Tianwen FANG; Meng DING; Jin ZHOU

    2008-01-01

    The characteristics of supersonic cold flows over cavities were investigated experimentally and numer-ically, and the effects of cavities of different sizes on super-sonic flow field were analyzed. The results indicate that the ratio of length to depth L/D within the range of 5-9 has little relevance to integral structures of cavity flow. The bevel angle of the rear wall does not alter the overall structure of the cavity flow within the range of 30°-60°, but it can exert obvious effect on the evolvement of shear layer and vortexes in cavities.

  20. Laser cooling of a diatomic molecule.

    Science.gov (United States)

    Shuman, E S; Barry, J F; Demille, D

    2010-10-14

    It has been roughly three decades since laser cooling techniques produced ultracold atoms, leading to rapid advances in a wide array of fields. Laser cooling has not yet been extended to molecules because of their complex internal structure. However, this complexity makes molecules potentially useful for a wide range of applications. For example, heteronuclear molecules possess permanent electric dipole moments that lead to long-range, tunable, anisotropic dipole-dipole interactions. The combination of the dipole-dipole interaction and the precise control over molecular degrees of freedom possible at ultracold temperatures makes ultracold molecules attractive candidates for use in quantum simulations of condensed-matter systems and in quantum computation. Also, ultracold molecules could provide unique opportunities for studying chemical dynamics and for tests of fundamental symmetries. Here we experimentally demonstrate laser cooling of the polar molecule strontium monofluoride (SrF). Using an optical cycling scheme requiring only three lasers, we have observed both Sisyphus and Doppler cooling forces that reduce the transverse temperature of a SrF molecular beam substantially, to a few millikelvin or less. At present, the only technique for producing ultracold molecules is to bind together ultracold alkali atoms through Feshbach resonance or photoassociation. However, proposed applications for ultracold molecules require a variety of molecular energy-level structures (for example unpaired electronic spin, Omega doublets and so on). Our method provides an alternative route to ultracold molecules. In particular, it bridges the gap between ultracold (submillikelvin) temperatures and the ∼1-K temperatures attainable with directly cooled molecules (for example with cryogenic buffer-gas cooling or decelerated supersonic beams). Ultimately, our technique should allow the production of large samples of molecules at ultracold temperatures for species that are chemically

  1. Cold molecular gas in the Perseus cluster core - Association with X-ray cavity, Halpha filaments and cooling flow -

    CERN Document Server

    Salomé, P; Crawford, C; Edge, A C; Erlund, M; Fabian, A C; Hatch, N A; Johnstone, R M; Sanders, J S; Wilman, R J

    2006-01-01

    Cold molecular gas has been recently detected in several cooling flow clusters of galaxies where huge optical nebulosities often stand. These optical filaments are tightly linked to the cooling flow and to the related phenomena, like the rising bubbles of relativistic plasma, fed by the radio jets. We present here a map in the CO(2-1) rotational line of the cold molecular gas associated with some Halpha filaments surrounding the central galaxy of the Perseus cluster: NGC 1275. The map, extending to about 50 kpc (135 arcsec) from the center of the galaxy, has been made with the 18-receiver array HERA, at the focus of the IRAM 30m telescope. Although most of the cold gas is concentrated to the center of the galaxy, the CO emission is also clearly associated to the extended filaments conspicuous in ionised gas and could trace a possible reservoir fueling the star formation there. Some of the CO emission is also found where the X-ray gas could cool down more efficiently: at the rims of the central X-ray cavity (w...

  2. Infinitesimal Conical Supersonic Flow

    Science.gov (United States)

    Busemann, Adolf

    1947-01-01

    The calculation of infinitesimal conical supersonic flow has been applied first to the simplest examples that have also been calculated in another way. Except for the discovery of a miscalculation in an older report, there was found the expected conformity. The new method of calculation is limited more definitely to the conical case.

  3. Chirped Pulse Microwave Spectroscopy in Pulsed Uniform Supersonic Flows

    Science.gov (United States)

    Abeysekera, Chamara; Oldham, James; Prozument, Kirill; Joalland, Baptiste; Park, Barratt; Field, Robert W.; Sims, Ian; Suits, Arthur; Zack, Lindsay

    2014-06-01

    We present preliminary results describing the development of a new instrument that combines two powerful techniques: Chirped Pulse-Fourier Transform MicroWave (CP-FTMW) spectroscopy and pulsed uniform supersonic flows. It promises a nearly universal detection method that can deliver quantitative isomer, conformer, and vibrational level specific detection, characterization of unstable reaction products and intermediates and perform unique spectroscopic, kinetics and dynamics measurements. We have constructed a new high-power K_a-band, 26-40 GHz, chirped pulse spectrometer with sub-MHz resolution, analogous to the revolutionary CP-FTMW spectroscopic technique developed in the Pate group at University of Virginia. In order to study smaller molecules, the E-band, 60-90 GHz, CP capability was added to our spectrometer. A novel strategy for generating uniform supersonic flow through a Laval nozzle is introduced. High throughput pulsed piezo-valve is used to produce cold (30 K) uniform flow with large volumes of 150 cm^3 and densities of 1014 molecules/cm3 with modest pumping facilities. The uniform flow conditions for a variety of noble gases extend as far as 20 cm from the Laval nozzle and a single compound turbo-molecular pump maintains the operating pressure. Two competing design considerations are critical to the performance of the system: a low temperature flow is needed to maximize the population difference between rotational levels, and high gas number densities are needed to ensure rapid cooling to achieve the uniform flow conditions. At the same time, collision times shorter than the chirp duration will give inaccurate intensities and reduced signal levels due to collisional dephasing of free induction decay. Details of the instrument and future directions and challenges will be discussed.

  4. Competition between inter- and intra-molecular hydrogen bonding: An infrared spectroscopic study of jet-cooled amino-ethanol and its dimer

    Science.gov (United States)

    Asselin, Pierre; Madebène, Bruno; Soulard, Pascale; Georges, Robert; Goubet, Manuel; Huet, Thérèse R.; Pirali, Olivier; Zehnacker-Rentien, Anne

    2016-12-01

    The Fourier transform IR vibrational spectra of amino-ethanol (AE) and its dimer have been recorded at room temperature and under jet-cooled conditions over the far and mid infrared ranges (50-4000 cm-1) using the White-type cell and the supersonic jet of the Jet-AILES apparatus at the synchrotron facility SOLEIL. Assignment of the monomer experimental frequencies has been derived from anharmonic frequencies calculated at a hybrid CCSD(T)-F12/MP2 level. Various thermodynamical effects in the supersonic expansion conditions including molar dilution of AE and nature of carrier gas have been used to promote or not the formation of dimers. Four vibrational modes of the observed dimer have been unambiguously assigned using mode-specific scaling factors deduced from the ratio between experimental and computed frequencies for the monomer. The most stable g'Gg' monomer undergoes strong deformation upon dimerization, leading to a homochiral head to head dimer involving two strong hydrogen bonds.

  5. Laser cooling of the OH(-) molecular anion in a theoretical investigation.

    Science.gov (United States)

    Wan, Ming-Jie; Huang, Duo-Hui; Yu, You; Zhang, Yun-Guang

    2017-10-03

    The schemes for laser cooling of the OH(-) anion are proposed using an ab initio method. Scalar relativistic corrections are considered using the Douglas-Kroll Hamilton. Spin-orbit coupling (SOC) effects are taken into account at the MRCI+Q level. SOC effects play important roles in the transition properties of the OH(-) anion. Transition strengths for the transition of the OH(-) anion cannot be ignored. Large vibrational branching ratios for the and transitions are determined. Short spontaneous radiative lifetimes for the a(3)Π1 and A(1)Π1 states are also predicted for rapid laser cooling. The vibrational branching loss ratio to the intervening states a(3)Π0 and a(3)Π1 for the transition is small enough to enable the building of a laser cooling project. The three required laser wavelengths for the and transitions are all in the visible region. The results imply the probability of laser cooling of the OH(-) anion via both a spin-forbidden transition and a three-electronic-level transition.

  6. Supersonic beams at high particle densities: model description beyond the ideal gas approximation.

    Science.gov (United States)

    Christen, Wolfgang; Rademann, Klaus; Even, Uzi

    2010-10-28

    Supersonic molecular beams constitute a very powerful technique in modern chemical physics. They offer several unique features such as a directed, collision-free flow of particles, very high luminosity, and an unsurpassed strong adiabatic cooling during the jet expansion. While it is generally recognized that their maximum flow velocity depends on the molecular weight and the temperature of the working fluid in the stagnation reservoir, not a lot is known on the effects of elevated particle densities. Frequently, the characteristics of supersonic beams are treated in diverse approximations of an ideal gas expansion. In these simplified model descriptions, the real gas character of fluid systems is ignored, although particle associations are responsible for fundamental processes such as the formation of clusters, both in the reservoir at increased densities and during the jet expansion. In this contribution, the various assumptions of ideal gas treatments of supersonic beams and their shortcomings are reviewed. It is shown in detail that a straightforward thermodynamic approach considering the initial and final enthalpy is capable of characterizing the terminal mean beam velocity, even at the liquid-vapor phase boundary and the critical point. Fluid properties are obtained using the most accurate equations of state available at present. This procedure provides the opportunity to naturally include the dramatic effects of nonideal gas behavior for a large variety of fluid systems. Besides the prediction of the terminal flow velocity, thermodynamic models of isentropic jet expansions permit an estimate of the upper limit of the beam temperature and the amount of condensation in the beam. These descriptions can even be extended to include spinodal decomposition processes, thus providing a generally applicable tool for investigating the two-phase region of high supersaturations not easily accessible otherwise.

  7. Prevalence and Molecular Characteristics of Waterborne Pathogen Legionella in Industrial Cooling Tower Environments

    Directory of Open Access Journals (Sweden)

    Lijie Li

    2015-10-01

    Full Text Available Cooling towers are a source of Legionnaires’ disease. It is important from a public health perspective to survey industrial cooling towers for the presence of Legionella. Prospective surveillance of the extent of Legionella pollution was conducted at factories in Shijiazhuang, China between March 2011 and September 2012. Overall, 35.7% of 255 industrial cooling tower water samples showed Legionella-positive, and their concentrations ranged from 100 Colony-Forming Units (CFU/liter to 88,000 CFU/liter, with an average concentration of 9100 CFU/liter. A total of 121 isolates were obtained. All isolates were L. pneumophila, and the isolated serogroups included serogroups 1 (68 isolates, 56.2%, 6 (25, 20.7%, 5 (12, 9.9%, 8 (8, 6.6%, 3 (6, 5.0% and 9 (2, 1.6%. All 121 isolates were analyzed by pulsed-field gel electrophoresis (PFGE and 64 different patterns were obtained. All 121 isolates were analyzed sequence-based typing (SBT, a full 7-allele profile was obtained from 117 isolates. One hundred and seventeen isolates were divided into 49 sequence types. Two virulence genes, lvh and rtxA, are analyzed by polymerase chain reaction (PCR. 92.6% (112/121 and 98.3% (119/121 isolates carried lvh and rtxA respectively and 90.9% (110/121 of tested isolates carried both genes. Our results demonstrated high prevalence and genetic polymorphism of L. pneumophila in industrial cooling tower environments in Shijiazhang, China, and the SBT and virulence gene PCR results suggested that the isolates were pathogenic. Improved control and prevention strategies are urgently needed.

  8. Continuous All-Optical Deceleration and Single-Photon Cooling of Molecular Beams

    Science.gov (United States)

    2014-02-21

    transform-limited τ = 7 ps Gaussian pulse. The operating point (highlighted with a white diamond in Fig. 1) corresponds to 4 W of average power focused to a...illustrated by Eq. (2). The cooling laser is detuned 9 MHz from the zero velocity class, which corresponds to a forward velocity near 7 m/s. The...Treacy, IEEE J. Quantum Electron. 5, 454 (1969). [41] J. S. Melinger, S. R. Gandhi , A. Hariharan, J. X. Tull, and W. S. Warren, Phys. Rev. Lett. 68, 2000

  9. Constant-temperature hot-wire anemometer practice in supersonic flows. II - The inclined wire

    Science.gov (United States)

    Smits, A. J.; Muck, K. C.

    1983-01-01

    The performance of a constant-temperature inclined hot-wire in a supersonic flow is critically examined. It is shown that calibration techniques applicable to subsonic flow, such as the cosine cooling law cannot be used when the flow is supersonic. Calibration and measurement procedures appropriate to supersonic flow are suggested, together with the possible limits on their validity. Experimental results for different wires indicate that the sensitivities do not seem to depend on flow direction according to any simple correlation. When the sensitivity exhibits a strong dependence on flow direction, the wire should be discarded to avoid errors due to nonlinear effects.

  10. Continuous supersonic plasma wind tunnel

    DEFF Research Database (Denmark)

    Andersen, S.A.; Jensen, Vagn Orla; Nielsen, P.

    1968-01-01

    The B field configuration of a Q-device has been modified into a magnetic Laval nozzle. Continuous supersonic plasma flow is observed with M≈3......The B field configuration of a Q-device has been modified into a magnetic Laval nozzle. Continuous supersonic plasma flow is observed with M≈3...

  11. Continuous supersonic plasma wind tunnel

    DEFF Research Database (Denmark)

    Andersen, S.A.; Jensen, Vagn Orla; Nielsen, P.

    1969-01-01

    The normal magnetic field configuration of a Q device has been modified to obtain a 'magnetic Laval nozzle'. Continuous supersonic plasma 'winds' are obtained with Mach numbers ~3. The magnetic nozzle appears well suited for the study of the interaction of supersonic plasma 'winds' with either...

  12. The Edge supersonic transport

    Science.gov (United States)

    Agosta, Roxana; Bilbija, Dushan; Deutsch, Marc; Gallant, David; Rose, Don; Shreve, Gene; Smario, David; Suffredini, Brian

    1992-01-01

    As intercontinental business and tourism volumes continue their rapid expansion, the need to reduce travel times becomes increasingly acute. The Edge Supersonic Transport Aircraft is designed to meet this demand by the year 2015. With a maximum range of 5750 nm, a payload of 294 passengers and a cruising speed of M = 2.4, The Edge will cut current international flight durations in half, while maintaining competitive first class, business class, and economy class comfort levels. Moreover, this transport will render a minimal impact upon the environment, and will meet all Federal Aviation Administration Part 36, Stage III noise requirements. The cornerstone of The Edge's superior flight performance is its aerodynamically efficient, dual-configuration design incorporating variable-geometry wingtips. This arrangement combines the benefits of a high aspect ratio wing at takeoff and low cruising speeds with the high performance of an arrow-wing in supersonic cruise. And while the structural weight concerns relating to swinging wingtips are substantial, The Edge looks to ever-advancing material technologies to further increase its viability. Heeding well the lessons of the past, The Edge design holds economic feasibility as its primary focus. Therefore, in addition to its inherently superior aerodynamic performance, The Edge uses a lightweight, largely windowless configuration, relying on a synthetic vision system for outside viewing by both pilot and passengers. Additionally, a fly-by-light flight control system is incorporated to address aircraft supersonic cruise instability. The Edge will be produced at an estimated volume of 400 aircraft and will be offered to airlines in 2015 at $167 million per transport (1992 dollars).

  13. Supersonic turbulence, filamentary accretion,and the rapid assembly of massive stars and disks

    CERN Document Server

    Banerjee, R; Anderson, D W; Banerjee, Robi; Pudritz, Ralph E.; Anderson, Dave W.

    2006-01-01

    We present a detailed computational study of the assembly of protostellar disks and massive stars in molecular clouds with supersonic turbulence. We follow the evolution of large scale filamentary structures in a cluster-forming clump down to protostellar length scales by means of very highly resolved, 3D adaptive mesh refined (AMR) simulations, and show how accretion disks and massive stars form in such environments. We find that an initially elongated cloud core which has a slight spin from oblique shocks collapses first to a filament and later develops a turbulent disk close to the center of the filament. The continued large scale flow that shocks with the filament maintains the high density and pressure within it. Material within the cooling filament undergoes gravitational collapse and an outside-in assembly of a massive protostar. Our simulations show that very high mass accretion rates of up to 10^-2 Msol/yr and high, supersonic, infall velocities result from such filamentary accretion. Accretion at th...

  14. High-resolution spectroscopy of jet-cooled CH{sub 5}{sup +}: Progress

    Energy Technology Data Exchange (ETDEWEB)

    Savage, C.; Dong, F.; Nesbitt, D. J. [JILA, University of Colorado and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440 (United States)

    2015-01-22

    Protonated methane (CH{sub 5}{sup +}) is thought to be a highly abundant molecular ion in interstellar medium, as well as a potentially bright μwave- mm wave emitter that could serve as a tracer for methane. This paper describes progress and first successful efforts to obtain a high resolution, supersonically cooled spectrum of CH{sub 5}{sup +} in the 2900-3100 cm{sup −1} region, formed in a slit supersonic discharge at low jet temperatures and with sub-Doppler resolution. Short term precision in frequency measurement (< 5 MHz on an hour time scale) is obtained from a thermally controlled optical transfer cavity servoloop locked onto a frequency stabilized HeNe laser. Long term precision (< 20 MHz day-to-day) due to pressure, temperature and humidity dependent index of refraction effects in the optical transfer cavity is also present and discussed.

  15. Ultracold molecular spectroscopy: toward the narrow-line cooling of molecules

    Science.gov (United States)

    Kobayashi, Jun; Ogino, Atsushi; Inouye, Shin

    2015-03-01

    A new spectroscopic method that utilizes microwave transition of ultracold molecules is demonstrated. The narrow spectral linewidth (approximately 100 Hz) was guaranteed by preparing molecules at low temperature, and a high signal-to-noise ratio was achieved by preparing a significant fraction of molecules in the target internal state. The repetition rate of the experiment was approximately 10 Hz, which was only limited by the time needed to load ultracold atoms into the magneto-optical trap. To demonstrate the performance, we investigated the hyperfine structures of the vibrational ground states of the {{X}1}{{Σ }+} and {{b}3}{{\\Pi }{{0+}}} states of KRb molecules. This technique not only allows us to pursue the narrow-line laser cooling of KRb molecules, but also provided us with essential information for realizing precision spectroscopies e.g., the search for the temporal variation of the electron-to-proton mass ratio.

  16. Femtosecond quantum dynamics and laser-cooling in thermal molecular systems

    CERN Document Server

    Warmuth, C

    2000-01-01

    of thermal trans-stilbene upon excitation at the omega sub 0 frequency. The experimental results are in good agreement with theoretical analysis. This work deals with coherent and incoherent vibrational phenomena in thermal systems, wave packet motion and laser-cooling. In the first part, the principle of COIN (Coherence Observation by Interference Noise) has been applied as a new approach to measuring wave packet motion. In the experiment pairs of phase-randomized femtosecond pulses with relative delay-time tau prepare interference fluctuations in the excited state population, so the variance of the correlated fluorescence intensity directly mimics the dynamics of the propagating wave packet. The scheme is demonstrated by measuring the vibrational coherence of wave packet-motion in the B-state of gaseous iodine. The COIN-interferograms obtained recover propagation, recurrences, spreading, and revivals as the typical signature of wave packets. Due to the disharmony of the B-state-potential, fractional revival...

  17. Mixing in Supersonic Turbulence

    CERN Document Server

    Pan, Liubin

    2010-01-01

    In many astrophysical environments, mixing of heavy elements occurs in the presence of a supersonic turbulent velocity field. Here we carry out the first systematic numerical study of such passive scalar mixing in isothermal supersonic turbulence. Our simulations show that the ratio of the scalar mixing timescale, $\\tau_{\\rm c}$, to the flow dynamical time, $\\tau_{\\rm dyn}$ (defined as the flow driving scale divided by the rms velocity), increases with the Mach number, $M$, for $M \\lsim3$, and becomes essentially constant for $M \\gsim3.$ This trend suggests that compressible modes are less efficient in enhancing mixing than solenoidal modes. However, since the majority of kinetic energy is contained in solenoidal modes at all Mach numbers, the overall change in $\\tau_{\\rm c}/\\tau_{\\rm dyn}$ is less than 20\\% over the range $1 \\lsim M \\lsim 6$. At all Mach numbers, if pollutants are injected at around the flow driving scale, $\\tau_{\\rm c}$ is close to $\\tau_{\\rm dyn}.$ This suggests that scalar mixing is drive...

  18. Implementation of a single femtosecond optical frequency comb for molecular cooling

    CERN Document Server

    Shi, W

    2010-01-01

    We show that a single femtosecond optical frequency comb may be used to induce two-photon transitions between molecular vibrational levels to form ultracold molecules, e.g., KRb. The phase across an individual pulse in the pulse train is sinusoidally modulated with a carefully chosen amplitude and modulation frequency. Piecewise adiabatic population transfer is fulfilled to the final state by each pulse in the applied pulse train providing a controlled population accumulation in the final state. Detuning the pule train parameters to less than the frequency difference between the initial and final states changes the time scale of molecular dynamics but leads to the same complete population transfer to the cold state.

  19. Molecular typing of Legionella pneumophila from air-conditioning cooling waters using mip gene, SBT, and FAFLP methods.

    Science.gov (United States)

    Gong, Xiangli; Li, Juntao; Zhang, Ying; Hou, Shuiping; Qu, Pinghua; Yang, Zhicong; Chen, Shouyi

    2017-08-01

    Legionella spp. are important waterborne pathogens. Molecular typing has become an important method for outbreaks investigations and source tracking of Legionnaires. In a survey program conducted by the Guangzhou Center for Disease Control and Prevention, multiple serotypes Legionella pneumophila (L. pneumophila) were isolated from waters in air-conditioning cooling towers in urban Guangzhou region, China between 2008 and 2011. Three genotyping methods, mip (macrophage infectivity potentiator) genotyping, SBT (sequence-based typing), and FAFLP (fluorescent amplified fragment length polymorphism analysis) were used to type these waterborne L. pneumophila isolates. The three methods were capable of typing all the 134 isolates and a reference strain of L. pneumophila (ATCC33153), with discriminatory indices of 0.7034, 0.9218, and 0.9376, for the mip, SBT, and FAFLP methods respectively. Among the 9 serotypes of the 134 isolates, 10, 50, and 34 molecular types were detected by the mip, SBT, and FAFLP methods respectively. The mip genotyping and SBT typing are more feasible for inter-laboratory results sharing and comparison of different types of L. pneumophila. The SBT and FAFLP typing methods were rapid with higher discriminatory abilities. Combinations of two or more of the typing methods enables more accurate typing of Legionella isolates for outbreak investigations and source tracking of Legionnaires. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Characterization of an atrazine molecularly imprinted polymer prepared by a cooling method

    Science.gov (United States)

    Royani, Idha; Widayani, Abdullah, Mikrajuddin; Khairurrijal

    2014-03-01

    A molecularly imprinted polymer (MIP) for atrazine was successfully prepared. Atrazine molecules as templates were incorporated into the pre-polymerization solution containing a functional monomer (methacrylic acid), a cross-linker (ethylene glycol dimethacrylate), and an initiator (benzoyl peroxide). The placement of a tube containing the pre-polymerization solution into a freezer was done to replace nitrogen pouring into the pre-polymerization solution. The sensing characteristic of the obtained MIP was examined and it was found that the amount of atrazine bound to the cavities in the MIP increases with increasing the initial concentration of atrazine. From Scatchard plots, it was found that the equilibrium dissociation constant KD and the apparent maximum number of binding sites Bmax, which are written as (KD, Bmax), are (6.4 μM, 13.41 mmol/g) and (6.5 μM, 4.55 mmol/g) for the 10 and 30 mg of MIP, respectively.

  1. Supersonic induction plasma jet modeling

    Energy Technology Data Exchange (ETDEWEB)

    Selezneva, S.E. E-mail: svetlana2@hermes.usherbS_Selezneva2@hermes.usherb; Boulos, M.I

    2001-06-01

    Numerical simulations have been applied to study the argon plasma flow downstream of the induction plasma torch. It is shown that by means of the convergent-divergent nozzle adjustment and chamber pressure reduction, a supersonic plasma jet can be obtained. We investigate the supersonic and a more traditional subsonic plasma jets impinging onto a normal substrate. Comparing to the subsonic jet, the supersonic one is narrower and much faster. Near-substrate velocity and temperature boundary layers are thinner, so the heat flux near the stagnation point is higher in the supersonic jet. The supersonic plasma jet is characterized by the electron overpopulation and the domination of the recombination over the dissociation, resulting into the heating of the electron gas. Because of these processes, the supersonic induction plasma permits to separate spatially different functions (dissociation and ionization, transport and deposition) and to optimize each of them. The considered configuration can be advantageous in some industrial applications, such as plasma-assisted chemical vapor deposition of diamond and polymer-like films and in plasma spraying of nanoscaled powders.

  2. Cooling molecular vibrations with shaped laser pulses: Optimal control theory exploiting the timescale separation between coherent excitation and spontaneous emission

    CERN Document Server

    Reich, Daniel M

    2013-01-01

    Laser cooling of molecules employing broadband optical pumping involves a timescale separation between laser excitation and spontaneous emission. Here, we optimize the optical pumping step using shaped laser pulses. We derive two optimization functionals to drive population into those excited state levels that have the largest spontaneous emission rates to the target state. We show that, when using optimal control, laser cooling of molecules works even if the Franck-Condon map governing the transitions is preferential to heating rather than cooling. Our optimization functional is also applicable to the laser cooling of other degrees of freedom provided the cooling cycle consists of coherent excitation and dissipative deexcitation steps whose timescales are separated.

  3. Laser cooling of dense atomic gases by collisional redistribution of radiation and spectroscopy of molecular dimers in a dense buffer gas environment

    CERN Document Server

    Saß, Anne; Christopoulos, Stavros; Knicker, Katharina; Moroshkin, Peter; Weitz, Martin

    2014-01-01

    We study laser cooling of atomic gases by collisional redistribution of fluorescence. In a high pressure buffer gas regime, frequent collisions perturb the energy levels of alkali atoms, which allows for the absorption of a far red detuned irradiated laser beam. Subsequent spontaneous decay occurs close to the unperturbed resonance frequency, leading to a cooling of the dense gas mixture by redistribution of fluorescence. Thermal deflection spectroscopy indicates large relative temperature changes down to and even below room temperature starting from an initial cell temperature near 700 K. We are currently performing a detailed analysis of the temperature distribution in the cell. As we expect this cooling technique to work also for molecular-noble gas mixtures, we also present initial spectroscopic experiments on alkali-dimers in a dense buffer gas surrounding.

  4. Trapping of molecular Oxygen together with Lithium atoms

    CERN Document Server

    Akerman, Nitzan; Segev, Yair; Bibelnik, Natan; Narevicius, Julia; Narevicius, Edvardas

    2016-01-01

    We demonstrate simultaneous deceleration and trapping of a cold atomic and molecular mixture. This is the first step towards studies of cold atom-molecule collisions at low temperatures as well as application of sympathetic cooling. Both atoms and molecules are cooled in a supersonic expansion and are loaded into a moving magnetic trap which brings them to rest via the Zeeman interaction from an initial velocity of 375 m/s. We use a beam seeded with molecular Oxygen, and entrain it with Lithium atoms by laser ablation prior to deceleration. The deceleration ends with loading of the mixture into a static quadrupole trap, which is generated by two permanent magnets. We estimate $10^9$ trapped O$_2$ molecules and $10^5$ Li atoms with background pressure limited lifetime on the order of 1 second. With further improvements to Lithium entrainment we expect that sympathetic cooling of molecules is within reach.

  5. Trapping of Molecular Oxygen together with Lithium Atoms

    Science.gov (United States)

    Akerman, Nitzan; Karpov, Michael; Segev, Yair; Bibelnik, Natan; Narevicius, Julia; Narevicius, Edvardas

    2017-08-01

    We demonstrate simultaneous deceleration and trapping of a cold atomic and molecular mixture. This is the first step towards studies of cold atom-molecule collisions at low temperatures as well as application of sympathetic cooling. Both atoms and molecules are cooled in a supersonic expansion and are loaded into a moving magnetic trap that brings them to rest via the Zeeman interaction from an initial velocity of 375 m /s . We use a beam seeded with molecular oxygen, and entrain it with lithium atoms by laser ablation prior to deceleration. The deceleration ends with loading of the mixture into a static quadrupole trap, which is generated by two permanent magnets. We estimate 1 09 trapped O2 molecules and 1 05 Li atoms with background pressure limited lifetime on the order of 1 sec. With further improvements to lithium entrainment we expect that sympathetic cooling of molecules is within reach.

  6. Properties of Supersonic Evershed Downflows

    Science.gov (United States)

    Pozuelo, S. Esteban; Bellot Rubio, L. R.; de la Cruz Rodríguez, J.

    2016-12-01

    We study supersonic Evershed downflows in a sunspot penumbra by means of high spatial resolution spectropolarimetric data acquired in the Fe i 617.3 nm line with the CRISP instrument at the Swedish 1 m Solar Telescope. Physical observables, such as Dopplergrams calculated from line bisectors and Stokes V zero-crossing wavelengths, and Stokes V maps in the far red-wing, are used to find regions where supersonic Evershed downflows may exist. We retrieve the line-of-sight velocity and the magnetic field vector in these regions using two-component inversions of the observed Stokes profiles with the help of the SIR code. We follow these regions during their lifetime to study their temporal behavior. Finally, we carry out a statistical analysis of the detected supersonic downflows to characterize their physical properties. Supersonic downflows are contained in compact patches moving outward, which are located in the mid- and outer penumbra. They are observed as bright, roundish structures at the outer end of penumbral filaments that resemble penumbral grains. The patches may undergo fragmentations and mergings during their lifetime; some of them are recurrent. Supersonic downflows are associated with strong and rather vertical magnetic fields with a reversed polarity compared to that of the sunspot. Our results suggest that downflows returning back to the solar surface with supersonic velocities are abruptly stopped in dense deep layers and produce a shock. Consequently, this shock enhances the temperature and is detected as a bright grain in the continuum filtergrams, which could explain the existence of outward-moving grains in the mid- and outer penumbra.

  7. Properties of Supersonic Evershed Downflows

    CERN Document Server

    Pozuelo, Sara Esteban; Rodriguez, Jaime de la Cruz

    2016-01-01

    We study supersonic Evershed downflows in a sunspot penumbra by means of high spatial resolution spectropolarimetric data acquired in the Fe I 617.3 nm line with the CRISP instrument at the Swedish 1-m Solar Telescope. Physical observables, such as Dopplergrams calculated from line bisectors and Stokes V zero-crossing wavelengths, and Stokes V maps in the far red wing, are used to find regions where supersonic Evershed downflows may exist. We retrieve the LOS velocity and the magnetic field vector in these regions using two-component inversions of the observed Stokes profiles with the help of the SIR code. We follow these regions during their lifetime to study their temporal behavior. Finally, we carry out a statistical analysis of the detected supersonic downflows to characterize their physical properties. Supersonic downflows are contained in compact patches moving outward, which are located in the mid and outer penumbra. They are observed as bright, roundish structures at the outer end of penumbral filamen...

  8. The shock waves in decaying supersonic turbulence

    CERN Document Server

    Smith, M D; Zuev, J M; Smith, Michael D.; Low, Mordecai-Mark Mac; Zuev, Julia M.

    2000-01-01

    We here analyse numerical simulations of supersonic, hypersonic andmagnetohydrodynamic turbulence that is free to decay. Our goals are tounderstand the dynamics of the decay and the characteristic properties of theshock waves produced. This will be useful for interpretation of observations ofboth motions in molecular clouds and sources of non-thermal radiation. We find that decaying hypersonic turbulence possesses an exponential tail offast shocks and an exponential decay in time, i.e. the number of shocks isproportional to t exp (-ktv) for shock velocity jump v and mean initialwavenumber k. In contrast to the velocity gradients, the velocity ProbabilityDistribution Function remains Gaussian with a more complex decay law. The energy is dissipated not by fast shocks but by a large number of low Machnumber shocks. The power loss peaks near a low-speed turn-over in anexponential distribution. An analytical extension of the mapping closuretechnique is able to predict the basic decay features. Our analytic descrip...

  9. Molecular characterization of viable Legionella spp. in cooling tower water samples by combined use of ethidium monoazide and PCR.

    Science.gov (United States)

    Inoue, Hiroaki; Fujimura, Reiko; Agata, Kunio; Ohta, Hiroyuki

    2015-01-01

    Viable Legionella spp. in environmental water samples were characterized phylogenetically by a clone library analysis combining the use of ethidium monoazide and quantitative PCR. To examine the diversity of Legionella spp., six cooling tower water samples and three bath water samples were collected and analyzed. A total of 617 clones were analyzed for their 16S rRNA gene sequences and classified into 99 operational taxonomic units (OTUs). The majority of OTUs were not clustered with currently described Legionella spp., suggesting the wide diversity of not-yet-cultured Legionella groups harbored in cooling tower water environments.

  10. Rotational state resolved photodissociation spectroscopy of translationally and vibrationally cold MgH+ ions: toward rotational cooling of molecular ions

    DEFF Research Database (Denmark)

    Højbjerre, Klaus; Hansen, Anders Kragh; Skyt, Peter Sandegaard

    2009-01-01

    and vibrationally cold MgH+ ions are presented, with and without the optical pumping laser being present. While rotational cooling is as yet not evident, first results showed evidence of a change in the rotational distribution in the presence of the optical pumping laser.......The first steps toward the implementation of a simple scheme for rotational cooling of MgH+ ions based on rotational state optical pumping is considered. The various aspects of such an experiment are described in detail, and the rotational state-selective dissociation spectra of translationally...

  11. Supersonic Plasma Flow Control Experiments

    Science.gov (United States)

    2005-12-01

    to liquid metals , for example, the conductivities of typical plasma and electrolyte flows are relatively low. Ref. 14 cites the conductivity of...heating is the dominant effect. 15. SUBJECT TERMS Supersonic, plasma , MHD , boundary-layer 16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE...horns in operation on Mach 5 wind tunnel with a plasma discharge. 31 Figure 17 Front view of a 100 mA DC discharge generated with upstream pointing

  12. Supersonic Chordwise Bending Flutter in Cascades

    Science.gov (United States)

    1975-05-31

    such a flutter boundary can be made by utilizing the trend lines predicted from a supersonic analysis based on supersonic cascade theory (Appendix I...bonding agent was injected via hypodermic needles after the blade tabs were properly inserted, The integrity and repeatability of the mounting of the indi...in conjunction with NASTRAN predictions and supersonic cascade aerodynamic computa- tions. Comparisons between theory and experiment are discussed. DD

  13. Supersonic flow imaging via nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Due to influence of compressibility,shock wave,instabilities,and turbulence on supersonic flows, current flow visualization and imaging techniques encounter some problems in high spatiotemporal resolution and high signal-to-noise ratio(SNR)measurements.Therefore,nanoparticle based planar laser scattering method(NPLS)is developed here.The nanoparticles are used as tracer,and pulse planar laser is used as light source in NPLS;by recording images of particles in flow field with CCD, high spatiotemporal resolution supersonic flow imaging is realized.The flow-following ability of nanoparticles in supersonic flows is studied according to multiphase flow theory and calibrating experiment of oblique shock wave.The laser scattering characteristics of nanoparticles are analyzed with light scattering theory.The results of theoretical and experimental studies show that the dynamic behavior and light scattering characteristics of nanoparticles highly enhance the spatiotemporal resolution and SNR of NPLS,with which the flow field involving shock wave,expansion,Mach disk,boundary layer,sliding-line,and mixing layer can be imaged clearly at high spatiotemporal resolution.

  14. Electron cooling

    Science.gov (United States)

    Meshkov, I.; Sidorin, A.

    2004-10-01

    The brief review of the most significant and interesting achievements in electron cooling method, which took place during last two years, is presented. The description of the electron cooling facilities-storage rings and traps being in operation or under development-is given. The applications of the electron cooling method are considered. The following modern fields of the method development are discussed: crystalline beam formation, expansion into middle and high energy electron cooling (the Fermilab Recycler Electron Cooler, the BNL cooler-recuperator, cooling with circulating electron beam, the GSI project), electron cooling in traps, antihydrogen generation, electron cooling of positrons (the LEPTA project).

  15. Stochastic Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Blaskiewicz, M.

    2011-01-01

    Stochastic Cooling was invented by Simon van der Meer and was demonstrated at the CERN ISR and ICE (Initial Cooling Experiment). Operational systems were developed at Fermilab and CERN. A complete theory of cooling of unbunched beams was developed, and was applied at CERN and Fermilab. Several new and existing rings employ coasting beam cooling. Bunched beam cooling was demonstrated in ICE and has been observed in several rings designed for coasting beam cooling. High energy bunched beams have proven more difficult. Signal suppression was achieved in the Tevatron, though operational cooling was not pursued at Fermilab. Longitudinal cooling was achieved in the RHIC collider. More recently a vertical cooling system in RHIC cooled both transverse dimensions via betatron coupling.

  16. Multiphoton ionization of jet-cooled nickelocene with tunable nanosecond laser pulses

    Science.gov (United States)

    Ketkov, Sergey Yu.; Selzle, Heinrich L.; Schlag, Edward W.; Titova, Sofia N.

    2003-08-01

    Efficient multiphoton ionization of nickelocene molecules in a supersonically cooled molecular beam has been performed for the first time with a nanosecond tunable dye laser operating in the 35,000-cm -1 region which corresponds to the lowest Rydberg transition observed in the one-photon absorption spectrum. The time-of-flight mass spectra obtained show strong signals of intact molecular ions Cp 2Ni + (Cp=η 5-C 5H 5) and weaker peaks of fragment ions CpNi +. The conditions have been found for generation of Cp 2Ni + as the only ionic product of multiphoton excitation. The ion signal dependence on the laser intensity and the resonance-enhanced multiphoton ionization spectrum measured at the mass of Cp 2Ni + testify for saturation of absorption and/or ionization steps at the laser pulse intensities used (2-6 MW cm -2). Possible mechanisms of multiphoton processes resulting in formation of the ions observed are discussed.

  17. Extensive theoretical study on electronically excited states of calcium monochloride: Molecular laser cooling and production of ultracold chlorine atoms

    Science.gov (United States)

    Fu, Mingkai; Ma, Haitao; Cao, Jianwei; Bian, Wensheng

    2016-05-01

    Nine doublet Λ-S states of calcium monochloride (CaCl) are calculated using the internally contracted multireference configuration interaction method with the Davidson correction. Both the core subvalence and spin-orbit coupling effects are taken into account. Laser cooling of CaCl and production of ultracold chlorine atoms are investigated and assessed. Our computed spectroscopic constants and radiative lifetimes match the available experimental data very well. The determined Franck-Condon factors and vibrational branching ratios of the A 2 Π 1 / 2 ( ν ' ) ← X 2 Σ1 / 2 + ( ν ) transition are highly diagonally distributed and the evaluated radiative lifetime for the A2Π1/2(ν' = 0) state is 28.2 ns, which is short enough for rapid laser cooling. Subsequently, detection of cold molecules via resonance enhanced multiphoton ionization to determine the final quantum state populations is discussed and the ionization energy calculated. A multi-pulse excitation scheme is proposed for producing ultracold chlorine atoms from zero-energy photodissociation of the cooled CaCl. Our results demonstrate the possibility of producing ultracold CaCl molecules and Cl atoms.

  18. Early Science with the Large Millimeter Telescope: COOL BUDHIES I - a pilot study of molecular and atomic gas at z ≃ 0.2

    Science.gov (United States)

    Cybulski, Ryan; Yun, Min S.; Erickson, Neal; De la Luz, Victor; Narayanan, Gopal; Montaña, Alfredo; Sánchez, David; Zavala, Jorge A.; Zeballos, Milagros; Chung, Aeree; Fernández, Ximena; van Gorkom, Jacqueline; Haines, Chris P.; Jaffé, Yara L.; Montero-Castaño, María; Poggianti, Bianca M.; Verheijen, Marc A. W.; Yoon, Hyein; Deshev, Boris Z.; Harrington, Kevin; Hughes, David H.; Morrison, Glenn E.; Schloerb, F. Peter; Velazquez, Miguel

    2016-07-01

    An understanding of the mass build-up in galaxies over time necessitates tracing the evolution of cold gas (molecular and atomic) in galaxies. To that end, we have conducted a pilot study called CO Observations with the LMT of the Blind Ultra-Deep H I Environment Survey (COOL BUDHIES). We have observed 23 galaxies in and around the two clusters Abell 2192 (z = 0.188) and Abell 963 (z = 0.206), where 12 are cluster members and 11 are slightly in the foreground or background, using about 28 total hours on the Redshift Search Receiver on the Large Millimeter Telescope (LMT) to measure the 12CO J = 1 → 0 emission line and obtain molecular gas masses. These new observations provide a unique opportunity to probe both the molecular and atomic components of galaxies as a function of environment beyond the local Universe. For our sample of 23 galaxies, nine have reliable detections (S/N ≥ 3.6) of the 12CO line, and another six have marginal detections (2.0 < S/N < 3.6). For the remaining eight targets we can place upper limits on molecular gas masses roughly between 109 and 1010 M⊙. Comparing our results to other studies of molecular gas, we find that our sample is significantly more abundant in molecular gas overall, when compared to the stellar and the atomic gas component, and our median molecular gas fraction lies about 1σ above the upper limits of proposed redshift evolution in earlier studies. We discuss possible reasons for this discrepancy, with the most likely conclusion being target selection and Eddington bias.

  19. Detonation in supersonic radial outflow

    KAUST Repository

    Kasimov, Aslan R.

    2014-11-07

    We report on the structure and dynamics of gaseous detonation stabilized in a supersonic flow emanating radially from a central source. The steady-state solutions are computed and their range of existence is investigated. Two-dimensional simulations are carried out in order to explore the stability of the steady-state solutions. It is found that both collapsing and expanding two-dimensional cellular detonations exist. The latter can be stabilized by putting several rigid obstacles in the flow downstream of the steady-state sonic locus. The problem of initiation of standing detonation stabilized in the radial flow is also investigated numerically. © 2014 Cambridge University Press.

  20. Early Science with the Large Millimeter Telescope: COOL BUDHIES I - a pilot study of molecular and atomic gas at z~0.2

    CERN Document Server

    Cybulski, Ryan; Erickson, Neal; De la Luz, Victor; Narayanan, Gopal; Montaña, Alfredo; Sánchez-Argülles, David; Zavala, Jorge A; Zeballos, Milagros; Chung, Aeree; Fernández, Ximena; van Gorkom, Jacqueline; Haines, Chris P; Jaffé, Yara L; Montero-Castaño, María; Poggianti, Bianca M; Verheijen, Marc A W; Yoon, Hyein; Harrington, Kevin; Hughes, David H; Morrison, Glenn E; Schloerb, F Peter; Velazquez, Miguel

    2015-01-01

    An understanding of the mass build-up in galaxies over time necessitates tracing the evolution of cold gas (molecular and atomic) in galaxies. To that end, we have conducted a pilot study called CO Observations with the LMT of the Blind Ultra-Deep H I Environment Survey (COOL BUDHIES). We have observed 23 galaxies in and around the two clusters Abell 2192 (z = 0.188) and Abell 963 (z = 0.206), where 12 are cluster members and 11 are slightly in the foreground or background, using about 28 total hours on the Redshift Search Receiver (RSR) on the Large Millimeter Telescope (LMT) to measure the $^{12}$CO J = 1 --> 0 emission line and obtain molecular gas masses. These new observations provide a unique opportunity to probe both the molecular and atomic components of galaxies as a function of environment beyond the local Universe. For our sample of 23 galaxies, nine have reliable detections (S/N$\\geq$3.6) of the $^{12}$CO line, and another six have marginal detections (2.0 < S/N < 3.6). For the remaining eig...

  1. Validation of IRS PCR, a molecular typing method, for the study of the diversity and population dynamics of Legionella in industrial cooling circuits.

    Science.gov (United States)

    Jakubek, D; Le Brun, M; Leblon, G; Dubow, M; Binet, M

    2013-02-01

    Legionella bacteria are ubiquitous in aquatic environments. Members of the species Legionella pneumophila are responsible for more than 98% of cases of Legionnaires' disease in France. Our objective was to validate a molecular typing method called infrequent restriction site PCR (IRS PCR), applied to the study of the ecology of Legionella and to compare this method with reference typing methods, pulsed-field gel electrophoresis (PFGE) and sequence-based Typing (SBT). PFGE and SBT are considered as gold methods for the epidemiological typing of Leg. pneumophila strains. However, these methods are not suitable to an ecological monitoring of Legionella in natural environments where a large number of strains has to be typed. Validation of IRS PCR method was performed by the identification of 45 Leg. pneumophila isolates from cooling circuits of thermal power plants by IRS PCR, PFGE and SBT. The parameters of each method were measured and compared to evaluate the effectiveness of IRS PCR. The results of this study showed that IRS PCR has a discriminating power similar or better than that of the reference methods and thus that, by its speed and low cost represents an appropriate tool for the study of the ecology of Legionella in cooling circuits.

  2. Photoinduced intramolecular charge-transfer reactions in 4-amino-3-methyl benzoic acid methyl ester: A fluorescence study in condensedphase and jet-cooled molecular beams

    Indian Academy of Sciences (India)

    Amrita Chakraborty; Samiran Kar; D N Nath; Nikhil Guchhait

    2007-03-01

    Photoinduced intramolecular charge-transfer reactions in 4-amino-3-methyl benzoic acid methyl ester (AMBME) have been investigated spectroscopically. AMBME, with its weak charge donor primary amino group, shows dual emission in polar solvents. Absorption and emission measurements in the condensed phase support the premise that the short wavelength emission band corresponds to local emission and the long wavelength emission band to the charge transfer emission. Laser-induced fluorescence excitation spectra show the presence of two low-energy conformers in jet-cooled molecular beams. Theoretical calculations using density functional theory help to determine structure, vibrational modes, potential energy surface, transition energy and oscillator strength for correlating experimental findings with theoretical results.

  3. Pdf prediction of supersonic hydrogen flames

    Science.gov (United States)

    Eifler, P.; Kollmann, W.

    1993-01-01

    A hybrid method for the prediction of supersonic turbulent flows with combustion is developed consisting of a second order closure for the velocity field and a multi-scalar pdf method for the local thermodynamic state. It is shown that for non-premixed flames and chemical equilibrium mixture fraction, the logarithm of the (dimensionless) density, internal energy per unit mass and the divergence of the velocity have several advantages over other sets of scalars. The closure model is applied to a supersonic non-premixed flame burning hydrogen with air supplied by a supersonic coflow and the results are compared with a limited set of experimental data.

  4. Influence of rarefaction on the flow dynamics of a stationary supersonic hot-gas expansion.

    Science.gov (United States)

    Abbate, G; Kleijn, C R; Thijsse, B J; Engeln, R; van de Sanden, M C M; Schram, D C

    2008-03-01

    The gas dynamics of a stationary hot-gas jet supersonically expanding into a low pressure environment is studied through numerical simulations. A hybrid coupled continuum-molecular approach is used to model the flow field. Due to the low pressure and high thermodynamic gradients, continuum mechanics results are doubtful, while, because of its excessive time expenses, a full molecular method is not feasible. The results of the hybrid coupled continuum-molecular approach proposed have been successfully validated against experimental data by R. Engeln [Plasma Sources Sci. Technol. 10, 595 (2001)] obtained by means of laser induced fluorescence. Two main questions are addressed: the necessity of applying a molecular approach where rarefaction effects are present in order to correctly model the flow and the demonstration of an invasion of the supersonic part of the flow by background particles. A comparison between the hybrid method and full continuum simulations demonstrates the inadequacy of the latter, due to the influence of rarefaction effects on both velocity and temperature fields. An analysis of the particle velocity distribution in the expansion-shock region shows clear departure from thermodynamic equilibrium and confirms the invasion of the supersonic part of the flow by background particles. A study made through particles and collisions tracking in the supersonic region further proves the presence of background particles in this region and explains how they cause thermodynamic nonequilibrium by colliding and interacting with the local particles.

  5. Photoionization studies with molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    Ng, C.Y.

    1976-09-01

    A molecular beam photoionization apparatus which combines the advantages of both the molecular beam method with photoionization mass spectrometry has been designed and constructed for carrying out some unique photoionization experiments. Rotational cooling during the supersonic expansion has resulted in high resolution photoionization efficiency curves for NO, ICl, C/sub 2/H/sub 2/ and CH/sub 3/I. The analysis of these spectra has yielded ionization potentials for these molecules to an accuracy of +- 3 MeV. Detailed autoionization structures were also resolved. This allows the investigation of the selection rules for autoionization, and the identification of the Rydberg series which converge to the excited states of the molecular ions. The degree of relaxation for thermally populated excited states has been examined using NO and ICl as examples. As a result of adiabatic cooling, a small percentage of dimers is also formed during the expansion. The photoionization efficiency curves for (NO)/sub 2/, ArICl, Ar/sub 2/, Kr/sub 2/ and Xe/sub 2/ have been obtained near the thresholds. Using the known dissociation energies of the (NO)/sub 2/, Ar/sub 2/, Kr/sub 2/ and Xe/sub 2/ van der Waals molecules, the corresponding dissociation energies for NO-NO/sup +/, Ar/sub 2//sup +/, Kr/sub 2//sup +/, and Xe/sub 2//sup +/ have been determined. The ionization mechanisms for this class of molecules are examined and discussed.

  6. Experiments on free and impinging supersonic microjets

    Energy Technology Data Exchange (ETDEWEB)

    Phalnikar, K.A.; Kumar, R.; Alvi, F.S. [Florida A and M University and Florida State University, Department of Mechanical Engineering, Tallahassee, FL (United States)

    2008-05-15

    The fluid dynamics of microflows has recently commanded considerable attention because of their potential applications. Until now, with a few exceptions, most of the studies have been limited to low speed flows. This experimental study examines supersonic microjets of 100-1,000 {mu}m in size with exit velocities in the range of 300-500 m/s. Such microjets are presently being used to actively control larger supersonic impinging jets, which occur in STOVL (short takeoff and vertical landing) aircraft, cavity flows, and flow separation. Flow properties of free as well as impinging supersonic microjets have been experimentally investigated over a range of geometric and flow parameters. The flowfield is visualized using a micro-schlieren system with a high magnification. These schlieren images clearly show the characteristic shock cell structure typically observed in larger supersonic jets. Quantitative measurements of the jet decay and spreading rates as well as shock cell spacing are obtained using micro-pitot probe surveys. In general, the mean flow features of free microjets are similar to larger supersonic jets operating at higher Reynolds numbers. However, some differences are also observed, most likely due to pronounced viscous effects associated with jets at these small scales. Limited studies of impinging microjets were also conducted. They reveal that, similar to the behavior of free microjets, the flow structure of impinging microjets strongly resembles that of larger supersonic impinging jets. (orig.)

  7. Experiments on free and impinging supersonic microjets

    Science.gov (United States)

    Phalnikar, K. A.; Kumar, R.; Alvi, F. S.

    2008-05-01

    The fluid dynamics of microflows has recently commanded considerable attention because of their potential applications. Until now, with a few exceptions, most of the studies have been limited to low speed flows. This experimental study examines supersonic microjets of 100-1,000 μm in size with exit velocities in the range of 300-500 m/s. Such microjets are presently being used to actively control larger supersonic impinging jets, which occur in STOVL (short takeoff and vertical landing) aircraft, cavity flows, and flow separation. Flow properties of free as well as impinging supersonic microjets have been experimentally investigated over a range of geometric and flow parameters. The flowfield is visualized using a micro-schlieren system with a high magnification. These schlieren images clearly show the characteristic shock cell structure typically observed in larger supersonic jets. Quantitative measurements of the jet decay and spreading rates as well as shock cell spacing are obtained using micro-pitot probe surveys. In general, the mean flow features of free microjets are similar to larger supersonic jets operating at higher Reynolds numbers. However, some differences are also observed, most likely due to pronounced viscous effects associated with jets at these small scales. Limited studies of impinging microjets were also conducted. They reveal that, similar to the behavior of free microjets, the flow structure of impinging microjets strongly resembles that of larger supersonic impinging jets.

  8. EOIL power scaling in a 1-5 kW supersonic discharge-flow reactor

    Science.gov (United States)

    Davis, Steven J.; Lee, Seonkyung; Oakes, David B.; Haney, Julie; Magill, John C.; Paulsen, Dwane A.; Cataldi, Paul; Galbally-Kinney, Kristin L.; Vu, Danthu; Polex, Jan; Kessler, William J.; Rawlins, Wilson T.

    2008-02-01

    Scaling of EOIL systems to higher powers requires extension of electric discharge powers into the kW range and beyond with high efficiency and singlet oxygen yield. We have previously demonstrated a high-power microwave discharge approach capable of generating singlet oxygen yields of ~25% at ~50 torr pressure and 1 kW power. This paper describes the implementation of this method in a supersonic flow reactor designed for systematic investigations of the scaling of gain and lasing with power and flow conditions. The 2450 MHz microwave discharge, 1 to 5 kW, is confined near the flow axis by a swirl flow. The discharge effluent, containing active species including O II(a1Δ g, b1Σ g +), O( 3P), and O 3, passes through a 2-D flow duct equipped with a supersonic nozzle and cavity. I2 is injected upstream of the supersonic nozzle. The apparatus is water-cooled, and is modular to permit a variety of inlet, nozzle, and optical configurations. A comprehensive suite of optical emission and absorption diagnostics is used to monitor the absolute concentrations of O II(a), O II(b), O( 3P), O 3, I II, I(2P 3/2), I(2P 1/2), small-signal gain, and temperature in both the subsonic and supersonic flow streams. We discuss initial measurements of singlet oxygen and I* excitation kinetics at 1 kW power.

  9. Dark matter merging induced turbulence as an efficient engine for gas cooling

    Science.gov (United States)

    Prieto, Joaquin; Jimenez, Raul; Martí, Jose

    2012-02-01

    We have performed a cosmological numerical simulation of primordial baryonic gas collapsing on to a 3 × 107 M⊙ dark matter (DM) halo. We show that the large scale baryonic accretion process and the merger of few ˜ 106 M⊙ DM haloes, triggered by the gravitational potential of the biggest halo, are enough to create supersonic (?) shocks and develop a turbulent environment. In this scenario, the post-shocked regions are able to produce both H2 and deuterated H2 molecules very efficiently, reaching maximum abundances of ? and nHD˜ few × 10-6 nH, enough to cool the gas below 100 K in some regions. The kinetic energy spectrum of the turbulent primordial gas is close to a Burgers spectrum, ?, which could favour the formation of low-mass primordial stars. The solenoidal-to-total kinetic energy ratio is 0.65 ≲Rk≲ 0.7 for a wide range of wavenumbers; this value is close to the Rk≈ 2/3 natural equipartition energy value of a random turbulent flow. In this way, turbulence and molecular cooling seem to work together in order to produce potential star formation regions of cold dense gas in primordial environments. We conclude that both the mergers and the collapse process on to the main DM halo provide enough energy to develop supersonic turbulence which favours the molecular coolant formation: this mechanism, which could be universal and the main route towards the formation of the first galaxies, is able to create potential star-forming regions at high redshift.

  10. Tracing cool molecular gas and star formation on $\\sim 100$pc scales within a $z=2.3$ galaxy

    CERN Document Server

    Thomson, A P; Owen, Frazer N; Danielson, A L R; Swinbank, A M; Smail, Ian

    2015-01-01

    We present new, high-angular resolution interferometric observations with the Karl G. Jansky Very Large Array of $^{12}$CO $J=1-0$ line emission and 4-8 GHz continuum emission in the strongly lensed, $z=2.3$ submillimetre galaxy, SMM J21352-0102. Using these data, we identify and probe the conditions in $\\sim 100$pc clumps within this galaxy, which we consider to be potential giant molecular cloud complexes, containing up to half of the total molecular gas in this system. In combination with far-infrared and submillimetre data, we investigate the far-infrared/radio correlation, measuring $q_{IR} = 2.39 \\pm 0.17$ across SMM J21352. We search for variations in the properties of the interstellar medium throughout the galaxy by measuring the spatially-resolved $q_{IR}$ and radio spectral index, ${\\alpha}_{\\rm radio}$, finding ranges $q_{IR} = [2.1, 2.6]$ and ${\\alpha}_{\\rm radio} = [-1.5, -0.7]$. We argue that these ranges in ${\\alpha}_{\\rm radio}$ and $q_{IR}$ may reflect variations in the age of the ISM materia...

  11. Molecular beam brightening by shock-wave suppression

    CERN Document Server

    Segev, Yair; Akerman, Nitzan; Shagam, Yuval; Luski, Alon; Karpov, Michael; Narevicius, Julia; Narevicius, Edvardas

    2016-01-01

    Supersonic beams are a prevalent source of cold molecules utilized in the study of chemical reactions, atom interferometry, gas-surface interactions, precision spectroscopy, molecular cooling and more. The triumph of this method emanates from the high densities produced in relation to other methods, however beam density remains fundamentally limited by interference with shock waves reflected from collimating surfaces. Here we show experimentally that this shock interaction can be reduced or even eliminated by cryo-cooling the interacting surface. An increase in beam density of nearly an order of magnitude was measured at the lowest surface temperature, with no further fundamental limitation reached. Visualization of the shock waves by plasma discharge and reproduction with direct simulation Monte Carlo calculations both indicate that the suppression of the shock structure is partially caused by lowering the momentum flux of reflected particles, and significantly enhanced by the adsorption of particles to the ...

  12. Danish Cool

    DEFF Research Database (Denmark)

    Toft, Anne Elisabeth

    2016-01-01

    Danish Cool. Keld Helmer-Petersen, Photography and the Photobook Handout exhibition text in English and Chinese by Anne Elisabeth Toft, Curator The exhibition Danish Cool. Keld Helmer-Petersen, Photography and the Photobook presents the ground-breaking work of late Danish photographer Keld Helmer...

  13. Nonequilibrium Supersonic Magnetogasdynamic Wind Tunnel

    Science.gov (United States)

    2007-12-31

    water cooled electromagnet, as shown in Figs. 1, 2, and attached to a 4 foot long, 6 inch diameter PVC vacuum pipe connected to the vacuum system. To...Voronkov, and Y.V. Aristov, "High-power semiconductor-based nano and subnanosecond pulse generator with a low delay time," IEEE Transactions on Plasma

  14. Design project: LONGBOW supersonic interceptor

    Science.gov (United States)

    Stoney, Robert; Baker, Matt; Capstaff, Joseph G.; Dishman, Robert; Fick, Gregory; Frick, Stephen N.; Kelly, Mark

    1993-01-01

    A recent white paper entitled 'From the Sea' has spotlighted the need for Naval Aviation to provide overland support to joint operations. The base for this support, the Aircraft Carrier (CVN), will frequently be unable to operate within close range of the battleground because of littoral land-based air and subsurface threats. A high speed, long range, carrier capable aircraft would allow the CVN to provide timely support to distant battleground operations. Such an aircraft, operating as a Deck-Launched Interceptor (DLI), would also be an excellent counter to Next Generation Russian Naval Aviation (NGRNA) threats consisting of supersonic bombers, such as the Backfire, equipped with the next generation of high-speed, long-range missiles. Additionally, it would serve as an excellent high speed Reconnaissance airplane, capable of providing Battle Force commanders with timely, accurate pre-mission targeting information and post-mission Bomb Damage Assessment (BDA). Recent advances in computational hypersonic airflow modeling has produced a method of defining aircraft shapes that fit a conical shock flow model to maximize the efficiency of the vehicle. This 'Waverider' concept provides one means of achieving long ranges at high speeds. A Request for Proposal (RFP) was issued by Professor Conrad Newberry that contained design requirements for an aircraft to accomplish the above stated missions, utilizing Waverider technology.

  15. On highly focused supersonic microjets

    CERN Document Server

    Tagawa, Yoshiyuki; Willem, Claas; Peters, Ivo R; van der Meer, Deveraj; Sun, Chao; Prosperetti, Andrea; Lohse, Detlef

    2011-01-01

    By focusing a laser pulse in a liquid-filled glass-microcapillary open at one end, a small mass of liquid is instantaneously vapourised. This leads to a shock wave which travels towards the concave free surface where it generates a high-speed microjet. The initial shape of the meniscus plays a dominant role in the process. The velocity of the jet can reach supersonic speeds up to 850\\,m/s while maintaining a very sharp geometry. The entire evolution of the jet is observed by high-speed recordings of up to $10^6\\,$fps. A parametric study of the jet velocity as a function of the contact angle of the liquid-glass interface, the energy absorbed by the liquid, the diameter of the capillary tube, and the distance between the laser focus and the free surface is performed, and the results are rationalised. The method could be used for needle-free injection of vaccines or drugs.

  16. Supersonic Cloud Collision-II

    CERN Document Server

    Anathpindika, S

    2009-01-01

    In this, second paper of the sequel of two papers, we present five SPH simulations of fast head-on cloud collisions and study the evolution of the ram pressure confined gas slab. Anathpindika (2008) (hereafter paper I) considered highly supersonic cloud collisions and examined the effect of bending and shearing instabilities on the shocked gas slab. The post-collision shock here, as in paper I, is also modelled by a simple barotropic equation of state (EOS). However, a much stiffer EOS is used to model the shock resulting from a low velocity cloud collision. We explore the parameter space by varying the pre-collision velocity and the impact parameter. We observe that pressure confined gas slabs become Jeans unstable if the sound crossing time, $t_{cr}$, is much larger than the freefall time, $t_{ff}$, of putative clumps condensing out of them. Self gravitating clumps may spawn multiple/larger $N$-body star clusters. We also suggest that warmer gas slabs are unlikely to fragment and may end up as diffuse gas c...

  17. Silent and Efficient Supersonic Bi-Directional Flying Wing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a Phase I study for a novel concept of a supersonic bi-directional (SBiDir) flying wing (FW) that has the potential to revolutionize supersonic flight...

  18. Quantum thermodynamic cooling cycle

    CERN Document Server

    Palao, J P; Gordon, J M; Palao, Jose P.; Kosloff, Ronnie; Gordon, Jeffrey M.

    2001-01-01

    The quantum-mechanical and thermodynamic properties of a 3-level molecular cooling cycle are derived. An inadequacy of earlier models is rectified in accounting for the spontaneous emission and absorption associated with the coupling to the coherent driving field via an environmental reservoir. This additional coupling need not be dissipative, and can provide a thermal driving force - the quantum analog of classical absorption chillers. The dependence of the maximum attainable cooling rate on temperature, at ultra-low temperatures, is determined and shown to respect the recently-established fundamental bound based on the second and third laws of thermodynamics.

  19. Mm-Wave Spectroscopy and Determination of the Radiative Branching Ratios of 11BH for Laser Cooling Experiments

    Science.gov (United States)

    Truppe, Stefan; Holland, Darren; Hendricks, Richard James; Hinds, Ed; Tarbutt, Michael

    2014-06-01

    We aim to slow a supersonic, molecular beam of 11BH using a Zeeman slower and subsequently cool the molecules to sub-millikelvin temperatures in a magneto-optical trap. Most molecules are not suitable for direct laser cooling because the presence of rotational and vibrational degrees of freedom means there is no closed-cycle transition which is necessary to scatter a large number of photons. As was pointed out by Di Rosa, there exists a class of molecules for which the excitation of vibrational modes is suppressed due to highly diagonal Franck-Condon factors. Furthermore, Stuhl et al. showed that angular momentum selection rules can be used to suppress leakage to undesired rotational states. Here we present a measurement of the radiative branching ratios of the A^1Π→ X^1Σ transition in 11BH - a necessary step towards subsequent laser cooling experiments. We also perform high-resolution mm-wave spectroscopy of the J'=1← J=0 rotational transition in the X^1Σ (v=0) state near 708 GHz. From this measurement we derive new, accurate hyper fine constants and compare these to theoretical descriptions. The measured branching ratios suggest that it is possible to laser cool 11BH molecules close to the recoil temperature of 4 μK using three laser frequencies only. M. D. Di Rosa, The European Physical Journal D, 31, 395, 2004 B. K. Stuhl et al., Physical Review Letters, 101, 243002, 2008

  20. Supersonic Flutter of Laminated Curved Panels

    Directory of Open Access Journals (Sweden)

    M. Ganapathi

    1995-04-01

    Full Text Available Supersonic flutter analysis of laminated composite curved panels is investigated using doubly-curved, quadrilateral, shear flexible, shell element based on field-consistency approach. The formulation includes transverse shear deformation, in-plane and rotary inertias. The aerodynamic force is evaluated using two-dimensional static aerodynamic approximation for high supersonic flow. Initially, the model developed here is verified for the flutter analysis of flat plates. Numerical results are presented for isotropic, orthotropic and laminated anisotropic curved panels. A detailed parametric study is carried out to observe the effects of aspect and thickness ratios, number of layers, lamination scheme, and boundary conditions on flutter boundary.

  1. Supersonic gas shell for puff pinch experiments

    Science.gov (United States)

    Smith, R. S., III; Doggett, W. O.; Roth, I.; Stallings, C.

    1982-09-01

    An easy-to-fabricate, conical, annular supersonic nozzle has been developed for use in high-power, puff gas z-pinch experiments. A fast responding conical pressure probe has also been developed as an accurate supersonic gas flow diagnostic for evaluating the transient gas jet formed by the nozzle. Density profile measurements show that the magnitude and radial position of the gas annulus are fairly constant with distance from the nozzle, but the gas density in the center of the annulus increases with distance from the nozzle.

  2. Ventilative Cooling

    DEFF Research Database (Denmark)

    Heiselberg, Per Kvols; Kolokotroni, Maria

    This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state-of-the-art of ventil......This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state...

  3. Supersonic Injection of Aerated Liquid Jet

    Science.gov (United States)

    Choudhari, Abhijit; Sallam, Khaled

    2016-11-01

    A computational study of the exit flow of an aerated two-dimensional jet from an under-expanded supersonic nozzle is presented. The liquid sheet is operating within the annular flow regime and the study is motivated by the application of supersonic nozzles in air-breathing propulsion systems, e.g. scramjet engines, ramjet engines and afterburners. The simulation was conducted using VOF model and SST k- ω turbulence model. The test conditions included: jet exit of 1 mm and mass flow rate of 1.8 kg/s. The results show that air reaches transonic condition at the injector exit due to the Fanno flow effects in the injector passage. The aerated liquid jet is alternately expanded by Prandtl-Meyer expansion fan and compressed by oblique shock waves due to the difference between the back (chamber) pressure and the flow pressure. The process then repeats itself and shock (Mach) diamonds are formed at downstream of injector exit similar to those typical of exhaust plumes of propulsion system. The present results, however, indicate that the flow field of supersonic aerated liquid jet is different from supersonic gas jets due to the effects of water evaporation from the liquid sheet. The contours of the Mach number, static pressure of both cases are compared to the theory of gas dynamics.

  4. Conditions for supersonic bent Marshak waves

    CERN Document Server

    Xu, Qiang; Li, Jing; Dan, Jia-kun; Wang, Kun-lun; Zhou, Shao-tong

    2014-01-01

    Supersonic radiation diffusion approximation is a useful way to study the radiation transportation. Considering the bent Marshak wave theory in 2-dimensions, and an invariable source temperature, we get the supersonic radiation diffusion conditions which are about the Mach number $M>8(1+\\sqrt{\\ep})/3$, and the optical depth $\\tau>1$. A large Mach number requires a high temperature, while a large optical depth requires a low temperature. Only when the source temperature is in a proper region these conditions can be satisfied. Assuming the material opacity and the specific internal energy depend on the temperature and the density as a form of power law, for a given density, these conditions correspond to a region about source temperature and the length of the sample. This supersonic diffusion region involves both lower and upper limit of source temperature, while that in 1-dimension only gives a lower limit. Taking $\\rm SiO_2$ and the Au for example, we show the supersonic region numerically.

  5. Numerical and experimental investigations on supersonic ejectors

    Energy Technology Data Exchange (ETDEWEB)

    Bartosiewicz, Y.; Aidoun, Z. [CETC-Varennes, Natural Resources Canada (Canada); Desevaux, P. [CREST-UMR 6000, Belfort (France); Mercadier, Y. [Sherbrooke Univ. (Canada). THERMAUS

    2005-02-01

    Supersonic ejectors are widely used in a range of applications such as aerospace, propulsion and refrigeration. The primary interest of this study is to set up a reliable hydrodynamics model of a supersonic ejector, which may be extended to refrigeration applications. The first part of this work evaluated the performance of six well-known turbulence models for the study of supersonic ejectors. The validation concentrated on the shock location, shock strength and the average pressure recovery prediction. Axial pressure measurements with a capillary probe performed previously [Int. J. Turbo Jet Engines 19 (2002) 71; Conference Proc., 10th Int. Symp. Flow Visualization, Kyoto, Japan, 2002], were compared with numerical simulations while laser tomography pictures were used to evaluate the non-mixing length. The capillary probe has been included in the numerical model and the non-mixing length has been numerically evaluated by including an additional transport equation for a passive scalar, which acted as an ideal colorant in the flow. At this point, the results show that the k-omega-sst model agrees best with experiments. In the second part, the tested model was used to reproduce the different operation modes of a supersonic ejector, ranging from on-design point to off-design. In this respect, CFD turned out to be an efficient diagnosis tool of ejector analysis (mixing, flow separation), for design, and performance optimization (optimum entrainment and recompression ratios). (Author)

  6. Cool snacks

    DEFF Research Database (Denmark)

    Grunert, Klaus G; Brock, Steen; Brunsø, Karen

    2016-01-01

    such a product requires an interdisciplinary effort where researchers with backgrounds in psychology, anthropology, media science, philosophy, sensory science and food science join forces. We present the COOL SNACKS project, where such a blend of competences was used first to obtain thorough insight into young...

  7. Stochastic cooling

    Energy Technology Data Exchange (ETDEWEB)

    Bisognano, J.; Leemann, C.

    1982-03-01

    Stochastic cooling is the damping of betatron oscillations and momentum spread of a particle beam by a feedback system. In its simplest form, a pickup electrode detects the transverse positions or momenta of particles in a storage ring, and the signal produced is amplified and applied downstream to a kicker. The time delay of the cable and electronics is designed to match the transit time of particles along the arc of the storage ring between the pickup and kicker so that an individual particle receives the amplified version of the signal it produced at the pick-up. If there were only a single particle in the ring, it is obvious that betatron oscillations and momentum offset could be damped. However, in addition to its own signal, a particle receives signals from other beam particles. In the limit of an infinite number of particles, no damping could be achieved; we have Liouville's theorem with constant density of the phase space fluid. For a finite, albeit large number of particles, there remains a residue of the single particle damping which is of practical use in accumulating low phase space density beams of particles such as antiprotons. It was the realization of this fact that led to the invention of stochastic cooling by S. van der Meer in 1968. Since its conception, stochastic cooling has been the subject of much theoretical and experimental work. The earliest experiments were performed at the ISR in 1974, with the subsequent ICE studies firmly establishing the stochastic cooling technique. This work directly led to the design and construction of the Antiproton Accumulator at CERN and the beginnings of p anti p colliding beam physics at the SPS. Experiments in stochastic cooling have been performed at Fermilab in collaboration with LBL, and a design is currently under development for a anti p accumulator for the Tevatron.

  8. Multiobjective Design Optimization of Supersonic Jet Engine in Different Cruise Mach Numbers

    Science.gov (United States)

    Ogawa, Masamichi; Sato, Tetsuya; Kobayashi, Hiroaki; Taguchi, Hideyuki

    The aim of this paper is to apply a multi-objective optimization generic algorithm (MOGA) to the conceptual design of the hypersonic/supersonic vehicles with different cruise Mach number. The pre-cooled turbojet engine is employed as a propulsion system and some engine parameters such as the precooler size, compressor size, compression ratio and fuel type are varied in the analysis. The result shows that the optimum cruise Mach number is about 4 if hydrogen fuel is used. Methane fuel instead of hydrogen reduces the vehicle gross weight by 33% in case of the Mach 2 vehicle.

  9. Dissipation and Heating in Supersonic Hydrodynamic and MHD Turbulence

    CERN Document Server

    Lemaster, M Nicole

    2008-01-01

    We study energy dissipation and heating by supersonic MHD turbulence in molecular clouds using Athena, a new higher-order Godunov code. We analyze the dependence of the saturation amplitude, energy dissipation characteristics, power spectra, sonic scaling, and indicators of intermittency in the turbulence on factors such as the magnetic field strength, driving scale, energy injection rate, and numerical resolution. While convergence in the energies is reached at moderate resolutions, we find that the power spectra require much higher resolutions that are difficult to obtain. In a 1024^3 hydro run, we find a power law relationship between the velocity dispersion and the spatial scale on which it is measured, while for an MHD run at the same resolution we find no such power law. The time-variability and temperature intermittency in the turbulence both show a dependence on the driving scale, indicating that numerically driving turbulence by an arbitrary mechanism may not allow a realistic representation of these...

  10. A very cool cooling system

    CERN Multimedia

    Antonella Del Rosso

    2015-01-01

    The NA62 Gigatracker is a jewel of technology: its sensor, which delivers the time of the crossing particles with a precision of less than 200 picoseconds (better than similar LHC detectors), has a cooling system that might become the precursor to a completely new detector technique.   The 115 metre long vacuum tank of the NA62 experiment. The NA62 Gigatracker (GTK) is composed of a set of three innovative silicon pixel detectors, whose job is to measure the arrival time and the position of the incoming beam particles. Installed in the heart of the NA62 detector, the silicon sensors are cooled down (to about -20 degrees Celsius) by a microfluidic silicon device. “The cooling system is needed to remove the heat produced by the readout chips the silicon sensor is bonded to,” explains Alessandro Mapelli, microsystems engineer working in the Physics department. “For the NA62 Gigatracker we have designed a cooling plate on top of which both the silicon sensor and the...

  11. Experimental observation of Anderson localization in laser-kicked molecular rotors

    Science.gov (United States)

    Bitter, Martin; Milner, Valery

    2016-05-01

    For the first time, the phenomenon of Anderson localization is observed and studied in a system of true quantum kicked rotors. Nitrogen molecules in a supersonic molecular jet are cooled down to 27 K and are rotationally excited by a periodic train of 24 high-intensity femtosecond pulses. Exponential distribution of the molecular angular momentum - the most unambiguous signature of Anderson localization - is measured directly by means of coherent Raman scattering. We demonstrate the suppressed growth of the molecular rotational energy with the number of laser kicks and study the dependence of the localization length on the kick strength. Both timing and amplitude noise in the pulse train is shown to destroy the localization and revive the diffusive growth of angular momentum.

  12. Experimental observation of Anderson localization in laser-kicked molecular rotors

    CERN Document Server

    Bitter, Martin

    2016-01-01

    We observe and study the phenomenon of Anderson localization in a system of true quantum kicked rotors. Nitrogen molecules in a supersonic molecular jet are cooled down to 27~K and are rotationally excited by a periodic train of 24~high-intensity femtosecond pulses. Exponential distribution of the molecular angular momentum - the most unambiguous signature of Anderson localization - is measured directly by means of coherent Raman scattering. We demonstrate the suppressed growth of the molecular rotational energy with the number of laser kicks and study the dependence of the localization length on the kick strength. Both timing and amplitude noise in the pulse train is shown to destroy the localization and revive the diffusive growth of angular momentum.

  13. Development of a water-mist cooling system: A 12,500 Kcal/h air-cooled chiller

    Directory of Open Access Journals (Sweden)

    Chung-Neng Huang

    2015-11-01

    Full Text Available Global warming and energy exhaustion problems are becoming a severe problems, of which energy conservation and carbon reduction are the most critical. Between 40% and 48% of the total electricity used in a building is consumed by air conditioning systems. The development of a supersonic water-misting cooling system with a fuzzy control system is proposed to optimize existing condenser noise, space, and energy consumption, as well as to address problems with cooling capacity resulting from improper control between compressors and condensers. An experimental platform was established for conducting tests, observing cooling efficiencies, and calculating power saving statuses. Comparing the observed cooling efficiency, a temperature difference of 5.4 °C was determined before and after the application; this is significant regarding efficiency. The method produces no pollution or water accumulation. When compared with fixed frequency air-cooled water chillers, an exceptional energy saving of 25% was observed. The newly developed supersonic mist-cooled chiller is an excellent solution to increasing water and electricity fees.

  14. Cooling technique

    Energy Technology Data Exchange (ETDEWEB)

    Salamon, Todd R; Vyas, Brijesh; Kota, Krishna; Simon, Elina

    2017-01-31

    An apparatus and a method are provided. Use is made of a wick structure configured to receive a liquid and generate vapor in when such wick structure is heated by heat transferred from heat sources to be cooled off. A vapor channel is provided configured to receive the vapor generated and direct said vapor away from the wick structure. In some embodiments, heat conductors are used to transfer the heat from the heat sources to the liquid in the wick structure.

  15. Supersonic Turbulent Boundary Layer: DNS and RANS

    Institute of Scientific and Technical Information of China (English)

    XU Jing-Lei; MA Hui-Yang

    2007-01-01

    We assess the performance of a few turbulence models for Reynolds averaged Navier-Stokes (RANS) simulation of supersonic boundary layers, compared to the direct numerical simulations (DNS) of supersonic flat-plate turbulent boundary layers, carried out by Gao et al. [Chin. Phys. Lett. 22 (2005) 1709] and Huang et al. [Sci.Chin. 48 (2005) 614], as well as some available experimental data. The assessment is made for two test cases, with incoming Mach numbers and Reynolds numbers M = 2.25, Re = 365, 000/in, and M = 4.5, Re - 1.7 × 107/m,respectively. It is found that in the first case the prediction of RANS models agrees well with the DNS and the experimental data, while for the second case the agreement of the DNS models with experiment is less satisfactory.The compressibility effect on the RANS models is discussed.

  16. Turbulent Shear Layers in Supersonic Flow

    CERN Document Server

    Smits, Alexander J

    2006-01-01

    A good understanding of turbulent compressible flows is essential to the design and operation of high-speed vehicles. Such flows occur, for example, in the external flow over the surfaces of supersonic aircraft, and in the internal flow through the engines. Our ability to predict the aerodynamic lift, drag, propulsion and maneuverability of high-speed vehicles is crucially dependent on our knowledge of turbulent shear layers, and our understanding of their behavior in the presence of shock waves and regions of changing pressure. Turbulent Shear Layers in Supersonic Flow provides a comprehensive introduction to the field, and helps provide a basis for future work in this area. Wherever possible we use the available experimental work, and the results from numerical simulations to illustrate and develop a physical understanding of turbulent compressible flows.

  17. Control of star formation by supersonic turbulence

    CERN Document Server

    MacLow, M M; Low, Mordecai-Mark Mac; Klessen, Ralf S.

    2004-01-01

    Understanding the formation of stars in galaxies is central to much of modern astrophysics. For several decades it has been thought that stellar birth is primarily controlled by the interplay between gravity and magnetostatic support, modulated by ambipolar diffusion. Recently, however, both observational and numerical work has begun to suggest that support by supersonic turbulence rather than magnetic fields controls star formation. In this review we outline a new theory of star formation relying on the control by turbulence. We demonstrate that although supersonic turbulence can provide global support, it nevertheless produces density enhancements that allow local collapse. Inefficient, isolated star formation is a hallmark of turbulent support, while efficient, clustered star formation occurs in its absence. The consequences of this theory are then explored for both local star formation and galactic scale star formation. (Abstract abbreviated)

  18. Conceptual Design of a Supersonic Jet Engine

    OpenAIRE

    Kareliusson, Joakim; Nordqvist, Melker

    2014-01-01

    This thesis is a response to the request for proposal issued by a joint collaboration between the AIAA Foundation and ASME/IGTI as a student competition to design a new turbofan engine intended for a conceptual supersonic business jet expected to enter service in 2025. Due to the increasing competition in the aircraft industry and the more stringent environmental legislations the new engine is expected to provide a lower fuel burn than the current engine intended for the aircraft to increase ...

  19. Chemically reacting supersonic flow calculation using an assumed PDF model

    Science.gov (United States)

    Farshchi, M.

    1990-01-01

    This work is motivated by the need to develop accurate models for chemically reacting compressible turbulent flow fields that are present in a typical supersonic combustion ramjet (SCRAMJET) engine. In this paper the development of a new assumed probability density function (PDF) reaction model for supersonic turbulent diffusion flames and its implementation into an efficient Navier-Stokes solver are discussed. The application of this model to a supersonic hydrogen-air flame will be considered.

  20. Research of low boom and low drag supersonic aircraft design

    OpenAIRE

    Feng Xiaoqiang; Li Zhanke; Song Bifeng

    2014-01-01

    Sonic boom reduction will be an issue of utmost importance in future supersonic transport, due to strong regulations on acoustic nuisance. The paper describes a new multi-objective optimization method for supersonic aircraft design. The method is developed by coupling Seebass–George–Darden (SGD) inverse design method and multi-objective genetic algorithm. Based on the method, different codes are developed. Using a computational architecture, a conceptual supersonic aircraft design environment...

  1. Supersonic and subsonic measurements of mesospheric ionization.

    Science.gov (United States)

    Hale, L. C.; Nickell, L. C.; Kennedy, B.; Powell, T. A.

    1972-01-01

    An Arcas rocket-parachute system was used at night to compare supersonic and subsonic ionization measurements below 75 km. A hemispherical nose-tip probe was used on ascent and a parachute-borne blunt probe on descent to measure polar conductivities, which were due entirely to positive and negative ions. The velocity of the supersonic probe was Mach 2.5 at 50 km and 1.75 at 70 km; the blunt probe was subsonic below 71 km. Between 65 and 75 km the ratio of negative to positive conductivities (and thus of mobilities) determined by the blunt probe was about 1.2, and it approached 1 below this altitude range. The ratio obtained by the nose-tip probe varied from 1.5 at 75 km to .6 at 65 km, thus indicating a rapid variation of the effects of the shock wave on the sampled ions. The absolute values of positive conductivity measured subsonically and supersonically were essentially identical from 60 to 75 km, indicating that the sampled ions were unchanged by the shock. However, below 60 km the shock apparently 'broke up' the positive ions, as indicated by higher measured conductivities.

  2. Supersonic Jet Excitation using Flapping Injection

    CERN Document Server

    Hafsteinsson, Haukur; Andersson, Niklas; Cuppoletti, Daniel; Gutmark, Ephraim; Prisell, Erik

    2013-01-01

    Supersonic jet noise reduction is important for high speed military aircraft. Lower acoustic levels would reduce structural fatigue leading to longer lifetime of the jet aircraft. It is not solely structural aspects which are of importance, health issues of the pilot and the airfield per- sonnel are also very important, as high acoustic levels may result in severe hearing damage. It remains a major challenge to reduce the overall noise levels of the aircraft, where the supersonic exhaust is the main noise source for near ground operation. Fluidic injection into the supersonic jet at the nozzle exhaust has been shown as a promising method for noise reduction. It has been shown to speed up the mix- ing process of the main jet, hence reducing the kinetic energy level of the jet and the power of the total acoustic radiation. Furthermore, the interaction mechanism between the fluidic injection and the shock structure in the jet exhaust plays a crucial role in the total noise radia- tion. In this study, LES is used...

  3. Supersonic Gas-Liquid Cleaning System

    Science.gov (United States)

    Kinney, Frank

    1996-01-01

    The Supersonic Gas-Liquid Cleaning System Research Project consisted mainly of a feasibility study, including theoretical and engineering analysis, of a proof-of-concept prototype of this particular cleaning system developed by NASA-KSC. The cleaning system utilizes gas-liquid supersonic nozzles to generate high impingement velocities at the surface of the device to be cleaned. The cleaning fluid being accelerated to these high velocities may consist of any solvent or liquid, including water. Compressed air or any inert gas is used to provide the conveying medium for the liquid, as well as substantially reduce the total amount of liquid needed to perform adequate surface cleaning and cleanliness verification. This type of aqueous cleaning system is considered to be an excellent way of conducting cleaning and cleanliness verification operations as replacements for the use of CFC 113 which must be discontinued by 1995. To utilize this particular cleaning system in various cleaning applications for both the Space Program and the commercial market, it is essential that the cleaning system, especially the supersonic nozzle, be characterized for such applications. This characterization consisted of performing theoretical and engineering analysis, identifying desirable modifications/extensions to the basic concept, evaluating effects of variations in operating parameters, and optimizing hardware design for specific applications.

  4. Characteristics of Supersonic Closed Loop with Disk CCMHD Generator

    Science.gov (United States)

    Yamasaki, Hiroyuki; Murakami, Tomoyuki; Okuno, Yoshihiro

    Results of experimental study on performance of the supersonic closed loop with a disk MHD generator are described. The high temperature (> 1900K) argon circulation was carried out successfully during 2.4 hours. The heat gain and loss of argon was investigated, and a large heat loss was found at the diffuser and the exhausting duct although an energy efficiency of recuperator was high. The large heat loss was ascribed to water cooling at the diffuser and the exhausting duct. At the same time, the enhancement of heat transfer coefficient was suggested. The argon temperature and the heat loss calculated under an assumption of four times larger heat transfer coefficient have shown a good agreement with experimental ones. The pressure ratio inside the loop was discussed, and the result has indicated that the total pressure at the upstream of nozzle throat is decided by the total temperature and the mass flow. On the other hand, the total pressure at the downstream is determined by the total mass in the loop and the total pressure at the upstream. The first power generation was carried out, and a good correlation between the load resistance and the Hall voltage was observed. However, the power output remained very small.

  5. Skin Friction and Pressure Measurements in Supersonic Inlets Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Supersonic propulsion systems include internal ducts, and therefore, the flow often includes shock waves, shear layers, vortices, and separated flows. Passive flow...

  6. ATLAS - Liquid Cooling Systems

    CERN Multimedia

    Bonneau, P.

    1998-01-01

    Photo 1 - Cooling Unit - Side View Photo 2 - Cooling Unit - Detail Manifolds Photo 3 - Cooling Unit - Rear View Photo 4 - Cooling Unit - Detail Pump, Heater and Exchanger Photo 5 - Cooling Unit - Detail Pump and Fridge Photo 6 - Cooling Unit - Front View

  7. The Density Variance--Mach Number Relation in Supersonic Turbulence: I. Isothermal, magnetised gas

    CERN Document Server

    Molina, F Z; Federrath, C; Klessen, R S

    2012-01-01

    It is widely accepted that supersonic, magnetised turbulence plays a fundamental role for star formation in molecular clouds. It produces the initial dense gas seeds out of which new stars can form. However, the exact relation between gas compression, turbulent Mach number, and magnetic field strength is still poorly understood. Here, we introduce and test an analytical prediction for the relation between the density variance and the root-mean-square Mach number in supersonic, isothermal, magnetised turbulent flows. We approximate the density and velocity structure of the interstellar medium as a superposition of shock waves. We obtain the density contrast considering the momentum continuity equation for a single magnetised shock and extrapolate this result to the entire cloud. Depending on the field geometry, we then make three different assumptions based on observational and theoretical constraints: B independent of density, B proportional to the root square of the density and B proportional to the density....

  8. Photoelectron photoion molecular beam spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Trevor, D.J.

    1980-12-01

    The use of supersonic molecular beams in photoionization mass spectroscopy and photoelectron spectroscopy to assist in the understanding of photoexcitation in the vacuum ultraviolet is described. Rotational relaxation and condensation due to supersonic expansion were shown to offer new possibilities for molecular photoionization studies. Molecular beam photoionization mass spectroscopy has been extended above 21 eV photon energy by the use of Stanford Synchrotron Radiation Laboratory (SSRL) facilities. Design considerations are discussed that have advanced the state-of-the-art in high resolution vuv photoelectron spectroscopy. To extend gas-phase studies to 160 eV photon energy, a windowless vuv-xuv beam line design is proposed.

  9. Investgation of gas puffing and supersonic molecular beam injection density feedback expriments on EAST*%基于超声分子束和普通充气的聚变等离子体密度反馈实验研究*

    Institute of Scientific and Technical Information of China (English)

    郑星炜; 李建刚; 胡建生; 李加宏; 曹斌; 吴金华

    2013-01-01

    To achieve desirable plasma density control, supersonic molecular beam injection (SMBI) feedback control system has been de-veloped on EAST tokamak recently. The performance of SMBI is compared with that of gas puffing feedback system. The performance of pulse width mode is better than that of pulse amplitude mode when gas puffing is used for density feedback control. In one-day experiment scenario, the variation of gas input and wall retention can be clarified into two stages. In the first stage the retention ratio is as high as 80%-90%, and the gas input is of about the order of 1022. However, in the second stage, the retention ratio is in a range of 50%-70%. The gas input of a single discharge is small and the net wall retention grows slowly. The result of SMBI feedback control experiment is also analyzed. The shorter delay time of SMBI makes it more quickly to feedback control the plasma density. Result shows that, compared with gas puffing, the gas input of SMBI decreaseds ∼ 30% and the wall retention is reduced ∼ 40%. This shows SMBI’s advantage for the long pulse high-density discharges in EAST.%  本文介绍了全超导托卡马克装置 EAST 实验中等离子体密度反馈的方法和结果. EAST 密度反馈采用普通充气(gas puffing)和超声分子束(supersonic molecule beam injection, SMBI)在放电过程中反馈进气,获得稳定、预期的等离子体密度.典型的一天放电实验中,每次放电的充气量和壁滞留的变化可分为两个阶段:第一阶段为初始约20次放电,该阶段充气量非常高且呈指数趋势下降,粒子滞留率为80%-90%,壁滞留迅速上升.第二阶段为随后的约50次放电,该阶段充气量较小且保持稳定,粒子滞留率为50%-70%,壁滞留缓慢上升. SMBI 的加料效率为15%-30%,延迟时间小于5 ms.因此使用 SMBI 进行密度反馈效果优于 gas puffing 反馈,相同条件下前者充气量较后者减少了∼30%,壁滞留减少了∼40%,

  10. Cool visitors

    CERN Multimedia

    2006-01-01

    Pictured, from left to right: Tim Izo (saxophone, flute, guitar), Bobby Grant (tour manager), George Pajon (guitar). What do the LHC and a world-famous hip-hop group have in common? They are cool! On Saturday, 1st July, before their appearance at the Montreux Jazz Festival, three members of the 'Black Eyed Peas' came on a surprise visit to CERN, inspired by Dan Brown's Angels and Demons. At short notice, Connie Potter (Head of the ATLAS secretariat) organized a guided tour of ATLAS and the AD 'antimatter factory'. Still curious, lead vocalist Will.I.Am met CERN physicist Rolf Landua after the concert to ask many more questions on particles, CERN, and the origin of the Universe.

  11. Vibrational Spectroscopy of Laser Cooled CaH

    Science.gov (United States)

    2015-10-28

    Molecular ions trapped in RF Paul traps and sympathetically- cooled with laser - cooled atomic ions have been shown to be a great platform to measure...Approved for public release; distribution is unlimited. Vibrational Spectroscopy of Laser Cooled CaH+ The views, opinions and/or findings contained in...Angeles, CA 90095 -1406 ABSTRACT Vibrational Spectroscopy of Laser Cooled CaH+ Report Title Cold molecules and molecular ions are leading to a renaissance

  12. Low Density Supersonic Decelerator (LDSD) Supersonic Flight Dynamics Test (SFDT) Plume Induced Environment Modelling

    Science.gov (United States)

    Mobley, B. L.; Smith, S. D.; Van Norman, J. W.; Muppidi, S.; Clark, I

    2016-01-01

    Provide plume induced heating (radiation & convection) predictions in support of the LDSD thermal design (pre-flight SFDT-1) Predict plume induced aerodynamics in support of flight dynamics, to achieve targeted freestream conditions to test supersonic deceleration technologies (post-flight SFDT-1, pre-flight SFDT-2)

  13. Investigation on the pressure matching performance of the constant area supersonic-supersonic ejector

    Directory of Open Access Journals (Sweden)

    Chen Jian

    2015-01-01

    Full Text Available The pressure matching performance of the constant area supersonic-supersonic ejector has been studied by varying the primary and secondary Mach numbers. The effect of the primary fluid injection configurations in ejector, namely peripheral and central, has been investigated as well. Schlieren pictures of flow structure in the former part of the mixing duct with different stagnation pressure ratio of the primary and secondary flows have been taken. Pressure ratios of the primary and secondary flows at the limiting condition have been obtained from the results of pressure and optical measurements. Additionally, a computational fluid dynamics analysis has been performed to clarify the physical meaning of the pressure matching performance diagram of the ejector. The obtained results show that the pressure matching performance of the constant area supersonic-supersonic ejector increases with the increase of the secondary Mach number, and the performance decreases slightly with the increase of the primary Mach number. The phenomenon of boundary layer separation induced by shock wave results in weaker pressure matching performance of the central ejector than that of the peripheral one. Furthermore, based on the observations of the experiment, a simplified analytical model has been proposed to predict the limiting pressure ratio, and the predicted values obtained by this model agree well with the experimental data.

  14. High speed titanium coating by Supersonic Laser Deposition

    OpenAIRE

    LUPOI, ROCCO

    2011-01-01

    PUBLISHED The importance of metal coating technologies drives the continuous improvement of metal deposition techniques for application in a wide range of industrial sectors. This work presents the foundations of a new process technology f or the deposition of t itanium coatings on steel tube substrates using supersonic powder streams and impact site laser heating , known as Supersonic Laser Deposition (SLD). M et...

  15. Advanced Noise Abatement Procedures for a Supersonic Business Jet

    Science.gov (United States)

    Berton, Jeffrey J.; Jones, Scott M.; Seidel, Jonathan A.; Huff, Dennis L.

    2017-01-01

    Supersonic civil aircraft present a unique noise certification challenge. High specific thrust required for supersonic cruise results in high engine exhaust velocity and high levels of jet noise during takeoff. Aerodynamics of thin, low-aspect-ratio wings equipped with relatively simple flap systems deepen the challenge. Advanced noise abatement procedures have been proposed for supersonic aircraft. These procedures promise to reduce airport noise, but they may require departures from normal reference procedures defined in noise regulations. The subject of this report is a takeoff performance and noise assessment of a notional supersonic business jet. Analytical models of an airframe and a supersonic engine derived from a contemporary subsonic turbofan core are developed. These models are used to predict takeoff trajectories and noise. Results indicate advanced noise abatement takeoff procedures are helpful in reducing noise along lateral sidelines.

  16. Multiphoton ionization of jet-cooled nickelocene with tunable nanosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Ketkov, Sergey Yu.; Selzle, Heinrich L.; Schlag, Edward W.; Titova, Sofia

    2003-08-15

    Efficient multiphoton ionization of nickelocene molecules in a supersonically cooled molecular beam has been performed for the first time with a nanosecond tunable dye laser operating in the 35,000-cm{sup -1} region which corresponds to the lowest Rydberg transition observed in the one-photon absorption spectrum. The time-of-flight mass spectra obtained show strong signals of intact molecular ions Cp{sub 2}Ni{sup +} (Cp={eta}{sup 5}-C{sub 5}H{sub 5}) and weaker peaks of fragment ions CpNi{sup +}. The conditions have been found for generation of Cp{sub 2}Ni{sup +} as the only ionic product of multiphoton excitation. The ion signal dependence on the laser intensity and the resonance-enhanced multiphoton ionization spectrum measured at the mass of Cp{sub 2}Ni{sup +} testify for saturation of absorption and/or ionization steps at the laser pulse intensities used (2-6 MW cm{sup -2}). Possible mechanisms of multiphoton processes resulting in formation of the ions observed are discussed.

  17. The effects of nitric oxide cooling and the photodissociation of molecular oxygen on the thermosphere/ionosphere system over the Argentine Islands

    Directory of Open Access Journals (Sweden)

    G. D. Wells

    Full Text Available In the past the global, fully coupled, time-dependent mathematical model of the Earth's thermosphere/ionosphere/plasmasphere (CTIP has been unable to reproduce accurately observed values of the maximum plasma frequency, foF2, at extreme geophysical locations such as the Argentine Islands during the summer solstice where the ionosphere remains in sunlight throughout the day. This is probably because the seasonal dependence of thermospheric cooling by 5.3 µm nitric oxide has been neglected and the photodissociation of O2 and heating rate calculations have been over-simplified. Now we have included an up-to-date calculation of the solar EUV and UV thermospheric heating rate, coupled with a new calculation of a diurnally varying O2 photodissociation rate, in the model. Seasonally dependent 5.3 µm nitric oxide cooling is also included. With these important improvements, it is found that model values of foF2 are in substantially better agreement with observation. The height of the F2-peak is reduced throughout the day, but remains within acceptable limits of values derived from observation, except at around 0600 h LT. We also carry out two studies of the sensitivity of the upper atmosphere to changes in the magnitude of nitric oxide cooling and photodissociation rates. We find that hmF2 increases with increased heating, whilst foF2 falls. The converse is true for an increase in the cooling rate. Similarly increasing the photodissociation rate increases both hmF2 and foF2. These changes are explained in terms of changes in the neutral temperature, composition and neutral wind.

  18. Design features of a low-disturbance supersonic wind tunnel for transition research at low supersonic Mach numbers

    Science.gov (United States)

    Wolf, Stephen W. D.; Laub, James A.; King, Lyndell S.; Reda, Daniel C.

    1992-01-01

    A unique, low-disturbance supersonic wind tunnel is being developed at NASA-Ames to support supersonic laminar flow control research at cruise Mach numbers of the High Speed Civil Transport (HSCT). The distinctive design features of this new quiet tunnel are a low-disturbance settling chamber, laminar boundary layers along the nozzle/test section walls, and steady supersonic diffuser flow. This paper discusses these important aspects of our quiet tunnel design and the studies necessary to support this design. Experimental results from an 1/8th-scale pilot supersonic wind tunnel are presented and discussed in association with theoretical predictions. Natural laminar flow on the test section walls is demonstrated and both settling chamber and supersonic diffuser performance is examined. The full-scale wind tunnel should be commissioned by the end of 1993.

  19. Supersonic Jet Interactions in a Plenum Chamber

    Directory of Open Access Journals (Sweden)

    K. M. Venugopal

    2004-07-01

    Full Text Available Understanding thè supersonic jet interactions in a plenum chamber is essential for thè design of hot launch systems. Static tests were conducted in a small-scale rocket motor ioaded with a typical nitramine propellaiit to produce a nozzle exit Mach number of 3. This supersonic jet is made to interact with plenum chambers having both open and closed sides. The distance between thè nozzle exit and thè back piate of plenum chamber are varied from 2. 5 to 7. 0 times thè nozzle exit diameter. The pressure rise in thè plenum chamber was measured using pressure transducers mounted at different locatìons. The pressure-time data were analysed to obtain an insight into thè flow field in thè plenum chamber. The maximum pressure exerted on thè back piate of plenum chamber is about 25-35 per cent. of thè maximum stagnation pressure developed in thè rocket motor. Ten static tests were carried out to obtain thè effect of axial distance between thè nozzle exit and thè plenum chamber back piate, and stagnation pressure in thè rocket motoron thè flow field in thè open-sided and closed-sided plenum chambers configurations.

  20. Numerical simulation of supersonic gap flow.

    Science.gov (United States)

    Jing, Xu; Haiming, Huang; Guo, Huang; Song, Mo

    2015-01-01

    Various gaps in the surface of the supersonic aircraft have a significant effect on airflows. In order to predict the effects of attack angle, Mach number and width-to-depth ratio of gap on the local aerodynamic heating environment of supersonic flow, two-dimensional compressible Navier-Stokes equations are solved by the finite volume method, where convective flux of space term adopts the Roe format, and discretization of time term is achieved by 5-step Runge-Kutta algorithm. The numerical results reveal that the heat flux ratio is U-shaped distribution on the gap wall and maximum at the windward corner of the gap. The heat flux ratio decreases as the gap depth and Mach number increase, however, it increases as the attack angle increases. In addition, it is important to find that chamfer in the windward corner can effectively reduce gap effect coefficient. The study will be helpful for the design of the thermal protection system in reentry vehicles.

  1. Numerical simulation of supersonic gap flow.

    Directory of Open Access Journals (Sweden)

    Xu Jing

    Full Text Available Various gaps in the surface of the supersonic aircraft have a significant effect on airflows. In order to predict the effects of attack angle, Mach number and width-to-depth ratio of gap on the local aerodynamic heating environment of supersonic flow, two-dimensional compressible Navier-Stokes equations are solved by the finite volume method, where convective flux of space term adopts the Roe format, and discretization of time term is achieved by 5-step Runge-Kutta algorithm. The numerical results reveal that the heat flux ratio is U-shaped distribution on the gap wall and maximum at the windward corner of the gap. The heat flux ratio decreases as the gap depth and Mach number increase, however, it increases as the attack angle increases. In addition, it is important to find that chamfer in the windward corner can effectively reduce gap effect coefficient. The study will be helpful for the design of the thermal protection system in reentry vehicles.

  2. Coupling dynamic of twin supersonic jets

    Science.gov (United States)

    Kuo, Ching-Wen; Cluts, Jordan; Samimy, Mo

    2015-11-01

    In a supersonic shock-containing jet, the interaction of large-scale structures in the jet's shear layer with the shock waves generates acoustic waves. The waves propagate upstream, excite the jet initial shear layer instability, establish a feedback loop at certain conditions, and generate screech noise. The screech normally contains different modes of various strengths. Similarly, twin-jet plumes contain screech tones. If the dynamics of the two jet plumes are synchronized, the screech amplitude could be significantly amplified. There is a proposed analytical model in the literature for screech synchronization in twin rectangular jets. This model shows that with no phase difference in acoustic waves arriving at neighboring nozzle lips, twin-jet plumes feature a strong coupling with a significant level of screech tones. In this work the maximum nozzle separation distance for sustained screech synchronization and strong coupling is analytically derived. This model is used with our round twin-jet experiments and the predicted coupling level agrees well with the experimental results. Near-field microphone measurements and schlieren visualization along with the analytical model are used to investigate the coupling mechanisms of twin supersonic jets. Supported by ONR.

  3. Magnetic geometry and particle source drive of supersonic divertor regimes

    Science.gov (United States)

    Bufferand, H.; Ciraolo, G.; Dif-Pradalier, G.; Ghendrih, P.; Tamain, Ph; Marandet, Y.; Serre, E.

    2014-12-01

    We present a comprehensive picture of the mechanisms driving the transition from subsonic to supersonic flows in tokamak plasmas. We demonstrate that supersonic parallel flows into the divertor volume are ubiquitous at low density and governed by the divertor magnetic geometry. As the density is increased, subsonic divertor plasmas are recovered. On detachment, we show the change in particle source can also drive the transition to a supersonic regime. The comprehensive theoretical analysis is completed by simulations in ITER geometry. Such results are essential in assessing the divertor performance and when interpreting measurements and experimental evidence.

  4. The IMF as a function of supersonic turbulence

    CERN Document Server

    Motta, Clio Bertelli; Glover, Simon C O; Klessen, Ralf S; Pasquali, Anna

    2016-01-01

    Recent studies seem to suggest that the stellar initial mass function (IMF) in early-type galaxies might be different from a classical Kroupa or Chabrier IMF, i.e. contain a larger fraction of the total mass in low-mass stars. From a theoretical point of view, supersonic turbulence has been the subject of interest in many analytical theories proposing a strong correlation with the characteristic mass of the core mass function (CMF) in star forming regions, and as a consequence with the stellar IMF. Performing two suites of smoothed particles hydrodynamics (SPH) simulations with different mass resolutions, we aim at testing the effects of variations in the turbulent properties of a dense, star forming molecular cloud on the shape of the system mass function in different density regimes. While analytical theories predict a shift of the peak of the CMF towards lower masses with increasing velocity dispersion of the cloud, we observe in the low-density regime the opposite trend, with high Mach numbers giving rise...

  5. Field Ionization detection of supersonic helium atom beams

    Science.gov (United States)

    Doak, R. B.

    2003-10-01

    Field ionization detectors (FID) may offer near-unity detection efficiency and nanoscale spatial resolution. To date, FID detection of molecular beams has been limited to effusive beams of broad Maxwellian velocity distributions. We report FID measurements on monoenergetic helium beams, including intensity measurements and time-of-flight measurements. The FID tips were carefully prepared and characterized in a field ionization microscope prior to use. With the supersonic helium beam we find a much smaller effective detection area ( 50 sq. nm) than was reported in the effusive helium beam experiments ( 200,000 sq. nm). This suggests that the FID ionization yield depends strongly on energy loss by the impinging atom during its initial collision with the FID surface: Our thermal energy, monoenergetic helium beam atoms likely lose little or no energy upon scattering from the clean tungsten FID surface, allowing the scattered atoms to escape the FID polarization field and therby reducing the ionization yield. To improve signal levels, inelastic scattering might be enhanced by use of lower beam velocities (present in the tails of a Maxwellian) or by adsorbing an overlayer on the FID tip (present at cryogenic tip temperatures). These factors likely explain the higher detection yields measured in the effusive beam experiments.

  6. Comparing Numerical Methods for Isothermal Magnetized Supersonic Turbulence

    Science.gov (United States)

    Kritsuk, Alexei G.; Nordlund, Åke; Collins, David; Padoan, Paolo; Norman, Michael L.; Abel, Tom; Banerjee, Robi; Federrath, Christoph; Flock, Mario; Lee, Dongwook; Li, Pak Shing; Müller, Wolf-Christian; Teyssier, Romain; Ustyugov, Sergey D.; Vogel, Christian; Xu, Hao

    2011-08-01

    Many astrophysical applications involve magnetized turbulent flows with shock waves. Ab initio star formation simulations require a robust representation of supersonic turbulence in molecular clouds on a wide range of scales imposing stringent demands on the quality of numerical algorithms. We employ simulations of supersonic super-Alfvénic turbulence decay as a benchmark test problem to assess and compare the performance of nine popular astrophysical MHD methods actively used to model star formation. The set of nine codes includes: ENZO, FLASH, KT-MHD, LL-MHD, PLUTO, PPML, RAMSES, STAGGER, and ZEUS. These applications employ a variety of numerical approaches, including both split and unsplit, finite difference and finite volume, divergence preserving and divergence cleaning, a variety of Riemann solvers, and a range of spatial reconstruction and time integration techniques. We present a comprehensive set of statistical measures designed to quantify the effects of numerical dissipation in these MHD solvers. We compare power spectra for basic fields to determine the effective spectral bandwidth of the methods and rank them based on their relative effective Reynolds numbers. We also compare numerical dissipation for solenoidal and dilatational velocity components to check for possible impacts of the numerics on small-scale density statistics. Finally, we discuss the convergence of various characteristics for the turbulence decay test and the impact of various components of numerical schemes on the accuracy of solutions. The nine codes gave qualitatively the same results, implying that they are all performing reasonably well and are useful for scientific applications. We show that the best performing codes employ a consistently high order of accuracy for spatial reconstruction of the evolved fields, transverse gradient interpolation, conservation law update step, and Lorentz force computation. The best results are achieved with divergence-free evolution of the

  7. Improved optical techniques for studying sonic and supersonic injection into Mach 3 flow

    Science.gov (United States)

    Buggele, Alvin E.; Seasholtz, Richard G.

    1997-11-01

    Filtered Rayleigh Scattering and shadowgraph flow visualization were used to characterize the penetration of helium or moist air injected transversely at several pressures to a Mach 3 flow in the NASA Lewis 3.81 inch by 10 inch continuous flow supersonic wind tunnel. This work is in support of the LOX augmented nuclear thermal rocket program. The present study used an injection-seeded, frequency doubled Nd:YAG pulsed laser to illuminate a transverse section of the injectant plume. Rayleigh scattered light was passed through an iodine absorption cell to suppress stray laser light and was imaged onto a cooled CCD camera. The scattering was based on condensation of water vapor in the injectant flow. Results are presented for various configurations of sonic and supersonic injector designs mounted primarily in the floor of the tunnel. Injectors studied include a single 0.25 inch diameter hole, five 0.112 inch diameter holes on 0.177 inch spacing, and a 7 degree half angle wedge. High speed shadowgraph flow visualization images were obtained with several video camera systems. Roof and floor static pressure data are presented several ways for the three configurations of injection designs with and without helium and/or air injection into Mach 3 flow.

  8. Gas turbine engine with supersonic compressor

    Science.gov (United States)

    Roberts, II, William Byron; Lawlor, Shawn P.

    2015-10-20

    A gas turbine engine having a compressor section using blades on a rotor to deliver a gas at supersonic conditions to a stator. The stator includes one or more of aerodynamic ducts that have converging and diverging portions for deceleration of the gas to subsonic conditions and to deliver a high pressure gas to combustors. The aerodynamic ducts include structures for changing the effective contraction ratio to enable starting even when designed for high pressure ratios, and structures for boundary layer control. In an embodiment, aerodynamic ducts are provided having an aspect ratio of two to one (2:1) or more, when viewed in cross-section orthogonal to flow direction at an entrance to the aerodynamic duct.

  9. Linear stability analysis of supersonic axisymmetric jets

    Directory of Open Access Journals (Sweden)

    Zhenhua Wan

    2014-01-01

    Full Text Available Stabilities of supersonic jets are examined with different velocities, momentum thicknesses, and core temperatures. Amplification rates of instability waves at inlet are evaluated by linear stability theory (LST. It is found that increased velocity and core temperature would increase amplification rates substantially and such influence varies for different azimuthal wavenumbers. The most unstable modes in thin momentum thickness cases usually have higher frequencies and azimuthal wavenumbers. Mode switching is observed for low azimuthal wavenumbers, but it appears merely in high velocity cases. In addition, the results provided by linear parabolized stability equations show that the mean-flow divergence affects the spatial evolution of instability waves greatly. The most amplified instability waves globally are sometimes found to be different from that given by LST.

  10. Aeroacoustic properties of supersonic elliptic jets

    Science.gov (United States)

    Kinzie, Kevin W.; McLaughlin, Dennis K.

    1999-09-01

    The aerodynamic and acoustic properties of supersonic elliptic and circular jets are experimentally investigated. The jets are perfectly expanded with an exit Mach number of approximately 1.5 and are operated in the Reynolds number range of 25 000 to 50 000. The reduced Reynolds number facilitates the use of conventional hot-wire anemometry and a glow discharge excitation technique which preferentially excites the varicose or flapping modes in the jets. In order to simulate the high-velocity and low-density effects of heated jets, helium is mixed with the air jets. This allows the large-scale structures in the jet shear layer to achieve a high enough convective velocity to radiate noise through the Mach wave emission process.

  11. Atomic physics experiments with cooled stored ions

    Science.gov (United States)

    Schuch, Reinhold

    2004-10-01

    This presentation contains examples of recent atomic physics experiments with stored and cooled ion beams from the CRYRING facility in Stockholm. One of these experiments uses the high luminosity of a cooled MeV proton beam in a He COLTRIMS apparatus (COLd supersonic He gas-jet Target for Recoil Ion Momentum Spectroscopy) for measuring correlation effects in transfer ionization. Another class of experiments exploits the cold electron beam available in the CRYRING electron cooler and cooled heavy-ion beams for recombination experiments. A section concerns the still rather open question of the puzzling recombination enhancement over the radiative recombination theory. Dielectronic resonances at meV-eV energy are measured with a resolution in the order of 10-3-10-2 eV with highly charged ions stored at several hundreds of MeV kinetic energy in the ring. These resonances provide a serious challenge to theories for describing correlation, relativistic, QED effects, and isotope shifts in highly ionized ions. Applications of recombination rates with complex highly charged ions for fusion and astrophysical plasmas are shown.

  12. Atomic physics experiments with cooled stored ions

    Energy Technology Data Exchange (ETDEWEB)

    Schuch, Reinhold E-mail: schuch@physto.se

    2004-10-11

    This presentation contains examples of recent atomic physics experiments with stored and cooled ion beams from the CRYRING facility in Stockholm. One of these experiments uses the high luminosity of a cooled MeV proton beam in a He COLTRIMS apparatus (COLd supersonic He gas-jet Target for Recoil Ion Momentum Spectroscopy) for measuring correlation effects in transfer ionization. Another class of experiments exploits the cold electron beam available in the CRYRING electron cooler and cooled heavy-ion beams for recombination experiments. A section concerns the still rather open question of the puzzling recombination enhancement over the radiative recombination theory. Dielectronic resonances at meV-eV energy are measured with a resolution in the order of 10{sup -3}-10{sup -2} eV with highly charged ions stored at several hundreds of MeV kinetic energy in the ring. These resonances provide a serious challenge to theories for describing correlation, relativistic, QED effects, and isotope shifts in highly ionized ions. Applications of recombination rates with complex highly charged ions for fusion and astrophysical plasmas are shown.

  13. ARBITRARY INTERACTION OF PLANE SUPERSONIC FLOWS

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2015-11-01

    Full Text Available Subject of study.We consider the Riemann problem for parameters at collision of two plane flows at a certain angle. The problem is solved in the exact statement. Most cases of interference, both stationary and non-stationary gas-dynamic discontinuities, followed by supersonic flows can be reduced to the problem of random interaction of two supersonic flows. Depending on the ratio of the parameters in the flows, outgoing discontinuities turn out to be shock waves, or rarefactionwaves. In some cases, there is no solution at all. It is important to know how to find the domain of existence for the relevant decisions, as the type of shock-wave structures in these domains is known in advance. The Riemann problem is used in numerical methods such as the method of Godunov. As a rule, approximate solution is used, known as the Osher solution, but for a number of problems with a high precision required, solution of this problem needs to be in the exact statement. Main results.Domains of existence for solutions with different types of shock-wave structure have been considered. Boundaries of existence for solutions with two outgoing shock waves are analytically defined, as well as with the outgoing shock wave and rarefaction wave. We identify the area of Mach numbers and angles at which the flows interact and there is no solution. Specific flows with two outgoing rarefaction waves are not considered. Practical significance. The results supplement interference theory of stationary gas-dynamic discontinuities and can be used to develop new methods of numerical calculation with extraction of discontinuities.

  14. Supersonic Wing Optimization Using SpaRibs

    Science.gov (United States)

    Locatelli, David; Mulani, Sameer B.; Liu, Qiang; Tamijani, Ali Y.; Kapania, Rakesh K.

    2014-01-01

    This research investigates the advantages of using curvilinear spars and ribs, termed SpaRibs, to design a supersonic aircraft wing-box in comparison to the use of classic design concepts that employ straight spars and ribs. The objective is to achieve a more efficient load-bearing mechanism and to passively control the deformation of the structure under the flight loads. Moreover, the use of SpaRibs broadens the design space and allows for natural frequencies and natural mode shape tailoring. The SpaRibs concept is implemented in a new optimization MATLAB-based framework referred to as EBF3SSWingOpt. This optimization scheme performs both the sizing and the shaping of the internal structural elements, connecting the optimizer with the analysis software. The shape of the SpaRibs is parametrically defined using the so called Linked Shape method. Each set of SpaRibs is placed in a one by one square domain of the natural space. The set of curves is subsequently transformed in the physical space for creating the wing structure geometry layout. The shape of each curve of each set is unique; however, mathematical relations link the curvature in an effort to reduce the number of design variables. The internal structure of a High Speed Commercial Transport aircraft concept developed by Boeing is optimized subjected to stress, subsonic flutter and supersonic flutter constraints. The results show that the use of the SpaRibs allows for the reduction of the aircraft's primary structure weight without violating the constraints. A weight reduction of about 15 percent is observed.

  15. 1 Ft. x 1 Ft. Supersonic Wind Tunnel, Bldg. 37

    Data.gov (United States)

    Federal Laboratory Consortium — The 1- by 1-Foot Supersonic Wind Tunnel (1x), located in the Engine Research Building, is one of the most active test facilities at the Glenn Research Center. Used...

  16. Supersonic Jet Noise: Main Sources and Reduction Methodologies

    Directory of Open Access Journals (Sweden)

    Mohammadreza Azimi

    2014-07-01

    Full Text Available The large velocity ratio and the presence of Shocks in the exhaust plume from low bypass engines or supersonic jetliners cause jet noise to be dominant component of overall aircraft noise, and therefore is an important issue in design of the next generation of civil supersonic transport. Jet noise reduction technology also has application in the design of highperformance tactical aircraft. Jet noise is of particular concern on aircraft carriers where it is necessary for deck crew to be in relatively close proximity to the aircraft at takeoff and landing. In this paper, a brief discussion about supersonic jet noise sources and a review of the main passive technologies employed for the reduction of supersonic jet noise are presented.

  17. THERMAL AND AERODYNAMIC PERFORMANCES OF THE SUPERSONIC MOTION

    Directory of Open Access Journals (Sweden)

    Dejan P Ninković

    2010-01-01

    Full Text Available Generally speaking, Mach number of 4 can be taken as a boundary value for transition from conditions for supersonic, into the area of hypersonic flow, distinguishing two areas: area of supersonic in which the effects of the aerodynamic heating can be neglected and the area of hypersonic, in which the thermal effects become dominant. This paper presents the effects in static and dynamic areas, as well as presentation of G.R.O.M. software for determination of the values of aerodynamic derivatives, which was developed on the basis of linearized theory of supersonic flow. Validation of developed software was carried out through different types of testing, proving its usefulness for engineering practice in the area of supersonic wing aerodynamic loading calculations, even at high Mach numbers, with dominant thermal effects.

  18. Direct Connect Supersonic Combustion Facility (Research Cell 22)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: RC22 is a continuous-flow, direct-connect supersonic-combustion research facility that is capable of simulating flight conditions from Mach 3.0 to Mach...

  19. Entropy Minimization Design Approach of Supersonic Internal Passages

    Directory of Open Access Journals (Sweden)

    Jorge Sousa

    2015-08-01

    Full Text Available Fluid machinery operating in the supersonic regime unveil avenues towards more compact technology. However, internal supersonic flows are associated with high aerodynamic and thermal penalties, which usually prevent their practical implementation. Indeed, both shock losses and the limited operational range represent particular challenges to aerodynamic designers that should be taken into account at the initial phase of the design process. This paper presents a design methodology for supersonic passages based on direct evaluations of the velocity field using the method of characteristics and computation of entropy generation across shock waves. This meshless function evaluation tool is then coupled to an optimization scheme, based on evolutionary algorithms that minimize the entropy generation across the supersonic passage. Finally, we assessed the results with 3D Reynolds Averaged Navier Stokes calculations.

  20. Hybrid radiator cooling system

    Science.gov (United States)

    France, David M.; Smith, David S.; Yu, Wenhua; Routbort, Jules L.

    2016-03-15

    A method and hybrid radiator-cooling apparatus for implementing enhanced radiator-cooling are provided. The hybrid radiator-cooling apparatus includes an air-side finned surface for air cooling; an elongated vertically extending surface extending outwardly from the air-side finned surface on a downstream air-side of the hybrid radiator; and a water supply for selectively providing evaporative cooling with water flow by gravity on the elongated vertically extending surface.

  1. Oxygen Absorption in Cooling Flows.

    Science.gov (United States)

    Buote

    2000-04-01

    The inhomogeneous cooling flow scenario predicts the existence of large quantities of gas in massive elliptical galaxies, groups, and clusters that have cooled and dropped out of the flow. Using spatially resolved, deprojected X-ray spectra from the ROSAT PSPC, we have detected strong absorption over energies approximately 0.4-0.8 keV intrinsic to the central approximately 1&arcmin; of the galaxy NGC 1399, the group NGC 5044, and the cluster A1795. These systems have among the largest nearby cooling flows in their respective classes and low Galactic columns. Since no excess absorption is indicated for energies below approximately 0.4 keV, the most reasonable model for the absorber is warm, collisionally ionized gas with T=105-106 K in which ionized states of oxygen provide most of the absorption. Attributing the absorption only to ionized gas reconciles the large columns of cold H and He inferred from Einstein and ASCA with the lack of such columns inferred from ROSAT and also is consistent with the negligible atomic and molecular H inferred from H i and CO observations of cooling flows. The prediction of warm ionized gas as the product of mass dropout in these and other cooling flows can be verified by Chandra and X-Ray Multimirror Mission.

  2. Heat transfer capability simulation of high-temperature heat pipe in supersonic vehicle leading edge applications

    Directory of Open Access Journals (Sweden)

    Donghuan Liu

    2016-04-01

    Full Text Available A numerical method is proposed to determine the heat transfer capability of the high-temperature heat pipe and the stagnation temperature with supersonic vehicle leading edge applications. The finite element method is employed here to perform the temperature field simulation. Without considering the heat transfer limitations of the heat pipe, such as capillary limit and sonic limit, both numerical and experimental results indicate that equivalent high thermal conductivity method is a reasonable way to simulate the heat transfer capability of the high-temperature heat pipe in preliminary design of a heat-pipe-cooled leading edge. Several important parameters’ effects on the thermal protection performance are also numerically investigated.

  3. A cryogenic supersonic nozzle apparatus to study homogeneous nucleation of Ar and other simple molecules.

    Science.gov (United States)

    Sinha, Somnath; Laksmono, Hartawan; Wyslouzil, Barbara E

    2008-11-01

    We present a supersonic nozzle apparatus to study homogeneous nucleation of argon and other simple molecules. Experiments can be conducted with pure condensable vapor or with condensable vapor-carrier gas mixtures. The flow through the nozzle is continuous, and expansions typically start at temperatures T(0) in the range of 100tube and fin heat exchanger by evaporating liquid nitrogen on the tube side. The nozzle sidewalls are also cooled with liquid nitrogen to maintain them at a temperature approximately 20 K higher than the stagnation temperature. Static pressure measurements detect the onset of condensation, and the other properties of the flow are derived by integrating the diabatic flow equations. We present sample experimental results for pure argon where at the onset of condensation, temperatures T(on) range from 47.5

  4. Review and prospect of supersonic business jet design

    Science.gov (United States)

    Sun, Yicheng; Smith, Howard

    2017-04-01

    This paper reviews the environmental issues and challenges appropriate to the design of supersonic business jets (SSBJs). There has been a renewed, worldwide interest in developing an environmentally friendly, economically viable and technologically feasible supersonic transport aircraft. A historical overview indicates that the SSBJ will be the pioneer for the next generation of supersonic airliners. As a high-end product itself, the SSBJ will likely take a market share in the future. The mission profile appropriate to this vehicle is explored considering the rigorous environmental constraints. Mitigation of the sonic boom and improvements aerodynamic efficiency in flight are the most challenging features of civil supersonic transport. Technical issues and challenges associated with this type of aircraft are identified, and methodologies for the SSBJ design are discussed. Due to the tightly coupled issues, a multidisciplinary design, analysis and optimization environment is regarded as the essential approach to the creation of a low-boom low-drag supersonic aircraft. Industrial and academic organizations have an interest in this type of vehicle are presented. Their investments in SSBJ design will hopefully get civil supersonic transport back soon.

  5. Computational and experimental investigation of supersonic convection over a laser heated target

    Science.gov (United States)

    Marineau, Eric C.

    This research concerns the development and validation of simulation of the beam-target interaction to determine the target temperature distribution as a function of time for a given target geometry, surface radiation intensity and free stream flow condition. The effect of a turbulent supersonic flow was investigated both numerically and experimentally. Experiments were in the Virginia Tech supersonic wind tunnel with a Mach 4 nozzle, ambient total temperature, total pressure of 160 psi and Reynolds number of 5x107/m. The target consisted of a 6.35 mm stainless steel plate painted at black. The target was irradiated with a 300 Watt continuous beam Ytterbium fiber laser generating a 4 mm Gaussian beam at 1.08 micron 10 cm from the leading edge where a 4 mm turbulent boundary layer prevailed. An absorbed laser power of 65, 81, 101, 120 Watts was used leading to a maximum heat flux between 1035 to 1910 W/cm 2. The target surface and backside temperature was measured using a mid-wave infrared camera. The backside temperature was also measured using eight type-K thermocouples. Two tests are made, one with the flow-on and the other with the flow-off. For the flow-on case, the laser is turned on after the tunnel starts and the flow reaches a steady state. For the flow-off case, the plate is heated at the same power but without the supersonic flow. The cooling effect is seen by subtracting the flow-off temperature from the flow-on temperature. This temperature subtraction is useful in cancelling the bias errors such that the overall uncertainty is significantly reduced. A new conjugate heat transfer algorithm was implemented in the GASP solver and validated by predicting the temperature distribution inside a cooled nozzle wall. The conjugate heat transfer algorithm was used to simulate the experiments at 81 and 65 Watts. Most computations were performed using the Spalart-Allmaras turbulence model on a 280; 320 cell grid. A grid convergence study was performed. At 65 Watts

  6. A Numerical Comparison of Symmetric and Asymmetric Supersonic Wind Tunnels

    Science.gov (United States)

    Clark, Kylen D.

    Supersonic wind tunnels are a vital aspect to the aerospace industry. Both the design and testing processes of different aerospace components often include and depend upon utilization of supersonic test facilities. Engine inlets, wing shapes, and body aerodynamics, to name a few, are aspects of aircraft that are frequently subjected to supersonic conditions in use, and thus often require supersonic wind tunnel testing. There is a need for reliable and repeatable supersonic test facilities in order to help create these vital components. The option of building and using asymmetric supersonic converging-diverging nozzles may be appealing due in part to lower construction costs. There is a need, however, to investigate the differences, if any, in the flow characteristics and performance of asymmetric type supersonic wind tunnels in comparison to symmetric due to the fact that asymmetric configurations of CD nozzle are not as common. A computational fluid dynamics (CFD) study has been conducted on an existing University of Michigan (UM) asymmetric supersonic wind tunnel geometry in order to study the effects of asymmetry on supersonic wind tunnel performance. Simulations were made on both the existing asymmetrical tunnel geometry and two axisymmetric reflections (of differing aspect ratio) of that original tunnel geometry. The Reynolds Averaged Navier Stokes equations are solved via NASAs OVERFLOW code to model flow through these configurations. In this way, information has been gleaned on the effects of asymmetry on supersonic wind tunnel performance. Shock boundary layer interactions are paid particular attention since the test section integrity is greatly dependent upon these interactions. Boundary layer and overall flow characteristics are studied. The RANS study presented in this document shows that the UM asymmetric wind tunnel/nozzle configuration is not as well suited to producing uniform test section flow as that of a symmetric configuration, specifically one

  7. Liquid-Cooled Garment

    Science.gov (United States)

    1977-01-01

    A liquid-cooled bra, offshoot of Apollo moon suit technology, aids the cancer-detection technique known as infrared thermography. Water flowing through tubes in the bra cools the skin surface to improve resolution of thermograph image.

  8. Data center cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Chainer, Timothy J; Dang, Hien P; Parida, Pritish R; Schultz, Mark D; Sharma, Arun

    2015-03-17

    A data center cooling system may include heat transfer equipment to cool a liquid coolant without vapor compression refrigeration, and the liquid coolant is used on a liquid cooled information technology equipment rack housed in the data center. The system may also include a controller-apparatus to regulate the liquid coolant flow to the liquid cooled information technology equipment rack through a range of liquid coolant flow values based upon information technology equipment temperature thresholds.

  9. Stationary flow conditions in pulsed supersonic beams.

    Science.gov (United States)

    Christen, Wolfgang

    2013-10-21

    We describe a generally applicable method for the experimental determination of stationary flow conditions in pulsed supersonic beams, utilizing time-resolved electron induced fluorescence measurements of high pressure jet expansions of helium. The detection of ultraviolet photons from electronically excited helium emitted very close to the nozzle exit images the valve opening behavior-with the decided advantage that a photon signal is not affected by beam-skimmer and beam-residual gas interactions; it thus allows to conclusively determine those operation parameters of a pulsed valve that yield complete opening. The studies reveal that a "flat-top" signal, indicating constant density and commonly considered as experimental criterion for continuous flow, is insufficient. Moreover, translational temperature and mean terminal flow velocity turn out to be significantly more sensitive in testing for the equivalent behavior of a continuous nozzle source. Based on the widely distributed Even-Lavie valve we demonstrate that, in principle, it is possible to achieve quasi-continuous flow conditions even with fast-acting valves; however, the two prerequisites are a minimum pulse duration that is much longer than standard practice and previous estimates, and a suitable tagging of the appropriate beam segment.

  10. Supersonic Jet Noise Reduction Using Microjets

    Science.gov (United States)

    Gutmark, Ephraim; Cuppoletti, Dan; Malla, Bhupatindra

    2013-11-01

    Fluidic injection for jet noise reduction involves injecting secondary jets into a primary jet to alter the noise characteristics of the primary jet. A major challenge has been determining what mechanisms are responsible for noise reduction due to varying injector designs, injection parameters, and primary jets. The current study provides conclusive results on the effect of injector angle and momentum ux ratio on the acoustics and shock structure of a supersonic Md = 1.56 jet. It is shown that the turbulent mixing noise scales primarily with the injector momentum flux ratio. Increasing the injector momentum flux ratio increases streamwise vorticity generation and reduces peak turbulence levels. It is found that the shock-related noise components are most affected by the interaction of the shocks from the injectors with the primary shock structure of the jet. Increasing momentum flux ratio causes shock noise reduction until a limit where shock noise increases again. It is shown that the shock noise components and mixing noise components are reduced through fundamentally different mechanisms and maximum overall noise reduction is achieved by balancing the reduction of both components.

  11. Coherent structures in a supersonic complex nozzle

    Science.gov (United States)

    Magstadt, Andrew; Berry, Matthew; Glauser, Mark

    2016-11-01

    The jet flow from a complex supersonic nozzle is studied through experimental measurements. The nozzle's geometry is motivated by future engine designs for high-performance civilian and military aircraft. This rectangular jet has a single plane of symmetry, an additional shear layer (referred to as a wall jet), and an aft deck representative of airframe integration. The core flow operates at a Mach number of Mj , c = 1 . 6 , and the wall jet is choked (Mj , w = 1 . 0). This high Reynolds number jet flow is comprised of intense turbulence levels, an intricate shock structure, shear and boundary layers, and powerful corner vortices. In the present study, stereo PIV measurements are simultaneously sampled with high-speed pressure measurements, which are embedded in the aft deck, and far-field acoustics in the anechoic chamber at Syracuse University. Time-resolved schlieren measurements have indicated the existence of strong flow events at high frequencies, at a Strouhal number of St = 3 . 4 . These appear to result from von Kàrmàn vortex shedding within the nozzle and pervade the entire flow and acoustic domain. Proper orthogonal decomposition is applied on the current data to identify coherent structures in the jet and study the influence of this vortex street. AFOSR Turbulence and Transition Program (Grant No. FA9550-15-1-0435) with program managers Dr. I. Leyva and Dr. R. Ponnappan.

  12. Accretion of Supersonic Winds on Boson Stars

    CERN Document Server

    Gracia-Linares, M

    2016-01-01

    We present the evolution of a supersonic wind interacting with a Boson Star (BS) and compare the resulting wind density profile with that of the shock cone formed when the wind is accreted by a non-rotating Black Hole (BH) of the same mass. The physical differences between these accretors are that a BS, unlike a BH has no horizon, it does not have a mechanical surface either and thus the wind is expected to trespass the BS. Despite these conditions, on the BS space-time the gas achieves a stationary flux with the gas accumulating in a high density elongated structure comparable to the shock cone formed behind a BH. The highest density resides in the center of the BS whereas in the case of the BH it is found on the downstream part of the BH near the event horizon. The maximum density of the gas is smaller in the BS than in the BH case. Our results indicate that the highest density of the wind is more similar on the BS to that on the BH when the BS has high self-interaction, when it is more compact and when the...

  13. Particle Streak Velocimetry of Supersonic Nozzle Flows

    Science.gov (United States)

    Willits, J. D.; Pourpoint, T. L.

    2016-01-01

    A novel velocimetry technique to probe the exhaust flow of a laboratory scale combustor is being developed. The technique combines the advantages of standard particle velocimetry techniques and the ultra-fast imaging capabilities of a streak camera to probe high speed flows near continuously with improved spatial and velocity resolution. This "Particle Streak Velocimetry" technique tracks laser illuminated seed particles at up to 236 picosecond temporal resolution allowing time-resolved measurement of one-dimensional flows exceeding 2000 m/s as are found in rocket nozzles and many other applications. Developmental tests with cold nitrogen have been performed to validate and troubleshoot the technique with supersonic flows of much lower velocity and without background noise due to combusting flow. Flow velocities on the order of 500 m/s have been probed with titanium dioxide particles and a continuous-wave laser diode. Single frame images containing multiple streaks are analyzed to find the average slope of all incident particles corresponding to the centerline axial flow velocity. Long term objectives for these tests are correlation of specific impulse to theoretical combustion predictions and direct comparisons between candidate green fuels and the industry standard, monomethylhydrazine, each tested under identical conditions.

  14. Supersonic collisions between two gas streams

    CERN Document Server

    Lee, H M; Ryu, D; Lee, Hyung Mok; Kang, Hyesung; Ryu, Dongsu

    1995-01-01

    A star around a massive black hole can be disrupted tidally by the gravity of the black hole. Then, its debris may form a precessing stream which may even collide with itself. In order to understand the dynamical effects of the stream-stream collision on the eventual accretion of the stellar debris onto the black hole, we have studied how gas flow behaves when the outgoing stream collides supersonically with the incoming stream. We have investigated the problem analytically with one-dimensional plane-parallel streams and numerically with more realistic three-dimensional streams. A shock formed around the contact surface converts the bulk of the orbital streaming kinetic energy into thermal energy. In three-dimensional simulations, the accumulated hot post-shock gas then expands adiabatically and drives another shock into the low density ambient region. Through this expansion, thermal energy is converted back to the kinetic energy associated with the expanding motion. Thus, in the end, only a small fraction of...

  15. Drag Force Anemometer Used in Supersonic Flow

    Science.gov (United States)

    Fralick, Gustave C.

    1998-01-01

    To measure the drag on a flat cantilever beam exposed transversely to a flow field, the drag force anemometer (beam probe) uses strain gauges attached on opposite sides of the base of the beam. This is in contrast to the hot wire anemometer, which depends for its operation on the variation of the convective heat transfer coefficient with velocity. The beam probe retains the high-frequency response (up to 100 kHz) of the hot wire anemometer, but it is more rugged, uses simpler electronics, is relatively easy to calibrate, is inherently temperature compensated, and can be used in supersonic flow. The output of the probe is proportional to the velocity head of the flow, 1/2 rho u(exp 2) (where rho is the fluid density and u is the fluid velocity). By adding a static pressure tap and a thermocouple to measure total temperature, one can determine the Mach number, static temperature, density, and velocity of the flow.

  16. Supersonic Magnetic Flows in the Quiet Sun

    CERN Document Server

    Borrero, J M; Schlichenmaier, R; Schmidt, W; Berkefeld, T; Solanki, S K; Bonet, J A; Iniesta, J C del Toro; Domingo, V; Barthol, P; Gandorfer, A

    2012-01-01

    In this contribution we describe some recent observations of high-speed magnetized flows in the quiet Sun granulation. These observations were carried out with the Imaging Magnetograph eXperiment (IMaX) onboard the stratospheric balloon {\\sc Sunrise}, and possess an unprecedented spatial resolution and temporal cadence. These flows were identified as highly shifted circular polarization (Stokes $V$) signals. We estimate the LOS velocity responsible for these shifts to be larger than 6 km s$^{-1}$, and therefore we refer to them as {\\it supersonic magnetic flows}. The average lifetime of the detected events is 81.3 s and they occupy an average area of about 23\\,000 km$^2$. Most of the events occur within granular cells and correspond therefore to upflows. However some others occur in intergranular lanes or bear no clear relation to the convective velocity pattern. We analyze a number of representative examples and discuss them in terms of magnetic loops, reconnection events, and convective collapse.

  17. External-Compression Supersonic Inlet Design Code

    Science.gov (United States)

    Slater, John W.

    2011-01-01

    A computer code named SUPIN has been developed to perform aerodynamic design and analysis of external-compression, supersonic inlets. The baseline set of inlets include axisymmetric pitot, two-dimensional single-duct, axisymmetric outward-turning, and two-dimensional bifurcated-duct inlets. The aerodynamic methods are based on low-fidelity analytical and numerical procedures. The geometric methods are based on planar geometry elements. SUPIN has three modes of operation: 1) generate the inlet geometry from a explicit set of geometry information, 2) size and design the inlet geometry and analyze the aerodynamic performance, and 3) compute the aerodynamic performance of a specified inlet geometry. The aerodynamic performance quantities includes inlet flow rates, total pressure recovery, and drag. The geometry output from SUPIN includes inlet dimensions, cross-sectional areas, coordinates of planar profiles, and surface grids suitable for input to grid generators for analysis by computational fluid dynamics (CFD) methods. The input data file for SUPIN and the output file from SUPIN are text (ASCII) files. The surface grid files are output as formatted Plot3D or stereolithography (STL) files. SUPIN executes in batch mode and is available as a Microsoft Windows executable and Fortran95 source code with a makefile for Linux.

  18. Stochastic cooling in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Brennan,J.M.; Blaskiewicz, M. M.; Severino, F.

    2009-05-04

    After the success of longitudinal stochastic cooling of bunched heavy ion beam in RHIC, transverse stochastic cooling in the vertical plane of Yellow ring was installed and is being commissioned with proton beam. This report presents the status of the effort and gives an estimate, based on simulation, of the RHIC luminosity with stochastic cooling in all planes.

  19. The IMF as a function of supersonic turbulence

    Science.gov (United States)

    Bertelli Motta, C.; Clark, P. C.; Glover, S. C. O.; Klessen, R. S.; Pasquali, A.

    2016-11-01

    Recent studies seem to suggest that the stellar initial mass function (IMF) in early-type galaxies might be different from a classical Kroupa or Chabrier IMF, i.e. contain a larger fraction of the total mass in low-mass stars. From a theoretical point of view, supersonic turbulence has been the subject of interest in many analytical theories proposing a strong correlation with the characteristic mass of the core mass function (CMF) in star-forming regions, and as a consequence with the stellar IMF. Performing two suites of smoothed particle hydrodynamics (SPH) simulations with different mass resolutions, we aim at testing the effects of variations in the turbulent properties of a dense, star-forming molecular cloud on the shape of the system mass function in different density regimes. While analytical theories predict a shift of the peak of the CMF towards lower masses with increasing velocity dispersion of the cloud, we observe in the low-density regime the opposite trend, with high Mach numbers giving rise to a top-heavy mass distribution. For the high-density regime we do not find any trend correlating the Mach number with the characteristic mass of the resulting IMF, implying that the dynamics of protostellar accretion discs and fragmentation on small scales is not strongly affected by turbulence driven at the scale of the cloud. Furthermore, we suggest that a significant fraction of dense cores are disrupted by turbulence before stars can be formed in their interior through gravitational collapse. Although this particular study has limitations in its numerical resolution, we suggest that our results, along with those from other studies, cast doubt on the turbulent fragmentation models on the IMF that simply map the CMF to the IMF.

  20. Laser Desorption Supersonic Jet Spectroscopy of Hydrated Tyrosine

    Science.gov (United States)

    Oba, Hikari; Shimozono, Yoko; Ishiuchi, Shun-Ichi; Fujii, Masaaki; Carcabal, Pierre

    2013-06-01

    The structure of tyrosine (tyr) consists of amino-acid chain and phenol, and it has roughly two possible binding sites for water, amino-acid site and phenolic OH site. Investigating how water molecule binds to tyr will give fundamental information for hydrations of peptide and protein. Resonance enhanced multi photon ionization (REMPI) spectrum of tyr-water 1:1 cluster has already been reported by de Vries and co-workers, however, no analysis on the hydrated structures has been reported. In the REMPI spectrum, two clusters of bands are observed; one appears at ˜35600 cm^{-1} energy region which is the almost same with 0-0 transitions of tyr monomer, and another is observed at ˜300 cm^{-1} lower than the former. Based on the electronic transition energy of phenylalanine and the hydrated clusters, the former is expected to be derived from a structure that water binds to amino acid site. On the other hand, it is plausibly predicted that the latter originates from a structure that water binds to phenolic OH group, because the electronic transition of mono hydrated phenol is ˜300 cm^{-1} red-shifted from the monomer. We applied IR dip spectroscopy which can measure conformer selective IR spectra to the tyr-(H_{2}O)_{1} clusters by using laser desorption supersonic jet technique to confirm the assignments. Especially in the phenolic OH bound isomer, it was found that the intra molecular hydrogen bond within amino-acid chain, which is far from the water molecule and cannot interact directly with each other, is strengthened by the hydration. A. Abio-Riziq et al., J. Phys. Chem. A, 115, 6077 (2011). Y. Shimozono, et al., Phys. Chem. Chem. Phys., (2013) DOI: 10.1039/c3cp43573c. T. Ebata et al., Phys. Chem. Chem. Phys., 8, 4783 (2006). T. Watanabe et al., J. Chem. Phys., 105, 408 (1996).

  1. Laser cooling of solids

    OpenAIRE

    Nemova, Galina

    2009-01-01

    Parallel to advances in laser cooling of atoms and ions in dilute gas phase, which has progressed immensely, resulting in physics Nobel prizes in 1997 and 2001, major progress has recently been made in laser cooling of solids. I compare the physical nature of the laser cooling of atoms and ions with that of the laser cooling of solids. I point out all advantages of this new and very promising area of laser physics. Laser cooling of solids (optical refrigeration) at the present time can be lar...

  2. Jet Cooled Rotational Studies of Dipeptides

    Science.gov (United States)

    Cabezas, C.; Mata, M. Varela S.; López, J. C.; Alonso, J. L.

    2011-06-01

    Rotational spectra of Gly-Pro and Pro-Gly dipeptides have been examined with laser ablation molecular beam Fourier transform microwave (LA-MB-FTMW) spectroscopy. Three conformers for Gly-Pro and one for Pro-Gly have been unequivocally identified in the supersonic expansion by the comparison of the experimental rotational and 14N (I=1) nuclear quadrupole coupling constants with those predicted by ab initio methods. The quadrupole hyperfine structure of two 14N nuclei has been totally resolved and it allows to experimentally characterize the main intramolecular forces which stabilize the assigned conformers. The biomimetic molecule Ac-Ala-NH_2 has been also studied. The C_7 and C_5 peptide conformations (intramolecularly hydrogen-bonded seven- or five-membered cycle, respectively) have been unequivocally identified in the supersonic expansion. The ability to identify peptide conformations suggest that it soon may be possible to explore the structures of larger peptides using LA-MB-FTMW spectroscopy. J. L. Alonso, C. Pérez, M. E. Sanz, J. C. López, S. Blanco, Phys. Chem. Chem. Phys. 11,617-627 (2009)and references therein

  3. The Inviscid Stability of Supersonic Flow Past Heated or Cooled Axisymmetric Bodies

    Science.gov (United States)

    1990-11-01

    the development environment, then for the reuser to obtain a copy of the component, a variety of options exist. The librarian may send it to the... reuser on a floppy disk or magnetic tape, or the component may be downloaded. This all depends on what resources are available to the project manage: and...

  4. Threshold ionization spectroscopic investigation of supersonic jet-cooled, laser-desorbed Tryptophan

    Science.gov (United States)

    Taherkhani, Mehran; Armentano, Antonio; Černý, Jiří; Müller-Dethlefs, Klaus

    2016-07-01

    Tryptophan (Trp) was studied by two-colour Photoionization Efficiency (PIE) and Mass Analysed Threshold Ionization (MATI) spectroscopy using a laser desorption apparatus. Conformer A of Trp was excited into the S1 state (34,878 cm-1) and the second laser was scanned around the D0 cation ground and the D1 excited state. No ionization signal into the D0 state could be found, but a clear threshold was observed for the D1 state with an ionization energy of 66,704 ± 3 cm-1 (8.27 eV). This observation is explained in terms of the electronic configurations of the S1 and cationic states.

  5. Dispersion of Own Frequency of Ion-Dipole by Supersonic Transverse Wave in Solid

    Directory of Open Access Journals (Sweden)

    Minasyan V.

    2010-10-01

    Full Text Available First, we predict an existence of transverse electromagnetic field formed by supersonic transverse wave in solid. This electromagnetic wave acquires frequency and speed of sound, and it propagates along of direction propagation of supersonic wave. We also show that own frequency of ion-dipole depends on frequency of supersonic transverse wave.

  6. Simulation of underexpanded supersonic jet flows with chemical reactions

    Directory of Open Access Journals (Sweden)

    Fu Debin

    2014-06-01

    Full Text Available To achieve a detailed understanding of underexpanded supersonic jet structures influenced by afterburning and other flow conditions, the underexpanded turbulent supersonic jet with and without combustions are investigated by computational fluid dynamics (CFD method. A program based on a total variation diminishing (TVD methodology capable of predicting complex shocks is created to solve the axisymmetric expanded Navier–Stokes equations containing transport equations of species. The finite-rate ratio model is employed to handle species sources in chemical reactions. CFD solutions indicate that the structure of underexpanded jet is typically influenced by the pressure ratio and afterburning. The shock reflection distance and maximum value of Mach number in the first shock cell increase with pressure ratio. Chemical reactions for the rocket exhaust mostly exist in the mixing layer of supersonic jet flows. This tends to reduce the intensity of shocks existing in the jet, responding to the variation of thermal parameters.

  7. Simulation of underexpanded supersonic jet flows with chemical reactions

    Institute of Scientific and Technical Information of China (English)

    Fu Debin; Yu Yong; Niu Qinglin

    2014-01-01

    To achieve a detailed understanding of underexpanded supersonic jet structures influenced by afterburning and other flow conditions, the underexpanded turbulent supersonic jet with and without combustions are investigated by computational fluid dynamics (CFD) method. A program based on a total variation diminishing (TVD) methodology capable of predicting complex shocks is created to solve the axisymmetric expanded Navier-Stokes equations containing transport equations of species. The finite-rate ratio model is employed to handle species sources in chemical reactions. CFD solutions indicate that the structure of underexpanded jet is typically influenced by the pressure ratio and afterburning. The shock reflection distance and maximum value of Mach number in the first shock cell increase with pressure ratio. Chemical reactions for the rocket exhaust mostly exist in the mixing layer of supersonic jet flows. This tends to reduce the intensity of shocks existing in the jet, responding to the variation of thermal parameters.

  8. The Turbulent Dynamo in Highly Compressible Supersonic Plasmas

    CERN Document Server

    Federrath, Christoph; Bovino, Stefano; Schleicher, Dominik R G

    2014-01-01

    The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly-compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early Universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024^3 cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = nu/eta = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm >= 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm_crit = 129 (+43, -31), showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present a...

  9. Study of the shock structure of supersonic, dual, coaxial, jets

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K. H.; Lee, J. H.; Kim, H. D. [Andong National Univ., Andong (Korea, Republic of)

    2001-07-01

    The shock structure of supersonic, dual, coaxial jet is experimentally investigated. Eight different kinds of coaxial, dual nozzles are employed to observe the major features of the near field shock structure of the supersonic, coaxial, dual jets. Four convergent-divergent supersonic nozzles having the Mach number of 2.0 and 3.0, and are used to compare the coaxial jet flows discharging from two sonic nozzles. The primary pressure ratio is changed in the range between 4.0 and 10.0 and the assistant jet pressure ratio from 1.0 to 4.0. The results obtained show that the impinging angle, nozzle geometry and pressure ratio significantly affect the near field shock structure, Mach disk location and Mach disk diameter. The annular shock system is found depending the assistant and primary jet pressure ratios.

  10. Hypersonic Engine Leading Edge Experiments in a High Heat Flux, Supersonic Flow Environment

    Science.gov (United States)

    Gladden, Herbert J.; Melis, Matthew E.

    1994-01-01

    A major concern in advancing the state-of-the-art technologies for hypersonic vehicles is the development of an aeropropulsion system capable of withstanding the sustained high thermal loads expected during hypersonic flight. Three aerothermal load related concerns are the boundary layer transition from laminar to turbulent flow, articulating panel seals in high temperature environments, and strut (or cowl) leading edges with shock-on-shock interactions. A multidisciplinary approach is required to address these technical concerns. A hydrogen/oxygen rocket engine heat source has been developed at the NASA Lewis Research Center as one element in a series of facilities at national laboratories designed to experimentally evaluate the heat transfer and structural response of the strut (or cowl) leading edge. A recent experimental program conducted in this facility is discussed and related to cooling technology capability. The specific objective of the experiment discussed is to evaluate the erosion and oxidation characteristics of a coating on a cowl leading edge (or strut leading edge) in a supersonic, high heat flux environment. Heat transfer analyses of a similar leading edge concept cooled with gaseous hydrogen is included to demonstrate the complexity of the problem resulting from plastic deformation of the structures. Macro-photographic data from a coated leading edge model show progressive degradation over several thermal cycles at aerothermal conditions representative of high Mach number flight.

  11. a Highly-Integrated Supersonic-Jet Fourier Transform Microwave Spectrometer

    Science.gov (United States)

    Gou, Qian; Feng, Gang; Grabow, Jens-Uwe

    2017-06-01

    A highly integrated supersonic-jet Fourier-transform microwave spectrometer of coaxially oriented beam-resonator arrangement (COBRA) type, covering 2-20GHz, has been recently built at Chongqing University, China. Built up almost entirely in an NI PXIe chassis, we take the advantage of the NI PXIe-5451 Dual-channel arbitrary waveform generator and the PXIe-5654 RF signal generator to create a spectrometer with wobbling capacity for fast resonator tuning. Based on the I/Q modulation, associate with PXI control and sequence boards built at the Leibniz Universitat Hannover, the design of the spectrometer is much simpler and very compact. The Fabry-Pérot resonator is semi-confocal with a spherical reflector of 630 mm diameter and a radius of 900 mm curvature and one circulator plate reflector of 630 mm diameter. The vacuum is effectuated by a three-stage mechanical (two-stage rotary vane and roots booster) pump at the fore line of a DN630 ISO-F 20000 L/s oil-diffusion pump. The supersonic-jet expansion is pulsed by a general valve Series 9 solenoid valve which is controlled by a general valve IOTA one driver governed by the experiment-sequence generation. First molecular examples to illustrate the performance of the new setup will include OCS and CF_3CHFCl.

  12. Numerical study on the generation of a planar supersonic gas-jet

    Energy Technology Data Exchange (ETDEWEB)

    Putignano, M., E-mail: massimilianoputignano@quasar-group.org [Cockcroft Institute, Daresbury Laboratory, Warrington (United Kingdom); University of Liverpool, Liverpool (United Kingdom); Welsch, C.P. [University of Liverpool, Liverpool (United Kingdom)

    2012-03-01

    Planar supersonic gas-jets are valuable tools for different applications such as state of the art molecular spectroscopy and accelerator beam instrumentation; however, the details of their expansion and generation have not yet been analyzed extensively, despite numerous studies addressing these same questions for the simpler case of the axis-symmetric jet. In this paper, we investigate numerically the generation and evolution of planar supersonic gas-jets, extending the optimization studies done for axis-symmetric jets and focusing in particular on applications in accelerator beam instrumentation. We introduce a set of dedicated quality factors and use them to investigate the effects of changes to the geometry and thermodynamic state of the nozzle-skimmer system used to generate the planar jet. This analysis leads to an innovative, optimized nozzle-skimmer system design, which features advantages in terms of planar jet quality when compared to traditional setups. The proposed design also gives the possibility to modify, by variation of the thermodynamic quantities alone, the gas-jet characteristics in a wide range, including jet splitting and local density modulation. Density profiles of the generated jets are plotted for different parameter set.

  13. Supersonic stall flutter of high-speed fans

    Science.gov (United States)

    Adamczyk, J. J.; Stevans, W.; Jutras, R.

    1981-01-01

    An analytical model is proposed for predicting the onset of supersonic stall bending flutter in high-speed rotors. The analysis is based on a modified two-dimensional, compressible, unsteady actuator disk theory. The stability boundary predicted by the analysis is shown to be in good agreement with the measured boundary of a high speed fan. The prediction that the flutter mode would be a forward traveling wave sensitive to wheel speed and aerodynamic loading is confirmed by experimental measurements. In addition, the analysis shows that reduced frequency and dynamic head also play a significant role in establishing the supersonic stall bending flutter boundary of an unshrouded fan.

  14. The impact of emerging technologies on an advanced supersonic transport

    Science.gov (United States)

    Driver, C.; Maglieri, D. J.

    1986-01-01

    The effects of advances in propulsion systems, structure and materials, aerodynamics, and systems on the design and development of supersonic transport aircraft are analyzed. Efficient propulsion systems with variable-cycle engines provide the basis for improved propulsion systems; the propulsion efficienies of supersonic and subsonic engines are compared. Material advances consist of long-life damage-tolerant structures, advanced material development, aeroelastic tailoring, and low-cost fabrication. Improvements in the areas of aerodynamics and systems are examined. The environmental problems caused by engine emissions, airport noise, and sonic boom are studied. The characteristics of the aircraft designed to include these technical advances are described.

  15. Continuing Validation of Computational Fluid Dynamics for Supersonic Retropropulsion

    Science.gov (United States)

    Schauerhamer, Daniel Guy; Trumble, Kerry A.; Kleb, Bil; Carlson, Jan-Renee; Edquist, Karl T.

    2011-01-01

    A large step in the validation of Computational Fluid Dynamics (CFD) for Supersonic Retropropulsion (SRP) is shown through the comparison of three Navier-Stokes solvers (DPLR, FUN3D, and OVERFLOW) and wind tunnel test results. The test was designed specifically for CFD validation and was conducted in the Langley supersonic 4 x4 Unitary Plan Wind Tunnel and includes variations in the number of nozzles, Mach and Reynolds numbers, thrust coefficient, and angles of orientation. Code-to-code and code-to-test comparisons are encouraging and possible error sources are discussed.

  16. Subsonic and Supersonic Jet Noise Calculations Using PSE and DNS

    Science.gov (United States)

    Balakumar, P.; Owis, Farouk

    1999-01-01

    Noise radiated from a supersonic jet is computed using the Parabolized Stability Equations (PSE) method. The evolution of the instability waves inside the jet is computed using the PSE method and the noise radiated to the far field from these waves is calculated by solving the wave equation using the Fourier transform method. We performed the computations for a cold supersonic jet of Mach number 2.1 which is excited by disturbances with Strouhal numbers St=.2 and .4 and the azimuthal wavenumber m=l. Good agreement in the sound pressure level are observed between the computed and the measured (Troutt and McLaughlin 1980) results.

  17. Molecular beam chemiluminescence studies of the NO + O/sub 3/ reaction and modeling of global NO/sub 2/ distribution

    Energy Technology Data Exchange (ETDEWEB)

    Kowalczyk, M.

    1980-11-01

    The results of a crossed molecular beam study of the chemiluminescent reaction NO + 0/sub 3/ ..-->.. NO/sub 2/ + 0/sub 2/ are discussed. The chemiluminescence as a function of collision energy and an excitation function were obtained using a translationally cooled supersonic NO beam. An investigation into the role of the internal energy states using an effusive NO beam and a supersonic O/sub 3/ beam has been presented. The results show that chemiluminescence enhancement occurs when high and low temperature NO experiments are compared. The role that other energy modes may have is discussed. The observed enhancement is consistent with the concept that the chemiluminescence cross section increases with NO molecular rotation for low J states. The second part discusses the role of NO/sub 2/ in preserving a global ozone balance. NO/sub 2/ vertical profiles based on Noxon's (1979) column measurements were derived. The method of instantaneous rates was used to calculate the rate of ozone production and destruction by O/sub x/ and NO/sub x/ on a grid that covered the entire globe. The results were presented as a function of altitude and latitude in contour plots.

  18. Stochastic cooling in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Brennan J. M.; Blaskiewicz, M.; Mernick, K.

    2012-05-20

    The full 6-dimensional [x,x'; y,y'; z,z'] stochastic cooling system for RHIC was completed and operational for the FY12 Uranium-Uranium collider run. Cooling enhances the integrated luminosity of the Uranium collisions by a factor of 5, primarily by reducing the transverse emittances but also by cooling in the longitudinal plane to preserve the bunch length. The components have been deployed incrementally over the past several runs, beginning with longitudinal cooling, then cooling in the vertical planes but multiplexed between the Yellow and Blue rings, next cooling both rings simultaneously in vertical (the horizontal plane was cooled by betatron coupling), and now simultaneous horizontal cooling has been commissioned. The system operated between 5 and 9 GHz and with 3 x 10{sup 8} Uranium ions per bunch and produces a cooling half-time of approximately 20 minutes. The ultimate emittance is determined by the balance between cooling and emittance growth from Intra-Beam Scattering. Specific details of the apparatus and mathematical techniques for calculating its performance have been published elsewhere. Here we report on: the method of operation, results with beam, and comparison of results to simulations.

  19. The Formation and Destruction of Molecular Clouds and Galactic Star Formation

    CERN Document Server

    Inutsuka, Shu-ichiro; Iwasaki, Kazunari; Hosokawa, Takashi

    2015-01-01

    We describe an overall picture of galactic-scale star formation. Recent high-resolution magneto-hydrodynamical simulations of two-fluid dynamics with cooling/heating and thermal conduction have shown that the formation of molecular clouds requires multiple episodes of supersonic compression. This finding enables us to create a scenario in which molecular clouds form in interacting shells or bubbles on a galactic scale. First we estimate the ensemble-averaged growth rate of molecular clouds over a timescale larger than a million years. Next we perform radiation hydrodynamics simulations to evaluate the destruction rate of magnetized molecular clouds by the stellar FUV radiation. We also investigate the resultant star formation efficiency within a cloud which amounts to a low value (a few percent) if we adopt the power-law exponent -2.5 for the mass distribution of stars in the cloud. We finally describe the time evolution of the mass function of molecular clouds over a long timescale (>1Myr) and discuss the st...

  20. Instability of Supersonic Cold Streams Feeding Galaxies I: Linear Kelvin-Helmholtz Instability with Body Modes

    Science.gov (United States)

    Mandelker, Nir; Padnos, Dan; Dekel, Avishai; Birnboim, Yuval; Burkert, Andreas; Krumholz, Mark R.; Steinberg, Elad

    2016-09-01

    Massive galaxies at high redshift are predicted to be fed from the cosmic web by narrow, dense streams of cold gas that penetrate through the hot medium encompassed by a stable shock near the virial radius of the dark-matter halo. Our long-term goal is to explore the heating and dissipation rate of the streams and their fragmentation and possible breakup, in order to understand how galaxies are fed, and how this affects their star-formation rate and morphology. We present here the first step, where we analyze the linear Kelvin-Helmholtz instability (KHI) of a cold, dense slab or cylinder in 3D flowing supersonically through a hot, dilute medium. The current analysis is limited to the adiabatic case with no gravity. By analytically solving the linear dispersion relation, we find a transition from a dominance of the familiar rapidly growing surface modes in the subsonic regime to more slowly growing body modes in the supersonic regime. The system is parametrized by three parameters: the density contrast between stream and medium, the Mach number of stream velocity with respect to the medium, and the stream width with respect to the halo virial radius. A realistic choice for these parameters places the streams near the mode transition, with the KHI exponential-growth time in the range 0.01-10 virial crossing times for a perturbation wavelength comparable to the stream width. We confirm our analytic predictions with idealized hydrodynamical simulations. Our linear estimates thus indicate that KHI may be effective in the evolution of streams before they reach the galaxy. More definite conclusions await the extension of the analysis to the nonlinear regime and the inclusion of cooling, thermal conduction, the halo potential well, self-gravity and magnetic fields.

  1. Instability of supersonic cold streams feeding galaxies - I. Linear Kelvin-Helmholtz instability with body modes

    Science.gov (United States)

    Mandelker, Nir; Padnos, Dan; Dekel, Avishai; Birnboim, Yuval; Burkert, Andreas; Krumholz, Mark R.; Steinberg, Elad

    2016-12-01

    Massive galaxies at high redshift are predicted to be fed from the cosmic web by narrow, dense streams of cold gas that penetrate through the hot medium encompassed by a stable shock near the virial radius of the dark-matter halo. Our long-term goal is to explore the heating and dissipation rate of the streams and their fragmentation and possible breakup, in order to understand how galaxies are fed, and how this affects their star formation rate and morphology. We present here the first step, where we analyse the linear Kelvin-Helmholtz instability (KHI) of a cold, dense slab or cylinder in 3D flowing supersonically through a hot, dilute medium. The current analysis is limited to the adiabatic case with no gravity. By analytically solving the linear dispersion relation, we find a transition from a dominance of the familiar rapidly growing surface modes in the subsonic regime to more slowly growing body modes in the supersonic regime. The system is parametrized by three parameters: the density contrast between stream and medium, the Mach number of stream velocity with respect to the medium and the stream width with respect to the halo virial radius. A realistic choice for these parameters places the streams near the mode transition, with the KHI exponential-growth time in the range 0.01-10 virial crossing times for a perturbation wavelength comparable to the stream width. We confirm our analytic predictions with idealized hydrodynamical simulations. Our linear estimates thus indicate that KHI may be effective in the evolution of streams before they reach the galaxy. More definite conclusions await the extension of the analysis to the non-linear regime and the inclusion of cooling, thermal conduction, the halo potential well, self-gravity and magnetic fields.

  2. Cooling by Thermodynamic Induction

    Science.gov (United States)

    Patitsas, S. N.

    2017-03-01

    A method is described for cooling conductive channels to below ambient temperature. The thermodynamic induction principle dictates that the electrically biased channel will cool if the electrical conductance decreases with temperature. The extent of this cooling is calculated in detail for both cases of ballistic and conventional transport with specific calculations for carbon nanotubes and conventional metals, followed by discussions for semiconductors, graphene, and metal-insulator transition systems. A theorem is established for ballistic transport stating that net cooling is not possible. For conventional transport, net cooling is possible over a broad temperature range, with the range being size-dependent. A temperature clamping scheme for establishing a metastable nonequilibrium stationary state is detailed and followed with discussion of possible applications to on-chip thermoelectric cooling in integrated circuitry and quantum computer systems.

  3. Cooling by Thermodynamic Induction

    Science.gov (United States)

    Patitsas, S. N.

    2016-11-01

    A method is described for cooling conductive channels to below ambient temperature. The thermodynamic induction principle dictates that the electrically biased channel will cool if the electrical conductance decreases with temperature. The extent of this cooling is calculated in detail for both cases of ballistic and conventional transport with specific calculations for carbon nanotubes and conventional metals, followed by discussions for semiconductors, graphene, and metal-insulator transition systems. A theorem is established for ballistic transport stating that net cooling is not possible. For conventional transport, net cooling is possible over a broad temperature range, with the range being size-dependent. A temperature clamping scheme for establishing a metastable nonequilibrium stationary state is detailed and followed with discussion of possible applications to on-chip thermoelectric cooling in integrated circuitry and quantum computer systems.

  4. Radiant Floor Cooling Systems

    DEFF Research Database (Denmark)

    Olesen, Bjarne W.

    2008-01-01

    In many countries, hydronic radiant floor systems are widely used for heating all types of buildings such as residential, churches, gymnasiums, hospitals, hangars, storage buildings, industrial buildings, and smaller offices. However, few systems are used for cooling.This article describes a floor...... cooling system that includes such considerations as thermal comfort of the occupants, which design parameters will influence the cooling capacity and how the system should be controlled. Examples of applications are presented....

  5. Sympathetic cooling of molecules with laser-cooled atoms

    Science.gov (United States)

    Hudson, Eric

    2014-05-01

    Cooling molecules through collisions with laser-cooled atoms is an attractive route to ultracold, ground state molecules. The technique is simple, applicable to a wide class of molecules, and does not require molecule specific laser systems. Particularly suited to this technique are charged molecules, which can be trapped indefinitely, even at room temperature, and undergo strong, short-ranged collisions with ultracold atoms. In this talk, I will focus on recent efforts to use the combination of a magneto-optical trap (MOT) and an ion trap, dubbed the MOTion trap, to produce cold, ground state diatomic charged molecules. The low-energy internal structure of these diatomic molecules, e.g. the electric dipole moment and vibrational, rotational, and Ω-doublet levels, presents a host of opportunities for advances in quantum simulation, precision measurement, cold chemistry, and quantum information. Excitingly, recent proof-of-principle experiments have demonstrated that the MOTion trap is extremely efficient at cooling the vibrational motion of molecular ions. Supported by the ARO and NSF.

  6. Initial Cooling Experiment (ICE)

    CERN Multimedia

    Photographic Service

    1978-01-01

    In 1977, in a record-time of 9 months, the magnets of the g-2 experiment were modified and used to build a proton/antiproton storage ring: the "Initial Cooling Experiment" (ICE). It served for the verification of the cooling methods to be used for the "Antiproton Project". Stochastic cooling was proven the same year, electron cooling followed later. Also, with ICE the experimental lower limit for the antiproton lifetime was raised by 9 orders of magnitude: from 2 microseconds to 32 hours. For its previous life as g-2 storage ring, see 7405430. More on ICE: 7711282, 7809081, 7908242.

  7. High energy electron cooling

    Energy Technology Data Exchange (ETDEWEB)

    Parkhomchuk, V. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation)

    1997-09-01

    High energy electron cooling requires a very cold electron beam. The questions of using electron cooling with and without a magnetic field are presented for discussion at this workshop. The electron cooling method was suggested by G. Budker in the middle sixties. The original idea of the electron cooling was published in 1966. The design activities for the NAP-M project was started in November 1971 and the first run using a proton beam occurred in September 1973. The first experiment with both electron and proton beams was started in May 1974. In this experiment good result was achieved very close to theoretical prediction for a usual two component plasma heat exchange.

  8. Power electronics cooling apparatus

    Science.gov (United States)

    Sanger, Philip Albert; Lindberg, Frank A.; Garcen, Walter

    2000-01-01

    A semiconductor cooling arrangement wherein a semiconductor is affixed to a thermally and electrically conducting carrier such as by brazing. The coefficient of thermal expansion of the semiconductor and carrier are closely matched to one another so that during operation they will not be overstressed mechanically due to thermal cycling. Electrical connection is made to the semiconductor and carrier, and a porous metal heat exchanger is thermally connected to the carrier. The heat exchanger is positioned within an electrically insulating cooling assembly having cooling oil flowing therethrough. The arrangement is particularly well adapted for the cooling of high power switching elements in a power bridge.

  9. Final Report for the Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2030 to 2035 Period, N+3 Supersonic Program

    Science.gov (United States)

    Morgenstern, John; Norstrud, Nicole; Stelmack, Marc; Skoch, Craig

    2010-01-01

    The N+3 Final Report documents the work and progress made by Lockheed Martin Aeronautics in response to the NASA sponsored program "N+3 NRA Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2030 to 2035 Period." The key technical objective of this effort was to generate promising supersonic concepts for the 2030 to 2035 timeframe and to develop plans for maturing the technologies required to make those concepts a reality. The N+3 program is aligned with NASA's Supersonic Project and is focused on providing alternative system-level solutions capable of overcoming the efficiency, environmental, and performance barriers to practical supersonic flight

  10. Research of low boom and low drag supersonic aircraft design

    Institute of Scientific and Technical Information of China (English)

    Feng Xiaoqiang; Li Zhanke; Song Bifeng

    2014-01-01

    Sonic boom reduction will be an issue of utmost importance in future supersonic trans-port, due to strong regulations on acoustic nuisance. The paper describes a new multi-objective optimization method for supersonic aircraft design. The method is developed by coupling Seebass-George-Darden (SGD) inverse design method and multi-objective genetic algorithm. Based on the method, different codes are developed. Using a computational architecture, a concep-tual supersonic aircraft design environment (CSADE) is constructed. The architecture of CSADE includes inner optimization level and out optimization level. The low boom configuration is gener-ated in inner optimization level by matching the target equivalent area distribution and actual equivalent area distribution. And low boom/low drag configuration is generated in outer optimiza-tion level by using NSGA-II multi-objective genetic algorithm to optimize the control parameters of SGD method and aircraft shape. Two objective functions, low sonic boom and low wave drag, are considered in CSADE. Physically reasonable Pareto solutions are obtained from the present optimization. Some supersonic aircraft configurations are selected from Pareto front and the optimization results indicate that the swept forward wing configuration has benefits in both sonic boom reduction and wave drag reduction. The results are validated by using computational fluid dynamics (CFD) analysis.

  11. Titanium honeycomb structure. [for supersonic aircraft wing structure

    Science.gov (United States)

    Davis, R. A.; Elrod, S. D.; Lovell, D. T.

    1972-01-01

    A brazed titanium honeycomb sandwich system for supersonic transport wing cover panels provides the most efficient structure spanwise, chordwise, and loadwise. Flutter testing shows that high wing stiffness is most efficient in a sandwich structure. This structure also provides good thermal insulation if liquid fuel is carried in direct contact with the wing structure in integral fuel tanks.

  12. SIMULATION OF THE LASER DISCHARGE IN A SUPERSONIC GAS FLOW

    Directory of Open Access Journals (Sweden)

    Tropina, A. A.

    2013-06-01

    Full Text Available A heat model of the laser discharge in a supersonic turbulent gas flow has been developed. A numerical investigation of the error of the method of velocity measurements, which is based on the nitrogen molecules excitation, has been carried out. It is shown that fast gas heating by the discharge causes the velocity profiles deformation.

  13. 76 FR 30231 - Civil Supersonic Aircraft Panel Discussion

    Science.gov (United States)

    2011-05-24

    ... for attendees. The purpose of the meeting is to raise public awareness of the continuing technological... joint meeting of the 159th Acoustical Society of America and NOISE-CON 2010 in Baltimore, Maryland 21202. The purpose of these meetings is to raise public awareness on advances in supersonic technology,...

  14. Experimental study of mixing enhancement using pylon in supersonic flow

    Science.gov (United States)

    Vishwakarma, Manmohan; Vaidyanathan, Aravind

    2016-01-01

    The Supersonic Combustion Ramjet (SCRAMJET) engine has been recognized as one of the most promising air breathing propulsion system for the supersonic/hypersonic flight mission requirements. Mixing and combustion of fuel inside scramjet engine is one of the major challenging tasks. In the current study the main focus has been to increase the penetration and mixing of the secondary jet inside the test chamber at supersonic speeds. In view of this, experiments are conducted to evaluate the effect of pylon on the mixing of secondary jet injection into supersonic mainstream flow at Mach 1.65. Two different pylons are investigated and the results are compared with those obtained by normal injection from a flat plate. The mixing studies are performed by varying the height of the pylon while keeping all other parameters the same. The study mainly focused on analyzing the area of spread and penetration depth achieved by different injection schemes based on the respective parameters. The measurements involved Mie scattering visualization and the flow features are analyzed using Schlieren images. The penetration height and spread area are the two parameters that are used for analyzing and comparing the performance of the pylons. It is observed that the secondary jet injection carried out from behind the big pylon resulted in maximum penetration and spread area of the jet as compared to the small pylon geometry. Moreover it is also evident that for obtaining maximum spreading and penetration of the jet, the same needs to be achieved at the injection location.

  15. NASA F-16XL supersonic laminar flow control program overview

    Science.gov (United States)

    Fischer, Michael C.

    1992-01-01

    The viewgraphs and discussion of the NASA supersonic laminar flow control program are provided. Successful application of laminar flow control to a High Speed Civil Transport (HSCT) offers significant benefits in reductions of take-off gross weight, mission fuel burn, cruise drag, structural temperatures, engine size, emissions, and sonic boom. The ultimate economic success of the proposed HSCT may depend on the successful adaption of laminar flow control, which offers the single most significant potential improvements in lift drag ratio (L/D) of all the aerodynamic technologies under consideration. The F-16XL Supersonic Laminar Flow Control (SLFC) Experiment was conceived based on the encouraging results of in-house and NASA supported industry studies to determine if laminar flow control is feasible for the HSCT. The primary objective is to achieve extensive laminar flow (50-60 percent chord) on a highly swept supersonic wing. Data obtained from the flight test will be used to validate existing Euler and Navier Stokes aerodynamic codes and transition prediction boundary layer stability codes. These validated codes and developed design methodology will be delivered to industry for their use in designing supersonic laminar flow control wings. Results from this experiment will establish preliminary suction system design criteria enabling industry to better size the suction system and develop improved estimates of system weight, fuel volume loss due to wing ducting, turbocompressor power requirements, etc. so that benefits and penalties can be more accurately assessed.

  16. Multiresolution analysis of density fluctuation in supersonic mixing layer

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Due to the difficulties in measuring supersonic density field, the multiresolution analysis of supersonic mixing layer based on experimental images is still a formidable challenge. By utilizing the recently developed nanoparticle based planar laser scattering method, the density field of a supersonic mixing layer was measured at high spatiotemporal resolution. According to the dynamic behavior of coherent structures, the multiresolution characteristics of density fluctuation signals and density field images were studied based on Taylor’s hypothesis of space-time conversion and wavelet analysis. The wavelet coefficients reflect the characteristics of density fluctuation signals at different scales, and the detailed coefficients reflect the differences of approximation at adjacent levels. The density fluctuation signals of supersonic mixing layer differ from the periodic sine signal and exhibit similarity to the fractal Koch signal. The similarity at different scales reveals the fractal characteristic of mixing layer flowfield. The two-dimensional wavelet decomposition and reconstruction of density field images extract the approximate and detailed signals at different scales, which effectively resolve the characteristic structures of the flowfield at different scales.

  17. A flamelet model for turbulent diffusion combustion in supersonic flow

    Institute of Scientific and Technical Information of China (English)

    LEE; ChunHian

    2010-01-01

    In order to develop a turbulent diffusion combustion model for supersonic flow, the physical argument of the extension of the flamelet model to supersonic flow was presented, and the flow field of a hydrogen/air diffusion combustion generated by axisymmetric supersonic jets was numerically simulated by employing the flamelet model. Using the experimental data, value of the model coefficient of scalar dissipation in the flamelet model was revised specifically for supersonic flow. The computational results of the modified flamelet model were compared with the experimental results, and it was indicated that the precision of the modified flamelet model was satisfying. Based on the numerical results and flamelet theory, the influence mechanisms of turbulence fluctuation on the average state equation and chemical reaction rate were studied for the first time. It was found that the fluctuation correlation of species mass fractions and temperature has little effect on the averaged gas state equation; the temperature fluctuation decreases the product of H2O, but its effect is small; the fluctuation of species mass fractions increases the product of H2O in the region close to oxidizer while decreases the product of H2O in other regions; the fluctuation correlation of species mass fractions and temperature largely decreases the product of H2O.

  18. Toward Active Control of Noise from Hot Supersonic Jets

    Science.gov (United States)

    2013-02-15

    applied a double divergence directly to the incompressible Reynolds stress giving Ö U’UI dxgJ = -£ijk(sijUJk + ryWfc). (1) This neglected...SUPERSONIC JETS | QUARTERLY RPT. 6 ^ EXPERIMENTAL FACILITY j^i;r\\’ii Mo/ P I V • Page 6 • Prev • Wart • Last • Full Screen • Close

  19. Research of low boom and low drag supersonic aircraft design

    Directory of Open Access Journals (Sweden)

    Feng Xiaoqiang

    2014-06-01

    Full Text Available Sonic boom reduction will be an issue of utmost importance in future supersonic transport, due to strong regulations on acoustic nuisance. The paper describes a new multi-objective optimization method for supersonic aircraft design. The method is developed by coupling Seebass–George–Darden (SGD inverse design method and multi-objective genetic algorithm. Based on the method, different codes are developed. Using a computational architecture, a conceptual supersonic aircraft design environment (CSADE is constructed. The architecture of CSADE includes inner optimization level and out optimization level. The low boom configuration is generated in inner optimization level by matching the target equivalent area distribution and actual equivalent area distribution. And low boom/low drag configuration is generated in outer optimization level by using NSGA-II multi-objective genetic algorithm to optimize the control parameters of SGD method and aircraft shape. Two objective functions, low sonic boom and low wave drag, are considered in CSADE. Physically reasonable Pareto solutions are obtained from the present optimization. Some supersonic aircraft configurations are selected from Pareto front and the optimization results indicate that the swept forward wing configuration has benefits in both sonic boom reduction and wave drag reduction. The results are validated by using computational fluid dynamics (CFD analysis.

  20. Dissipation of Molecular Cloud Turbulence by Magnetohydrodynamic Shockwaves

    Science.gov (United States)

    Lehmann, Andrew; Wardle, Mark

    2015-08-01

    The character of star formation is intimately related to the supersonic magnetohydrodynamic (MHD) turbulent dynamics of the giant molecular clouds in which stars form. A significant amount of the turbulent energy dissipates in low velocity shock waves. These shocks cause molecular line cooling of the compressed and heated gas, and so their radiative signatures probe the nature of the turbulence. In MHD fluids the three distinct families of shocks—fast, intermediate and slow—differ in how they compress and heat the molecular gas, and so observational differences between them may also distinguish driving modes of turbulent regions.Here we use a two-fluid model to compare the characteristics of one-dimensional fast and slow MHD shocks. Fast MHD shocks are magnetically driven, forcing ion species to stream through the neutral gas ahead of the shock front. This magnetic precursor heats the gas sufficiently to create a large, warm transition zone where all the fluid variables only weakly change in the shock front. In contrast, slow MHD shocks are driven by gas pressure where neutral species collide with ion species in a thin hot slab that closely resembles an ordinary gas dynamic shock.We computed observational diagnostics for fast and slow shocks at velocities vs = 2-4 km/s and preshock Hydrogen nuclei densities n(H) = 102-4 cm-3. We followed the abundances of molecules relevant for a simple oxygen chemistry and include cooling by CO, H2 and H2O. Estimates of intensities of CO rotational lines show that high-J lines, above J = 6→5, are more strongly excited in slow MHD shocks. We discuss how these shocks could help interpret recently observed anomalously strong mid- and high-J CO lines emitted by warm gas in the Milky Way and external galaxies, and implications for simulations of MHD turbulence.

  1. Apparatus for laser slowing and cooling of molecules

    Science.gov (United States)

    2016-10-09

    SECURITY CLASSIFICATION OF: This is the final report for our DURIP grant entitled "Apparatus for Laser Slowing and cooling of Molecules". We have... cooling of a new molecular species, TlF. We have also successfully acquired and assembled the parts for a custom laser system, which produces long...Distribution Unlimited UU UU UU UU 09-10-2016 1-Sep-2012 31-Aug-2014 Final Report: Apparatus for laser slowing and cooling of molecules The views

  2. Elastocaloric cooling: Stretch to actively cool

    Science.gov (United States)

    Ossmer, Hinnerk; Kohl, Manfred

    2016-10-01

    The elastocaloric effect can be exploited in solid-state cooling technologies as an alternative to conventional vapour compression. Now, an elastocaloric device based on the concept of active regeneration achieves a temperature lift of 15.3 K and efficiencies competitive with other caloric-based approaches.

  3. Measure Guideline: Ventilation Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Springer, D.; Dakin, B.; German, A.

    2012-04-01

    The purpose of this measure guideline on ventilation cooling is to provide information on a cost-effective solution for reducing cooling system energy and demand in homes located in hot-dry and cold-dry climates. This guideline provides a prescriptive approach that outlines qualification criteria, selection considerations, and design and installation procedures.

  4. The final cool down

    CERN Multimedia

    Thursday 29th May, the cool-down of the final sector (sector 4-5) of LHC has begun, one week after the start of the cool-down of sector 1-2. It will take five weeks for the sectors to be cooled from room temperature to 5 K and a further two weeks to complete the cool down to 1.9 K and the commissioning of cryogenic instrumentation, as well as to fine tune the cryogenic plants and the cooling loops of cryostats.Nearly a year and half has passed since sector 7-8 was cooled for the first time in January 2007. For Laurent Tavian, AT/CRG Group Leader, reaching the final phase of the cool down is an important milestone, confirming the basic design of the cryogenic system and the ability to operate complete sectors. “All the sectors have to operate at the same time otherwise we cannot inject the beam into the machine. The stability and reliability of the cryogenic system and its utilities are now very important. That will be the new challenge for the coming months,” he explains. The status of the cool down of ...

  5. Solar absorption cooling

    NARCIS (Netherlands)

    Kim, D.-S.

    2007-01-01

    As the world concerns more and more on global climate changes and depleting energy resources, solar cooling technology receives increasing interests from the public as an environment-friendly and sustainable alternative. However, making a competitive solar cooling machine for the market still

  6. Passive evaporative cooling

    NARCIS (Netherlands)

    Tzoulis, A.

    2011-01-01

    This "designers' manual" is made during the TIDO-course AR0531 Smart & Bioclimatic Design. Passive techniques for cooling are a great way to cope with the energy problem of the present day. This manual introduces passive cooling by evaporation. These methods have been used for many years in traditi

  7. Data center cooling method

    Energy Technology Data Exchange (ETDEWEB)

    Chainer, Timothy J.; Dang, Hien P.; Parida, Pritish R.; Schultz, Mark D.; Sharma, Arun

    2015-08-11

    A method aspect for removing heat from a data center may use liquid coolant cooled without vapor compression refrigeration on a liquid cooled information technology equipment rack. The method may also include regulating liquid coolant flow to the data center through a range of liquid coolant flow values with a controller-apparatus based upon information technology equipment temperature threshold of the data center.

  8. Liquid Cooled Garments

    Science.gov (United States)

    1979-01-01

    Astronauts working on the surface of the moon had to wear liquid-cooled garments under their space suits as protection from lunar temperatures which sometimes reach 250 degrees Fahrenheit. In community service projects conducted by NASA's Ames Research Center, the technology developed for astronaut needs has been adapted to portable cooling systems which will permit two youngsters to lead more normal lives.

  9. Solar absorption cooling

    NARCIS (Netherlands)

    Kim, D.-S.

    2007-01-01

    As the world concerns more and more on global climate changes and depleting energy resources, solar cooling technology receives increasing interests from the public as an environment-friendly and sustainable alternative. However, making a competitive solar cooling machine for the market still remain

  10. Coherent electron cooling

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko,V.

    2009-05-04

    Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation is still too feeble, while the efficiency of two other cooling methods, stochastic and electron, falls rapidly either at high bunch intensities (i.e. stochastic of protons) or at high energies (e-cooling). In this talk a specific scheme of a unique cooling technique, Coherent Electron Cooling, will be discussed. The idea of coherent electron cooling using electron beam instabilities was suggested by Derbenev in the early 1980s, but the scheme presented in this talk, with cooling times under an hour for 7 TeV protons in the LHC, would be possible only with present-day accelerator technology. This talk will discuss the principles and the main limitations of the Coherent Electron Cooling process. The talk will describe the main system components, based on a high-gain free electron laser driven by an energy recovery linac, and will present some numerical examples for ions and protons in RHIC and the LHC and for electron-hadron options for these colliders. BNL plans a demonstration of the idea in the near future.

  11. Stretchable nanocomposite electrodes with tunable mechanical properties by supersonic cluster beam implantation in elastomers

    Energy Technology Data Exchange (ETDEWEB)

    Borghi, F.; Podestà, A.; Milani, P., E-mail: pmilani@mi.infn.it [CIMAINA and Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); Melis, C.; Colombo, L. [Dipartimento di Fisica, Università di Cagliari, Cittadella Universitaria, I-09042 Monserrato (Italy); Ghisleri, C.; Ravagnan, L. [WISE srl, Piazza Duse 2, 20122 Milano (Italy)

    2015-03-23

    We demonstrate the fabrication of gold-polydimethylsiloxane nanocomposite electrodes, by supersonic cluster beam implantation, with tunable Young's modulus depending solely on the amount of metal clusters implanted in the elastomeric matrix. We show both experimentally and by atomistic simulations that the mechanical properties of the nanocomposite can be maintained close to that of the bare elastomer for significant metal volume concentrations. Moreover, the elastic properties of the nanocomposite, as experimentally characterized by nanoindentation and modeled with molecular dynamics simulations, are also well described by the Guth-Gold classical model for nanoparticle-filled rubbers, which depends on the presence, concentration, and aspect ratio of metal nanoparticles, and not on the physical and chemical modification of the polymeric matrix due to the embedding process. The elastic properties of the nanocomposite can therefore be determined and engineered a priori, by controlling only the nanoparticle concentration.

  12. Modeling gasodynamic vortex cooling

    Science.gov (United States)

    Allahverdyan, A. E.; Fauve, S.

    2017-08-01

    We aim at studying gasodynamic vortex cooling in an analytically solvable, thermodynamically consistent model that can explain limitations on the cooling efficiency. To this end, we study an angular plus radial flow between two (coaxial) rotating permeable cylinders. Full account is taken of compressibility, viscosity, and heat conductivity. For a weak inward radial flow the model qualitatively describes the vortex cooling effect, in terms of both temperature and the decrease of the stagnation enthalpy, seen in short uniflow vortex (Ranque) tubes. The cooling does not result from external work and its efficiency is defined as the ratio of the lowest temperature reached adiabatically (for the given pressure gradient) to the lowest temperature actually reached. We show that for the vortex cooling the efficiency is strictly smaller than 1, but in another configuration with an outward radial flow, we find that the efficiency can be larger than 1. This is related to both the geometry and the finite heat conductivity.

  13. Hydronic rooftop cooling systems

    Science.gov (United States)

    Bourne, Richard C.; Lee, Brian Eric; Berman, Mark J.

    2008-01-29

    A roof top cooling unit has an evaporative cooling section that includes at least one evaporative module that pre-cools ventilation air and water; a condenser; a water reservoir and pump that captures and re-circulates water within the evaporative modules; a fan that exhausts air from the building and the evaporative modules and systems that refill and drain the water reservoir. The cooling unit also has a refrigerant section that includes a compressor, an expansion device, evaporator and condenser heat exchangers, and connecting refrigerant piping. Supply air components include a blower, an air filter, a cooling and/or heating coil to condition air for supply to the building, and optional dampers that, in designs that supply less than 100% outdoor air to the building, control the mixture of return and ventilation air.

  14. INITIAL COOLING EXPERIMENT (ICE)

    CERN Multimedia

    1979-01-01

    ICE was built in 1977, using the modified bending magnets of the g-2 muon storage ring (see 7405430). Its purpose was to verify the validity of stochastic and electron cooling for the antiproton project. Stochastic cooling proved a resounding success early in 1978 and the antiproton project could go ahead, now entirely based on stochastic cooling. Electron cooling was experimented with in 1979. The 26 kV equipment is housed in the cage to the left of the picture, adjacent to the "e-cooler" located in a straight section of the ring. With some modifications, the cooler was later transplanted into LEAR (Low Energy Antiproton Ring) and then, with further modifications, into the AD (Antiproton Decelerator), where it cools antiprotons to this day (2006). See also: 7711282, 7802099, 7809081.

  15. INITIAL COOLING EXPERIMENT (ICE)

    CERN Multimedia

    1978-01-01

    ICE was built in 1977, in a record time of 9 months, using the modified bending magnets of the g-2 muon storage ring. Its purpose was to verify the validity of stochastic and electron cooling for the antiproton project, to be launched in 1978. Already early in 1978, stochastic cooling proved a resounding success, such that the antiproton (p-pbar)project was entirely based on it. Tests of electron cooling followed later: protons of 46 MeV kinetic energy were cooled with an electron beam of 26 kV and 1.3 A. The cage seen prominently in the foreground houses the HV equipment, adjacent to the "cooler" installed in a straight section of the ring. With some modifications, the cooler was later transplanted into LEAR (Low Energy Antiproton Ring) and then, with further modifications, into the AD (Antiproton Decelerator), where it cools antiprotons to this day (2006). See also: 7711282, 7802099, 7908242.

  16. Thermal Design and Analysis of the Supersonic Flight Dynamics Test Vehicle for the Low Density Supersonic Decelerator Project

    Science.gov (United States)

    Mastropietro, A. J.; Pauken, Michael; Sunada, Eric; Gray, Sandria

    2013-01-01

    The thermal design and analysis of the experimental Supersonic Flight Dynamics Test (SFDT) vehicle is presented. The SFDT vehicle is currently being designed as a platform to help demonstrate key technologies for NASA's Low Density Supersonic Decelerator (LDSD) project. The LDSD project is charged by NASA's Office of the Chief Technologist (OCT) with the task of advancing the state of the art in Mars Entry, Descent, and Landing (EDL) systems by developing and testing three new technologies required for landing heavier payloads on Mars. The enabling technologies under development consist of a large 33.5 meter diameter Supersonic Ringsail (SSRS) parachute and two different types of Supersonic Inflatable Aerodynamic Decelerator (SIAD) devices - a robotic class, SIAD-R, that inflates to a 6 meter diameter torus, and an exploration class, SIAD-E, that inflates to an 8 meter diameter isotensoid. As part of the technology development effort, the various elements of the new supersonic decelerator system must be tested in a Mars-like environment. This is currently planned to be accomplished by sending a series of SFDT vehicles into Earth's stratosphere. Each SFDT vehicle will be lifted to a stable float altitude by a large helium carrier balloon. Once at altitude, the SFDT vehicles will be released from their carrier balloon and spun up via spin motors to provide trajectory stability. An onboard third stage solid rocket motor will propel each test vehicle to supersonic flight in the upper atmosphere. After main engine burnout, each vehicle will be despun and testing of the deceleration system will begin: first an inflatable decelerator will be deployed around the aeroshell to increase the drag surface area, and then the large parachute will be deployed to continue the deceleration and return the vehicle back to the Earth's surface. The SFDT vehicle thermal system must passively protect the vehicle structure and its components from cold temperatures experienced during the

  17. Signatures of fast and slow magnetohydrodynamic shocks in turbulent molecular clouds

    CERN Document Server

    Lehmann, Andrew

    2015-01-01

    The character of star formation is intimately related to the supersonic magnetohydrodynamic (MHD) turbulent dynamics of the giant molecular clouds in which stars form. A significant amount of the turbulent energy dissipates in low-velocity shock waves. These shocks cause molecular line cooling of the compressed and heated gas, and so their radiative signatures probe the nature of the turbulence. In MHD fluids the three distinct families of shocks---fast, intermediate and slow---differ in how they compress and heat the molecular gas, and so observational differences between them may also distinguish driving modes of turbulent regions. Here we use a two-fluid model to compare the characteristics of one-dimensional fast and slow MHD shocks propagating at low speeds (a few km/s) in molecular clouds. Fast MHD shocks are magnetically driven, forcing ion species to stream through the neutral gas ahead of the shock front. This magnetic precursor heats the gas sufficiently to create a large, warm transition zone where...

  18. Ultraviolet laser desorption/ionization mass spectrometry of single-core and multi-core polyaromatic hydrocarbons under variable conditions of collisional cooling: insights into the generation of molecular ions, fragments and oligomers.

    Science.gov (United States)

    Gámez, Francisco; Hortal, Ana R; Martínez-Haya, Bruno; Soltwisch, Jens; Dreisewerd, Klaus

    2014-11-01

    The ultraviolet laser desorption/ionization of polyaromatic hydrocarbons (PAHs) has been investigated under different background pressures of an inert gas (up to 1.2 mbar of N2) in the ion source of a hybrid, orthogonal-extracting time-of-flight mass spectrometer (oTOF-MS). The study includes an ensemble of six model PAHs with isolated single polyaromatic cores and four ones with multiple cross-linked aromatic and polyaromatic cores. In combination with a weak ion extraction field, the variation of the buffer gas pressure allowed to control the degree of collisional cooling of the desorbed PAHs and, thus, to modulate their decomposition into fragments. The dominant fragmentation channels observed are related to dehydrogenation of the PAHs, in most cases through the cleavage of even numbers of C-H bonds. Breakage of C-C bonds leading to the fragmentation of rings, side chains and core linkages is also observed, in particular, at low buffer gas pressures. The precise patterns of the combined fragmentation processes vary significantly between the PAHs. The highest abundances of molecular PAH ions and cleanest mass spectra were consistently obtained at the highest buffer gas pressure of 1.2 mbar. The effective quenching of the fragmentation pathways at this elevated pressure improves the sensitivity and data interpretation for analytical applications, although the fragmentation of side chains and of bonds between (poly)aromatic cores is not completely suppressed in all cases. Moreover, these results suggest that the detected fragments are generated through thermal equilibrium processes rather than as a result of rapid photolysis. This assumption is further corroborated by a laser desorption/ionization post-source decay analysis using an axial time-of-flight MS. In line with these findings, covalent oligomers of the PAHs, which are presumably formed by association of two or more dehydrogenated fragments, are detected with higher abundances at the lower buffer gas

  19. Direct laser cooling of the BH molecule

    Science.gov (United States)

    Holland, Darren; Truppe, Stefan; Hendricks, Richard; Sauer, Ben; Tarbutt, Michael

    2015-03-01

    Ultracold polar molecules are of interest for a variety of applications, including tests of fundamental physics, ultracold chemistry, and simulation of many-body quantum systems. The laser cooling techniques that have been so successful in producing ultracold atoms are difficult to apply to molecules. Recently however, laser cooling has been applied successfully to a few molecular species, and a magneto-optical trap of SrF molecules has now been demonstrated. We have investigated the BH molecule as a candidate for laser cooling. We have produced a molecular beam of BH and have measured the branching ratios for the excited electronic state, A1 Π (v' = 0) , to decay to the various vibrational states of the ground electronic state, X1 Σ . We verify that the branching ratio for the spin-forbidden transition to an intermediate triplet state is inconsequentially small. We measure the frequency of the lowest rotational transition of the X state, and the hyperfine structure in the relevant levels of both the X and A states, and determine the nuclear electric quadrupole and magnetic dipole coupling constants. Our results show that a relatively simple laser cooling scheme can be used to cool, slow and trap BH molecules.

  20. Second sector cool down

    CERN Multimedia

    2007-01-01

    At the beginning of July, cool-down is starting in the second LHC sector, sector 4-5. The cool down of sector 4-5 may occasionally generate mist at Point 4, like that produced last January (photo) during the cool-down of sector 7-8.Things are getting colder in the LHC. Sector 7-8 has been kept at 1.9 K for three weeks with excellent stability (see Bulletin No. 16-17 of 16 April 2007). The electrical tests in this sector have got opt to a successful start. At the beginning of July the cryogenic teams started to cool a second sector, sector 4-5. At Point 4 in Echenevex, where one of the LHC’s cryogenic plants is located, preparations for the first phase of the cool-down are underway. During this phase, the sector will first be cooled to 80 K (-193°C), the temperature of liquid nitrogen. As for the first sector, 1200 tonnes of liquid nitrogen will be used for the cool-down. In fact, the nitrogen circulates only at the surface in the ...

  1. Measuring the coolness of interactive products: the COOL questionnaire

    DEFF Research Database (Denmark)

    Bruun, Anders; Raptis, Dimitrios; Kjeldskov, Jesper;

    2016-01-01

    is the COOL questionnaire. We based the creation of the questionnaire on literature suggesting that perceived coolness is decomposed to outer cool (the style of a product) and inner cool (the personality characteristics assigned to it). In this paper, we focused on inner cool, and we identified 11 inner cool......, rebelliousness and usability. These factors and their underlying 16 question items comprise the COOL questionnaire. The whole process of creating the questionnaire is presented in detail in this paper and we conclude by discussing our work against related work on coolness and HCI....

  2. Cool WISPs for stellar cooling excesses

    Energy Technology Data Exchange (ETDEWEB)

    Giannotti, Maurizio [Barry Univ., Miami Shores, FL (United States). Physical Sciences; Irastorza, Igor [Zaragoza Univ. (Spain). Dept. de Fisica Teorica; Redondo, Javier [Zaragoza Univ. (Spain). Dept. de Fisica Teorica; Max-Planck-Institut fuer Physik, Muenchen (Germany); Ringwald, Andreas [DESY Hamburg (Germany). Theory Group

    2015-12-15

    Several stellar systems (white dwarfs, red giants, horizontal branch stars and possibly the neutron star in the supernova remnant Cassiopeia A) show a preference for a mild non-standard cooling mechanism when compared with theoretical models. This exotic cooling could be provided by Weakly Interacting Slim Particles (WISPs), produced in the hot cores and abandoning the star unimpeded, contributing directly to the energy loss. Taken individually, these excesses do not show a strong statistical weight. However, if one mechanism could consistently explain several of them, the hint could be significant. We analyze the hints in terms of neutrino anomalous magnetic moments, minicharged particles, hidden photons and axion-like particles (ALPs). Among them, the ALP represents the best solution. Interestingly, the hinted ALP parameter space is accessible to the next generation proposed ALP searches, such as ALPS II and IAXO.

  3. Cool WISPs for stellar cooling excesses

    CERN Document Server

    Giannotti, Maurizio; Redondo, Javier; Ringwald, Andreas

    2015-01-01

    Several stellar systems (white dwarfs, red giants, horizontal branch stars and possibly the neutron star in the supernova remnant Cassiopeia A) show a preference for a mild non-standard cooling mechanism when compared with theoretical models. This exotic cooling could be provided by Weakly Interacting Slim Particles (WISPs), produced in the hot cores and abandoning the star unimpeded, contributing directly to the energy loss. Taken individually, these excesses do not show a strong statistical weight. However, if one mechanism could consistently explain several of them, the hint could be significant. We analyze the hints in terms of neutrino anomalous magnetic moments, minicharged particles, hidden photons and axion-like particles (ALPs). Among them, the ALP represents the best solution. Interestingly, the hinted ALP parameter space is accessible to the next generation proposed ALP searches, such as ALPS II and IAXO.

  4. Homogeneous cooling of mixtures of particle shapes

    Science.gov (United States)

    Hidalgo, R. C.; Serero, D.; Pöschel, T.

    2016-07-01

    In this work, we examine theoretically the cooling dynamics of binary mixtures of spheres and rods. To this end, we introduce a generalized mean field analytical theory, which describes the free cooling behavior of the mixture. The relevant characteristic time scale for the cooling process is derived, depending on the mixture composition and the aspect ratio of the rods. We simulate mixtures of spherocylinders and spheres using a molecular dynamics algorithm implemented on graphics processing unit (GPU) architecture. We systematically study mixtures composed of spheres and rods with several aspect ratios and varying the mixture composition. A homogeneous cooling state, where the time dependence of the system's intensive variables occurs only through a global granular temperature, is identified. We find cooling dynamics in excellent agreement with Haff's law, when using an adequate time scale. Using the scaling properties of the homogeneous cooling dynamics, we estimated numerically the efficiency of the energy interchange between rotational and translational degrees of freedom for collisions between spheres and rods.

  5. Water-cooled electronics

    CERN Document Server

    Dumont, G; Righini, B

    2000-01-01

    LHC experiments demand on cooling of electronic instrumentation will be extremely high. A large number of racks will be located in underground caverns and counting rooms, where cooling by conventional climatisation would be prohibitively expensive. A series of tests on the direct water cooling of VMEbus units and of their standard power supplies is reported. A maximum dissipation of 60 W for each module and more than 1000 W delivered by the power supply to the crate have been reached. These values comply with the VMEbus specifications. (3 refs).

  6. Cooling Devices in Laser therapy.

    Science.gov (United States)

    Das, Anupam; Sarda, Aarti; De, Abhishek

    2016-01-01

    Cooling devices and methods are now integrated into most laser systems, with a view to protecting the epidermis, reducing pain and erythema and improving the efficacy of laser. On the basis of method employed, it can be divided into contact cooling and non-contact cooling. With respect to timing of irradiation of laser, the nomenclatures include pre-cooling, parallel cooling and post-cooling. The choice of the cooling device is dictated by the laser device, the physician's personal choice with respect to user-friendliness, comfort of the patient, the price and maintenance costs of the device. We hereby briefly review the various techniques of cooling, employed in laser practice.

  7. LHC cooling gains ground

    CERN Multimedia

    Huillet-Miraton Catherine

    The nominal cryogenic conditions of 1.9 K have been achieved in sectors 5-6 and 7-8. This means that a quarter of the machine has reached the nominal conditions for LHC operation, having attained a temperature of below 2 K (-271°C), which is colder than interstellar space! Elsewhere, the cryogenic system in Sector 8-1 has been filled with liquid helium and cooled to 2K and will soon be available for magnet testing. Sectors 6-7 and 2-3 are being cooled down and cool-down operations have started in Sector 3-4. Finally, preparations are in hand for the cool-down of Sector 1-2 in May and of Sector 4-5, which is currently being consolidated. The LHC should be completely cold for the summer. For more information: http://lhc.web.cern.ch/lhc/Cooldown_status.htm.

  8. Why Exercise Is Cool

    Science.gov (United States)

    ... to Know About Puberty Train Your Temper Why Exercise Is Cool KidsHealth > For Kids > Why Exercise Is ... day and your body will thank you later! Exercise Makes Your Heart Happy You may know that ...

  9. Waveguide cooling system

    Science.gov (United States)

    Chen, B. C. J.; Hartop, R. W.

    1981-04-01

    An improved system is described for cooling high power waveguides by the use of cooling ducts extending along the waveguide, which minimizes hot spots at the flanges where waveguide sections are connected together. The cooling duct extends along substantially the full length of the waveguide section, and each flange at the end of the section has a through hole with an inner end connected to the duct and an opposite end that can be aligned with a flange hole in another waveguide section. Earth flange is formed with a drainage groove in its face, between the through hole and the waveguide conduit to prevent leakage of cooling fluid into the waveguide. The ducts have narrowed sections immediately adjacent to the flanges to provide room for the installation of fasteners closely around the waveguide channel.

  10. Warm and Cool Dinosaurs.

    Science.gov (United States)

    Mannlein, Sally

    2001-01-01

    Presents an art activity in which first grade students draw dinosaurs in order to learn about the concept of warm and cool colors. Explains how the activity also helped the students learn about the concept of distance when drawing. (CMK)

  11. Cooling of wood briquettes

    Directory of Open Access Journals (Sweden)

    Adžić Miroljub M.

    2013-01-01

    Full Text Available This paper is concerned with the experimental research of surface temperature of wood briquettes during cooling phase along the cooling line. The cooling phase is an important part of the briquette production technology. It should be performed with care, otherwise the quality of briquettes could deteriorate and possible changes of combustion characteristics of briquettes could happen. The briquette surface temperature was measured with an IR camera and a surface temperature probe at 42 sections. It was found that the temperature of briquette surface dropped from 68 to 34°C after 7 minutes spent at the cooling line. The temperature at the center of briquette, during the 6 hour storage, decreased to 38°C.

  12. Stacking with stochastic cooling

    Energy Technology Data Exchange (ETDEWEB)

    Caspers, Fritz E-mail: Fritz.Caspers@cern.ch; Moehl, Dieter

    2004-10-11

    Accumulation of large stacks of antiprotons or ions with the aid of stochastic cooling is more delicate than cooling a constant intensity beam. Basically the difficulty stems from the fact that the optimized gain and the cooling rate are inversely proportional to the number of particles 'seen' by the cooling system. Therefore, to maintain fast stacking, the newly injected batch has to be strongly 'protected' from the Schottky noise of the stack. Vice versa the stack has to be efficiently 'shielded' against the high gain cooling system for the injected beam. In the antiproton accumulators with stacking ratios up to 10{sup 5} the problem is solved by radial separation of the injection and the stack orbits in a region of large dispersion. An array of several tapered cooling systems with a matched gain profile provides a continuous particle flux towards the high-density stack core. Shielding of the different systems from each other is obtained both through the spatial separation and via the revolution frequencies (filters). In the 'old AA', where the antiproton collection and stacking was done in one single ring, the injected beam was further shielded during cooling by means of a movable shutter. The complexity of these systems is very high. For more modest stacking ratios, one might use azimuthal rather than radial separation of stack and injected beam. Schematically half of the circumference would be used to accept and cool new beam and the remainder to house the stack. Fast gating is then required between the high gain cooling of the injected beam and the low gain stack cooling. RF-gymnastics are used to merge the pre-cooled batch with the stack, to re-create free space for the next injection, and to capture the new batch. This scheme is less demanding for the storage ring lattice, but at the expense of some reduction in stacking rate. The talk reviews the 'radial' separation schemes and also gives some

  13. Cooling of electronic equipment

    DEFF Research Database (Denmark)

    A. Kristensen, Anders Schmidt

    2003-01-01

    Cooling of electronic equipment is studied. The design size of electronic equipment decrease causing the thermal density to increase. This affect the cooling which can cause for example failures of critical components due to overheating or thermal induced stresses. Initially a pin fin heat sink...... is considered as extruded profiles are inadequate for compact designs. An optimal pin fin shape and configuration is sought also taking manufacturing costs into consideration. Standard methods for geometrical modeling and thermal analysis are applied....

  14. Anomalous law of cooling

    OpenAIRE

    Lapas, Luciano C.; Ferreira, Rogelma M. S.; Oliveira, Fernando A.; Rubí, J. Miguel

    2014-01-01

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergo a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature ma...

  15. Cooling tower waste reduction

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, S.J.; Celeste, J.; Chine, R.; Scott, C.

    1998-05-01

    At Lawrence Livermore National Laboratory (LLNL), the two main cooling tower systems (central and northwest) were upgraded during the summer of 1997 to reduce the generation of hazardous waste. In 1996, these two tower systems generated approximately 135,400 lbs (61,400 kg) of hazardous sludge, which is more than 90 percent of the hazardous waste for the site annually. At both, wet decks (cascade reservoirs) were covered to block sunlight. Covering the cascade reservoirs reduced the amount of chemical conditioners (e.g. algaecide and biocide), required and in turn the amount of waste generated was reduced. Additionally, at the northwest cooling tower system, a sand filtration system was installed to allow cyclical filtering and backflushing, and new pumps, piping, and spray nozzles were installed to increase agitation. the appurtenance upgrade increased the efficiency of the cooling towers. The sand filtration system at the northwest cooling tower system enables operators to continuously maintain the cooling tower water quality without taking the towers out of service. Operational costs (including waste handling and disposal) and maintenance activities are compared for the cooling towers before and after upgrades. Additionally, the effectiveness of the sand filter system in conjunction with the wet deck covers (northwest cooling tower system), versus the cascade reservoir covers alone (south cooling tower south) is discussed. the overall expected return on investment is calculated to be in excess of 250 percent. this upgrade has been incorporated into the 1998 DOE complex-wide water conservation project being led by Sandia National Laboratory/Albuquerque.

  16. Cooling with Superfluid Helium

    CERN Document Server

    Lebrun, P

    2014-01-01

    The technical properties of helium II (‘superfluid’ helium) are presented in view of its applications to the cooling of superconducting devices, particularly in particle accelerators. Cooling schemes are discussed in terms of heat transfer performance and limitations. Large-capacity refrigeration techniques below 2 K are reviewed, with regard to thermodynamic cycles as well as process machinery. Examples drawn from existing or planned projects illustrate the presentation. Keywords: superfluid helium, cryogenics

  17. Laser cooling of solids

    Energy Technology Data Exchange (ETDEWEB)

    Epstein, Richard I [Los Alamos National Laboratory; Sheik-bahae, Mansoor [UNM

    2008-01-01

    We present an overview of solid-state optical refrigeration also known as laser cooling in solids by fluorescence upconversion. The idea of cooling a solid-state optical material by simply shining a laser beam onto it may sound counter intuitive but is rapidly becoming a promising technology for future cryocooler. We chart the evolution of this science in rare-earth doped solids and semiconductors.

  18. Supersonic flow past a flat lattice of cylindrical rods

    Science.gov (United States)

    Guvernyuk, S. V.; Maksimov, F. A.

    2016-06-01

    Two-dimensional supersonic laminar ideal gas flows past a regular flat lattice of identical circular cylinders lying in a plane perpendicular to the free-stream velocity are numerically simulated. The flows are computed by applying a multiblock numerical technique with local boundary-fitted curvilinear grids that have finite regions overlapping the global rectangular grid covering the entire computational domain. Viscous boundary layers are resolved on the local grids by applying the Navier-Stokes equations, while the aerodynamic interference of shock wave structures occurring between the lattice elements is described by the Euler equations. In the overlapping grid regions, the functions are interpolated to the grid interfaces. The regimes of supersonic lattice flow are classified. The parameter ranges in which the steady flow around the lattice is not unique are detected, and the mechanisms of hysteresis phenomena are examined.

  19. Passive Acoustic Radar for Detecting Supersonic Cruise Missile

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; XIAO Hui

    2005-01-01

    A Passive Acoustic Radar is presented as a necessary complement to electromagnetic wave radar, which will be expected to be an effective means for detecting cruise missiles. Acoustic characteristics of supersonic flying projectiles with diverse shapes are expounded via experiment. It is pointed out that simulation experiment could be implemented using bullet or shell instead of cruise missile. Based on theoretical analysis and experiment, the "acoustic fingerprint" character of cruise missile is illustrated to identify it in a strong noise environment. After establishing a locating mathematical model,the technique of acoustic embattling is utilized to resolve a problem of confirming the time of early-warning, considering the fact that velocity of sound is much slower than that of light. Thereby, a whole system of passive acoustic radar for detecting supersonic cruise missile is formed.

  20. Ethylene tetrafluoroethylene nanofibers prepared by CO2 laser supersonic drawing

    Directory of Open Access Journals (Sweden)

    A. Suzuki

    2013-06-01

    Full Text Available Ethylene tetrafluoroethylene (ETFE nanofibers were prepared by carbon dioxide (CO2 laser irradiation of asspun ETFE fibers with four different melt flow rates (MFRs in a supersonic jet that was generated by blowing air into a vacuum chamber through the fiber injection orifice. The drawability and superstructure of fibers produced by CO2 laser supersonic drawing depend on the laser power, the chamber pressure, the fiber injection speed, and the MFR. Nanofibers obtained using a laser power of 20 W, a chamber pressure of 20 kPa, and an MFR of 308 g•10 min–1 had an average diameter of 0.303 µm and a degree of crystallinity of 54%.

  1. Features of Ignition and Stable Combustion in Supersonic Combustor

    Science.gov (United States)

    Goldfeld, M.; Starov, A.; Timofeev, K.

    2009-01-01

    Present paper describes the results of experimental investigations of the supersonic combustor with entrance Mach numbers from 2 to 4 at static pressure from 0.8 to 2.5 bars, total temperature from 2000K to 3000K. Hydrogen and kerosene were used as fuel. The conditions, under which the self-ignition and intensive combustion of the fuel realized were found. Position of ignition area in the channel was determined and features of flame propagation in the channel presented. A possibility to ensure an efficient combustion of hydrogen and kerosene at a high supersonic flow velocity at the combustor entrance without special throttling and/or pseudo-shock introduction was shown. Analysis of applicability of existing methods of criterion descriptions of conditions of self-ignition and extinction of combustion is executed for generalization of experimental results on the basis of results obtained.

  2. Supersonic laser-induced jetting of aluminum micro-droplets

    Energy Technology Data Exchange (ETDEWEB)

    Zenou, M. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel); Sa' ar, A. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Kotler, Z. [Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel)

    2015-05-04

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets.

  3. Dynamical friction for supersonic motion in a homogeneous gaseous medium

    CERN Document Server

    Thun, Daniel; Schmidt, Franziska; Kley, Wilhelm

    2016-01-01

    The supersonic motion of gravitating objects through a gaseous medium constitutes a classical problem in theoretical astrophysics. Its application covers a broad range of objects and scales from planets up to galaxies. Especially the dynamical friction, caused by the forming wake behind the object, plays an important role for the dynamics of the system. To calculate the dynamical friction, standard formulae, based on linear theory are often used. It is our goal to check the general validity of these formulae and provide suitable expressions for the dynamical friction acting on the moving object, based on the basic physical parameters of the problem. We perform sequences of high resolution numerical studies of rigid bodies moving supersonically through a homogeneous medium, and calculate the total drag acting on the object, which is the sum of gravitational and hydro drag. We study cases without gravity with purely hydrodynamical drag, as well as gravitating objects. From the final equilibrium state of the sim...

  4. The effects of profiles on supersonic jet noise

    Science.gov (United States)

    Tiwari, S. N.; Bhat, T. R. S.

    1994-01-01

    The effect of velocity profiles on supersonic jet noise are studied by using stability calculations made for a shock-free coannular jet, with both the inner and outer flows supersonic. The Mach wave emission process is modeled as the noise generated by the large scale turbulent structures or the instability waves in the mixing region. Both the vortex-sheet and the realistic finite thickness shear layer models are considered. The stability calculations were performed for both inverted and normal velocity profiles. Comparisons are made with the results for an equivalent single jet, based on equal thrust, mass flow rate and exit area to that of the coannular jet. The advantages and disadvantages of these velocity profiles as far as noise radiation is concerned are discussed. It is shown that the Rayleigh's model prediction of the merits and demerits of different velocity profiles are in good agreement with the experimental data.

  5. Effect of Microjet Injection on Supersonic Jet Noise

    Science.gov (United States)

    Zaman, K. B. M. Q.; Podboy, G. G.

    2010-01-01

    The effect of microjet (jet) injection on the noise from supersonic jets is investigated. Three convergent-divergent (C-D) nozzles and one convergent nozzle, all having the same exit diameters, are used in the study. The jets are injected perpendicular to the primary jet close to the nozzle lip from six equally-spaced ports having a jet-to-primary-jet diameter ratio of 0.0054. Effects in the over-expanded, fully expanded as well as underexpanded flow regimes are explored. Relative to the effect on subsonic jets, larger reductions in the overall sound pressure level (OASPL) are achieved in most supersonic conditions. The largest reductions are typically associated with suppression of screech and transonic tones. For a shock-free, fully expanded case, the OASPL reductions achieved are comparable to that in the subsonic case; the same correlation, found for subsonic jet noise reduction at shallow observation angle, applies.

  6. Flight Research and Validation Formerly Experimental Capabilities Supersonic Project

    Science.gov (United States)

    Banks, Daniel

    2009-01-01

    This slide presentation reviews the work of the Experimental Capabilities Supersonic project, that is being reorganized into Flight Research and Validation. The work of Experimental Capabilities Project in FY '09 is reviewed, and the specific centers that is assigned to do the work is given. The portfolio of the newly formed Flight Research and Validation (FRV) group is also reviewed. The various projects for FY '10 for the FRV are detailed. These projects include: Eagle Probe, Channeled Centerbody Inlet Experiment (CCIE), Supersonic Boundary layer Transition test (SBLT), Aero-elastic Test Wing-2 (ATW-2), G-V External Vision Systems (G5 XVS), Air-to-Air Schlieren (A2A), In Flight Background Oriented Schlieren (BOS), Dynamic Inertia Measurement Technique (DIM), and Advanced In-Flight IR Thermography (AIR-T).

  7. Stacking with Stochastic Cooling

    CERN Document Server

    Caspers, Friedhelm

    2004-01-01

    Accumulation of large stacks of antiprotons or ions with the aid of stochastic cooling is more delicate than cooling a constant intensity beam. Basically the difficulty stems from the fact that the optimized gain and the cooling rate are inversely proportional to the number of particles seen by the cooling system. Therefore, to maintain fast stacking, the newly injected batch has to be strongly protected from the Schottky noise of the stack. Vice versa the stack has to be efficiently shielded against the high gain cooling system for the injected beam. In the antiproton accumulators with stacking ratios up to 105, the problem is solved by radial separation of the injection and the stack orbits in a region of large dispersion. An array of several tapered cooling systems with a matched gain profile provides a continuous particle flux towards the high-density stack core. Shielding of the different systems from each other is obtained both through the spatial separation and via the revolution frequencies (filters)....

  8. Alternative Room Cooling System

    Directory of Open Access Journals (Sweden)

    Md. Fazle Rabbi

    2015-06-01

    Full Text Available The rapidly growing population results in an increasing demand for much more residential and commercial buildings, which leads to vertical growth of the buildings and needs proper ventilation of those buildings. Natural air ventilation system is not sufficient for conventional building structures. Hence fans and air-conditioners are must to meet the requirement of proper ventilation as well as space conditioning. Globally building sector consumes largest energy in heating, cooling, ventilation and space conditioning. This load can be minimized by the application of solar chimney and modification in building structure for heating, cooling, ventilation and space conditioning. Passive solar cooling is a subject of interest to provide cooling by using the sun, a powerful energy source. This is done for ensuring human comfort in hot climates. ASHRAE (American Society of Heating, Refrigerating and Air Conditioning Engineers defines Comfort as ‘that state of mind which expresses satisfaction with the thermal environment.’ The present paper describes the development of a solar passive cooling system, which can provide thermal cooling throughout the summer season in hot and humid climates. The constructed passive system works on natural convection mode of air. Such system reduces the inside temperature of up to 5°C from the atmospheric temperature. Temperature can further be reduced by the judicious use of night ventilation.

  9. Handbook of Supersonic Aerodynamics. Section 18. Shock Tubes

    Science.gov (United States)

    1959-12-01

    Supersonic Aerodynamics. The continued encouragement received from Dr. G. N. Patterson is sincerely acknowledged. Thanks are due to E. 0. Gadamer , K...the focal point. However, it is assumed that it is smoothed out very quickly (Ref. 1). This type of wave is difficult to generate in practice , as it...since in practice they quickly turn into a shock front. 2a1The piston velocity u 1--1 - (N - 1), and following the method of Eq. (6), the piston

  10. Supersonic Vortex Gerdien Arc with Magnetic Thermal Insulation

    Science.gov (United States)

    Winterberg, F.

    1988-02-01

    Temperatures up to ~ 5 x 104 oK have been obtained with water vortex Gerdien arcs, and temperatures of ~ 105oK have been reached in hydrogen plasma arcs with magnetic thermal insulation through an externally applied strong magnetic field. It is suggested that a further increase in arc temperatures up to 106oK can conceivably be attained by a combination of both techniques, using a Gerdien arc with a supersonic hydrogen gas vortex.

  11. Wave-driven Rotation in Supersonically Rotating Mirrors

    Energy Technology Data Exchange (ETDEWEB)

    A. Fetterman and N.J. Fisch

    2010-02-15

    Supersonic rotation in mirrors may be produced by radio frequency waves. The waves produce coupled diffusion in ion kinetic and potential energy. A population inversion along the diffusion path then produces rotation. Waves may be designed to exploit a natural kinetic energy source or may provide the rotation energy on their own. Centrifugal traps for fusion and isotope separation may benefit from this wave-driven rotation.

  12. Dynamical separation of spherical bodies in supersonic flow

    OpenAIRE

    Laurence, Stuart; Parziale, N. J.; Deiterding, Ralf

    2012-01-01

    An experimental and computational investigation of the unsteady separation behaviour of two spheres in a highly supersonic flow is carried out. The spherical bodies, initially touching, are released with negligible relative velocity, an arrangement representing the idealized binary fragmentation of a meteoritic body in the atmosphere. In experiments performed in a Mach-4 Ludwieg tube, nylon spheres are initially suspended in the test section by weak threads and, following detachment of ...

  13. Aeroelastic coupling in sonic boom optimization of a supersonic aircraft

    OpenAIRE

    Vázquez, Mariano; Dervieux, Alain; Koobus, Bruno

    2003-01-01

    In this paper, we consider a multi-disciplinary optimization problem where the initial shape of a wing is sought in order to cope, after elastic deformation by the flow, with some optimality conditions. We propose a medium-strong coupling which allows to consider different softwares communicating a small number of times. Applications to the optimization of the AGARD Wing 445.6 and a flexible supersonic aircraft wing are presented.

  14. Study on the Characteristics of Supersonic Coanda Jet

    Institute of Scientific and Technical Information of China (English)

    ShigeruMatsuo; ShenYu; 等

    1998-01-01

    Techniques using coanda effect have been applied to the fluid control devices.In this field,experimental studies were so far performed for the spiral jet obtained by the Coanda jet issuing from a conical cylinder with an annular slit ,thrust vectoring of supersonic Coanda jets and so on,It is important from the viewpoints of effective applications to investigate the characteristics of the supersonic coanda jet in detail,In the present study,The effects of pressure rations and nozzle configurations on the characteristics of the supersonic COanda jet have been investigated.experimentally by a schlieren optical method and pressure measurements.Furthermore.Navier-Stokes equations were solved numerically using a 2nd-order TVD finite-volume scheme with a 3rd-order three stage Runge-Kutta method for time integration,κ-ε model was used in the computations.The effects of initial conditions on Coanda flow were investigated numerically.As a result,the simulated flow fields were compared with experimental data in good agreement qualitatively.

  15. Research on the mechanics of underwater supersonic gas jets

    Science.gov (United States)

    Shi, Honghui; Wang, Boyi; Dai, Zhenqing

    2010-03-01

    An experimental research was carried out to study the fluid mechanics of underwater supersonic gas jets. High pressure air was injected into a water tank through converging-diverging nozzles (Laval nozzles). The jets were operated at different conditions of over-, full- and under-expansions. The jet sequences were visualized using a CCD camera. It was found that the injection of supersonic air jets into water is always accompanied by strong flow oscillation, which is related to the phenomenon of shock waves feedback in the gas phase. The shock wave feedback is different from the acoustic feedback when a supersonic gas jet discharges into open air, which causes screech tone. It is a process that the shock waves enclosed in the gas pocket induce a periodic pressure with large amplitude variation in the gas jet. Consequently, the periodic pressure causes the jet oscillation including the large amplitude expansion. Detailed pressure measurements were also conducted to verify the shock wave feedback phenomenon. Three kinds of measuring methods were used, i.e., pressure probe submerged in water, pressure measurements from the side and front walls of the nozzle devices respectively. The results measured by these methods are in a good agreement. They show that every oscillation of the jets causes a sudden increase of pressure and the average frequency of the shock wave feedback is about 5-10 Hz.

  16. Technical and environmental challenges for the next generation supersonic transport

    Energy Technology Data Exchange (ETDEWEB)

    Pacull, M. [Aerospatiale (France); Hume, Ch. [British Aerospace (United Kingdom)

    1994-12-31

    The next century will be marked by the entry into service of new supersonic transport. The real question concerning the next generation supersonic transport is not will it happen, but when, and how. There is a general agreement that such an airplane will result from a worldwide venture. Who will participate, to what extend and how we will put the vehicle and partners together, are an interesting concern that will need some time to resolve. The other challenges will be to design, build and market an aircraft that will be a viable product: for the passenger, who wants the service of a fast airliner with a reasonable surcharge; for the airline which wants competitive operating cost so that it will make sense to introduce such an airplane in its fleet; for the manufacturer, which not only does not want to go bankruptcy, but seeks to make a profit in the long term within the environmental constraints: no adverse impact on high atmosphere ozone; compliance with noise requirements, operations compatible with sonic boom. This paper does not try to answer all these question, but rather highlight major technical and environmental issues for the next generation supersonic transport. The topics discussed are: general specification, noise, atmospheric emissions, sonic boom, aerodynamics, structures, engine integration, systems. (authors)

  17. Hydrogen tube vehicle for supersonic transport: 2. Speed and energy

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Arnold R. [Vehicle Projects Inc and Supersonic Tubevehicle LLC, 200 Violet St, Suite 100, Golden, CO 80401 (United States)

    2010-06-15

    The central concept of a new idea in high-speed transport is that operation of a vehicle in a hydrogen atmosphere, because of the low density of hydrogen, would increase sonic speed by a factor of 3.8 and decrease drag by 15 relative to air. A hydrogen atmosphere requires that the vehicle operate within a hydrogen-filled tube or pipeline, which serves as a phase separator. The supersonic tube vehicle (STV) can be supersonic with respect to air outside the tube while remaining subsonic inside. It breathes hydrogen fuel for its propulsion fuel cells from the tube itself. This paper, second in a series on the scientific foundations of the supersonic tube vehicle, tests the hypothesis that the STV will be simultaneously fast and energy efficient by comparing its predicted speed and energy consumption with that of four long-haul passenger transport modes: road, rail, maglev, and air. The study establishes the speed ranking STV >> airplane > maglev > train > coach (intercity bus) and the normalized energy consumption ranking Airplane >> coach > maglev > train > STV. Consistent with the hypothesis, the concept vehicle is both the fastest and lowest energy consuming mode. In theory, the vehicle can cruise at Mach 2.8 while consuming less than half the energy per passenger of a Boeing 747 at a cruise speed of Mach 0.81. (author)

  18. Interaction of a swept shock wave and a supersonic wake

    Science.gov (United States)

    He, G.; Zhao, Y. X.; Zhou, J.

    2017-03-01

    The interaction of a swept shock wave and a supersonic wake has been studied. The swept shock wave is generated by a swept compression sidewall, and the supersonic wake is generated by a wake generator. The flow field is visualized with the nanoparticle-based planar laser scattering method, and a supplementary numerical simulation is conducted by solving the Reynolds-averaged Navier-Stokes equations. The results show that the pressure rise induced by the swept shock wave can propagate upstream in the wake, which makes the location where vortices are generated move upstream, thickens the laminar section of the wake, and enlarges the generated vortices. The wake is swept away from the swept compression sidewall by the pressure gradient of the swept shock wave. This pressure gradient is not aligned with the density gradient of the supersonic wake, so the baroclinic torque generates streamwise vorticity and changes the distribution of the spanwise vorticity. The wake shock is curved, so the flow downstream of it is non-uniform, leaving the swept shock wave being distorted. A three-dimensional Mach disk structure is generated when the wake shock interacts with the swept shock wave.

  19. Research on the mechanics of underwater supersonic gas jets

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An experimental research was carried out to study the fluid mechanics of underwater supersonic gas jets. High pressure air was injected into a water tank through converging-diverging nozzles (Laval nozzles). The jets were operated at different conditions of over-, full- and under-expansions. The jet sequences were visualized using a CCD camera. It was found that the injection of supersonic air jets into water is always accompanied by strong flow oscillation, which is related to the phenomenon of shock waves feedback in the gas phase. The shock wave feedback is different from the acoustic feedback when a supersonic gas jet discharges into open air, which causes screech tone. It is a process that the shock waves enclosed in the gas pocket induce a periodic pressure with large amplitude variation in the gas jet. Consequently, the periodic pressure causes the jet oscillation including the large amplitude expansion. Detailed pressure measurements were also conducted to verify the shock wave feedback phenomenon. Three kinds of measuring methods were used, i.e., pressure probe submerged in water, pressure measurements from the side and front walls of the nozzle devices respectively. The results measured by these methods are in a good agreement. They show that every oscillation of the jets causes a sudden increase of pressure and the average frequency of the shock wave feedback is about 5–10 Hz.

  20. Interaction of a swept shock wave and a supersonic wake

    Science.gov (United States)

    He, G.; Zhao, Y. X.; Zhou, J.

    2017-09-01

    The interaction of a swept shock wave and a supersonic wake has been studied. The swept shock wave is generated by a swept compression sidewall, and the supersonic wake is generated by a wake generator. The flow field is visualized with the nanoparticle-based planar laser scattering method, and a supplementary numerical simulation is conducted by solving the Reynolds-averaged Navier-Stokes equations. The results show that the pressure rise induced by the swept shock wave can propagate upstream in the wake, which makes the location where vortices are generated move upstream, thickens the laminar section of the wake, and enlarges the generated vortices. The wake is swept away from the swept compression sidewall by the pressure gradient of the swept shock wave. This pressure gradient is not aligned with the density gradient of the supersonic wake, so the baroclinic torque generates streamwise vorticity and changes the distribution of the spanwise vorticity. The wake shock is curved, so the flow downstream of it is non-uniform, leaving the swept shock wave being distorted. A three-dimensional Mach disk structure is generated when the wake shock interacts with the swept shock wave.

  1. Manufacturing of A micro probe using supersonic aided electrolysis process

    CERN Document Server

    Shyu, R F; Ho, Chi-Ting

    2008-01-01

    In this paper, a practical micromachining technology was applied for the fabrication of a micro probe using a complex nontraditional machining process. A series process was combined to machine tungsten carbide rods from original dimension. The original dimension of tungsten carbide rods was 3mm ; the rods were ground to a fixed-dimension of 50 micrometers using precision grinding machine in first step. And then, the rod could be machined to a middle-dimension of 20 micrometers by electrolysis. A final desired micro dimension can be achieved using supersonic aided electrolysis. High-aspect-ratio of micro tungsten carbide rod was easily obtained by this process. Surface roughness of the sample with supersonic aided agitation was compared with that with no agitation in electrolysis. The machined surface of the sample is very smooth due to ionized particles of anode could be removed by supersonic aided agitation during electrolysis. Deep micro holes can also be achieved by the machined high-aspect-rati tungsten c...

  2. THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS

    Energy Technology Data Exchange (ETDEWEB)

    Federrath, Christoph [Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611 (Australia); Schober, Jennifer [Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Strasse 2, D-69120 Heidelberg (Germany); Bovino, Stefano; Schleicher, Dominik R. G., E-mail: christoph.federrath@anu.edu.au [Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany)

    2014-12-20

    The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024{sup 3} cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = ν/η = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm ≥ 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm{sub crit}=129{sub −31}{sup +43}, showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present and early universe, we conclude that magnetic fields need to be taken into account during structure formation from the early to the present cosmic ages, because they suppress gas fragmentation and drive powerful jets and outflows, both greatly affecting the initial mass function of stars.

  3. Mixed exhaust flow supersonic jet engine and method

    Energy Technology Data Exchange (ETDEWEB)

    Klees, G.W.

    1993-06-08

    A method of operating a supersonic jet engine installation is described comprising (a) providing an engine having a variable area air inlet means and an outlet to discharge engine exhaust; (b) providing a secondary air passageway means; (c) receiving ambient air in the air inlet means and providing the ambient air as primary air to the engine inlet and secondary air to the secondary air passageway means; (d) providing a mixing section having an inlet portion and an exit portion, utilizing the mixing section in directing the exhaust from the engine to primary convergent/divergent exit passageway segments, where the exhaust is discharged at supersonic velocity as primary flow components, and directing secondary air flow from the secondary air passageway means to secondary exit passageway segments which are interspersed with the primary segments and from which the secondary air is discharged at subsonic velocity as secondary flow components; and (e) providing an exhaust section to receive the primary and secondary flow components in a mixing region and causing the primary and secondary flow components to mix to create a supersonic mixed flow, the exhaust section having a variable area final nozzle through which the mixed flow is discharged.

  4. Mass flow and its pulsation measurements in supersonic wing wake

    Science.gov (United States)

    Shmakov, A. S.; Shevchenko, A. M.; Yatskikh, A. A.; Yermolaev, Yu. G.

    2016-10-01

    The results of experimental study of the flow in the wing wake are presented. Experiments were carried out in supersonic wind tunnel T-325 of ITAM SB RAS. Rectangle half-wing with sharp edges with a chord length of 30 mm and semispan of 95 mm was used to generate vortex wake. Experimental data were obtained in the cross section located 6 chord length downstream of the trailing edge at Mach numbers of 2.5 and 4 and at wing angles of attack of 4 and 10 degrees. Constant temperature hot-wire anemometer was used to measure disturbances in supersonic flow. Hot-wire was made of a tungsten wire with a diameter of 10 μm and length of 1.5 mm. Shlieren flow visualization were performed. As a result, the position and size of the vortex core in the wake of a rectangular wing were determined. For the first time experimental data on the mass flow distribution and its pulsations in the supersonic longitudinal vortex were obtained.

  5. Study of the flow characteristics of supersonic coaxial jets

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K.H. [Andong National University, Andong (Korea); Koo, B.S. [Andong National University Graudate School, Andong (Korea)

    2001-12-01

    Supersonic coaxial jets are investigated numerically by using the axisymmetric, Navier-Stokes equations which are solved using a fully implicit finite volume method. Three different kinds of coaxial nozzles are employed to understand the flow physics involved in the supersonic coaxial jets. Two convergent-divergent supersonic nozzles are designed to have the same Mach number 2.0, and used to compare the coaxial jet flows with those discharging from one constant-area nozzle. The impingement angle of the annular jets are varied. The primary pressure ratio is changed in the range from 2.0 to 10.0 and the assistant jet ratio from 1.0 to 3.0. The results obtained show that the fluctuations of the total pressure and Mach number along the jet axis are much higher in the constant-area nozzle than those in the convergent-divergent nozzles, and the constant-area nozzle lead to higher total pressure losses, compared with the convergent-divergent nozzles. The assistant jets from the annular nozzle affect the coaxial jet flows within the distance less than about ten times the nozzle throat diameter, but beyond it the coaxial jet is conical with self-similar velocity profiles. Increasing both the primary jet pressure ratio and the assistant jet pressure ratio produces a longer coaxial jet core. (author). 14 refs., 9 figs.

  6. Flow and acoustic features of a supersonic tapered nozzle

    Science.gov (United States)

    Gutmark, E.; Bowman, H. L.; Schadow, K. C.

    1992-05-01

    The acoustic and flow characteristics of a supersonic tapered jet were measured for free and shrouded flow configurations. Measurements were performed for a full range of pressure ratios including over- and underexpanded and design conditions. The supersonic tapered jet is issued from a converging-diverging nozzle with a 3∶1 rectangular slotted throat and a conical diverging section leading to a circular exit. The jet was compared to circular and rectangular supersonic jets operating at identical conditions. The distinct feature of the jet is the absence of screech tones in the entire range of operation. Its near-field pressure fluctuations have a wide band spectrum in the entire range of measurements, for Mach numbers of 1 to 2.5, for over- and underexpanded conditions. The free jet's spreading rate is nearly constant and similar to the rectangular jet, and in a shroud, the pressure drop it is inducing is linearly proportional to the primary jet Mach number. This behavior persisted in high adverse pressure gradients at overexpanded conditions, and with nozzle divergence angles of up to 35°, no inside flow separation was observed.

  7. Comparing Social Stories™ to Cool versus Not Cool

    Science.gov (United States)

    Leaf, Justin B.; Mitchell, Erin; Townley-Cochran, Donna; McEachin, John; Taubman, Mitchell; Leaf, Ronald

    2016-01-01

    In this study we compared the cool versus not cool procedure to Social Stories™ for teaching various social behaviors to one individual diagnosed with autism spectrum disorder. The researchers randomly assigned three social skills to the cool versus not cool procedure and three social skills to the Social Stories™ procedure. Naturalistic probes…

  8. Comparison of calculated and measured heat transfer coefficients for transonic and supersonic boundary-layer flows

    Energy Technology Data Exchange (ETDEWEB)

    Huerst, C.; Schulz, A.; Wittig, S. [Univ. Karlsruhe (Germany). Lehrstuhl und Inst. fuer Thermische Stroemungsmaschinen

    1995-04-01

    The present study compares measured and computed heat transfer coefficients for high-speed boundary layer nozzle flows under engine Reynolds number conditions (U{sub {infinity}} = 230 {divided_by} 880 m/s, Re* = 0.37 {divided_by} 1.07 {times} 10{sup 6}). Experimental data have been obtained by heat transfer measurements in a two-dimensional, nonsymmetric, convergent-divergent nozzle. The nozzle wall is convectively cooled using water passages. The coolant heat transfer data and nozzle surface temperatures are used as boundary conditions for a three-dimensional finite-element code, which is employed to calculate the temperature distribution inside the nozzle wall. Heat transfer coefficients along the hot gas nozzle wall are derived from the temperature gradients normal to the surface. The results are compared with numerical heat transfer predictions using the low-Reynolds-number {kappa}-{epsilon} turbulence model by Lam and Bremhorst. Influence of compressibility in the transport equations for the turbulence properties is taken into account by using the local averaged density. The results confirm that this simplification leads to good results for transonic and low supersonic flows.

  9. Solidification analysis of micro-scale metallic particles in the laser supersonic heating technique

    Science.gov (United States)

    Lin, Shih-Lung; Lin, Jehnming

    2004-04-01

    In this paper, the authors analysed the solidification phenomenon in the laser supersonic heating technique used for producing metallic particles. A mathematical model was established to predict the velocity, temperature and solidification situation of metallic particles leaving a spray nozzle. The numerical analysis method was used to simulate the flow field structure of shock waves and to proceed with related experiment. In the experiment, a pulsed Nd-YAG laser was used as the heat source on a carbon steel target within the nozzle, and carbon steel particles were ejected by high pressure air. The solidification problem of carbon steel particles with radii of 1-50 µm in the compressible flow field was calculated and compared with experimental results. The result shows that the shock wave flow fields are generated at different entrance pressures (3-7 bar), and there is no significant difference in the radii of carbon steel particles produced by a fixed laser energy; however, in the flow field without the shock wave effect, the cooling effect is less evident in the solidification process.

  10. DETECTION OF SUPERSONIC DOWNFLOWS AND ASSOCIATED HEATING EVENTS IN THE TRANSITION REGION ABOVE SUNSPOTS

    Energy Technology Data Exchange (ETDEWEB)

    Kleint, L.; Martínez-Sykora, J. [Bay Area Environmental Research Institute, 625 2nd Street, Ste. 209, Petaluma, CA (United States); Antolin, P. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Tian, H.; Testa, P.; Reeves, K. K.; McKillop, S.; Saar, S.; Golub, L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Judge, P. [High Altitude Observatory/NCAR, P.O. Box 3000, Boulder, CO 80307 (United States); De Pontieu, B.; Wuelser, J. P.; Boerner, P.; Hurlburt, N.; Lemen, J.; Tarbell, T. D.; Title, A. [Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover St., Org. ADBS, Bldg. 252, Palo Alto, CA 94304 (United States); Carlsson, M.; Hansteen, V. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway); Jaeggli, S., E-mail: lucia.kleint@fhnw.ch [Department of Physics, Montana State University, Bozeman, P.O. Box 173840, Bozeman, MT 59717 (United States); and others

    2014-07-10

    Interface Region Imaging Spectrograph data allow us to study the solar transition region (TR) with an unprecedented spatial resolution of 0.''33. On 2013 August 30, we observed bursts of high Doppler shifts suggesting strong supersonic downflows of up to 200 km s{sup –1} and weaker, slightly slower upflows in the spectral lines Mg II h and k, C II 1336, Si IV 1394 Å, and 1403 Å, that are correlated with brightenings in the slitjaw images (SJIs). The bursty behavior lasts throughout the 2 hr observation, with average burst durations of about 20 s. The locations of these short-lived events appear to be the umbral and penumbral footpoints of EUV loops. Fast apparent downflows are observed along these loops in the SJIs and in the Atmospheric Imaging Assembly, suggesting that the loops are thermally unstable. We interpret the observations as cool material falling from coronal heights, and especially coronal rain produced along the thermally unstable loops, which leads to an increase of intensity at the loop footpoints, probably indicating an increase of density and temperature in the TR. The rain speeds are on the higher end of previously reported speeds for this phenomenon, and possibly higher than the free-fall velocity along the loops. On other observing days, similar bright dots are sometimes aligned into ribbons, resembling small flare ribbons. These observations provide a first insight into small-scale heating events in sunspots in the TR.

  11. Experimental investigation of the structure of supersonic two-dimensional air microjets

    Science.gov (United States)

    Timofeev, Ivan; Aniskin, Vladimir; Mironov, Sergey

    2016-10-01

    We have experimentally studied the structure of supersonic underexpanded room-temperature air jets escaping from micronozzles with characteristic heights from 47 to 175 µm and widths within 2410-3900 µm in a range of Reynolds numbers of 1280-9460. The dimensions of the first shock cell are established. The supersonic core length of supersonic underexpanded air jets has been determined for the first time. A flow regime with a large supersonic core length has observed for air jets escaping from a 47µm high nozzle.

  12. An experimental study of the structure of supersonic flat underexpanded microjets

    Science.gov (United States)

    Aniskin, V. M.; Maslov, A. A.; Mironov, S. G.; Tsyryulnikov, I. S.; Timofeev, I. V.

    2015-05-01

    We have experimentally studied the structure of supersonic flat underexpanded room-temperature air jets escaping from micro nozzles with characteristic heights from 47 to 175 μm and widths within 2410-3900 μm in a range of Reynolds numbers of 1280-9460. The dimensions of the first shock cell are established. The supersonic core length of supersonic flat underexpanded air jets has been determined for the first time. A flow regime with a large supersonic core length has been observed for air jets escaping from a 47-μm-high nozzle.

  13. Measuring the coolness of interactive products: the COOL questionnaire

    DEFF Research Database (Denmark)

    Bruun, Anders; Raptis, Dimitrios; Kjeldskov, Jesper

    2016-01-01

    characteristics. These were used to create an initial pool of question items and 2236 participants were asked to assess 16 mobile devices. By performing exploratory and confirmatory factor analyses, we identified three factors that can measure the perceived inner coolness of interactive products: desirability...... is the COOL questionnaire. We based the creation of the questionnaire on literature suggesting that perceived coolness is decomposed to outer cool (the style of a product) and inner cool (the personality characteristics assigned to it). In this paper, we focused on inner cool, and we identified 11 inner cool...

  14. Sub-Doppler infrared spectroscopy and formation dynamics of triacetylene in a slit supersonic expansion.

    Science.gov (United States)

    Chang, Chih-Hsuan; Agarwal, Jay; Allen, Wesley D; Nesbitt, David J

    2016-02-21

    Infrared spectroscopy and formation dynamics of triacetylene are investigated in a slit jet supersonic discharge and probed with sub-Doppler resolution (≈60 MHz) on the fundamental antisymmetric CH stretch mode (ν5). The triacetylene is generated in the throat of the discharge by sequential attack of ethynyl radical with acetyelene and diacetylene: (i) HCCH → HCC + H, (ii) HCC + HCCH → HCCCCH + H, (iii) HCC + HCCCCH → HCCCCCCH + H, cooled rapidly in the slit expansion to 15 K, and probed by near shot-noise-limited absorption sensitivity with a tunable difference-frequency infrared laser. The combination of jet cooled temperatures (Trot = 15 K) and low spectral congestion permits (i) analysis of rotationally avoided crossings in the ν5 band ascribed to Coriolis interactions, as well as (ii) first detection of ν5 Π-Π hot band progressions built on the ν12 sym CC bend and definitively assigned via state-of-the-art ab initio vibration-rotation interaction parameters (αi), which make for interesting comparison with recent spectroscopic studies of Doney et al. [J. Mol. Spectrosc. 316, 54 (2015)]. The combined data provide direct evidence for significantly non-equilibrium populations in the CC bending manifold, dynamically consistent with a strongly bent radical intermediate and transition states for forming triacetylene product. The presence of intense triacetylene signals under cold, low density slit jet conditions provides support for (i) barrierless addition of HCC with HCCCCH and (ii) a high quantum yield for HCCCCCCH formation. Complete basis set calculations for energetics [CCSD(T)-f12/VnZ-f12, n = 2,3] and frequencies [CCSD(T)-f12/VdZ-f12] are presented for both radical intermediate and transition state species, predicting collision stabilization in the slit jet expansion to be competitive with unimolecular decomposition with increasing polyyne chain length.

  15. Pressure distribution and aerodynamic coefficients associated with heat addition to supersonic air stream adjacent to two-dimensional supersonic wing

    Science.gov (United States)

    Pinkel, I Irving; Serafini, John S; Gregg, John L

    1952-01-01

    The modifications in the pressure distributions and the aerodynamic coefficients associated with additions of heat to the two-dimensional supersonic in viscid flow field adjacetnt to the lower surface of of a 5-percent-thickness symmetrical circular-arc wing are presented in this report. The pressure distributions are obtained by the use of graphical method which gives the two-dimensional supersonic inviscid flow field obtained with moderate heat addition. The variation is given of the lift-drag ratio and of the aerodynamic coefficients of lift, drag, and moment with free stream Mach number, angle of attack, and parameters defining extent and amount of heat addition. The six graphical solutions used in this study included Mach numbers of 3.0 and 5.0 and angles of attack of 0 degrees and 2 degrees.

  16. Laser cooling of a diatomic molecule

    CERN Document Server

    Shuman, E S; DeMille, D

    2011-01-01

    It has been roughly three decades since laser cooling techniques produced ultracold atoms, leading to rapid advances in a vast array of fields. Unfortunately laser cooling has not yet been extended to molecules because of their complex internal structure. However, this complexity makes molecules potentially useful for many applications. For example, heteronuclear molecules possess permanent electric dipole moments which lead to long-range, tunable, anisotropic dipole-dipole interactions. The combination of the dipole-dipole interaction and the precise control over molecular degrees of freedom possible at ultracold temperatures make ultracold molecules attractive candidates for use in quantum simulation of condensed matter systems and quantum computation. Also ultracold molecules may provide unique opportunities for studying chemical dynamics and for tests of fundamental symmetries. Here we experimentally demonstrate laser cooling of the molecule strontium monofluoride (SrF). Using an optical cycling scheme re...

  17. On the Comparison of the Long Penetration Mode (LPM) Supersonic Counterflowing Jet to the Supersonic Screech Jet

    Science.gov (United States)

    Farr, Rebecca A.; Chang, Chau-Lyan.; Jones, Jess H.; Dougherty, N. Sam

    2015-01-01

    The authors provide a brief overview of the classic tonal screech noise problem created by underexpanded supersonic jets, briefly describing the fluid dynamic-acoustics feedback mechanism that has been long established as the basis for this well-known aeroacoustics problem. This is followed by a description of the Long Penetration Mode (LPM) supersonic underexpanded counterflowing jet phenomenon which has been demonstrated in several wind tunnel tests and modeled in several computational fluid dynamics (CFD) simulations. The authors provide evidence from test and CFD analysis of LPM that indicates that acoustics feedback and fluid interaction seen in LPM are analogous to the aeroacoustics interactions seen in screech jets. Finally, the authors propose applying certain methodologies to LPM which have been developed and successfully demonstrated in the study of screech jets and mechanically induced excitation in fluid oscillators for decades. The authors conclude that the large body of work done on jet screech, other aeroacoustic phenomena, and fluid oscillators can have direct application to the study and applications of LPM counterflowing supersonic cold flow jets.

  18. The definition of cool

    Energy Technology Data Exchange (ETDEWEB)

    Nichiporuk, A.

    2005-05-01

    A new air cooling system at Agnico-Eagle's LaRonde mine, located in the Abitibi Region of Quebec is described. The new system serves a mine operating at 7,250 plus feet level. The system is installed at the surface; it utilizes ammonia to cool water, which cools the air. The system consists of four compressors which lower the temperature of the ammonia to minus 2 degrees C. Water, which at this temperature is 14 degrees, and ammonia pass through a plate heat exchanger simultaneously, however, without coming into contact with each other. The heat transfer that occurs causes the water's temperature to drop to 2 degrees C. The total volume of water cooled is 220 litres per second. The system is capable of reducing 636,000 cfm of air from 30 degrees C to 6 degrees C, to which 214,000 cfm of non-cooled air is added. This mixture, which is maintained at approximately 8 degrees C throughout the summer season, is sent underground to the deepest parts of the mine. The system runs from June to September, depending on the weather. In the evenings, when the temperature dips to around four to five degrees C, the water is shut down and side doors are opened to prevent the water from freezing.

  19. Aspects of Household Cooling Technology

    OpenAIRE

    Mrzyglod, Matthias; Holzer, Stefan

    2014-01-01

    Actually available household cooling appliances in the highest efficiency class may consume less then 10W average electrical power. To achieve such power consumptions special challenges for the cooling system had to overcome. The related cooling system design has to consider several effects, which arise from the corresponding low cooling capacity demand, start/stop cycles and additional power consumptions by control accessories. The lecture provides symptomatic aspects of cooling technology, ...

  20. Comparison between Cooling Rate Dependence of Macroscopic and Microscopic Quantities in Simulated Aluminium Glass

    Institute of Scientific and Technical Information of China (English)

    LIU Chang-Song; ZHU Zhen-Gang

    2000-01-01

    Constant-pressure molecular dynamics simulations and an analysis of the local atomic structures have been performed to study the cooling rate dependence of some macroscopic and microscopic quantities in aluminium glass. Macroscopic quantities, enthalpy and density, see an observable but small dependence on the cooling rate. Icosahedral ordering units exhibit strong cooling rate dependence, which is responsible for the dependence of the enthalpy and the density on the cooling rate; while the almost independence of some microstructural units such as the 1541, 1431 and 1421 pairs of the cooling rate may lead to a small dependence of the enthalpy and the density on the cooling rate.

  1. Doppler cooling a microsphere

    CERN Document Server

    Barker, P F

    2010-01-01

    Doppler cooling the center-of-mass motion of an optically levitated microsphere via the velocity dependent scattering force from narrow whispering gallery mode (WGM) resonances is described. Light that is red detuned from the WGM resonance can be used to damp the center-of-mass motion in a process analogous to the Doppler cooling of atoms. Leakage of photons out of the microsphere when the incident field is near resonant with the narrow WGM resonance acts to damp the motion of the sphere. The scattering force is not limited by saturation, but can be controlled by the incident power. Cooling times on the order of seconds are calculated for a 20 micron diameter silica microsphere trapped within optical tweezers, with a Doppler temperature limit in the microKelvin regime.

  2. Natural radiative cooling

    Energy Technology Data Exchange (ETDEWEB)

    Lazzarin, R.

    1979-01-01

    Natural radiative cooling at night was measured based on the surface-radiation spectrum after the heat balance of the surface exposed to the sun had been reradiated. A concept equivalent to the sky temperature and a concept useful for obtaining the net heat flux are discussed. The highest possible equilibrium temperature of the selective surface can be lowered; however, how to apply this practically is not yet known. A simple radiator, completely enclosed by a transparent screen, can produce a significant and inexpensive cooling effect. The results of experiments carried out in an area such as Padua, Italy, where the climate is not suitable for cooling purposes can still be predicted theoretically. The possibility of using the collector for heat collection during the day and as a radiator at night is indicated.

  3. Clean cooling; Saubere Kuehlung

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1998-07-01

    The round hybrid cooling towers which Balcke-Duerr GmbH is currently building for the 550-MW-IGCC-power-station of a refinery project on Sardinia have to meet particularly stringent requirements as seawater is used for cooling. The advantages are: Avoidance of visible plume with minimal energy consumption, optimal plume exit velocity and discharge, greatest possible stability of the plume column, avoidance of interference and recirculation, high operating reliability of the cooling tower. (orig.) [Deutsch] Derzeit werden die Kuehltuerme fuer ein 550-MW-IGCC-Kraftwerk einer Raffinierie auf Sardinien errichtet. Die Anforderungen an die Technik sind hoch, denn gekuehlt wird mit Seewasser. Zum Einsatz kommen Hybridrundkuehltuerme der Balcke-Duerr GmbH, Ratingen. Damit setzt das Unternehmen diesen Typ erstmals ausserhalb von Deutschland ein. (orig.)

  4. Monitoring Cray Cooling Systems

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, Don E [ORNL; Ezell, Matthew A [ORNL; Becklehimer, Jeff [Cray, Inc.; Donovan, Matthew J [ORNL; Layton, Christopher C [ORNL

    2014-01-01

    While sites generally have systems in place to monitor the health of Cray computers themselves, often the cooling systems are ignored until a computer failure requires investigation into the source of the failure. The Liebert XDP units used to cool the Cray XE/XK models as well as the Cray proprietary cooling system used for the Cray XC30 models provide data useful for health monitoring. Unfortunately, this valuable information is often available only to custom solutions not accessible by a center-wide monitoring system or is simply ignored entirely. In this paper, methods and tools used to harvest the monitoring data available are discussed, and the implementation needed to integrate the data into a center-wide monitoring system at the Oak Ridge National Laboratory is provided.

  5. Research on Cooling Effectiveness in Stepped Slot Film Cooling Vane

    Institute of Scientific and Technical Information of China (English)

    LI Yulong; WU Hong; ZHOU Feng; RONG Chengjun

    2016-01-01

    As one of the most important developments in air cooling technology for hot parts of the aero-engine,film cooling technology has been widely used.Film cooling hole structure exists mainly in areas that have high temperature,uneven cooling effectiveness issues when in actual use.The first stage turbine vanes of the aero-engine consume the largest portion of cooling air,thereby the research on reducing the amount of cooling air has the greatest potential.A new stepped slot film cooling vane with a high cooling effectiveness and a high cooling uniformity was researched initially.Through numerical methods,the affecting factors of the cooling effectiveness of a vane with the stepped slot film cooling structure were researched.This paper focuses on the cooling effectiveness and the pressure loss in different blowing ratio conditions,then the most reasonable and scientific structure parameter can be obtained by analyzing the results.The results show that 1.0 mm is the optimum slot width and 10.0 is the most reasonable blowing ratio.Under this condition,the vane achieved the best cooling result and the highest cooling effectiveness,and also retained a low pressure loss.

  6. Anomalous law of cooling.

    Science.gov (United States)

    Lapas, Luciano C; Ferreira, Rogelma M S; Rubí, J Miguel; Oliveira, Fernando A

    2015-03-14

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics.

  7. Anomalous law of cooling

    Science.gov (United States)

    Lapas, Luciano C.; Ferreira, Rogelma M. S.; Rubí, J. Miguel; Oliveira, Fernando A.

    2015-03-01

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics.

  8. Superconductor rotor cooling system

    Science.gov (United States)

    Gamble, Bruce B.; Sidi-Yekhlef, Ahmed; Schwall, Robert E.; Driscoll, David I.; Shoykhet, Boris A.

    2002-01-01

    A system for cooling a superconductor device includes a cryocooler located in a stationary reference frame and a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with a rotating reference frame in which the superconductor device is located. A method of cooling a superconductor device includes locating a cryocooler in a stationary reference frame, and transferring heat from a superconductor device located in a rotating reference frame to the cryocooler through a closed circulation system external to the cryocooler. The closed circulation system interfaces the stationary reference frame with the rotating reference frame.

  9. A Cool Emperor Penguin

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    哇,这只帝企鹅的胸前居然有个心形!It’s cool!(乐天:没错,它的胸前少了这幺撮毛,应该会感觉挺凉快的)cool在这里可不是“凉快”的意思,而是“酷.帅气”的意思。我们《英语大王》的英文名字就叫English Cool Kids哦!(乐天拿出一副墨镜戴上:

  10. Rapid cooled lens cell

    Science.gov (United States)

    Stubbs, David M.; Hsu, Ike C.

    1991-12-01

    This paper describes the optomechanical design, thermal analysis, fabrication, and test evaluation processes followed in developing a rapid cooled, infrared lens cell. Thermal analysis was the key engineering discipline exercised in the design phase. The effect of thermal stress on the lens, induced by rapid cooling of the lens cell, was investigated. Features of this lens cell that minimized the thermal stress will be discussed in a dedicated section. The results of thermal analysis on the selected lens cell design and the selection of the flow channel design in the heat exchanger will be discussed. Throughout the paper engineering drawings, illustrations, analytical results, and photographs of actual hardware are presented.

  11. Gas cooled fast reactor

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1972-06-01

    Although most of the development work on fast breeder reactors has been devoted to the use of liquid metal cooling, interest has been expressed for a number of years in alternative breeder concepts using other coolants. One of a number of concepts in which interest has been retained is the Gas-Cooled Fast Reactor (GCFR). As presently envisioned, it would operate on the uranium-plutonium mixed oxide fuel cycle, similar to that used in the Liquid Metal Fast Breeder Reactor (LMFBR), and would use helium gas as the coolant.

  12. Laboratory modeling of standing shocks and radiatively cooled jets with angular momentum

    CERN Document Server

    Ampleford, D J; Ciardi, A; Bland, S N; Bott, S C; Hall, G N; Naz, N; Jennings, C A; Sherlock, M; Chittenden, J P; Palmer, J B A; Frank, A; Blackman, E

    2007-01-01

    The first laboratory astrophysics experiments to produce a radiatively cooled plasma jet with dynamically significant angular momentum are discussed. A new configuration of wire array z-pinch, the twisted conical wire array, is used to produce convergent plasma flows each rotating about the central axis. Collision of the flows produces a standing shock and jet that each have supersonic azimuthal velocities. By varying the twist angle of the array, the rotation velocity of the system can be controlled, with jet rotation velocities ~18% of the propagation velocity directly measured.

  13. High Sensitivity 1-D and 2-D Microwave Spectroscopy via Cryogenic Buffer Gas Cooling

    Science.gov (United States)

    Patterson, David; Eibenberger, Sandra

    2017-06-01

    All rotationally resolved spectroscopic methods rely on sources of cold molecules. For the last three decades, the workhorse technique for producing highly supersaturated samples of cold molecules has been the pulsed supersonic jet. We present here progress on our alternative method, cryogenic buffer gas cooling. Our high density, continuous source, and low noise temperature allow us to record microwave spectra at unprecedented sensitivity, with a dynamic range in excess of 10^6 achievable in a few minutes of integration time. This high sensitivity enables new protocols in both 1-D and 2-D microwave spectroscopy, including sensitive chiral analysis via nonlinear three wave mixing and applications as an analytical chemistry tool

  14. Development of a Water Based, Critical Flow, Non-Vapor Compression cooling Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Hosni, Mohammad H.

    2014-03-30

    Expansion of a high-pressure liquid refrigerant through the use of a thermostatic expansion valve or other device is commonplace in vapor-compression cycles to regulate the quality and flow rate of the refrigerant entering the evaporator. In vapor-compression systems, as the condensed refrigerant undergoes this expansion, its pressure and temperature drop, and part of the liquid evaporates. We (researchers at Kansas State University) are developing a cooling cycle that instead pumps a high-pressure refrigerant through a supersonic converging-diverging nozzle. As the liquid refrigerant passes through the nozzle, its velocity reaches supersonic (or critical-flow) conditions, substantially decreasing the refrigerant’s pressure. This sharp pressure change vaporizes some of the refrigerant and absorbs heat from the surrounding conditions during this phase change. Due to the design of the nozzle, a shockwave trips the supersonic two-phase refrigerant back to the starting conditions, condensing the remaining vapor. The critical-flow refrigeration cycle would provide space cooling, similar to a chiller, by running a secondary fluid such as water or glycol over one or more nozzles. Rather than utilizing a compressor to raise the pressure of the refrigerant, as in a vapor-cycle system, the critical-flow cycle utilizes a high-pressure pump to drive refrigerant liquid through the cooling cycle. Additionally, the design of the nozzle can be tailored for a given refrigerant, such that environmentally benign substances can act as the working fluid. This refrigeration cycle is still in early-stage development with prototype development several years away. The complex multi-phase flow at supersonic conditions presents numerous challenges to fully understanding and modeling the cycle. With the support of DOE and venture-capital investors, initial research was conducted at PAX Streamline, and later, at Caitin. We (researchers at Kansas State University) have continued development

  15. The role of finite-difference methods in design and analysis for supersonic cruise

    Science.gov (United States)

    Townsend, J. C.

    1976-01-01

    Finite-difference methods for analysis of steady, inviscid supersonic flows are described, and their present state of development is assessed with particular attention to their applicability to vehicles designed for efficient cruise flight. Current work is described which will allow greater geometric latitude, improve treatment of embedded shock waves, and relax the requirement that the axial velocity must be supersonic.

  16. Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2018 to 2020 Period

    Science.gov (United States)

    Morgenstern, John; Norstrud, Nicole; Sokhey, Jack; Martens, Steve; Alonso, Juan J.

    2013-01-01

    Lockheed Martin Aeronautics Company (LM), working in conjunction with General Electric Global Research (GE GR), Rolls-Royce Liberty Works (RRLW), and Stanford University, herein presents results from the "N+2 Supersonic Validations" contract s initial 22 month phase, addressing the NASA solicitation "Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2018 to 2020 Period." This report version adds documentation of an additional three month low boom test task. The key technical objective of this effort was to validate integrated airframe and propulsion technologies and design methodologies. These capabilities aspired to produce a viable supersonic vehicle design with environmental and performance characteristics. Supersonic testing of both airframe and propulsion technologies (including LM3: 97-023 low boom testing and April-June nozzle acoustic testing) verified LM s supersonic low-boom design methodologies and both GE and RRLW's nozzle technologies for future implementation. The N+2 program is aligned with NASA s Supersonic Project and is focused on providing system-level solutions capable of overcoming the environmental and performance/efficiency barriers to practical supersonic flight. NASA proposed "Initial Environmental Targets and Performance Goals for Future Supersonic Civil Aircraft". The LM N+2 studies are built upon LM s prior N+3 100 passenger design studies. The LM N+2 program addresses low boom design and methodology validations with wind tunnel testing, performance and efficiency goals with system level analysis, and low noise validations with two nozzle (GE and RRLW) acoustic tests.

  17. Numerical Simulation of Jet Behavior and Impingement Characteristics of Preheating Shrouded Supersonic Jets

    Institute of Scientific and Technical Information of China (English)

    Guang-sheng WEI; Rong ZHU; Ting CHENG; Fei ZHAO

    2016-01-01

    As a novel supersonic j et technology,preheating shrouded supersonic j et was developed to deliver oxygen into molten bath efficiently and affordably.However,there has been limited research on the jet behavior and im-pingement characteristics of preheating shrouded supersonic j ets.Computational fluid dynamics (CFD)models were established to investigate the effects of main and shrouding gas temperatures on the characteristics of flow field and impingement of shrouded supersonic j et.The preheating shrouded supersonic j et behavior was simulated and meas-ured by numerical simulation and j et measurement experiment respectively.The influence of preheating shrouded su-personic j et on gas j et penetration and fluid flow in liquid bath was calculated by the CFD model which was validated against water model experiments.The results show that the uptrend of the potential core length of shrouded super-sonic j et would be accelerated with increasing the main and shrouding gas temperatures.Also,preheating supersonic j ets demonstrated significant advantages in penetrating and stirring the liquid bath.

  18. Bibliography of Supersonic Cruise Research (SCR) program from 1980 to 1983

    Science.gov (United States)

    Hoffman, S.

    1984-01-01

    A bibliography for the Supersonic Cruise Research (SCR) and Variable Cycle Engine (VCE) Programs is presented. An annotated bibliography for the last 123 formal reports and a listing of titles for 44 articles and presentations is included. The studies identifies technologies for producing efficient supersonic commercial jet transports for cruise Mach numbers from 2.0 to 2.7.

  19. 3 TUNNELS IN THE ENGINE RESEARCH BUILDING ERB - IN CELL CE-26 VARIABLE REYNOLDS NUMBER SUPERSONIC NO

    Science.gov (United States)

    1956-01-01

    3 TUNNELS IN THE ENGINE RESEARCH BUILDING ERB - IN CELL CE-26 VARIABLE REYNOLDS NUMBER SUPERSONIC NOZZLE - CELL CE-4 6X6 INCH MACH NUMBER 2.96 SUPERSONIC AIRPLANE - CELL 1-NW 1X1 FOOT MACH 3.12 SUPERSONIC TUNNEL

  20. Measure Guideline: Ventilation Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Springer, D. [Alliance for Residential Building Innovation (ARBI), David, CA (United States); Dakin, B. [Alliance for Residential Building Innovation (ARBI), David, CA (United States); German, A. [Alliance for Residential Building Innovation (ARBI), David, CA (United States)

    2012-04-01

    The purpose of this measure guideline is to provide information on a cost-effective solution for reducing cooling system energy and demand in homes located in hot-dry and cold-dry climates. This guideline provides a prescriptive approach that outlines qualification criteria, selection considerations, and design and installation procedures.

  1. Cooling of Neutron Stars

    Directory of Open Access Journals (Sweden)

    Grigorian H.

    2010-10-01

    Full Text Available We introduce the theoretical basis for modeling the cooling evolution of compact stars starting from Boltzmann equations in curved space-time. We open a discussion on observational verification of different neutron star models by consistent statistics. Particular interest has the question of existence of quark matter deep inside of compact object, which has to have a specific influence on the cooling history of the star. Besides of consideration of several constraints and features of cooling evolution, which are susceptible of being critical for internal structure of hot compact stars we have introduced a method of extraction of the mass distribution of the neutron stars from temperature and age data. The resulting mass distribution has been compared with the one suggested by supernove simulations. This method can be considered as an additional checking tool for the consistency of theoretical modeling of neutron stars. We conclude that the cooling data allowed existence of neutron stars with quark cores even with one-flavor quark matter.

  2. Elementary stochastic cooling

    Energy Technology Data Exchange (ETDEWEB)

    Tollestrup, A.V.; Dugan, G

    1983-12-01

    Major headings in this review include: proton sources; antiproton production; antiproton sources and Liouville, the role of the Debuncher; transverse stochastic cooling, time domain; the accumulator; frequency domain; pickups and kickers; Fokker-Planck equation; calculation of constants in the Fokker-Planck equation; and beam feedback. (GHT)

  3. ELECTRON COOLING FOR RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    BEN-ZVI,I.

    2001-05-13

    The Accelerator Collider Department (CAD) at Brookhaven National Laboratory is operating the Relativistic Heavy Ion Collider (RHIC), which includes the dual-ring, 3.834 km circumference superconducting collider and the venerable AGS as the last part of the RHIC injection chain. CAD is planning on a luminosity upgrade of the machine under the designation RHIC II. One important component of the RHIC II upgrade is electron cooling of RHIC gold ion beams. For this purpose, BNL and the Budker Institute of Nuclear Physics in Novosibirsk entered into a collaboration aimed initially at the development of the electron cooling conceptual design, resolution of technical issues, and finally extend the collaboration towards the construction and commissioning of the cooler. Many of the results presented in this paper are derived from the Electron Cooling for RHIC Design Report [1], produced by the, BINP team within the framework of this collaboration. BNL is also collaborating with Fermi National Laboratory, Thomas Jefferson National Accelerator Facility and the University of Indiana on various aspects of electron cooling.

  4. Unsteady Flow in a Supersonic Turbine with Variable Specific Heats

    Science.gov (United States)

    Dorney, Daniel J.; Griffin, Lisa W.; Huber, Frank; Sondak, Douglas L.; Turner, James (Technical Monitor)

    2001-01-01

    Modern high-work turbines can be compact, transonic, supersonic, counter-rotating, or use a dense drive gas. The vast majority of modern rocket turbine designs fall into these Categories. These turbines usually have large temperature variations across a given stage, and are characterized by large amounts of flow unsteadiness. The flow unsteadiness can have a major impact on the turbine performance and durability. For example, the Space Transportation Main Engine (STME) fuel turbine, a high work, transonic design, was found to have an unsteady inter-row shock which reduced efficiency by 2 points and increased dynamic loading by 24 percent. The Revolutionary Reusable Technology Turbopump (RRTT), which uses full flow oxygen for its drive gas, was found to shed vortices with such energy as to raise serious blade durability concerns. In both cases, the sources of the problems were uncovered (before turbopump testing) with the application of validated, unsteady computational fluid dynamics (CFD) to the designs. In the case of the RRTT and the Alternate Turbopump Development (ATD) turbines, the unsteady CFD codes have been used not just to identify problems, but to guide designs which mitigate problems due to unsteadiness. Using unsteady flow analyses as a part of the design process has led to turbine designs with higher performance (which affects temperature and mass flow rate) and fewer dynamics problems. One of the many assumptions made during the design and analysis of supersonic turbine stages is that the values of the specific heats are constant. In some analyses the value is based on an average of the expected upstream and downstream temperatures. In stages where the temperature can vary by 300 to 500 K, however, the assumption of constant fluid properties may lead to erroneous performance and durability predictions. In this study the suitability of assuming constant specific heats has been investigated by performing three-dimensional unsteady Navier

  5. Climate impact of supersonic air traffic: an approach to optimize a potential future supersonic fleet – results from the EU-project SCENIC

    Directory of Open Access Journals (Sweden)

    L. Gulstad

    2007-05-01

    Full Text Available The demand for intercontinental transportation is increasing and people are requesting short travel times, which supersonic air transportation would enable. However, besides noise and sonic boom issues, which we are not referring to in this investigation, emissions from supersonic aircraft are known to alter the atmospheric composition, in particular the ozone layer, and hence affect climate significantly more than subsonic aircraft. Here, we suggest a metric to quantitatively assess different options for supersonic transport with regard to the potential destruction of the ozone layer and climate impacts. Options for fleet size, engine technology (nitrogen oxide emission level, cruising speed, range, and cruising altitude, are analyzed, based on SCENIC emissions scenarios for 2050, which underlay the requirements to be as realistic as possible in terms of e.g. economic markets and profitable market penetration. This methodology is based on a number of atmosphere-chemistry and climate models to reduce model dependencies. The model results differ significantly in terms of the response to a replacement of subsonic aircraft by supersonic aircraft. However, model differences are smaller when comparing the different options for a supersonic fleet. The base scenario, where supersonic aircraft get in service in 2015, a first fleet fully operational in 2025 and a second in 2050, lead in our simulations to a near surface temperature increase in 2050 of around 7 mK and with constant emissions afterwards to around 21 mK in 2100. The related total radiative forcing amounts to 22 mWm²in 2050, with an uncertainty between 9 and 29 mWm². A reduced supersonic cruise altitude or speed (from March 2 to Mach 1.6 reduces both, climate impact and ozone destruction, by around 40%. An increase in the range of the supersonic aircraft leads to more emissions at lower latitudes since more routes to SE Asia are taken into account, which increases ozone depletion, but

  6. Flying qualities design criteria applicable to supersonic cruise aircraft

    Science.gov (United States)

    Chalk, C. R.

    1980-01-01

    A comprehensive set of flying qualities design criteria was prepared for use in the supersonic cruise research program. The framework for stating the design criteria is established and design criteria are included which address specific failures, approach to dangerous flight conditions, flight at high angle of attack, longitudinal and lateral directional stability and control, the primary flight control system, and secondary flight controls. Examples are given of lateral directional design criteria limiting lateral accelerations at the cockpit, time to roll through 30 deg of bank, and time delay in the pilot's command path. Flight test data from the Concorde certification program are used to substantiate a number of the proposed design criteria.

  7. Development of air to air ejector for supersonic wind tunnel

    Directory of Open Access Journals (Sweden)

    Kracík Jan

    2014-03-01

    Full Text Available The contribution deals with the development of design of new conception of ejector with twelve primary annular nozzles arranged around the inlet part of the mixing chamber. The ejector is proposed to be used for propulsion of supersonic experimental wind tunnel with variable test section, which is now in development. The ejector is considered to be placed on outlet of this wind tunnel. The original design of the ejector has been modified to ensure its manufacturability. Software Ansys Fluent 14.0 was used for numerical verification of earlier work. The new design and dissimilarities of numerical results are presented in this work.

  8. Direct formulation of the supersonic acoustic intensity in space domain

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn; Leclre, Quentin

    2012-01-01

    This paper proposes and examines a direct formulation in space domain of the so-called supersonic acoustic intensity. This quantity differs from the usual (active) intensity by excluding the circulating energy in the near-field of the source, providing a map of the acoustic energy that is radiated...... by means of a two-dimensional convolution between the acoustic field and a spatial filter mask that corresponds to the space domain representation of the radiation circle. Therefore, the acoustic field that propagates effectively to the far field is calculated via direct filtering in space domain...

  9. Accuracy Of Hot-Wire Anemometry In Supersonic Turbulence

    Science.gov (United States)

    Logan, Pamela; Mckenzie, Robert L.; Bershader, Daniel

    1989-01-01

    Sensitivity of hot-wire probe compared to laser-induced-florescence measurements. Report discusses factors affecting readings of hot-wire anemometer in turbulent supersonic boundary layer. Presents theoretical analysis of responses of hot-wire probe to changes in flow; also compares measurements by hot-wire probe with measurements of same flows by laser-induced fluorescence (LIF). Because LIF provides spatially and temporally resolved data on temperature, density, and pressure, provides independent means to determine responses of hot-wire anemometers to these quantities.

  10. Laboratory plasma physics experiments using merging supersonic plasma jets

    OpenAIRE

    Hsu, S C; Moser, A. L.; Merritt, E. C.; Adams, C. S.; Dunn, J. P.; Brockington, S.; Case, A; Gilmore, M.; Lynn, A. G.; Messer, S. J.; Witherspoon, F. D.

    2014-01-01

    We describe a laboratory plasma physics experiment at Los Alamos National Laboratory that uses two merging supersonic plasma jets formed and launched by pulsed-power-driven rail guns. The jets can be formed using any atomic species or mixture available in a compressed-gas bottle and have the following nominal initial parameters at the railgun nozzle exit: $n_e\\approx n_i \\sim 10^{16}$ cm$^{-3}$, $T_e \\approx T_i \\approx 1.4$ eV, $V_{\\rm jet}\\approx 30$-100 km/s, mean charge $\\bar{Z}\\approx 1$...

  11. Pulsed supersonic helium beams for plasma edge diagnosis

    Science.gov (United States)

    Diez-Rojo, T.; Herrero, V. J.; Tanarro, I.; Tabarés, F. L.; Tafalla, D.

    1997-03-01

    An experimental setup for the production of pulsed supersonic He beams to be used for plasma edge diagnosis in fusion devices is described. A compromise between compact design, low cost, and good quality of the probe beams has been met. The main characteristics of the generated beams, such as pulse shape, absolute flux intensity, and velocity distribution, differ in general from those expected for ideal beam performance and have been determined and optimized experimentally. A first test of this He beam source at the TJ-I UP Torsatron in Madrid is also reported.

  12. Pulsed supersonic helium beams for plasma edge diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Diez-Rojo, T.; Herrero, V.J.; Tanarro, I. [Instituto de Estructura de la Materia (CSIC), Serrano 123, 28006 Madrid (Spain); Tabares, F.L.; Tafalla, D. [Asociacion EURATOM-CIEMAT para Fusion, Avenue Complutense 22, 28040 Madrid (Spain)

    1997-03-01

    An experimental setup for the production of pulsed supersonic He beams to be used for plasma edge diagnosis in fusion devices is described. A compromise between compact design, low cost, and good quality of the probe beams has been met. The main characteristics of the generated beams, such as pulse shape, absolute flux intensity, and velocity distribution, differ in general from those expected for ideal beam performance and have been determined and optimized experimentally. A first test of this He beam source at the TJ-I UP Torsatron in Madrid is also reported. {copyright} {ital 1997 American Institute of Physics.}

  13. Sorption cooling: a valid extension to passive cooling

    NARCIS (Netherlands)

    Doornink, D.J.; Burger, J.F.; Brake, ter H.J.M.

    2008-01-01

    Passive cooling has shown to be a very dependable cryogenic cooling method for space missions. Several missions employ passive radiators to cool down their delicate sensor systems for many years, without consuming power, without exporting vibrations or producing electromagnetic interference. So for

  14. Comments on Ionization Cooling Channel Characteristics

    CERN Document Server

    Neuffer, David

    2013-01-01

    Ionization cooling channels with a wide variety of characteristics and cooling properties are being developed. These channels can produce cooling performances that are largely consistent with the ionization cooling theory developed previously. In this paper we review ionization cooling theory, discuss its application to presently developing cooling channels, and discuss criteria for optimizing cooling.

  15. Comments on Ionization Cooling Channel Characteristics

    OpenAIRE

    Neuffer, David

    2013-01-01

    Ionization cooling channels with a wide variety of characteristics and cooling properties are being developed. These channels can produce cooling performances that are largely consistent with the ionization cooling theory developed previously. In this paper we review ionization cooling theory, discuss its application to presently developing cooling channels, and discuss criteria for optimizing cooling.

  16. STOCHASTIC COOLING FOR BUNCHED BEAMS.

    Energy Technology Data Exchange (ETDEWEB)

    BLASKIEWICZ, M.

    2005-05-16

    Problems associated with bunched beam stochastic cooling are reviewed. A longitudinal stochastic cooling system for RHIC is under construction and has been partially commissioned. The state of the system and future plans are discussed.

  17. ALP hints from cooling anomalies

    CERN Document Server

    Giannotti, Maurizio

    2015-01-01

    We review the current status of the anomalies in stellar cooling and argue that, among the new physics candidates, an axion-like particle would represent the best option to account for the hinted additional cooling.

  18. Cooling devices in laser therapy

    Directory of Open Access Journals (Sweden)

    Anupam Das

    2016-01-01

    Full Text Available Cooling devices and methods are now integrated into most laser systems, with a view to protecting the epidermis, reducing pain and erythema and improving the efficacy of laser. On the basis of method employed, it can be divided into contact cooling and non-contact cooling. With respect to timing of irradiation of laser, the nomenclatures include pre-cooling, parallel cooling and post-cooling. The choice of the cooling device is dictated by the laser device, the physician′s personal choice with respect to user-friendliness, comfort of the patient, the price and maintenance costs of the device. We hereby briefly review the various techniques of cooling, employed in laser practice.

  19. High Resolution Infrared Spectra of Plasma Jet-Cooled - and Triacetylene in the C-H Stretch Region by CW Cavity Ring-Down Spectroscopy

    Science.gov (United States)

    Zhao, D.; Guss, J.; Walsh, A.; Doney, K.; Linnartz, H.

    2013-06-01

    Polyacetylenes form an important series of unsaturated hydrocarbons that are of astrophysical interest. Small polyacetylenes have been detected from infrared observations in dense atmosphere of Titan and in a protoplanetary nebula CRL 618. We present here high-resolution mid-infrared spectra of diacetylene (HC_{4}H) and triacetylene (HC_{6}H) that are recorded in a supersonically expanded pulsed planar plasma using an ultra-sensitive detection technique. This method uses an all fiber-laser-based optical parametric oscillator (OPO), in combination with continuous wave cavity ring-down spectroscopy (cw-CRDS) as a direct absorption detection tool. A hardware-based multi-trigger concept is developed to apply cw-CRDS to pulsed plasmas. Vibrationally hot but rotationally cold HC_{4}H and HC_{6}H are produced by discharging a C_{2}H_{2}/He/Ar gas mixture which is supersonically expanded into a vacuum chamber through a slit discharge nozzle. Experimental spectra are recorded at a resolution of ˜100 MHz in the 3305-3340 cm^{-1} region, which is characteristic of the C-H stretch vibrations of HC_{4}H and HC_{6}H. Jet-cooling in our experiment reduces the rotational temperature of both HC_{4}H and HC_{6}H to <20 K. In total, ˜2000 lines are measured. More than fourteen (vibrationally hot) bands for HC_{4}H and four bands for HC_{6}H are assigned based on Loomis-Wood diagrams, and nearly half of these bands are analyzed for the first time. For both molecules improved and new molecular constants of a series of vibrational levels are presented. The accurate molecular data reported here, particularly those for low-lying (bending) vibrational levels may be used to interpret the ro-vibrational transitions in the FIR and submillimeter/THz region. D. Zhao, J. Guss, A. Walsh, H. Linnartz Chem. Phys. Lett., {dx.doi.org/10.1016/j.cplett.2013.02.025}, in press, 2013.

  20. Jet-Cooled Spectroscopy on the Ailes Infrared Beamline of the Synchrotron Radiation Facility Soleil

    Science.gov (United States)

    Georges, Robert

    2015-06-01

    The Advanced Infrared Line Exploited for Spectroscopy (AILES) extracts the bright far infrared (FIR) synchrotron continuum of the third generation radiation facility SOLEIL. This beamline is equipped with a high resolution (10-3 cm-1) Bruker IFS125 Fourier transform spectrometer which can be operated in the FIR but also in the mid and near infrared by using its internal conventional sources. The jet-AILES consortium (IPR, PhLAM, MONARIS, SOLEIL) has implemented a supersonic-jet apparatus on the beamline to record absorption spectra at very low temperature (5-50 K) and in highly supersaturated gaseous conditions. Heatable slit-nozzles of various lengths and widths are used to set properly the stagnation conditions. A mechanical pumping (roots pumps) was preferred for its ability to evacuate important mass flow rates and therefore to boost the experimental sensitivity of the set-up, the counterpart being a non-negligible consumption of both carrier (argon, helium or nitrogen) and spectroscopic gases. Various molecular systems were investigated up to now using the Jet-AILES apparatus. The very low temperature achieved in the gas expansion was either used to simplify the rotation-vibration structure of monomers, such as SF6, CF4 or naphthalene, or to stabilize the formation of weakly bonded molecular complexes such as the trimer of HF or the dimer of acetic acid. The nucleation of water vapor and the nuclear spin conversion of water were also investigated under free-jet conditions in the mid infrared. High-resolution spectroscopy and analysis of the νb{2} + νb{3} combination band of SF6 in a supersonic jet expansion. V. Boudon, P. Asselin, P. Soulard, M. Goubet, T. R. Huet, R. Georges, O. Pirali, P. Roy, Mol. Phys. 111, 2154-2162 (2013) The far infrared spectrum of naphthalene characterized by high resolution synchrotron FTIR spectroscopy and anharmonic DFT calculations. O. Pirali, M. Goubet, T.R. Huet, R. Georges, P. Soulard, P. Asselin, J. Courbe, P. Roy and M

  1. Noise reduction in supersonic jets by nozzle fluidic inserts

    Science.gov (United States)

    Morris, Philip J.; McLaughlin, Dennis K.; Kuo, Ching-Wen

    2013-08-01

    Professor Philip Doak spent a very productive time as a consultant to the Lockheed-Georgia Company in the early 1970s. The focus of the overall research project was the prediction and reduction of noise from supersonic jets. Now, 40 years on, the present paper describes an innovative methodology and device for the reduction of supersonic jet noise. The goal is the development of a practical active noise reduction technique for low bypass ratio turbofan engines. This method introduces fluidic inserts installed in the divergent wall of a CD nozzle to replace hard-wall corrugation seals, which have been demonstrated to be effective by Seiner (2005) [1]. By altering the configuration and operating conditions of the fluidic inserts, active noise reduction for both mixing and shock noise has been obtained. Substantial noise reductions have been achieved for mixing noise in the maximum noise emission direction and in the forward arc for broadband shock-associated noise. To achieve these reductions (on the order of greater than 4 and 2 dB for the two main components respectively), practically achievable levels of injection mass flow rates have been used. The total injected mass flow rates are less than 4% of the core mass flow rate and the effective operating injection pressure ratio has been maintained at or below the same level as the nozzle pressure ratio of the core flow.

  2. Instability of a supersonic shock free elliptic jet

    Energy Technology Data Exchange (ETDEWEB)

    Baty, R.S. (Sandia National Labs., Albuquerque, NM (USA)); Seiner, J.M.; Ponton, M.K. (National Aeronautics and Space Administration, Hampton, VA (USA). Langley Research Center)

    1990-01-01

    This paper presents a comparison of the measured and the computed spatial stability properties of an aspect ratio 2 supersonic shock free elliptic jet. The shock free nature of the elliptic jet provides an ideal test of validity of modeling the large scale coherent structures in the initial mixing region of noncircular supersonic jets with linear hydrodynamic stability theory. Both aerodynamic and acoustic data were measured. The data are used to compute the mean velocity profiles and to provide a description of the spatial composition of pressure waves in the elliptic jet. A hybrid numerical scheme is applied to solve the Rayleigh problem governing the inviscid linear spatial stability of the jet. The measured mean velocity profiles are used to provide a qualitative model for the cross sectional geometry and the smooth velocity profiles used in the stability analysis. Computational results are presented for several modes of instability at two jet cross sections. The acoustic measurements show that a varicose instability is the jet's perferred mode of motion. The stability analysis predicts that the Strouhal number varies linearly as a function of axial distance in the jet's initial mixing region, which is in good qualitative agreement with previous measurements. 18 refs., 18 figs., 1 tab.

  3. Thermonuclear dynamo inside ultracentrifuge with supersonic plasma flow stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Winterberg, F. [University of Nevada, Reno, Reno, Nevada (United States)

    2016-01-15

    Einstein's general theory of relativity implies the existence of virtual negative masses in the rotational reference frame of an ultracentrifuge with the negative mass density of the same order of magnitude as the positive mass density of a neutron star. In an ultracentrifuge, the repulsive gravitational field of this negative mass can simulate the attractive positive mass of a mini-neutron star, and for this reason can radially confine a dense thermonuclear plasma placed inside the centrifuge, very much as the positive mass of a star confines its plasma by its own attractive gravitational field. If the centrifuge is placed in an externally magnetic field to act as the seed field of a magnetohydrodynamic generator, the configuration resembles a magnetar driven by the release of energy through nuclear fusion, accelerating the plasma to supersonic velocities, with the magnetic field produced by the thermomagnetic Nernst effect insulating the hot plasma from the cold wall of the centrifuge. Because of the supersonic flow and the high plasma density the configuration is stable.

  4. Experiments on supersonic turbulent flow development in a square duct

    Science.gov (United States)

    Gessner, F. B.; Ferguson, S. D.; Lo, C. H.

    1986-01-01

    The nature of supersonic, turbulent, adiabatic-wall flow in a square duct is investigated experimentally over a development length of x/D between 0 and 20 for a uniform flow, Mach 3.9 condition at the duct inlet. Initial discussion centers on the duct configuration itself, which was designed specifically to minimize wave effects and nozzle-induced distortion in the flow. Total pressure contours and local skin friction coefficient distributions are presented which show that the flow develops in a manner similar to that observed for the incompressible case. In particular, undulations exist in total pressure contours within the cross plane and in transverse skin friction coefficient distributions, which are indicative of the presence of a well-defined secondary flow superimposed upon the primary flow. The results are analyzed to show that local law-of-the-wall behavior extends well into the corner region, which implies that wall functions conventionally applied in two-equation type turbulence models, when suitably defined for compressible flow, may also be applied to supersonic streamwise corner flows.

  5. Supersonic Line Broadening within Young and Massive Super Star Clusters

    CERN Document Server

    Tenorio-Tagle, G; Silich, S; Munoz-Tunon, C; Palous, J

    2009-01-01

    The origin of supersonic infrared and radio recombination nebular lines often detected in young and massive superstar clusters are discussed. We suggest that these arise from a collection of repressurizing shocks (RSs), acting effectively to re-establish pressure balance within the cluster volume and from the cluster wind which leads to an even broader although much weaker component. The supersonic lines are here shown to occur in clusters that undergo a bimodal hydrodynamic solution (Tenorio-Tagle et al. 2007), that is within clusters that are above the threshold line in the mechanical luminosity or cluster mass vs the size of the cluster (Silich et al. 2004). The plethora of repressurizing shocks is due to frequent and recurrent thermal instabilities that take place within the matter reinserted by stellar winds and supernovae. We show that the maximum speed of the RSs and of the cluster wind, are both functions of the temperature reached at the stagnation radius. This temperature depends only on the cluster...

  6. Observation of supersonic turbulent wakes by laser Fourier densitometry (LFD)

    Science.gov (United States)

    Gresillon, D.; Cabrit, B.; Bonnet, J. P.; Gemaux, G.

    Laser Fourier Densitometry (LFD) is an optical method appropriate for turbulent flow observations. It uses the collective scattering of coherent light, by optical index inhomogeneities. The principle of this method is described. It provides a signal proportional to the space Fourier transform amplitude of index distribution for a wavevector k defined by the optical arrangement. For a fluctuating flow, this amplitude is a function of time, and its frequency spectrum can be observed. The spectrum shape provides elementary parameters of the flow, such as: direction, modulus of mean velocity, and local temperature. It also provides means to distinguish different kinds of density fluctuations, such as convected inhomogeneities, or acoustic waves. The respective level of these different fluctuations types can be measured, as well as their power scale-law and absolute level. A compact optical bench has been set on a nozzle flow. The results of measurements performed in two supersonic wake configurations are presented, for Mach numbers of 1.6 and 4.2. These include density fluctuation spectra in supersonic flows, acoustic waves, variations with position, and comparison with hot wire anemometry.

  7. A compressible multiphase framework for simulating supersonic atomization

    Science.gov (United States)

    Regele, Jonathan D.; Garrick, Daniel P.; Hosseinzadeh-Nik, Zahra; Aslani, Mohamad; Owkes, Mark

    2016-11-01

    The study of atomization in supersonic combustors is critical in designing efficient and high performance scramjets. Numerical methods incorporating surface tension effects have largely focused on the incompressible regime as most atomization applications occur at low Mach numbers. Simulating surface tension effects in high speed compressible flow requires robust numerical methods that can handle discontinuities caused by both material interfaces and shocks. A shock capturing/diffused interface method is developed to simulate high-speed compressible gas-liquid flows with surface tension effects using the five-equation model. This includes developments that account for the interfacial pressure jump that occurs in the presence of surface tension. A simple and efficient method for computing local interface curvature is developed and an acoustic non-dimensional scaling for the surface tension force is proposed. The method successfully captures a variety of droplet breakup modes over a range of Weber numbers and demonstrates the impact of surface tension in countering droplet deformation in both subsonic and supersonic cross flows.

  8. Gas-Liquid Supersonic Cleaning and Cleaning Verification Spray System

    Science.gov (United States)

    Parrish, Lewis M.

    2009-01-01

    NASA Kennedy Space Center (KSC) recently entered into a nonexclusive license agreement with Applied Cryogenic Solutions (ACS), Inc. (Galveston, TX) to commercialize its Gas-Liquid Supersonic Cleaning and Cleaning Verification Spray System technology. This technology, developed by KSC, is a critical component of processes being developed and commercialized by ACS to replace current mechanical and chemical cleaning and descaling methods used by numerous industries. Pilot trials on heat exchanger tubing components have shown that the ACS technology provides for: Superior cleaning in a much shorter period of time. Lower energy and labor requirements for cleaning and de-scaling uper.ninih. Significant reductions in waste volumes by not using water, acidic or basic solutions, organic solvents, or nonvolatile solid abrasives as components in the cleaning process. Improved energy efficiency in post-cleaning heat exchanger operations. The ACS process consists of a spray head containing supersonic converging/diverging nozzles, a source of liquid gas; a novel, proprietary pumping system that permits pumping liquid nitrogen, liquid air, or supercritical carbon dioxide to pressures in the range of 20,000 to 60,000 psi; and various hoses, fittings, valves, and gauges. The size and number of nozzles can be varied so the system can be built in configurations ranging from small hand-held spray heads to large multinozzle cleaners. The system also can be used to verify if a part has been adequately cleaned.

  9. Structural concept trends for commercial supersonic cruise aircraft design

    Science.gov (United States)

    Sakat, I. F.; Davis, G. W.; Saelman, B.

    1980-01-01

    Structural concept trends for future commercial supersonic transport aircraft are considered. Highlights, including the more important design conditions and requirements, of two studies are discussed. Knowledge of these design parameters, as determined through studies involving the application of flexible mathematical models, enabled inclusion of aeroelastic considerations in the structural-material concepts evaluation. The design trends and weight data of the previous contractual study of Mach 2.7 cruise aircraft were used as the basis for incorporating advanced materials and manufacturing approaches to the airframe for reduced weight and cost. Structural studies of design concepts employing advanced aluminum alloys, advanced composites, and advanced titanium alloy and manufacturing techniques are compared for a Mach 2.0 arrow-wing configuration concept. Appraisals of the impact of these new materials and manufacturing concepts to the airframe design are shown and compared. The research and development to validate the potential sources of weight and cost reduction identified as necessary to attain a viable advanced commercial supersonic transport are discussed.

  10. Flow Simulation of Supersonic Inlet with Bypass Annular Duct

    Science.gov (United States)

    Kim, HyoungJin; Kumano, Takayasu; Liou, Meng-Sing; Povinelli, Louis A.; Conners, Timothy R.

    2011-01-01

    A relaxed isentropic compression supersonic inlet is a new concept that produces smaller cowl drag than a conventional inlet, but incurs lower total pressure recovery and increased flow distortion in the (radially) outer flowpath. A supersonic inlet comprising a bypass annulus to the relaxed isentropic compression inlet dumps out airflow of low quality through the bypass duct. A reliable computational fluid dynamics solution can provide considerable useful information to ascertain quantitatively relative merits of the concept, and further provide a basis for optimizing the design. For a fast and reliable performance evaluation of the inlet performance, an equivalent axisymmetric model whose area changes accounts for geometric and physical (blockage) effects resulting from the original complex three-dimensional configuration is proposed. In addition, full three-dimensional calculations are conducted for studying flow phenomena and verifying the validity of the equivalent model. The inlet-engine coupling is carried out by embedding numerical propulsion system simulation engine data into the flow solver for interactive boundary conditions at the engine fan face and exhaust plane. It was found that the blockage resulting from complex three-dimensional geometries in the bypass duct causes significant degradation of inlet performance by pushing the terminal normal shock upstream.

  11. Self pumping magnetic cooling

    Science.gov (United States)

    Chaudhary, V.; Wang, Z.; Ray, A.; Sridhar, I.; Ramanujan, R. V.

    2017-01-01

    Efficient thermal management and heat recovery devices are of high technological significance for innovative energy conservation solutions. We describe a study of a self-pumping magnetic cooling device, which does not require external energy input, employing Mn-Zn ferrite nanoparticles suspended in water. The device performance depends strongly on magnetic field strength, nanoparticle content in the fluid and heat load temperature. Cooling (ΔT) by ~20 °C and ~28 °C was achieved by the application of 0.3 T magnetic field when the initial temperature of the heat load was 64 °C and 87 °C, respectively. These experiments results were in good agreement with simulations performed with COMSOL Multiphysics. Our system is a self-regulating device; as the heat load increases, the magnetization of the ferrofluid decreases; leading to an increase in the fluid velocity and consequently, faster heat transfer from the heat source to the heat sink.

  12. Cooled particle accelerator target

    Science.gov (United States)

    Degtiarenko, Pavel V.

    2005-06-14

    A novel particle beam target comprising: a rotating target disc mounted on a retainer and thermally coupled to a first array of spaced-apart parallel plate fins that extend radially inwardly from the retainer and mesh without physical contact with a second array of spaced-apart parallel plate fins that extend radially outwardly from and are thermally coupled to a cooling mechanism capable of removing heat from said second array of spaced-apart fins and located within the first array of spaced-apart parallel fins. Radiant thermal exchange between the two arrays of parallel plate fins provides removal of heat from the rotating disc. A method of cooling the rotating target is also described.

  13. Water Cooled Mirror Design

    Energy Technology Data Exchange (ETDEWEB)

    Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Holloway, Michael Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pulliam, Elias Noel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-30

    This design is intended to replace the current mirror setup being used for the NorthStar Moly 99 project in order to monitor the target coupon. The existing setup has limited movement for camera alignment and is difficult to align properly. This proposed conceptual design for a water cooled mirror will allow for greater thermal transfer between the mirror and the water block. It will also improve positioning of the mirror by using flexible vacuum hosing and a ball head joint capable of a wide range of motion. Incorporating this design into the target monitoring system will provide more efficient cooling of the mirror which will improve the amount of diffraction caused by the heating of the mirror. The process of aligning the mirror for accurate position will be greatly improved by increasing the range of motion by offering six degrees of freedom.

  14. Magnetic entropy and cooling

    DEFF Research Database (Denmark)

    Hansen, Britt Rosendahl; Kuhn, Luise Theil; Bahl, Christian Robert Haffenden

    2010-01-01

    Some manifestations of magnetism are well-known and utilized on an everyday basis, e.g. using a refrigerator magnet for hanging that important note on the refrigerator door. Others are, so far, more exotic, such as cooling by making use of the magnetocaloric eect. This eect can cause a change...... or nitrogen liquefaction or for room-temperature cooling. The magnetocaloric eect can further be used to determine phase transition boundaries, if a change in the magnetic state occurs at the boundary.In this talk, I will introduce the magnetocaloric eect (MCE) and the two equations, which characterize...... in the temperature of a magnetic material when a magnetic eld is applied or removed. For many years, experimentalists have made use of dilute paramagnetic materials to achieve milliKelvin temperatures by use of the magnetocaloric eect. Also, research is done on materials, which might be used for hydrogen, helium...

  15. Cooling Floor AC Systems

    Science.gov (United States)

    Jun, Lu; Hao, Ding; Hong, Zhang; Ce, Gao Dian

    The present HVAC equipments for the residential buildings in the Hot-summer-and-Cold-winter climate region are still at a high energy consuming level. So that the high efficiency HVAC system is an urgently need for achieving the preset government energy saving goal. With its advantage of highly sanitary, highly comfortable and uniform of temperature field, the hot-water resource floor radiation heating system has been widely accepted. This paper has put forward a new way in air-conditioning, which combines the fresh-air supply unit and such floor radiation system for the dehumidification and cooling in summer or heating in winter. By analyze its advantages and limitations, we found that this so called Cooling/ Heating Floor AC System can improve the IAQ of residential building while keep high efficiency quality. We also recommend a methodology for the HVAC system designing, which will ensure the reduction of energy cost of users.

  16. Heating, ventilation and cooling

    CSIR Research Space (South Africa)

    Osburn, L

    2009-02-01

    Full Text Available content and is evaporated by the air stream with less moisture. Enthalpy wheels are more effective at transferring energy between the air streams as both sensible and latent heat is transferred. Ground-Coupled Heat Exchanger Ground-coupled heat... with high diurnal temperature variations. Evaporative Coolers Evaporative coolers work on the concept that the evaporation of water has a cooling effect on its immediate environment due to the latent heat that it absorbs in order to evaporate...

  17. Cooled Ion Frequency Standard.

    Science.gov (United States)

    2014-09-26

    when the cooling laser is turned off, the ions are heated by: (1) background gas collisions and (2) a plasma heating process which may be " resonant ...causes heating in our Penning traps. One way resonant particle transport is mediated is by misalignm.nt between the trap’s magnetic and electric axis...using computer solutions. The trap of Fig. 1 is noteworthy because although the inner surfaces of the trap are machined with simple conical cuts, the

  18. Proposal for Laser Cooling of Complex Polyatomic Molecules.

    Science.gov (United States)

    Kozyryev, Ivan; Baum, Louis; Matsuda, Kyle; Doyle, John M

    2016-11-18

    An experimentally feasible strategy for direct laser cooling of polyatomic molecules with six or more atoms is presented. Our approach relies on the attachment of a metal atom to a complex molecule, where it acts as an active photon cycling site. We describe a laser cooling scheme for alkaline earth monoalkoxide free radicals taking advantage of the phase space compression of a cryogenic buffer-gas beam. Possible applications are presented including laser cooling of chiral molecules and slowing of molecular beams using coherent photon processes. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Signatures of fast and slow magnetohydrodynamic shocks in turbulent molecular clouds

    Science.gov (United States)

    Lehmann, Andrew; Wardle, Mark

    2016-01-01

    The character of star formation is intimately related to the supersonic magnetohydrodynamic (MHD) turbulent dynamics of the molecular clouds in which stars form. A significant amount of the turbulent energy dissipates in low-velocity shocks. Fast and slow MHD shocks differ in how they compress and heat the molecular gas, and so their radiative signatures reveal distinct physical conditions. We use a two-fluid model to compare one-dimensional fast and slow MHD shocks propagating at low speeds (a few km s- 1). Fast shocks are magnetically driven, forcing ion species to stream through the neutral gas ahead of the shock front. This magnetic precursor heats the gas sufficiently to create a large, warm transition zone where all the fluid variables smoothly change in the shock front. In contrast, slow shocks are driven by gas pressure, and neutral species collide with ion species in a thin hot slab that closely resembles an ordinary gas dynamic shock. We consider shocks at velocities vs = 2-4 km s- 1 and pre-shock hydrogen nuclei densities nH = 102-104 cm-3. We include a simple oxygen chemistry and cooling by CO, H2 and H2O. CO rotational lines above J = 6-5 are more strongly excited in slow shocks. These slow-shock signatures may have already been observed in infrared dark clouds in the Milky Way.

  20. Electron Cooling of RHIC

    CERN Document Server

    Ben-Zvi, Ilan; Barton, Donald; Beavis, Dana; Blaskiewicz, Michael; Bluem, Hans; Brennan, Joseph M; Bruhwiler, David L; Burger, Al; Burov, Alexey; Burrill, Andrew; Calaga, Rama; Cameron, Peter; Chang, Xiangyun; Cole, Michael; Connolly, Roger; Delayen, Jean R; Derbenev, Yaroslav S; Eidelman, Yury I; Favale, Anthony; Fedotov, Alexei V; Fischer, Wolfram; Funk, L W; Gassner, David M; Hahn, Harald; Harrison, Michael; Hershcovitch, Ady; Holmes, Douglas; Hseuh Hsiao Chaun; Johnson, Peter; Kayran, Dmitry; Kewisch, Jorg; Kneisel, Peter; Koop, Ivan; Lambiase, Robert; Litvinenko, Vladimir N; MacKay, William W; Mahler, George; Malitsky, Nikolay; McIntyre, Gary; Meng, Wuzheng; Merminga, Lia; Meshkov, Igor; Mirabella, Kerry; Montag, Christoph; Nagaitsev, Sergei; Nehring, Thomas; Nicoletti, Tony; Oerter, Brian; Parkhomchuk, Vasily; Parzen, George; Pate, David; Phillips, Larry; Preble, Joseph P; Rank, Jim; Rao, Triveni; Rathke, John; Roser, Thomas; Russo, Thomas; Scaduto, Joseph; Schultheiss, Tom; Sekutowicz, Jacek; Shatunov, Yuri; Sidorin, Anatoly O; Skrinsky, Aleksander Nikolayevich; Smirnov, Alexander V; Smith, Kevin T; Todd, Alan M M; Trbojevic, Dejan; Troubnikov, Grigory; Wang, Gang; Wei, Jie; Williams, Neville; Wu, Kuo-Chen; Yakimenko, Vitaly; Zaltsman, Alex; Zhao, Yongxiang; ain, Animesh K

    2005-01-01

    We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.ags...

  1. Low mass integrated cooling

    CERN Document Server

    Mapelli, Alessandro

    2014-01-01

    Low mass on - detec tor cooling systems are being developed and stud ied by the Detector Technology group (PH - DT) in the CERN Physics Department in close collaboration with LHC and non - LHC experiments . Two approaches are currently being investigated. The first approach, for barrel configurations, consists in integrating the cooli ng apparatus in light mechanical structures support ing the detectors. In this case , the thermal management can be achieved either with light cooling pipes and thin plates or with a network of microchannels embedded in thin strips of silicon or polyimide . Both configuratio ns are being investigated in the context of the 2018 upgrade program of the ALICE Inner Tracking System (ITS). Moreover, it is also possible to use a s ilicon microchannel cooling device itself as structural support for the detectors and electronics. Such a configur ation has been adopted by the NA62 collaboration for the ir GigaTracKer (GTK) as well as by the LHCb collaboration for the 2018 major upgrade of...

  2. Simulation of Desiccant Cooling

    Directory of Open Access Journals (Sweden)

    Kamaruddin A.

    2017-06-01

    Full Text Available Desiccant cooling system has been an attractive topic for study lately, due to its environmentally friendly nature. It also consume less electricity and capable to be operated without refrigerant. A simulation study was conducted using 1.5 m long ducting equipped with one desiccant wheel, one sensible heat exchanger wheel, one evaporative cooling chamber and two blowers and one electric heater. The simulation study used 8.16 m/s primary air, the drying coefficient from desiccant wheel, k1=2.1 (1/s, mass transfer coefficient in evaporative cooling, k2=1.2 kg vapor/s, heat transfer coefficient in desiccant wheel, h1=4.5 W/m2 oC, and heat transfer coefficient in sensible heat exchanger wheel h2= 4.5 W/m2 oC. The simulation results show that the final temperature before entering into the air conditioning room was 25 oC and RH of 65 %, were in accordance with the Indonesian comfort index.

  3. Ultraefficient Cooling of Resonators: Beating Sideband Cooling with Quantum Control

    Science.gov (United States)

    Wang, Xiaoting; Vinjanampathy, Sai; Strauch, Frederick; Jacobs, Kurt

    2012-02-01

    There is presently a great deal of interest in cooling high-frequency micro- and nano-mechanical oscillators to their ground states. The present state of the art in cooling mechanical resonators is a version of sideband cooling, which was originally developed in the context of cooling trapped ions. Here we present a method based on quantum control that uses the same configuration as sideband cooling--coupling the resonator to be cooled to a second microwave (or optical) auxiliary resonator--but will cool significantly colder. This is achieved by applying optimal control and varying the strength of the coupling between the two resonators over a time on the order of the period of the mechanical resonator. As part of our analysis, we also obtain a method for fast, high-fidelity quantum information transfer between resonators.

  4. Cooling lubricants; Kuehlschmierstoffe

    Energy Technology Data Exchange (ETDEWEB)

    Pfeiffer, W. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Breuer, D. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Blome, H. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Deininger, C. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Hahn, J.U. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Kleine, H. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Nies, E. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Pflaumbaum, W. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Stockmann, R. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Willert, G. [Berufsgenossenschaftliches Inst. fuer Arbeitssicherheit, St. Augustin (Germany); Sonnenschein, G. [Maschinenbau- und Metall-Berufsgenossenschaft, Duesseldorf (Germany)

    1996-08-01

    As a rule, the base substances used are certain liquid hydrocarbons from mineral oils as well as from native and synthetic oils. Through the addition of further substances the cooling lubricant takes on the particular qualities required for the use in question. Employees working with cooling lubricants are exposed to various hazards. The assessment of the concentrations at the work station is carried out on the basis of existing technical rules for contact with hazardous substances. However, the application/implementation of compulsory investigation and supervision in accordance with these rules is made difficult by the fact that cooling lubricants are, as a rule, made up of complicated compound mixtures. In addition to protecting employees from exposure to mists and vapours from the cooling lubricants, protection for the skin is also of particular importance. Cooling lubricants should not, if at all possible, be brought into contact with the skin. Cleansing the skin and skin care is just as important as changing working clothes regularly, and hygiene and cleanliness at the workplace. Unavoidable emissions are to be immediately collected at the point where they arise or are released and safely disposed of. This means taking into account all sources of emissions. The programme presented in this report therefore gives a very detailed account of the individual protective measures and provides recommendations for the design of technical protection facilities. (orig./MG) [Deutsch] Als Basisstoffe dienen in der Regel bestimmte fluessige Kohlenwasserstoffverbindungen aus Mineraloelen sowie aus nativen oder synthetischen Oelen. Durch die Zugabe von weiteren Stoffen erlangt der Kuehlschmierstoff seine fuer den jeweiligen Anwendungsabfall geforderten Eigenschaften. Beschaeftigte, die mit Kuehlschmierstoffen umgehen, sind unterschiedliche Gefahren ausgesetzt. Die Beurteilung der Kuehlschmierstoffkonzentrationen in der Luft am Arbeitsplatz erfolgt auf der Grundlage bestehender

  5. Experimental and numerical investigation of an air to air supersonic ejector for propulsion of a small supersonic wind tunnel

    Directory of Open Access Journals (Sweden)

    Kracík Jan

    2015-01-01

    Full Text Available The article deals with experimental and numerical investigation of an air to air supersonic ejector with twelve primary nozzles. The ejector is supposed to be used for propulsion of a small experimental supersonic wind tunnel which is situated in laboratories of Technical University of Liberec. A novel arrangement with 12 primary nozzles is used. The nozzles are placed at the periphery of the mixing chamber. The secondary stream enters the ejector through the free centre of the mixing chamber and is sucked into the space between the primary nozzles. Moreover the declination of the primary nozzles towards to ejector axis is 8.2° and the shape of the mixing chamber and diffuser walls is given by normal cubic spline function, which was investigated in previous work. The declination of the primary nozzles is supposed to eliminate reversal flow in the centre of the mixing chamber. Experimental results for different numbers of simultaneously activated primary nozzles are carried out. Experimental results are compared to the numerical simulation made with the help of Ansys Fluent software.

  6. Fourier transform infrared absorption spectroscopy of jet-cooled radicals

    Science.gov (United States)

    Rohrs, Henry W.; Wickham-Jones, C. Tom; Ellison, G. Barney; Berry, David; Argrow, Brian M.

    1995-03-01

    We describe an experiment that couples a high-resolution Fourier transform spectrometer (FTS) to a supersonic jet of radicals. A 1-mm-i.d. cylindrical SiC nozzle is resistively heated to 1500 K in order to decompose organic precursors and generate expansions of jet-cooled radicals. We have used this apparatus to pyrolyze alkyl nitrites to make alkoxy and nitric oxide radicals. The residence time of radicals in this hot nozzle is roughly 20 μs RONO→ΔRO+NO. We use the FTS to detect the IR absorption of the product NO (ν0=1876.1 cm-1) at resolutions as fine as 0.005 cm-1 FWHM. We observe the product NO from the pyrolysis of CH3CH2ONO to be rotationally cooled to roughly 50 K. The IR spectra indicate that the optical path length is about 3/4 cm and that the nitrites pyrolyze to produce approximately 1014 NO radicals cm-3 some 9 mm downstream from the nozzle. Our spectrometer is capable of detecting an absorption signal of 0.1% over a bandwidth of 100 cm-1 at 0.005 cm-1 resolution. Depending on the infrared cross section of the radical, this implies that we are able to monitor diatomic radical densities of roughly 5×1012 cm-3 (quantum state)-1.

  7. Effect of swirling device on flow behavior in a supersonic separator for natural gas dehydration

    DEFF Research Database (Denmark)

    Wen, Chuang; Li, Anqi; Walther, Jens Honore;

    2016-01-01

    The supersonic separator is a revolutionary device to remove the condensable components from gas mixtures. One of the key issues for this novel technology is the complex supersonic swirling flow that is not well understood. A swirling device composed of an ellipsoid and several helical blades is ...... the separation performance. When the swirling flow passes through the annular nozzle, it will damage the expansion characteristics of the annular nozzle. The blade angles and numbers are both optimized by evaluating the swirling and expansion effects for the supersonic separation....

  8. Process integration: Cooling water systems design

    CSIR Research Space (South Africa)

    Gololo, KV

    2010-10-01

    Full Text Available This paper presents a technique for grassroot design of cooling water system for wastewater minimization which incorporates the performances of the cooling towers involved. The study focuses mainly on cooling systems consisting of multiple cooling...

  9. Cooling water systems design using process integration

    CSIR Research Space (South Africa)

    Gololo, KV

    2010-09-01

    Full Text Available Cooling water systems are generally designed with a set of heat exchangers arranged in parallel. This arrangement results in higher cooling water flowrate and low cooling water return temperature thus reducing cooling tower efficiency. Previous...

  10. Radiative forcing from particle emissions by future supersonic aircraft

    Directory of Open Access Journals (Sweden)

    G. Pitari

    2008-07-01

    Full Text Available In this work we focus on the direct radiative forcing (RF of black carbon (BC and sulphuric acid particles emitted by future supersonic aircraft, as well as on the ozone RF due to changes produced by emissions of both gas species (NOx, H2O and aerosol particles capable of affecting stratospheric ozone chemistry. Heterogeneous chemical reactions on the surface of sulphuric acid stratospheric particles (SSA-SAD are the main link between ozone chemistry and supersonic aircraft emissions of sulphur precursors (SO2 and particles (H2O–H2SO4. Photochemical O3 changes are compared from four independent 3-D atmosphere-chemistry models (ACMs, using as input the perturbation of SSA-SAD calculated in the University of L'Aquila model, which includes on-line a microphysics code for aerosol formation and growth. The ACMs in this study use aircraft emission scenarios for the year 2050 developed by AIRBUS as a part of the EU project SCENIC, assessing options for fleet size, engine technology (NOx emission index, Mach number, range and cruising altitude. From our baseline modeling simulation, the impact of supersonic aircraft on sulphuric acid aerosol and BC mass burdens is 53 and 1.5 μg/m2, respectively, with a direct RF of −11.4 and 4.6 mW/m2 (net RF=−6.8 mW/m2. This paper discusses the similarities and differences amongst the participating models in terms of changes to O3 precursors due to aircraft emissions (NOx, HOx,Clx,Brx and the stratospheric ozone sensitivity to them. In the baseline case, the calculated global ozone change is −0.4 ±0.3 DU, with a net radiative forcing (IR+UV of −2.5± 2 mW/m2. The fraction of this O3-RF attributable to SSA-SAD changes is, however, highly variable among the models, depending on the NOx removal

  11. Photoionization mass spectrometric studies of selected compounds in a molecular beam

    Energy Technology Data Exchange (ETDEWEB)

    Trott, W.M.

    1979-03-01

    Photoionization efficiency curves have been measured at moderate to high resolution for several species produced in supersonic molecular beams of acetone, acetone-d/sub 6/ and CS/sub 2/. The molecular beam photoionization mass spectrometer which has been assembled for this work is described. The performance of this instrument has been characterized by a number of experiments and calculations.

  12. Laser-cooled continuous ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Schiffer, J.P.; Hangst, J.S.; Nielsen, J.S. [and others

    1995-08-01

    A collaboration with a group in Arhus, Denmark, using their storage ring ASTRID, brought about better understanding of ion beams cooled to very low temperatures. The longitudinal Schottky fluctuation noise signals from a cooled beam were studied. The fluctuation signals are distorted by the effects of space charge as was observed in earlier measurements at other facilities. However, the signal also exhibits previously unobserved coherent components. The ions` velocity distribution, measured by a laser fluorescence technique suggests that the coherence is due to suppression of Landau damping. The observed behavior has important implications for the eventual attainment of a crystalline ion beam in a storage ring. A significant issue is the transverse temperature of the beam -- where no direct diagnostics are available and where molecular dynamics simulations raise interesting questions about equilibrium.

  13. Laser-cooling-assisted mass spectrometry

    CERN Document Server

    Schneider, Christian; Chen, Kuang; Sullivan, Scott T; Hudson, Eric R

    2014-01-01

    Mass spectrometry is used in a wide range of scientific disciplines including proteomics, pharmaceutics, forensics, and fundamental physics and chemistry. Given this ubiquity, there is a worldwide effort to improve the efficiency and resolution of mass spectrometers. However, the performance of all techniques is ultimately limited by the initial phase-space distribution of the molecules being analyzed. Here, we dramatically reduce the width of this initial phase-space distribution by sympathetically cooling the input molecules with laser-cooled, co-trapped atomic ions, improving both the mass resolution and detection efficiency of a time-of-flight mass spectrometer by over an order of magnitude. Detailed molecular dynamics simulations verify the technique and aid with evaluating its effectiveness. Our technique appears to be applicable to other types of mass spectrometers.

  14. Laser-Cooling-Assisted Mass Spectrometry

    Science.gov (United States)

    Schneider, Christian; Schowalter, Steven J.; Chen, Kuang; Sullivan, Scott T.; Hudson, Eric R.

    2014-09-01

    Mass spectrometry is used in a wide range of scientific disciplines including proteomics, pharmaceutics, forensics, and fundamental physics and chemistry. Given this ubiquity, there is a worldwide effort to improve the efficiency and resolution of mass spectrometers. However, the performance of all techniques is ultimately limited by the initial phase-space distribution of the molecules being analyzed. Here, we dramatically reduce the width of this initial phase-space distribution by sympathetically cooling the input molecules with laser-cooled, cotrapped atomic ions, improving both the mass resolution and detection efficiency of a time-of-flight mass spectrometer by over an order of magnitude. Detailed molecular-dynamics simulations verify the technique and aid with evaluating its effectiveness. This technique appears to be applicable to other types of mass spectrometers.

  15. Solar heating and cooling.

    Science.gov (United States)

    Duffie, J A; Beckman, W A

    1976-01-16

    We have adequate theory and engineering capability to design, install, and use equipment for solar space and water heating. Energy can be delivered at costs that are competitive now with such high-cost energy sources as much fuel-generated, electrical resistance heating. The technology of heating is being improved through collector developments, improved materials, and studies of new ways to carry out the heating processes. Solar cooling is still in the experimental stage. Relatively few experiments have yielded information on solar operation of absorption coolers, on use of night sky radiation in locations with clear skies, on the combination of a solar-operated Rankine engine and a compression cooler, and on open cycle, humidification-dehumidification systems. Many more possibilities for exploration exist. Solar cooling may benefit from collector developments that permit energy delivery at higher temperatures and thus solar operation of additional kinds of cycles. Improved solar cooling capability can open up new applications of solar energy, particularly for larger buildings, and can result in markets for retrofitting existing buildings. Solar energy for buildings can, in the next decade, make a significant contribution to the national energy economy and to the pocketbooks of many individual users. very large-aggregate enterprises in manufacture, sale, and installation of solar energy equipment can result, which can involve a spectrum of large and small businesses. In our view, the technology is here or will soon be at hand; thus the basic decisions as to whether the United States uses this resource will be political in nature.

  16. Laser Cooling of Solids

    Science.gov (United States)

    2009-01-01

    observed in a range of glasses and crystals doped with Yb3+ (ZBLANP [19–22], ZBLAN [23,24], CNBZn [9,25] BIG [25, 26], KGd(WO4)2 [9], KY(WO4)2 [9], YAG [27...Yb3+-doped fluorozirconate glass ZBLAN , Phys. Rev. B 75, 144302 (2007). [40] C. W. Hoyt, Laser Cooling in Thulium-doped Solids, Ph. D. Thesis...date, optical refrigeration research has been confined to glasses and crystals doped with rare- earth elements and direct-band semiconductors such as

  17. Performance of Several High Order Numerical Methods for Supersonic Combustion

    Science.gov (United States)

    Sjoegreen, Bjoern; Yee, H. C.; Don, Wai Sun; Mansour, Nagi N. (Technical Monitor)

    2001-01-01

    The performance of two recently developed numerical methods by Yee et al. and Sjoegreen and Yee using postprocessing nonlinear filters is examined for a 2-D multiscale viscous supersonic react-live flow. These nonlinear filters can improve nonlinear instabilities and at the same time can capture shock/shear waves accurately. They do not, belong to the class of TVD, ENO or WENO schemes. Nevertheless, they combine stable behavior at discontinuities and detonation without smearing the smooth parts of the flow field. For the present study, we employ a fourth-order Runge-Kutta in time and a sixth-order non-dissipative spatial base scheme for the convection and viscous terms. We denote the resulting nonlinear filter schemes ACM466-RK4 and WAV66-RK4.

  18. Optical wavefront distortion due to supersonic flow fields

    Institute of Scientific and Technical Information of China (English)

    CHEN ZhiQiang; FU Song

    2009-01-01

    The optical wavefront distortion caused by a supersonic flow field around a half model of blunt nose cone was studied in a wind tunnel. A Shack-Hartmann wavefront sensor was used to measure the dis-totted optical wavefront. Interesting optical parameters including the peak variation (PV), root of mean square (RMS) and Strehl ratio were obtained under different test conditions during the experiment. During the establishing process of the flow field in the wind tunnel test section, the wavefront shape was unstable. However after the flow field reached the steady flow state, the wavefront shape kept sta-ble, and the relative error of wavefront aberration was found small. The Shack-Hartmann wavefront sensor developed was proved to be credible in measuring quantitatively the optical phase change of light traveling through the flow field around model window.

  19. Supersonic jets of hydrogen and helium for laser wakefield acceleration

    CERN Document Server

    Svensson, K.; Wojda, F.; Senje, L.; Burza, M.; Aurand, B.; Genoud, G.; Persson, A.; Wahlström, C.-G.; Lundh, O.

    2016-01-01

    The properties of laser wakefield accelerated electrons in supersonic gas flows of hydrogen and helium are investigated. At identical backing pressure, we find that electron beams emerging from helium show large variations in their spectral and spatial distributions, whereas electron beams accelerated in hydrogen plasmas show a higher degree of reproducibility. In an experimental investigation of the relation between neutral gas density and backing pressure, it is found that the resulting number density for helium is ∼30% higher than for hydrogen at the same backing pressure. The observed differences in electron beam properties between the two gases can thus be explained by differences in plasma electron density. This interpretation is verified by repeating the laser wakefield acceleration experiment using similar plasma electron densities for the two gases, which then yielded electron beams with similar properties.

  20. Survey of supersonic combustion ramjet research at Langley

    Science.gov (United States)

    Northam, G. B.; Anderson, G. Y.

    1986-01-01

    The Hypersonic Propulsion Branch at NASA Langley Research Center has maintained an active research program in supersonic combustion ramjet (scramjet) and high speed ramjet propulsion since the 1960s. The focus for this research has centered on propulsion for manned reuseable vehicles with cryogenic hydrogen fuel. This paper presents some highlights of this research. The design philosophy of the Langley fixed-geometry airframe-integrated modular scramjet is discussed. The component development and research programs that have supported the successful demonstration of the engine concept using subscale engine module hardware is reviewed and a brief summary of the engine tests presented. An extensive bibliography of research supported by the Langley program is also included.

  1. Survey of supersonic combustion ramjet research at Langley

    Science.gov (United States)

    Northam, G. B.; Anderson, G. Y.

    1986-01-01

    The Hypersonic Propulsion Branch at NASA Langley Research Center has maintained an active research program in supersonic combustion ramjet (scramjet) and high speed ramjet propulsion since the 1960s. The focus for this research has centered on propulsion for manned reuseable vehicles with cryogenic hydrogen fuel. This paper presents some highlights of this research. The design philosophy of the Langley fixed-geometry airframe-integrated modular scramjet is discussed. The component development and research programs that have supported the successful demonstration of the engine concept using subscale engine module hardware is reviewed and a brief summary of the engine tests presented. An extensive bibliography of research supported by the Langley program is also included.

  2. Vortex development on slender missiles at supersonic speeds

    Science.gov (United States)

    Allen, J. M.; Dillenius, M. F. E.

    1979-01-01

    A theoretical and experimental effort has been made to develop a vortex-prediction capability on circular and noncircular missiles at supersonic speeds. Predicted vortex patterns are computed by two linear-theory computer codes. One calculates the strengths and initial locations of the vortices, and the other calculates their trajectories. A short color motion picture has been produced from the calculations to illustrate the predicted vortex patterns on a typical missile. Experimental vapor-screen photographs are presented to show the longitudinal development of the vortices on a fin-control missile. Comparisons are made between these data and the predicted vortices to assess the accuracy of the theory. The theory appears to be fairly accurate in predicting the number, locations, and relative strengths of individual vortices which develop over the missile, but cannot predict vortex sheets or diffuse vorticity whenever they occur.

  3. Gas dynamics of a supersonic radial jet. Part II

    Science.gov (United States)

    Kosarev, V. F.; Klinkov, S. V.; Zaikovskii, V. N.

    2016-05-01

    The paper presents the radial distributions of the pressure measured with a Pitot tube for the case of a radial jet with/without swirling of the input flow in the pre-chamber; the length of the supersonic part of the jet, dependency of the jet thickness as a function of the distance from the nozzle outlet, and approximating analytical formula for the jet thickness that generalizes the experimental data. Experimental data demonstrated that at the deposition distances lower than 4-6 gauges from the nozzle outlet, the solid particle velocity and temperature are almost uniform over the jet cross section. This means that the target surface can be allocated here without loss in coating quality and deposition coefficient. The maximal recommended distance where the deposition is still possible is the length of l s0 ~ 16 gauges.

  4. Supersonic flutter analysis of thin cracked functionally graded material plates

    CERN Document Server

    Natarajan, S; Bordas, S

    2012-01-01

    In this paper, the flutter behaviour of simply supported square functionally graded material plates immersed in a supersonic flow is studied. An enriched 4-noded quadrilateral element based on field consistency approach is used for this study and the crack is modelled independent of the underlying mesh. The material properties are assumed to be temperature dependent and graded only in the thickness direction. The effective material properties are estimated using the rule of mixtures. The formulation is based on the first order shear deformation theory and the shear correction factors are evaluated employing the energy equivalence principle. The influence of the crack length, the crack orientation, the flow angle and the gradient index on the aerodynamic pressure and the frequency are numerically studied. The results obtained here reveal that the critical frequency and the critical pressure decreases with increase in crack length and it is minimum when the crack is aligned to the flow angle.

  5. Modeling supersonic combustion using a fully-implicit numerical method

    Science.gov (United States)

    Maccormack, Robert W.; Wilson, Gregory J.

    1990-01-01

    A fully-implicit finite-volume algorithm for two-dimensional axisymmetric flows has been coupled to a detailed hydrogen-air reaction mechanism (13 species and 33 reactions) so that supersonic combustion phenomena may be investigated. Numerical computations are compared with ballistic-range shadowgraphs of Lehr (1972) that exhibit two discontinuities caused by a blunt body as it passes through a premixed stoichiometric hydrogen-air mixture. The suitability of the numerical procedure for simulating these double-front flows is shown. The requirements for the physical formulation and the numerical modeling of these flowfields are discussed. Finally, the sensitivity of these external flowfields to changes in certain key reaction rate constants is examined.

  6. Nonlinear closures for scale separation in supersonic magnetohydrodynamic turbulence

    CERN Document Server

    Grete, Philipp; Schmidt, Wolfram; Schleicher, Dominik R G; Federrath, Christoph

    2015-01-01

    Turbulence in compressible plasma plays a key role in many areas of astrophysics and engineering. The extreme plasma parameters in these environments, e.g. high Reynolds numbers, supersonic and super-Alfvenic flows, however, make direct numerical simulations computationally intractable even for the simplest treatment -- magnetohydrodynamics (MHD). To overcome this problem one can use subgrid-scale (SGS) closures -- models for the influence of unresolved, subgrid-scales on the resolved ones. In this work we propose and validate a set of constant coefficient closures for the resolved, compressible, ideal MHD equations. The subgrid-scale energies are modeled by Smagorinsky-like equilibrium closures. The turbulent stresses and the electromotive force (EMF) are described by expressions that are nonlinear in terms of large scale velocity and magnetic field gradients. To verify the closures we conduct a priori tests over 137 simulation snapshots from two different codes with varying ratios of thermal to magnetic pre...

  7. Overexpanded viscous supersonic jet interacting with a unilateral barrier

    Science.gov (United States)

    Dobrynin, B. M.; Maslennikov, V. G.; Sakharov, V. A.; Serova, E. V.

    1986-07-01

    The interaction of a two-dimensional supersonic jet with a unilateral barrier parallel to the flow symmetry plane was studied to account for effects due to gas viscosity and backgound-gas ejection from the region into which the jet expands. In the present experiments, the incident shock wave was reflected at the end of a shock tube equipped with a nozzle. The jet emerged into a pressure chamber 6 cu m in volume and the environmental pressure ratio of the flow in the quasi-stationary phase remained constant. The light source was an OGM-20 laser operating in the giant-pulse mode. Due to background-gas ejection, the gas density in the vicinity of the barrier is much less than on the unconfined side of the jet. The resulting flow is characterized by two distinct environmental pressure ratios: the flow is underexpanded near the barrier, while on the other side it is overexpanded.

  8. Supersonic Relative Velocity Effect on the Baryonic Acoustic Oscillation Measurements

    CERN Document Server

    Yoo, Jaiyul; Seljak, Uros

    2011-01-01

    We investigate the effect of supersonic relative velocities between baryons and dark matter, recently shown to arise generically at high redshift, on baryonic acoustic oscillation (BAO) measurements at low redshift. The amplitude of the relative velocity effect at low redshift is model-dependent, but can be parameterized by using an unknown bias. We find that if unaccounted, the relative velocity effect can shift the BAO peak position and bias estimates of the dark energy equation-of-state due to its non-smooth, out-of-phase oscillation structure around the BAO scale. Fortunately, the relative velocity effect can be easily modeled in constraining cosmological parameters without substantially inflating the error budget. We also demonstrate that the presence of the relative velocity effect gives rise to a unique signature in the galaxy bispectrum, which can be utilized to isolate this effect. Future dark energy surveys can accurately measure the relative velocity effect and subtract it from the power spectrum a...

  9. Comparing Numerical Methods for Isothermal Magnetized Supersonic Turbulence

    CERN Document Server

    Kritsuk, Alexei G; Collins, David; Padoan, Paolo; Norman, Michael L; Abel, Tom; Banerjee, Robi; Federrath, Christoph; Flock, Mario; Lee, Dongwook; Li, Pak Shing; Mueller, Wolf-Christian; Teyssier, Romain; Ustyugov, Sergey D; Vogel, Christian; Xu, Hao

    2011-01-01

    We employ simulations of supersonic super-Alfv\\'enic turbulence decay as a benchmark test problem to assess and compare the performance of nine astrophysical MHD methods actively used to model star formation. The set of nine codes includes: ENZO, FLASH, KT-MHD, LL-MHD, PLUTO, PPML, RAMSES, STAGGER, and ZEUS. We present a comprehensive set of statistical measures designed to quantify the effects of numerical dissipation in these MHD solvers. We compare power spectra for basic fields to determine the effective spectral bandwidth of the methods and rank them based on their relative effective Reynolds numbers. We also compare numerical dissipation for solenoidal and dilatational velocity components to check for possible impacts of the numerics on small-scale density statistics. Finally, we discuss convergence of various characteristics for the turbulence decay test and impacts of various components of numerical schemes on the accuracy of solutions. We show that the best performing codes employ a consistently high...

  10. High-frequency supersonic heating of hydrogen for propulsion

    Energy Technology Data Exchange (ETDEWEB)

    Bonneville, Jacques M.

    1963-03-15

    The possibility of increasing the specific impulse of hydrogen by supersonic heating is shown on the basis of thermodynamics. The application of high-frequency electric fields to heat the gas permits a control over the heating rates in the nozzle, and results in a reduction in energy losses to walls, electrodes, etc. The efficiencies of the various energy transfer processes are considered in some detail. A simple process of expansion and heating is presented. Results of calculations of heat transfer rates to the nozzle wall are given. A consistent set of electron densities and electric fields are also calculated and presented. Some qualitative results of experimental work previously carried out are included. It is concluded that the process should increase the specific impulse of hydrogen appreciably, in a reasonably efficient manner, and that further experimental work is indicated. (auth)

  11. Fluid-structure interaction of panel in supersonic fluid passage

    Institute of Scientific and Technical Information of China (English)

    LIU Zhan-sheng; ZHANG Yun-feng; TIAN Xin

    2008-01-01

    Fluid-structure interaction of panel in supersonic fluid passage is studied with subcycling and spline interpolation based predict-correct scheme.The passage is formed with two parallel panels,one is risid and the other is flexible.The interaction between fluid flows and flexible panel is numerically studied,mainly focused on the effect of dynamic pressure and distance between two parallel panels.Subcycling and spline interpolation based predict-correct scheme is utihzed to combine the vibration and fluid analysis and to stabilize long-term calculations to get accurate resuhs.It's demonstrated that the flutter characteristic of flexible panel is more complex with the increase of dynamic pressure and the decrease of distance between two parallel panels.Via analyzing the propagation and reflection of disturbance in passage,it's determined as a main cause of the variations.

  12. An analytical theory of heated duct flows in supersonic combustors

    Directory of Open Access Journals (Sweden)

    Chenxi Wu

    2014-01-01

    Full Text Available One-dimensional analytical theory is developed for supersonic duct flow with variation of cross section, wall friction, heat addition, and relations between the inlet and outlet flow parameters are obtained. By introducing a selfsimilar parameter, effects of heat releasing, wall friction, and change in cross section area on the flow can be normalized and a self-similar solution of the flow equations can be found. Based on the result of self-similar solution, the sufficient and necessary condition for the occurrence of thermal choking is derived. A relation of the maximum heat addition leading to thermal choking of the duct flow is derived as functions of area ratio, wall friction, and mass addition, which is an extension of the classic Rayleigh flow theory, where the effects of wall friction and mass addition are not considered. The present work is expected to provide fundamentals for developing an integral analytical theory for ramjets and scramjets.

  13. Use of advanced particle methods in modeling space propulsion and its supersonic expansions

    Science.gov (United States)

    Borner, Arnaud

    This research discusses the use of advanced kinetic particle methods such as Molecular Dynamics (MD) and direct simulation Monte Carlo (DSMC) to model space propulsion systems such as electrospray thrusters and their supersonic expansions. MD simulations are performed to model an electrospray thruster for the ionic liquid (IL) EMIM--BF4 using coarse-grained (CG) potentials. The model is initially featuring a constant electric field applied in the longitudinal direction. Two coarse-grained potentials are compared, and the effective-force CG (EFCG) potential is found to predict the formation of the Taylor cone, the cone-jet, and other extrusion modes for similar electric fields and mass flow rates observed in experiments of a IL fed capillary-tip-extractor system better than the simple CG potential. Later, one-dimensional and fully transient three-dimensional electric fields, the latter solving Poisson's equation to take into account the electric field due to space charge at each timestep, are computed by coupling the MD model to a Poisson solver. It is found that the inhomogeneous electric field as well as that of the IL space-charge improve agreement between modeling and experiment. The boundary conditions (BCs) are found to have a substantial impact on the potential and electric field, and the tip BC is introduced and compared to the two previous BCs, named plate and needle, showing good improvement by reducing unrealistically high radial electric fields generated in the vicinity of the capillary tip. The influence of the different boundary condition models on charged species currents as a function of the mass flow rate is studied, and it is found that a constant electric field model gives similar agreement to the more rigorous and computationally expensive tip boundary condition at lower flow rates. However, at higher mass flow rates the MD simulations with the constant electric field produces extruded particles with higher Coulomb energy per ion, consistent with

  14. Plasma-enhanced mixing and flameholding in supersonic flow

    Science.gov (United States)

    Firsov, Alexander; Savelkin, Konstantin V.; Yarantsev, Dmitry A.; Leonov, Sergey B.

    2015-01-01

    The results of experimental study of plasma-based mixing, ignition and flameholding in a supersonic model combustor are presented in the paper. The model combustor has a length of 600 mm and cross section of 72 mm width and 60 mm height. The fuel is directly injected into supersonic airflow (Mach number M=2, static pressure Pst=160–250 Torr) through wall orifices. Two series of tests are focused on flameholding and mixing correspondingly. In the first series, the near-surface quasi-DC electrical discharge is generated by flush-mounted electrodes at electrical power deposition of Wpl=3–24 kW. The scope includes parametric study of ignition and flame front dynamics, and comparison of three schemes of plasma generation: the first and the second layouts examine the location of plasma generators upstream and downstream from the fuel injectors. The third pattern follows a novel approach of combined mixing/ignition technique, where the electrical discharge distributes along the fuel jet. The last pattern demonstrates a significant advantage in terms of flameholding limit. In the second series of tests, a long discharge of submicrosecond duration is generated across the flow and along the fuel jet. A gasdynamic instability of thermal cavity developed after a deposition of high-power density in a thin plasma filament promotes the air–fuel mixing. The technique studied in this work has weighty potential for high-speed combustion applications, including cold start/restart of scramjet engines and support of transition regime in dual-mode scramjet and at off-design operation. PMID:26170434

  15. Supersonic Stall Flutter of High Speed Fans. [in turbofan engines

    Science.gov (United States)

    Adamczyk, J. J.; Stevens, W.; Jutras, R.

    1981-01-01

    An analytical model is developed for predicting the onset of supersonic stall bending flutter in axial flow compressors. The analysis is based on a modified two dimensional, compressible, unsteady actuator disk theory. It is applied to a rotor blade row by considering a cascade of airfoils whose geometry and dynamic response coincide with those of a rotor blade element at 85 percent of the span height (measured from the hub). The rotor blades are assumed to be unshrouded (i.e., free standing) and to vibrate in their first flexural mode. The effects of shock waves and flow separation are included in the model through quasi-steady, empirical, rotor total-pressure-loss and deviation-angle correlations. The actuator disk model predicts the unsteady aerodynamic force acting on the cascade blading as a function of the steady flow field entering the cascade and the geometry and dynamic response of the cascade. Calculations show that the present model predicts the existence of a bending flutter mode at supersonic inlet Mach numbers. This flutter mode is suppressed by increasing the reduced frequency of the system or by reducing the steady state aerodynamic loading on the cascade. The validity of the model for predicting flutter is demonstrated by correlating the measured flutter boundary of a high speed fan stage with its predicted boundary. This correlation uses a level of damping for the blade row (i.e., the log decrement of the rotor system) that is estimated from the experimental flutter data. The predicted flutter boundary is shown to be in good agreement with the measured boundary.

  16. THE COOLING OF CORONAL PLASMAS. IV. CATASTROPHIC COOLING OF LOOPS

    Energy Technology Data Exchange (ETDEWEB)

    Cargill, P. J. [Space and Atmospheric Physics, The Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom); Bradshaw, S. J., E-mail: p.cargill@imperial.ac.uk [Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States)

    2013-07-20

    We examine the radiative cooling of coronal loops and demonstrate that the recently identified catastrophic cooling is due to the inability of a loop to sustain radiative/enthalpy cooling below a critical temperature, which can be >1 MK in flares, 0.5-1 MK in active regions, and 0.1 MK in long tenuous loops. Catastrophic cooling is characterized by a rapid fall in coronal temperature, while the coronal density changes by a small amount. Analytic expressions for the critical temperature are derived and show good agreement with numerical results. This effect considerably limits the lifetime of coronal plasmas below the critical temperature.

  17. Cooling Performance of an Impingement Cooling Device Combined with Pins

    Institute of Scientific and Technical Information of China (English)

    Dongliang QUAN; Songling LIU; Jianghai LI; Gaowen LIU

    2005-01-01

    Experimental study and one dimensional model analysis were conducted to investigate cooling performance of an integrated impingement and pin fin cooling device. A typical configuration specimen was made and tested in a large scale low speed closed-looped wind tunnel. Detailed two-dimensional contour maps of the temperature and cooling effectiveness were obtained for different pressure ratios and therefore different coolant flow-rates through the tested specimen. The experimental results showed that very high cooling effectiveness can be achieved by this cooling device with relatively small amount of coolant flow. Based on the theory of transpiration cooling in porous material, a one dimensional heat transfer model was established to analyze the effect of various parameters on cooling effectiveness. It was found from this model that the variation of heat transfer on the gas side, including heat transfer coefficient and film cooling effectiveness, of the specimen created much more effect on its cooling effectiveness than that of the coolant side. The predictions of the one-dimensional mode were compared and agreed well with the experimental data.

  18. Numerical Study for Hysteresis Phenomena of Shock Wave Reflection in Overexpanded Axisymmetric Supersonic Jet

    Institute of Scientific and Technical Information of China (English)

    Tsuyoshi Yasunobu; Ken Matsuoka; Hideo Kashimura; Shigeru Matsuo; Toshiaki Setoguchi

    2006-01-01

    When the high-pressure gas is exhausted to the vacuum chamber from the supersonic nozzle, the overexpanded supersonic jet is formed at specific condition. In two-dimensional supersonic jet, furthermore, it is known that the hysteresis phenomena for the reflection type of shock wave in the flow field is occurred under the quasi-steady flow and for instance, the transitional pressure ratio between the regular reflection (RR) and Mach reflection (MR) is affected by this phenomenon. Many papers have described the hysteresis phenomena for underexpanded supersonic jet, but this phenomenon under the overexpanded axisymmetric jet has not been detailed in the past papers. The purpose of this study is to clear the hysteresis phenomena for the reflection type of shock wave at the overexpanded axisymmetric jet using the TVD method and to discuss the characteristic of hysteresis phenomena.

  19. Supersonic unstalled flutter. [aerodynamic loading of thin airfoils induced by cascade motion

    Science.gov (United States)

    Adamczyk, J. J.; Goldstein, M. E.; Hartmann, M. J.

    1978-01-01

    Flutter analyses were developed to predict the onset of supersonic unstalled flutter of a cascade of two-dimensional airfoils. The first of these analyzes the onset of supersonic flutter at low levels of aerodynamic loading (i.e., backpressure), while the second examines the occurrence of supersonic flutter at moderate levels of aerodynamic loading. Both of these analyses are based on the linearized unsteady inviscid equations of gas dynamics to model the flow field surrounding the cascade. These analyses are utilized in a parametric study to show the effects of cascade geometry, inlet Mach number, and backpressure on the onset of single and multi degree of freedom unstalled supersonic flutter. Several of the results are correlated against experimental qualitative observation to validate the models.

  20. Unsteady flow in a supersonic cascade with strong in-passage shocks

    Science.gov (United States)

    Goldstein, M. E.; Braun, W.; Adamczyk, J. J.

    1977-01-01

    Linearized theory is used to study the unsteady flow in a supersonic cascade with in-passage shock waves. We use the Wiener-Hopf technique to obtain a closed-form analytical solution for the supersonic region. To obtain a solution for the rotational flow in the subsonic region we must solve an infinite set of linear algebraic equations. The analysis shows that it is possible to correlate quantitatively the oscillatory shock motion with the Kutta condition at the trailing edges of the blades. This feature allows us to account for the effect of shock motion on the stability of the cascade. Unlike the theory for a completely supersonic flow, the present study predicts the occurrence of supersonic bending flutter. It therefore provides a possible explanation for the bending flutter that has recently been detected in aircraft-engine compressors at higher blade loadings.

  1. Zeroth-order flutter prediction for cantilevered plates in supersonic flow

    CSIR Research Space (South Africa)

    Meijer, M-C

    2015-08-01

    Full Text Available An aeroelastic prediction framework in MATLAB with modularity in the quasi-steady aerodynamic methodology is developed. Local piston theory (LPT) is integrated with quasi-steady methods including shock-expansion theory and the Supersonic Hypersonic...

  2. Influences of friction drag on spontaneous condensation in water vapor supersonic flows

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A mathematical model was developed to investigate the water vapor spontaneous condensation under supersonic flow conditions. A numerical simulation was performed for the water vapor condensable supersonic flows through Laval nozzles under different flow friction conditions. The comparison between numerical and experimental results shows that the model is accurate enough to investigate the supersonic spontaneous condensation flow of water vapor inside Laval nozzles. The influences of flow friction drag on supersonic spontaneous condensation flow of water vapor inside Laval nozzles were investigated. It was found that the flow friction has a direct effect on the spontaneous condensation process and therefore it is important for an accurate friction prediction in designing this kind of Laval nozzles.

  3. Numerical simulation of carbon dioxide removal from natural gas using supersonic nozzles

    Science.gov (United States)

    Sun, Wenjuan; Cao, Xuewen; Yang, Wen; Jin, Xuetang

    2017-03-01

    Supersonic separation is a technology potentially applicable to natural gas decarbonation process. Preliminary research on the performance of supersonic nozzle in the removal of carbon dioxide from natural gas is presented in this study. Computational Fluid Dynamics (CFD) technique is used to simulate the flow behavior inside the supersonic nozzle. The CFD model is validated successfully by comparing its results to the data borrowed from the literature. The results indicate that the liquefaction of carbon dioxide can be achieved in the properly designed nozzle. Shock wave occurs in the divergent section of the nozzle with the increase of the back pressure, destroying the liquefaction process. In the supersonic separator, the shock wave should be kept outside of the nozzle.

  4. Energy-Deposition to Reduce Skin Friction in Supersonic Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has drawn attention to an impending need to improve energy-efficiency in low supersonic (M<~3) platforms. Aerodynamic efficiency is the foundation of...

  5. Experimental Investigation on Noise Suppression in Supersonic Jets from Convergent-Divergent Nozzles with Baffles

    Institute of Scientific and Technical Information of China (English)

    Yoshiaki Miyazato; Yong-Hun Kweon; Toshiyuki Aoki; Mitsuharu Masuda; Kwon-Hee Lee; Heuy-Dong Kim; Toshiaki Setoguchi; Kazuyasu Matsuo

    2003-01-01

    The acoustic properties of supersonic jet noise from a convergent-divergent nozzle with a baffle have been studied experimentally over the range of nozzle pressure ratios from 2.0 to 8.0. Acoustic measurements were conducted in a carefully designed anechoic room providing a free-field environment. A new approach for screech noise suppression by a cross-wire is proposed. Schlieren photographs were taken to visualize the shock wave patterns in the supersonic jet with and without the cross-wire. The effects of the baffle and the cross-wire on acoustic properties are discussed. It is shown that the baffle has little effect on the screech frequency for the underexpanded supersonic jet without the cross-wire. Also, the cross-wire introduced in supersonic jets is found to lead to a significant reduction in overall sound pressure level.

  6. Sting Supported Bell XS-2 in the 9 Inch Supersonic Tunnel

    Science.gov (United States)

    1947-01-01

    A sting supported model of the Bell XS-2 was tested in the 9 Inch Supersonic Tunnel. Photograph published in Engineer in Charge: A History of the Langley Aeronautical Laboratory, 1917-1958 by James R. Hansen. Page 316.

  7. Effect of Nonequilibrium Homogenous COndensation on Flow Fields in a Supersonic Nozzle

    Institute of Scientific and Technical Information of China (English)

    ToshiakiSetoguchi; ShenYu; 等

    1997-01-01

    When condensation occurs in a supersonic flow field,the flow is affected by the latent heat released.In the present study,a condensing flow was produced by an expansion of moist air in a supersonic circular nozzle,and,by inserting a wedge-type shock generator placed in the supersonic part of the nozzle,the experimental investigations were carried out to clarify the effect of condensation on the normal shock wave and the boundary layer.As a result,the position of the shock wave relative to the condensation zone was discussed,together with the effect of condensation on pressure fluctuations.Furthermore,a compressible viscous two-phase flow of moist air in a supersonic half nozzle was calculated to investigate the effect of condensation on boundary layer.

  8. Self—Induced Oscillation of Supersonic Jet During Impingement on Cylindrical Body

    Institute of Scientific and Technical Information of China (English)

    HideoKashimura; ShenYu; 等

    1998-01-01

    The phenomena of the interaction between a supersonic jet and an obstacle are related to the problems of the aeronautical and other industrial engineerings.When a supersonic jet impinges on an obstacle,the self induced oscillation occurs under several conditions.The flow charactersitics caused by the impingement of underexpanded supersonic jet on an obstacle have been investigated.However,it seems that the mechanism of self induced oscillation and the factor which dominates if have not been detailed in the published papers,The characteristics of the self induced oscillation of the supersonic jet during the impingement on a cylindrical body are investigated using the visualization of flow fields and the numerical calculations in this study.

  9. Sub-scale Direct Connect Supersonic Combustion Facility (Research Cell 18)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: RC18 is a continuous-flow, direct-connect, supersonic-combustion research facility that is capable of simulating flight conditions from Mach 3.0 to Mach...

  10. Influences of friction drag on spontaneous condensation in water vapor supersonic flows

    Institute of Scientific and Technical Information of China (English)

    JIANG WenMing; LIU ZhongLiang; LIU HengWei; PANG HuiZhong; BAO LingLing

    2009-01-01

    A mathematical model was developed to investigate the water vapor spontaneous condensation under supersonic flow conditions. A numerical simulation was performed for the water vapor condensable supersonic flows through Laval nozzles under different flow friction conditions. The comparison be-tween numerical and experimental results shows that the model is accurate enough to investigate the supersonic spontaneous condensation flow of water vapor inside Laval nozzles. The influences of flow friction drag on supersonic spontaneous condensation flow of water vapor inside Laval nozzles were investigated, It was found that the flow friction has a direct effect on the spontaneous condensation process and therefore it is important for an accurate friction prediction in designing this kind of Laval nozzles.

  11. Electronic cooling using thermoelectric devices

    Energy Technology Data Exchange (ETDEWEB)

    Zebarjadi, M., E-mail: m.zebarjadi@rutgers.edu [Department of Mechanical and Aerospace Engineering, Rutgers University, Piscataway, New Jersey 08854 (United States); Institute of Advanced Materials, Devices, and Nanotechnology, Rutgers University, Piscataway, New Jersey 08854 (United States)

    2015-05-18

    Thermoelectric coolers or Peltier coolers are used to pump heat in the opposite direction of the natural heat flux. These coolers have also been proposed for electronic cooling, wherein the aim is to pump heat in the natural heat flux direction and from hot spots to the colder ambient temperature. In this manuscript, we show that for such applications, one needs to use thermoelectric materials with large thermal conductivity and large power factor, instead of the traditionally used high ZT thermoelectric materials. We further show that with the known thermoelectric materials, the active cooling cannot compete with passive cooling, and one needs to explore a new set of materials to provide a cooling solution better than a regular copper heat sink. We propose a set of materials and directions for exploring possible materials candidates suitable for electronic cooling. Finally, to achieve maximum cooling, we propose to use thermoelectric elements as fins attached to copper blocks.

  12. Optical stochastic cooling in Tevatron

    CERN Document Server

    Lebedev, V

    2012-01-01

    Intrabeam scattering is the major mechanism resulting in a growth of beam emittances and fast luminosity degradation in the Tevatron. As a result in the case of optimal collider operation only about 40% of antiprotons are used to the store end and the rest are discarded. Beam cooling is the only effective remedy to increase the particle burn rate and, consequently, the luminosity. Unfortunately neither electron nor stochastic cooling can be effective at the Tevatron energy and bunch density. Thus the optical stochastic cooling (OSC) is the only promising technology capable to cool the Tevatron beam. Possible ways of such cooling implementation in the Tevatron and advances in the OSC cooling theory are discussed in this paper. The technique looks promising and potentially can double the average Tevatron luminosity without increasing its peak value and the antiproton production.

  13. A Preliminary Evaluation of Supersonic Transport Category Vehicle Operations in the National Airspace System

    Science.gov (United States)

    Underwood, Matthew C.; Guminsky, Michael D.

    2015-01-01

    Several public sector businesses and government agencies, including the National Aeronautics and Space Administration are currently working on solving key technological barriers that must be overcome in order to realize the vision of low-boom supersonic flights conducted over land. However, once these challenges are met, the manner in which this class of aircraft is integrated in the National Airspace System may become a potential constraint due to the significant environmental, efficiency, and economic repercussions that their integration may cause. Background research was performed on historic supersonic operations in the National Airspace System, including both flight deck procedures and air traffic controller procedures. Using this information, an experiment was created to test some of these historic procedures in a current-day, emerging Next Generation Air Transportation System (NextGen) environment and observe the interactions between commercial supersonic transport aircraft and modern-day air traffic. Data was gathered through batch simulations of supersonic commercial transport category aircraft operating in present-day traffic scenarios as a base-lining study to identify the magnitude of the integration problems and begin the exploration of new air traffic management technologies and architectures which will be needed to seamlessly integrate subsonic and supersonic transport aircraft operations. The data gathered include information about encounters between subsonic and supersonic aircraft that may occur when supersonic commercial transport aircraft are integrated into the National Airspace System, as well as flight time data. This initial investigation is being used to inform the creation and refinement of a preliminary Concept of Operations and for the subsequent development of technologies that will enable overland supersonic flight.

  14. The Intensity of the Light Diffraction by Supersonic Longitudinal Waves in Solid

    Directory of Open Access Journals (Sweden)

    Minasyan V.

    2010-04-01

    Full Text Available First, we predict existence of transverse electromagnetic field created by supersonic longitudinal waves in solid. This electromagnetic wave with frequency of ultrasonic field is moved by velocity of supersonic field toward of direction propagation of one. The average Poynting vector of superposition field is calculated by presence of the transverse electromagnetic and the optical fields which in turn provides appearance the diffraction of light.

  15. A Direct-Fire Trajectory Model for Supersonic, Transonic, and Subsonic Projectile Flight

    Science.gov (United States)

    2014-07-01

    motions of the projectile about the trajectory due to the angular motion of the projectile . For a stable projectile , these motions are typically small...A Direct-Fire Trajectory Model for Supersonic, Transonic, and Subsonic Projectile Flight by Paul Weinacht ARL-TR-6998 July 2014...Direct-Fire Trajectory Model for Supersonic, Transonic, and Subsonic Projectile Flight Paul Weinacht Weapons and Materials Research Directorate, ARL

  16. Aerodynamic Optimization of a Supersonic Bending Body Projectile by a Vector-Evaluated Genetic Algorithm

    Science.gov (United States)

    2016-12-01

    ARL-CR-0810 ● DEC 2016 US Army Research Laboratory Aerodynamic Optimization of a Supersonic Bending Body Projectile by a Vector...not return it to the originator. ARL-CR-0810 ● DEC 2016 US Army Research Laboratory Aerodynamic Optimization of a ...Supersonic Bending Body Projectile by a Vector-Evaluated Genetic Algorithm prepared by Justin L Paul Academy of Applied Science 24 Warren Street

  17. Electron Cooling Experiments in CSR

    CERN Document Server

    Xiaodong, Yang

    2011-01-01

    The six species heavy ion beam was accumulated with the help of electron cooling in the main ring of Cooler Storage Ring of Heavy Ion Research Facility in Lanzhou(HIRFL-CSR), the ion beam accumulation dependence on the parameters of cooler was investigated experimentally. The 400MeV/u 12C6+ and 200MeV/u 129Xe54+ was stored and cooled in the experimental ring CSRe, the cooling force was measured in different condition.

  18. Radiative cooling for thermophotovoltaic systems

    Science.gov (United States)

    Zhou, Zhiguang; Sun, Xingshu; Bermel, Peter

    2016-09-01

    Radiative cooling has recently garnered a great deal of attention for its potential as an alternative method for photovoltaic thermal management. Here, we will consider the limits of radiative cooling for thermal management of electronics broadly, as well as a specific application to thermal power generation. We show that radiative cooling power can increase rapidly with temperature, and is particularly beneficial in systems lacking standard convective cooling. This finding indicates that systems previously operating at elevated temperatures (e.g., 80°C) can be passively cooled close to ambient under appropriate conditions with a reasonable cooling area. To examine these general principles for a previously unexplored application, we consider the problem of thermophotovoltaic (TPV) conversion of heat to electricity via thermal radiation illuminating a photovoltaic diode. Since TPV systems generally operate in vacuum, convective cooling is sharply limited, but radiative cooling can be implemented with proper choice of materials and structures. In this work, realistic simulations of system performance are performed using the rigorous coupled wave analysis (RCWA) techniques to capture thermal emitter radiation, PV diode absorption, and radiative cooling. We subsequently optimize the structural geometry within realistic design constraints to find the best configurations to minimize operating temperature. It is found that low-iron soda-lime glass can potentially cool the PV diode by a substantial amount, even to below ambient temperatures. The cooling effect can be further improved by adding 2D-periodic photonic crystal structures. We find that the improvement of efficiency can be as much as an 18% relative increase, relative to the non-radiatively cooled baseline, as well as a potentially significant improvement in PV diode lifetime.

  19. To Be Cool or Uncool?

    Institute of Scientific and Technical Information of China (English)

    袁会珍

    2007-01-01

    The western world has always been divided into two types of people-the cool and the uncool. It is a division that __1__ in school. The cool kids are good at __2__. They are __3__ with the opposite sex. They are good-looking and people want to __4__ their style. They can do their homework but they don't make a big effort. That would __5__ be cool.

  20. Electron cooling experiments in CSR

    Institute of Scientific and Technical Information of China (English)

    PARKHOMCHUK; Vasily; REVA; Vladimir

    2011-01-01

    The six species heavy ion beam was accumulated with the help of electron cooling in the main ring of Cooler Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSR). The ion beam accumulation dependence on the parameters of cooler was investigated experimentally. The 400 MeV/u 12C6+ and 200 MeV/u 129Xe54+ were stored and cooled in the experimental ring CSRe, and the cooling force was measured in different conditions.

  1. Workshop 4 Converter cooling & recuperation

    Science.gov (United States)

    Iles, Peter; Hindman, Don

    1995-01-01

    Cooling the PV converter increases the overall TPV system efficiency, and more than offsets the losses incurred in providing cooling systems. Convective air flow methods may be sufficient, and several standard water cooling systems, including thermo-syphon radiators, capillary pumps or microchannel plates, are available. Recuperation is used to increase system efficiency, rather than to increase the emitter temperature. Recuperators operating at comparable high temperatures, such as in high temperature turbines have worked effectively.

  2. Stochastic cooling technology at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Pasquinelli, R.J. E-mail: pasquin@fnal.gov

    2004-10-11

    The first antiproton cooling systems were installed and commissioned at Fermilab in 1984-1985. In the interim period, there have been several major upgrades, system improvements, and complete reincarnation of cooling systems. This paper will present some of the technology that was pioneered at Fermilab to implement stochastic cooling systems in both the Antiproton Source and Recycler accelerators. Current performance data will also be presented.

  3. 超-超引射器多目标优化设计%Multi-objective optimization of supersonic-supersonic ejector

    Institute of Scientific and Technical Information of China (English)

    陈钦; 陈吉明; 蔡光明; 任泽斌

    2012-01-01

    推导出了超-超引射器性能计算和优化设计模型,借助Pareto优胜、Pareto最优解和Pareto前端等概念,采用基于多目标进化/分解算法(MOEA/D)的多目标优化方法,计算得到超-超引射器多目标优化问题的Pareto前端,解决了超-超引射器多目标优化设计问题,并与常规参数分析方法进行了比较.结果表明:超超引射器性能影响参数相互关系复杂,增压比和引射系数作为引射器主要性能参数相互冲突,通过常规分析难以得到较清晰的设计准则,利用多目标优化设计方法可有效地辅助多属性决策和系统优化设计.%For supersonic-supersonic ejector, the design model and corresponding analysis were presented, and the relation of design parameters and the performance was partly revealed. The results revealed the confliction of two performance objectives and the complexity of the design problem. To clarify the entangled relation of design parameters and objectives and to afford facilities for the design process, the Pareto front(PF) concept was introduced and an MOEA/D algorithm was programmed to calculate the PFs of specific supersonic-supersonic ejector multi-objective optimization problems. The methodology adopted here proved to be effective and efficient for the supersonic-supersonic ejector design problem.

  4. Direct cooled power electronics substrate

    Science.gov (United States)

    Wiles, Randy H [Powell, TN; Wereszczak, Andrew A [Oak Ridge, TN; Ayers, Curtis W [Kingston, TN; Lowe, Kirk T [Knoxville, TN

    2010-09-14

    The disclosure describes directly cooling a three-dimensional, direct metallization (DM) layer in a power electronics device. To enable sufficient cooling, coolant flow channels are formed within the ceramic substrate. The direct metallization layer (typically copper) may be bonded to the ceramic substrate, and semiconductor chips (such as IGBT and diodes) may be soldered or sintered onto the direct metallization layer to form a power electronics module. Multiple modules may be attached to cooling headers that provide in-flow and out-flow of coolant through the channels in the ceramic substrate. The modules and cooling header assembly are preferably sized to fit inside the core of a toroidal shaped capacitor.

  5. Cooling clothing utilizing water evaporation

    DEFF Research Database (Denmark)

    Sakoi, Tomonori; Tominaga, Naoto; Melikov, Arsen Krikor

    2014-01-01

    We developed cooling clothing that utilizes water evaporation to cool the human body and has a mechanism to control the cooling intensity. Clean water was supplied to the outer surface of the T-shirt of the cooling clothing, and a small fan was used to enhance evaporation on this outer surface...... temperature ranging from 27.4 to 30.7 °C to establish a suitable water supply control method. A water supply control method that prevents water accumulation in the T-shirt and water dribbling was validated; this method is established based on the concept of the water evaporation capacity under the applied...

  6. Regeneratively Cooled Porous Media Jacket

    Science.gov (United States)

    Mungas, Greg (Inventor); Fisher, David J. (Inventor); London, Adam Pollok (Inventor); Fryer, Jack Merrill (Inventor)

    2013-01-01

    The fluid and heat transfer theory for regenerative cooling of a rocket combustion chamber with a porous media coolant jacket is presented. This model is used to design a regeneratively cooled rocket or other high temperature engine cooling jacket. Cooling jackets comprising impermeable inner and outer walls, and porous media channels are disclosed. Also disclosed are porous media coolant jackets with additional structures designed to transfer heat directly from the inner wall to the outer wall, and structures designed to direct movement of the coolant fluid from the inner wall to the outer wall. Methods of making such jackets are also disclosed.

  7. On the Nature of Feedback Heating in Cooling Flow Clusters

    CERN Document Server

    Pizzolato, F; Pizzolato, Fabio; Soker, Noam

    2004-01-01

    We study the feedback between heating and cooling of the intra-cluster medium (ICM) in cooling flow (CF) galaxies and clusters. We adopt the popular view that the heating is due to an active galactic nucleus (AGN), i.e. a central black hole accreting mass and launching jets and/or winds. We propose that the feedback occurs with the entire cool inner region (r2 cool fast and are removed from the ICM before experiencing the next major AGN heating event. We term this scenario cold-feedback. Some of these blobs cool and sink toward the central black hole, while others might form stars and cold molecular clouds. We derive the conditions under which the dense blobs formed by perturbations might cool to low temperatures (T < 10^4 K), and feed the black hole. The main conditions are found to be: (1) An over-dense blob must be prevented from reaching an equilibrium position in the ICM: therefore it has to cool fast, and the density profile of the ambient gas should be shallow; (2) Non-linear perturbations are requi...

  8. Interstellar molecular clouds

    Science.gov (United States)

    Bally, J.

    1986-04-01

    The physical properties of the molecular phase of the interstellar medium are studied with regard to star formation and the structure of the Galaxy. Most observations of molecular clouds are made with single-dish, high-surface precision radio telescopes, with the best resolution attainable at 0.2 to 1 arcmin; the smallest structures that can be resolved are of order 10 to the 17th cm in diameter. It is now believed that: (1) most of the mass of the Galaxy is in the form of giant molecular clouds; (2) the largest clouds and those responsible for most massive star formation are concentrated in spiral arms; (3) the molecular clouds are the sites of perpetual star formation, and are significant in the chemical evolution of the Galaxy; (4) giant molecular clouds determine the evolution of the kinematic properties of galactic disk stars; (5) the total gas content is diminishing with time; and (6) most clouds have supersonic internal motions and do not form stars on a free-fall time scale. It is concluded that though progress has been made, more advanced instruments are needed to inspect the processes operating within stellar nurseries and to study the distribution of the molecular clouds in more distant galaxies. Instruments presently under construction which are designed to meet these ends are presented.

  9. Fluid cooled electrical assembly

    Science.gov (United States)

    Rinehart, Lawrence E.; Romero, Guillermo L.

    2007-02-06

    A heat producing, fluid cooled assembly that includes a housing made of liquid-impermeable material, which defines a fluid inlet and a fluid outlet and an opening. Also included is an electrical package having a set of semiconductor electrical devices supported on a substrate and the second major surface is a heat sink adapted to express heat generated from the electrical apparatus and wherein the second major surface defines a rim that is fit to the opening. Further, the housing is constructed so that as fluid travels from the fluid inlet to the fluid outlet it is constrained to flow past the opening thereby placing the fluid in contact with the heat sink.

  10. ATLAS' major cooling project

    CERN Multimedia

    2005-01-01

    In 2005, a considerable effort has been put into commissioning the various units of ATLAS' complex cryogenic system. This is in preparation for the imminent cooling of some of the largest components of the detector in their final underground configuration. The liquid helium and nitrogen ATLAS refrigerators in USA 15. Cryogenics plays a vital role in operating massive detectors such as ATLAS. In many ways the liquefied argon, nitrogen and helium are the life-blood of the detector. ATLAS could not function without cryogens that will be constantly pumped via proximity systems to the superconducting magnets and subdetectors. In recent weeks compressors at the surface and underground refrigerators, dewars, pumps, linkages and all manner of other components related to the cryogenic system have been tested and commissioned. Fifty metres underground The helium and nitrogen refrigerators, installed inside the service cavern, are an important part of the ATLAS cryogenic system. Two independent helium refrigerators ...

  11. Climate impact of supersonic air traffic: an approach to optimize a potential future supersonic fleet - results from the EU-project SCENIC

    Science.gov (United States)

    Grewe, V.; Stenke, A.; Ponater, M.; Sausen, R.; Pitari, G.; Iachetti, D.; Rogers, H.; Dessens, O.; Pyle, J.; Isaksen, I. S. A.; Gulstad, L.; Søvde, O. A.; Marizy, C.; Pascuillo, E.

    2007-10-01

    The demand for intercontinental transportation is increasing and people are requesting short travel times, which supersonic air transportation would enable. However, besides noise and sonic boom issues, which we are not referring to in this investigation, emissions from supersonic aircraft are known to alter the atmospheric composition, in particular the ozone layer, and hence affect climate significantly more than subsonic aircraft. Here, we suggest a metric to quantitatively assess different options for supersonic transport with regard to the potential destruction of the ozone layer and climate impacts. Options for fleet size, engine technology (nitrogen oxide emission level), cruising speed, range, and cruising altitude, are analyzed, based on SCENIC emission scenarios for 2050, which underlay the requirements to be as realistic as possible in terms of e.g., economic markets and profitable market penetration. This methodology is based on a number of atmosphere-chemistry and climate models to reduce model dependencies. The model results differ significantly in terms of the response to a replacement of subsonic aircraft by supersonic aircraft, e.g., concerning the ozone impact. However, model differences are smaller when comparing the different options for a supersonic fleet. Those uncertainties were taken into account to make sure that our findings are robust. The base case scenario, where supersonic aircraft get in service in 2015, a first fleet fully operational in 2025 and a second in 2050, leads in our simulations to a near surface temperature increase in 2050 of around 7 mK and with constant emissions afterwards to around 21 mK in 2100. The related total radiative forcing amounts to 22 mWm2 in 2050, with an uncertainty between 9 and 29 mWm2. A reduced supersonic cruise altitude or speed (from Mach 2 to Mach 1.6) reduces both, climate impact and ozone destruction, by around 40%. An increase in the range of the supersonic aircraft leads to more emissions at

  12. Air cooled absorption chillers for solar cooling applications

    Science.gov (United States)

    Biermann, W. J.; Reimann, R. C.

    1982-03-01

    The chemical composition of a 'best' absorption refrigerant system is identified, and those properties of the system necessary to design hot water operated, air cooled chilling equipment are determined. Air cooled chillers from single family residential sizes into the commercial rooftop size range are designed and operated.

  13. Tunable far-IR laser spectroscopy of jet-cooled carbon clusters: the nu 2 bending vibration of C3.

    Science.gov (United States)

    Schmuttenmaer, C A; Cohen, R C; Pugliano, N; Heath, J R; Cooksy, A L; Busarow, K L; Saykally, R J

    1990-08-24

    Seven rovibrational transitions of the (01(1)0) fundamental bending band of C3 have been measured with high precision with the use of a tunable far-infrared laser spectrometer. The C3 molecules were produced by laser vaporization of a graphite rod and cooled in a supersonic expansion. The astrophysically important nu 2 fundamental frequency is determined to be 63.416529(40) cm-1. These measurements provide the basis for studies of C3 in the interstellar medium with far-infrared astronomy.

  14. A buffer gas cooled beam of barium monohydride

    Science.gov (United States)

    Iwata, Geoffrey; Tarallo, Marco; Zelevinsky, Tanya

    2016-05-01

    Significant advances in direct laser cooling of diatomic molecules have opened up a wide array of molecular species to precision studies spanning many-body physics, quantum collisions and ultracold dissociation. We present a cryogenic beam source of barium monohydride (BaH), and study laser ablation of solid precursor targets as well as helium buffer gas cooling dynamics. Additionally, we cover progress towards a molecular magneto-optical trap, with spectroscopic studies of relevant cooling transitions in the B2 Σ molecules, including resolution of hyperfine structure and precision measurements of the vibrational Frank-Condon factors. Finally, we examine the feasibility of photo dissociation of trapped BaH molecules to yield optically accessible samples of ultracold hydrogen.

  15. Sisyphus Laser Cooling of a Polyatomic Molecule

    CERN Document Server

    Kozyryev, Ivan; Matsuda, Kyle; Augenbraun, Benjamin L; Anderegg, Loic; Sedlack, Alexander P; Doyle, John M

    2016-01-01

    We perform magnetically-assisted Sisyphus laser cooling of the triatomic free radical strontium monohydroxide (SrOH). This is achieved with principal optical cycling in the rotationally closed $P\\left(N"=1\\right)$ branch of either the $\\tilde{X}^{2}\\Sigma^{+}\\left(000\\right)\\leftrightarrow\\tilde{A}^{2}\\Pi_{1/2}\\left(000\\right)$ or the $\\tilde{X}^{2}\\Sigma^{+}\\left(000\\right)\\leftrightarrow\\tilde{B}^{2}\\Sigma^{+}\\left(000\\right)$ vibronic transitions. Molecules lost into the excited vibrational states during the cooling process are repumped back through the $\\tilde{B}\\left(000\\right)$ state for both the $\\left(100\\right)$ level of the Sr-O stretching mode and the $\\left(02^{0}0\\right)$ level of the bending mode. The transverse temperature of a SrOH molecular beam is reduced in one dimension by two orders of magnitude to $\\sim700\\ {\\rm \\mu K}$. This approach opens a path towards creating a variety of ultracold polyatomic molecules, including much larger ones, by means of direct laser cooling.

  16. Sisyphus Laser Cooling of a Polyatomic Molecule.

    Science.gov (United States)

    Kozyryev, Ivan; Baum, Louis; Matsuda, Kyle; Augenbraun, Benjamin L; Anderegg, Loic; Sedlack, Alexander P; Doyle, John M

    2017-04-28

    We perform magnetically assisted Sisyphus laser cooling of the triatomic free radical strontium monohydroxide (SrOH). This is achieved with principal optical cycling in the rotationally closed P(N^{''}=1) branch of either the X[over ˜]^{2}Σ^{+}(000)↔A[over ˜]^{2}Π_{1/2}(000) or the X[over ˜]^{2}Σ^{+}(000)↔B[over ˜]^{2}Σ^{+}(000) vibronic transitions. Molecules lost into the excited vibrational states during the cooling process are repumped back through the B[over ˜](000) state for both the (100) level of the Sr-O stretching mode and the (02^{0}0) level of the bending mode. The transverse temperature of a SrOH molecular beam is reduced in one dimension by 2 orders of magnitude to ∼750  μK. This approach opens a path towards creating a variety of ultracold polyatomic molecules by means of direct laser cooling.

  17. Feasibility assessment of vacuum cooling followed by immersion vacuum cooling on water-cooked pork.

    Science.gov (United States)

    Dong, Xiaoguang; Chen, Hui; Liu, Yi; Dai, Ruitong; Li, Xingmin

    2012-01-01

    Vacuum cooling followed by immersion vacuum cooling was designed to cool water-cooked pork (1.5±0.05 kg) compared with air blast cooling (4±0.5°C, 2 m/s), vacuum cooling (10 mbar) and immersion vacuum cooling. This combined cooling method was: vacuum cooling to an intermediate temperature of 25°C and then immersion vacuum cooling with water of 10°C to the final temperature of 10°C. It was found that the cooling loss of this combined cooling method was significantly lower (Pvacuum cooling. This combined cooling was faster (Pvacuum cooling in terms of cooling rate. Moreover, the pork cooled by combined cooling method had significant differences (P<0.05) in water content, color and shear force. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. The impact of primordial supersonic flows on early structure formation, reionization and the lowest-mass dwarf galaxies

    CERN Document Server

    Maio, Umberto; Ciardi, Benedetta

    2010-01-01

    Tseliakhovich & Hirata recently discovered that higher-order corrections to the cosmological linear-perturbation theory lead to supersonic coherent baryonic flows just after recombination (i.e.\\ $z \\approx 1020$), with rms velocities of $\\sim$30 km/s relative to the underlying dark-matter distribution, on comoving scales of $\\la 3$ Mpc\\,$h^{-1}$. To study the impact of these coherent flows we performed high-resolution N-body plus SPH simulations in boxes of 5.0 and 0.7 Mpc\\,$h^{-1}$, for bulk-flow velocities of 0 (as reference), 30 and 60 km/s. The simulations follow the evolution of cosmic structures by taking into account detailed, primordial, non-equilibrium gas chemistry (i.e.\\ H, He, H$_2$, HD, HeH, etc.), cooling, star formation, and feedback effects from stellar evolution. We find that these bulk flows suppress star formation in low-mass haloes (i.e.\\ $M_{\\rm vir} \\la 10^8$M$_{\\odot}$ until $z\\sim 13$), lower the abundance of the first objects by $\\sim 1%-20%$, and, as consequence, delay cosmic sta...

  19. Sub-Doppler infrared spectroscopy of propargyl radical (H{sub 2}CCCH) in a slit supersonic expansion

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chih-Hsuan; Nesbitt, David J. [JILA, National Institute of Standards and Technology, University of Colorado, Boulder, Colorado 80309, USA and Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80309 (United States)

    2015-06-28

    The acetylenic CH stretch mode (ν{sub 1}) of propargyl (H{sub 2}CCCH) radical has been studied at sub-Doppler resolution (∼60 MHz) via infrared laser absorption spectroscopy in a supersonic slit-jet discharge expansion, where low rotational temperatures (T{sub rot} = 13.5(4) K) and lack of spectral congestion permit improved determination of band origin and rotational constants for the excited state. For the lowest J states primarily populated in the slit jet cooled expansion, fine structure due to the unpaired electron spin is resolved completely, which permits accurate analysis of electron spin-rotation interactions in the vibrationally excited states (ε{sub aa} = − 518.1(1.8), ε{sub bb} = − 13.0(3), ε{sub cc} = − 1.8(3) MHz). In addition, hyperfine broadening in substantial excess of the sub-Doppler experimental linewidths is observed due to nuclear spin–electron spin contributions at the methylenic (—CH{sub 2}) and acetylenic (—CH) positions, which permits detailed modeling of the fine/hyperfine structure line contours. The results are consistent with a delocalized radical spin density extending over both methylenic and acetylenic C atoms, in excellent agreement with simple resonance structures as well as ab initio theoretical calculations.

  20. Measurements of leading edge vortices in a supersonic stream

    Science.gov (United States)

    Milanovic, Ivana Milija

    An experimental investigation of the leading edge vortices from a 75° sweptback, sharp edge delta wing has been carried out in a Mach 2.49 stream. Five-hole conical probe traverses were conducted vertically and horizontally through the primary vortices at the trailing edge and at one half chord downstream station for 7° and 12° angles of attack. The main objective was to determine the Mach number and pressure distributions in the primary vortex and to present comparisons of flow properties at different survey stations. In response to the continued interest in efficient supersonic flight vehicles, particularly in the missile arena, the motivation for this research has been to provide the quantitative details of supersonic leading edge vortices, the understanding of which up to now has been largely based on flow visualizations and presumed similarity to low speed flows. As a prerequisite to the measurement campaign, the employed five-hole conical probe was numerically calibrated using a three-dimensional Thin Layer Navier-Stokes solver in order to circumvent the traditional experimental approach vastly demanding on resources. The pressure readings at the probe orifices were computed for a range of Mach numbers and pitch angles, and subsequently verified in wind tunnel tests. The calibration phase also demonstrated the profound influence of the probe bluntness on the nearby static pressure ports, its relevance to the ultimate modeling strategy and the resulting calibration charts. Flow diagnostics of the leading edge vortices included both qualitative flow visualizations, as well as quantitative measurements. Shadowgraphs provided information regarding the trajectory and relative size of the generated vortices while assuring that no probe-induced vortex breakdown occurred. Surface oil patterns revealed the general spanwise locations of leeward vortices, and confirmed topological similarity to their low speed counterparts. The probe measurements revealed substantial