WorldWideScience

Sample records for cylindrical micro combustors

  1. Micro-mixer/combustor

    KAUST Repository

    Badra, Jihad Ahmad; Masri, Assaad Rachid

    2014-01-01

    A micro-mixer/combustor to mix fuel and oxidant streams into combustible mixtures where flames resulting from combustion of the mixture can be sustained inside its combustion chamber is provided. The present design is particularly suitable

  2. Micro-mixer/combustor

    KAUST Repository

    Badra, Jihad Ahmad

    2014-09-18

    A micro-mixer/combustor to mix fuel and oxidant streams into combustible mixtures where flames resulting from combustion of the mixture can be sustained inside its combustion chamber is provided. The present design is particularly suitable for diffusion flames. In various aspects the present design mixes the fuel and oxidant streams prior to entering a combustion chamber. The combustion chamber is designed to prevent excess pressure to build up within the combustion chamber, which build up can cause instabilities in the flame. A restriction in the inlet to the combustion chamber from the mixing chamber forces the incoming streams to converge while introducing minor pressure drop. In one or more aspects, heat from combustion products exhausted from the combustion chamber may be used to provide heat to at least one of fuel passing through the fuel inlet channel, oxidant passing through the oxidant inlet channel, the mixing chamber, or the combustion chamber. In one or more aspects, an ignition strip may be positioned in the combustion chamber to sustain a flame without preheating.

  3. Thermal performance of a micro-combustor for micro-gas turbine system

    International Nuclear Information System (INIS)

    Cao, H.L.; Xu, J.L.

    2007-01-01

    Premixed combustion of hydrogen gas and air was performed in a stainless steel based micro-annular combustor for a micro-gas turbine system. Micro-scale combustion has proved to be stable in the micro-combustor with a gap of 2 mm. The operating range of the micro-combustor was measured, and the maximum excess air ratio is up to 4.5. The distribution of the outer wall temperature and the temperature of exhaust gas of the micro-combustor with excess air ratio were obtained, and the wall temperature of the micro-combustor reaches its maximum value at the excess air ratio of 0.9 instead of 1 (stoichiometric ratio). The heat loss of the micro-combustor to the environment was calculated and even exceeds 70% of the total thermal power computed from the consumed hydrogen mass flow rate. Moreover, radiant heat transfer covers a large fraction of the total heat loss. Measures used to reduce the heat loss were proposed to improve the thermal performance of the micro-combustor. The optimal operating status of the micro-combustor and micro-gas turbine is analyzed and proposed by analyzing the relationship of the temperature of the exhaust gas of the micro-combustor with thermal power and excess air ratio. The investigation of the thermal performance of the micro-combustor is helpful to design an improved micro-combustor

  4. Thermodynamics of premixed combustion in a heat recirculating micro combustor

    International Nuclear Information System (INIS)

    Rana, Uttam; Chakraborty, Suman; Som, S.K.

    2014-01-01

    A thermodynamic model has been developed to evaluate exergy transfer and its destruction in the process of premixed combustion in a heat recirculating micro combustor. Exergy destruction caused by process irreversibilities is characterized by entropy generation in the process. The entropy transport equation along with the solution of temperature and species concentration fields in the wake of flame sheet assumptions have been used to determine the different components of entropy generation. The role of thermal conductivity and thickness of combustor wall, and Peclet number on transfer and destruction rate of exergy is depicted in the process of flame stabilization via heat recirculation. The entropy generations due to gas phase heat conduction and chemical reaction are identified as the major sources of exergy destruction. The total irreversibility in pre-flame region is confined only within a small distance upstream of the flame. It has been observed that the local volumetric entropy generation is higher near the axis than that near the combustor wall. The second law efficiency is almost invariant with heat loss from the combustor, Peclet number, and thermal conductivity and thickness of combustor wall. - Highlights: • Irreversibility in the combustor is mainly due to conduction and chemical reaction. • Entropy generation near the axis is higher compared to that near the wall. • Heat recirculation and process irreversibility decrease with heat loss. • The second law efficiency is almost independent of Peclet number. • Second law efficiency is almost independent of wall thermal conductivity

  5. Combustion and direct energy conversion inside a micro-combustor

    International Nuclear Information System (INIS)

    Lei, Yafeng; Chen, Wei; Lei, Jiang

    2016-01-01

    Highlights: • The flammability range of micro-combustor was broadened with heat recirculation. • The quenching diameter decreased with heat recirculation compared to without recirculation. • The surface areas to volume ratio was the most important parameter affecting the energy conversion efficiency. • The maximum conversion efficiency (3.15%) was achieved with 1 mm inner diameter. - Abstract: Electrical energy can be generated by employing a micro-thermophotovoltaic (TPV) cell which absorbs thermal radiation from combustion taking place in a micro-combustor. The stability of combustion in a micro-combustor is essential for operating a micro-power system using hydrogen and hydrocarbon fuels as energy source. To understand the mechanism of sustaining combustion within the quenching distance of fuel, this study proposed an annular micro combustion tube with recirculation of exhaust heat. To explore the feasibility of combustion in the micro annular tube, the parameters influencing the combustion namely, quenching diameter, and flammability were studied through numerical simulation. The results indicated that combustion could be realized in micro- combustor using heat recirculation. Following results were obtained from simulation. The quenching diameter reduced from 1.3 mm to 0.9 mm for heat recirculation at equivalence ratio of 1; the lean flammability was 2.5%–5% lower than that of without heat recirculation for quenching diameters between 2 mm and 5 mm. The overall energy conversion efficiency varied at different inner diameters. A maximum efficiency of 3.15% was achieved at an inner diameter of 1 mm. The studies indicated that heat recirculation is an effective strategy to maintain combustion and to improve combustion limits in micro-scale system.

  6. Flame dynamics in a micro-channeled combustor

    International Nuclear Information System (INIS)

    Hussain, Taaha; Balachandran, Ramanarayanan; Markides, Christos N.

    2015-01-01

    The increasing use of Micro-Electro-Mechanical Systems (MEMS) has generated a significant interest in combustion-based power generation technologies, as a replacement of traditional electrochemical batteries which are plagued by low energy densities, short operational lives and low power-to-size and power-to-weight ratios. Moreover, the versatility of integrated combustion-based systems provides added scope for combined heat and power generation. This paper describes a study into the dynamics of premixed flames in a micro-channeled combustor. The details of the design and the geometry of the combustor are presented in the work by Kariuki and Balachandran [1]. This work showed that there were different modes of operation (periodic, a-periodic and stable), and that in the periodic mode the flame accelerated towards the injection manifold after entering the channels. The current study investigates these flames further. We will show that the flame enters the channel and propagates towards the injection manifold as a planar flame for a short distance, after which the flame shape and propagation is found to be chaotic in the middle section of the channel. Finally, the flame quenches when it reaches the injector slots. The glow plug position in the exhaust side ignites another flame, and the process repeats. It is found that an increase in air flow rate results in a considerable increase in the length (and associated time) over which the planar flame travels once it has entered a micro-channel, and a significant decrease in the time between its conversion into a chaotic flame and its extinction. It is well known from the literature that inside small channels the flame propagation is strongly influenced by the flow conditions and thermal management. An increase of the combustor block temperature at high flow rates has little effect on the flame lengths and times, whereas at low flow rates the time over which the planar flame front can be observed decreases and the time of

  7. Flame dynamics in a micro-channeled combustor

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Taaha; Balachandran, Ramanarayanan, E-mail: r.balachandran@ucl.ac.uk [Department of Mechanical Engineering, University College London, London (United Kingdom); Markides, Christos N. [Clean Energy Processes Laboratory, Department of Chemical Engineering, Imperial College London, London (United Kingdom)

    2015-01-22

    The increasing use of Micro-Electro-Mechanical Systems (MEMS) has generated a significant interest in combustion-based power generation technologies, as a replacement of traditional electrochemical batteries which are plagued by low energy densities, short operational lives and low power-to-size and power-to-weight ratios. Moreover, the versatility of integrated combustion-based systems provides added scope for combined heat and power generation. This paper describes a study into the dynamics of premixed flames in a micro-channeled combustor. The details of the design and the geometry of the combustor are presented in the work by Kariuki and Balachandran [1]. This work showed that there were different modes of operation (periodic, a-periodic and stable), and that in the periodic mode the flame accelerated towards the injection manifold after entering the channels. The current study investigates these flames further. We will show that the flame enters the channel and propagates towards the injection manifold as a planar flame for a short distance, after which the flame shape and propagation is found to be chaotic in the middle section of the channel. Finally, the flame quenches when it reaches the injector slots. The glow plug position in the exhaust side ignites another flame, and the process repeats. It is found that an increase in air flow rate results in a considerable increase in the length (and associated time) over which the planar flame travels once it has entered a micro-channel, and a significant decrease in the time between its conversion into a chaotic flame and its extinction. It is well known from the literature that inside small channels the flame propagation is strongly influenced by the flow conditions and thermal management. An increase of the combustor block temperature at high flow rates has little effect on the flame lengths and times, whereas at low flow rates the time over which the planar flame front can be observed decreases and the time of

  8. Design Optimization of a Micro-Combustor for Lean, Premixed Fuel-Air Mixtures

    Science.gov (United States)

    Powell, Leigh Theresa

    Present technology has been shifting towards miniaturization of devices for energy production for portable electronics. Micro-combustors, when incorporated into a micro-power generation system, provide the energy desired in the form of hot gases to power such technology. This creates the need for a design optimization of the micro-combustor in terms of geometry, fuel choice, and material selection. A total of five micro-combustor geometries, three fuels, and three materials were computationally simulated in different configurations in order to determine the optimal micro-combustor design for highest efficiency. Inlet velocity, equivalence ratio, and wall heat transfer coefficient were varied in order to test a comprehensive range of micro-combustor parameters. All simulations completed for the optimization study used ANSYS Fluent v16.1 and post-processing of the data was done in CFD Post v16.1. It was found that for lean, premixed fuel-air mixtures (φ = 0.6 - 0.9) ethane (C 2H6) provided the highest flame temperatures when ignited within the micro-combustor geometries. An aluminum oxide converging micro-combustor burning ethane and air at an equivalence ratio of 0.9, an inlet velocity of 0.5 m/s, and heat transfer coefficient of 5 W/m2-K was found to produce the highest combustor efficiency, making it the optimal choice for a micro-combustor design. It is proposed that this geometry be experimentally and computationally investigated further in order to determine if additional optimization can be achieved.

  9. Optimal combustor dimensions for the catalytic combustion of methane-air mixtures in micro-channels

    International Nuclear Information System (INIS)

    Chen, Junjie; Song, Wenya; Xu, Deguang

    2017-01-01

    Highlights: • The effect of combustor dimensions on the combustion stability was elucidated. • Wall thermal properties are important for optimizing combustor dimensions. • The optimal wall thickness increases with flow velocity. • The optimal combustor length depends on the wall thermal conductivity. • Stability diagrams were constructed and design recommendations were made. - Abstract: This paper addresses the question of choosing appropriate combustor dimensions for the self-sustained catalytic combustion in parallel plate micro-channels. The combustion characteristics and stability of methane-air mixtures over platinum in catalytic micro-combustors were studied, using a two-dimensional computational fluid dynamics (CFD) model with detailed chemistry and transport. The effects of gap size, wall thickness, and combustor length on the combustion stability and combustor performance were explored to provide guidelines for optimal design of combustor dimensions. Combustion stability diagrams were constructed, and design recommendations were made. The effect of wall thermal conductivity on the mechanisms of extinction and blowout, and its implications on optimal combustor geometry were studied. It was shown that combustor dimensions are vital in determining the combustion stability of the system. The choice of appropriate combustor dimensions is crucial in achieving stable combustion, due to a rather narrow operating space determined by stability, material, and conversion constraints. The optimal gap size depends on whether the flow velocity or flow rate is kept constant. For most practical wall materials in the range of metals to highly conductive ceramics, larger combustors are more stable at a fixed flow velocity, whereas smaller combustors are recommended for a fixed flow rate at the expense of hot spots. The optimal wall thickness increases with flow velocity. Higher flow velocities can be sustained in combustors with low-conductivity materials using

  10. Experimental study of a plat-flame micro combustor burning DME for thermoelectric power generation

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, L.Q.; Zhao, D.Q.; Guo, C.M.; Wang, X.H. [Key Laboratory of Renewable Energy and Gas Hydrate, CAS, Guangzhou Institute of Energy Conversion of CAS, Guangzhou 510640 (China)

    2011-01-15

    A centimeter magnitude thermoelectric (TE) power generation system based on a plat-flame micro combustor burning DME (dimethyl ether) has been developed. The chamber wall of this micro combustor was made of two parallel sintered porous plates which acted as mixture inlet. The main virtue of this combustor is that it can keep combustor wall at lower temperature for reducing heat loss when sustaining a stable flame. Experimental test results showed it was feasible to obtain stable DME/air premixed flame at lean combustion situations in the micro combustor. The combustion load of this 0.48 cm{sup 3} chamber capacity was 20-200 W at equivalence ratio {phi} = 0.6. Though the flame temperature was above 1000 C, the combustor's wall temperature was near 600 C lower than flame temperature. In the demonstrated TE power generation system which integrated the plat-flame micro combustor, a heat spreader had good effect on uniforming the hot side temperature field of TE modules. Cooled by water and with 150 W input power at {phi} = 0.7, the system produced 10 V output at open circuit and 4 V at 10 {omega} load. The maximum power output was above 2 W, and the maximum overall chemical-electric energy conversion efficiency was 1.25%. (author)

  11. Combustor

    Energy Technology Data Exchange (ETDEWEB)

    Boden, J C; Fuller, J; Styles, A C

    1987-02-18

    A combustor suitable for disposing of lean fuel gas mixtures, e.g. solvent-laden exhaust streams, has a combustion chamber, a heat exchanger comprising a matrix of elongate tubes for supplying lean fuel gas to the combustion chamber and a burner located within the combustion chamber. The burner is adapted to mix fuel gas and the lean fuel gas which enters at an inlet and issues from the elongate tube outlets. The heat exchanger is in an heat exchange relationship with flue gas emerging from the outlet and the combustion chamber. The passage of the flue gases from the combustion chamber over the external surfaces of the tubes of the heat exchanger enables the pre-heating of the lean fuel gas mixture prior to its entry into the combustion chamber.

  12. Experimental study on premixed CH{sub 4}/air mixture combustion in micro Swiss-roll combustors

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Bei-Jing; Wang, Jian-Hua [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China)

    2010-12-15

    Excess enthalpy combustion is a promising approach to stabilize flame in micro-combustors. Using a Swiss-roll combustor configuration, excess enthalpy combustion can be conveniently achieved. In this work, three types of Swiss-roll combustors with double spiral-shaped channels were designed and fabricated. The combustors were tested using methane/air mixtures of various equivalence ratios. Both temperature distributions and extinction limits were determined for each combustor configuration at different methane mass flow rates. Results indicate that the Swiss-roll combustors developed in the current study greatly enhance combustion stability in center regions of the combustors. At the same time, excess enthalpy combustors of the Swiss-roll configuration significantly extend the extinction limits of methane/air mixtures. In addition, the effects of combustor configurations and thermal insulation arrangements on temperature distributions and extinction limits were evaluated. With heat losses to the environment being significant, the use of thermal insulations further enhances the flame stability in center regions of the Swiss-roll combustors and extends flammable ranges. (author)

  13. Combustion of hydrogen-air in micro combustors with catalytic Pt layer

    Energy Technology Data Exchange (ETDEWEB)

    Yang Wang; Zhijun Zhou; Weijuan Yang; Junhu Zhou; Jianzhong Liu; Zhihua Wang; Cen, Kefa [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, Zhejiang (China)

    2010-06-15

    Micro power generators have high power density. However, their key components micro combustors have low stability. In this experiment, catalyst is applied to improve the stability. The catalytic micro combustor is made from an alumina ceramic tube. It has inner diameter of 1 mm, outer diameter of 2.02 mm and length of 24.5 mm. It is prepared through impregnation of aqueous solution of H{sub 2}PtCl{sub 6}. The flammability limits and surface temperatures under different operation conditions are measured. The flow rates range from 0.08 to 0.4 L/min. According to the experimental results, catalyst is effective to inhibit extinction. For example, At 0.8 L/min, the stability limit is 0.193-14.9 in the non-catalytic combustor. After applying catalyst, the lean limit is near 0, and the rich limit is 29.3. But catalyst is less effective to inhibit blow out. Increasing flow rates also inhibits extinction. In the non-catalytic combustor, while the flow rates increase from 0.08 to 0.2 L/min, the lean stability limit decreases from 0.193 to 0.125. The experimental results indicate that catalyst induces shift downstream in the stoichiometric and rich cases. The numeric simulation verifies that the heterogeneous reaction weakens the homogeneous reaction through consuming fuels. Thus, the insufficient heat recirculation makes the reaction region shift downstream. However, lean mixture has intense reaction in the catalytic combustor. It is attributed to the high mass diffusion and low thermal diffusion of lean mixture. (author)

  14. Combustion of hydrogen-air in micro combustors with catalytic Pt layer

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yang; Zhou Zhijun [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, Zhejiang (China); Yang Weijuan, E-mail: 10508107@zju.edu.c [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, Zhejiang (China); Zhou Junhu; Liu Jianzhong; Wang Zhihua; Cen Kefa [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, Zhejiang (China)

    2010-06-15

    Micro power generators have high power density. However, their key components micro combustors have low stability. In this experiment, catalyst is applied to improve the stability. The catalytic micro combustor is made from an alumina ceramic tube. It has inner diameter of 1 mm, outer diameter of 2.02 mm and length of 24.5 mm. It is prepared through impregnation of aqueous solution of H{sub 2}PtCl{sub 6}. The flammability limits and surface temperatures under different operation conditions are measured. The flow rates range from 0.08 to 0.4 L/min. According to the experimental results, catalyst is effective to inhibit extinction. For example, At 0.8 L/min, the stability limit is 0.193-14.9 in the non-catalytic combustor. After applying catalyst, the lean limit is near 0, and the rich limit is 29.3. But catalyst is less effective to inhibit blow out. Increasing flow rates also inhibits extinction. In the non-catalytic combustor, while the flow rates increase from 0.08 to 0.2 L/min, the lean stability limit decreases from 0.193 to 0.125. The experimental results indicate that catalyst induces shift downstream in the stoichiometric and rich cases. The numeric simulation verifies that the heterogeneous reaction weakens the homogeneous reaction through consuming fuels. Thus, the insufficient heat recirculation makes the reaction region shift downstream. However, lean mixture has intense reaction in the catalytic combustor. It is attributed to the high mass diffusion and low thermal diffusion of lean mixture.

  15. Combustion of hydrogen-air in micro combustors with catalytic Pt layer

    International Nuclear Information System (INIS)

    Wang Yang; Zhou Zhijun; Yang Weijuan; Zhou Junhu; Liu Jianzhong; Wang Zhihua; Cen Kefa

    2010-01-01

    Micro power generators have high power density. However, their key components micro combustors have low stability. In this experiment, catalyst is applied to improve the stability. The catalytic micro combustor is made from an alumina ceramic tube. It has inner diameter of 1 mm, outer diameter of 2.02 mm and length of 24.5 mm. It is prepared through impregnation of aqueous solution of H 2 PtCl 6 . The flammability limits and surface temperatures under different operation conditions are measured. The flow rates range from 0.08 to 0.4 L/min. According to the experimental results, catalyst is effective to inhibit extinction. For example, At 0.8 L/min, the stability limit is 0.193-14.9 in the non-catalytic combustor. After applying catalyst, the lean limit is near 0, and the rich limit is 29.3. But catalyst is less effective to inhibit blow out. Increasing flow rates also inhibits extinction. In the non-catalytic combustor, while the flow rates increase from 0.08 to 0.2 L/min, the lean stability limit decreases from 0.193 to 0.125. The experimental results indicate that catalyst induces shift downstream in the stoichiometric and rich cases. The numeric simulation verifies that the heterogeneous reaction weakens the homogeneous reaction through consuming fuels. Thus, the insufficient heat recirculation makes the reaction region shift downstream. However, lean mixture has intense reaction in the catalytic combustor. It is attributed to the high mass diffusion and low thermal diffusion of lean mixture.

  16. Superconducting vortex dynamics in cylindrical Nb micro- and nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Fomin, Vladimir M. [Institute for Integrative Nanosciences, IFW-Dresden, D-01069 Dresden (Germany); Rezaev, Roman O. [Institute for Integrative Nanosciences, IFW-Dresden, D-01069 Dresden (Germany); Laboratory of Mathematical Physics, Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); Schmidt, Oliver G. [Institute for Integrative Nanosciences, IFW-Dresden, D-01069 Dresden (Germany); Material Systems for Nanoelectronics, Chemnitz University of Technology, D-09107 Chemnitz (Germany)

    2012-07-01

    Advancements in fabrication of rolled-up micro- and nanotubes including superconductor layers (e.g., InGaAs/GaAs/Nb) open new ways for investigation of the vortex matter in superconductors with curved geometries. Geometry determines the dynamics of vortices in the presence of transport currents in open superconductor micro- and nanotubes subject to a magnetic field orthogonal to the axis. Vortices nucleate periodically at one edge of the tube, subsequently move along the tube under the action of the Lorentz force and denucleate at the opposite edge of the tube. Characteristic times of nonequilibrium vortex dynamics in an open tube are efficiently controlled by the tube radius. The magnetic field, at which the vortices begin to nucleate at the edge of the structure, is increased several times by rolling up a planar film in a tube. This effect is caused not only by a spatial dependence of the magnetic field component normal to the cylindrical surface, but also by correlations between the states of the superconducting order parameter in the opposite areas of the cylindrical surface.

  17. A micro fuel reformer integrated with a combustor and a microchannel evaporator

    Science.gov (United States)

    Yoshida, Kazushi; Tanaka, Shuji; Hiraki, Hisashi; Esashi, Masayoshi

    2006-09-01

    This paper describes the development of a micro fuel reformer integrated with a combustor and an evaporator. Fuel reforming tests were performed by using a mixture of methanol and water as reforming fuel and hydrogen as combustion fuel. It was found that the design of the microchannel evaporator is critical to obtain larger hydrogen output. Hydrogen output and CO concentration were investigated by varying the input combustion power at different fuel feeding rates. 32.9 sccm of hydrogen, which is equivalent to 5.9 W in lower heating value, was produced, when input combustion power was 11 W.

  18. Flame stability and heat transfer analysis of methane-air mixtures in catalytic micro-combustors

    International Nuclear Information System (INIS)

    Chen, Junjie; Song, Wenya; Xu, Deguang

    2017-01-01

    Highlights: • The mechanisms of heat and mass transfer for loss of stability were elucidated. • Stability diagrams were constructed and design recommendations were made. • Flame characteristics were examined to determine extinction and blowout limits. • Heat loss greatly affects extinction whereas wall materials greatly affect blowout. • Radiation causes the flame to shift downstream. - Abstract: The flame stability and heat transfer characteristics of methane-air mixtures in catalytic micro-combustors were studied, using a two-dimensional computational fluid dynamics (CFD) model with detailed chemistry and transport. The effects of wall thermal conductivity, surface emissivity, fuel, flow velocity, and equivalence ratio were explored to provide guidelines for optimal design. Furthermore, the underlying mechanisms of heat and mass transfer for loss of flame stability were elucidated. Finally, stability diagrams were constructed and design recommendations were made. It was found that the heat loss strongly affects extinction, whereas the wall thermal conductivity greatly affects blowout. The presence of homogeneous chemistry extends blowout limits, especially for inlet velocities higher than 6 m/s. Increasing transverse heat transfer rate reduces stability, whereas increasing transverse mass transfer rate improves stability. Surface radiation behaves similarly to the heat conduction within the walls, but opposite trends are observed. High emissivity causes the flame to shift downstream. Methane exhibits much broader blowout limits. For a combustor with gap size of 0.8 mm, a residence time higher than 3 ms is required to prevent breakthrough, and inlet velocities lower than 0.8 m/s are the most desirable operation regime. Further increase of the wall thermal conductivity beyond 80 W/(m·K) could not yield an additional increase in stability.

  19. Variable volume combustor

    Science.gov (United States)

    Ostebee, Heath Michael; Ziminsky, Willy Steve; Johnson, Thomas Edward; Keener, Christopher Paul

    2017-01-17

    The present application provides a variable volume combustor for use with a gas turbine engine. The variable volume combustor may include a liner, a number of micro-mixer fuel nozzles positioned within the liner, and a linear actuator so as to maneuver the micro-mixer fuel nozzles axially along the liner.

  20. Measurement of triboelectric charging of moving micro particles by means of an inductive cylindrical probe

    International Nuclear Information System (INIS)

    Nesterov, A; Loeffler, F; Koenig, K; Trunk, U; Leibe, K; Felgenhauer, T; Bischoff, F R; Breitling, F; Lindenstruth, V; Stadler, V; Hausmann, M

    2007-01-01

    We present a method based on induced currents in a cylindrical probe which allows analysis of the micro-particle charging processes in an aerosol. The micro particles were triboelectrically charged by passing through a dielectric tube coaxially mounted into the probe. The cylindrical probe enabled the quantification of particle charging without prior calibration of the probe. An analytic model was developed for the description of the measured induced currents and implemented into a computer simulation program. The combination of model simulations and an appropriate experimental setup revealed comprehensive data for the determination of the particles' electric charge against time of flight through the tube. In methodological proof of principle experiments, the formations of particle clouds with charges of different signs were observed using magnetite micro particles

  1. Bio-Inspired Wide-Angle Broad-Spectrum Cylindrical Lens Based on Reflections from Micro-Mirror Array on a Cylindrical Elastomeric Membrane

    Directory of Open Access Journals (Sweden)

    Chi-Chieh Huang

    2014-06-01

    Full Text Available We present a wide-angle, broad-spectrum cylindrical lens based on reflections from an array of three-dimensional, high-aspect-ratio micro-mirrors fabricated on a cylindrical elastomeric substrate, functionally inspired by natural reflecting superposition compound eyes. Our device can perform one-dimensional focusing and beam-shaping comparable to conventional refraction-based cylindrical lenses, while avoiding chromatic aberration. The focal length of our cylindrical lens is 1.035 mm, suitable for micro-optical systems. Moreover, it demonstrates a wide field of view of 152° without distortion, as well as modest spherical aberrations. Our work could be applied to diverse applications including laser diode collimation, barcode scanning, holography, digital projection display, microlens arrays, and optical microscopy.

  2. Mathematical modelling of liquid meniscus shape in cylindrical micro-channel for normal and micro gravity conditions

    Science.gov (United States)

    Marchuk, Igor; Lyulin, Yuriy

    2017-10-01

    Mathematical model of liquid meniscus shape in cylindrical micro-channel of the separator unit of condensing/separating system is presented. Moving liquid meniscus in the 10 μm cylindrical microchannel is used as a liquid lock to recover the liquid obtained by condensation from the separators. The main goal of the liquid locks to prevent penetration of a gas phase in the liquid line at the small flow rate of the condensate and because of pressure fluctuations in the vapor-gas-liquid loop. Calculation of the meniscus shape has been performed for liquid FC-72 at different values of pressure difference gas - liquid and under normal and micro gravity conditions.

  3. Numerical study of effect of wall parameters on catalytic combustion characteristics of CH4/air in a heat recirculation micro-combustor

    International Nuclear Information System (INIS)

    Yan, Yunfei; Wang, Haibo; Pan, Wenli; Zhang, Li; Li, Lixian; Yang, Zhongqing; Lin, Changhai

    2016-01-01

    Highlights: • Combustion in heat recuperation micro-combustors with different materials was studied. • Heat concentration is more obvious with thermal conductivity decreasing. • Combustor with copper baffles has uniform temperature distribution and best preheating effectiveness. • Influence of wall thermal conductivity is negligible on OH(s) coverage. • Methane conversion rate firstly increases and then decreases with h increasing. - Abstract: Premixed combustion of methane/air mixture in heat recuperation micro-combustors made of different materials (corundum, quartz glass, copper and ferrochrome) was investigated. The effects of wall parameters on the combustion characters of a CH 4 /air mixture under Rhodium catalyst as well as the influence of wall materials and convection heat transfer coefficients on the stable combustion limit, temperature field, and free radicals was explored using numerical analysis methodology. The results show that with a decrease of thermal conductivity of wall materials, the temperature of the reaction region increases and hot spots becomes more obvious. The combustor with copper baffles has uniform temperature distribution and best preheating effectiveness, but when inlet velocity is too small, the maximum temperature in the combustor with copper or ferrochrome baffles is well beyond the melting point of the materials. With an increase in thermal conductivity, the preheat zone for premixed gas increases, but the influence of thermal conductivity on OH(s) coverage is negligible. With an increase of the wall convection heat transfer coefficient, the methane conversion rate firstly increases, then decreases reaching a maximum value at h = 8.5 W/m 2 K, however, the average temperature of both the axis and exterior surface of the combustor decrease.

  4. CATALYTIC COMBUSTION OF METHANE OVER Pt/γ-Al2O3 IN MICRO-COMBUSTOR WITH DETAILED CHEMICAL KINETIC MECHANISMS

    Directory of Open Access Journals (Sweden)

    JUNJIE CHEN

    2014-11-01

    Full Text Available Micro-scale catalytic combustion characteristics and heat transfer processes of preheated methane-air mixtures (φ = 0.4 in the plane channel were investigated numerically with detailed chemical kinetic mechanisms. The plane channel of length L = 10.0 mm, height H =1.0 mm and wall thickness δ = 0.1 mm, which inner horizontal surfaces contained Pt/γ-Al2O3 catalyst washcoat. The computational results indicate that the presence of the gas phase reactions extends mildly the micro-combustion stability limits at low and moderate inlet velocities due to the strong flames establishment, and have a more profound effect on extending the high-velocity blowout limits by allowing for additional heat release originating mainly from the incomplete CH4 gas phase oxidation in the plane channel. When the same mass flow rate (ρin × Vin is considered, the micro-combustion stability limits at p: 0.1 MPa are much narrower than at p: 0.6 MPa due to both gas phase and catalytic reaction activities decline with decreasing pressure. Catalytic micro-combustor can achieve stable combustion at low solid thermal conductivity ks < 0.1 W∙m-1•K-1, while the micro-combustion extinction limits reach their larger extent for the higher thermal conductivity ks = 20.0-100.0 W∙m-1•K-1. The existence of surface radiation heat transfers significantly effects on the micro-combustion stability limits and micro-combustors energy balance. Finally, gas phase combustion in catalytic micro-combustors can be sustained at the sub-millimeter scale (plane channel height of 0.25 mm.

  5. A study of self-propelled elastic cylindrical micro-swimmers using modeling and computation

    Science.gov (United States)

    Shi, Lingling; Čanić, Sunčica; Quaini, Annalisa; Pan, Tsorng-Whay

    2016-06-01

    We study propulsion of micro-swimmers in 3D creeping flow. The swimmers are assumed to be made of elastic cylindrical hollow tubes. The swimming is generated by the contractions of the tube's elastic membrane walls producing a traveling wave in the form of a ;step-function; traversing the swimmer from right to left, propelling the swimmer from left to right. The problem is motivated by medical applications such as drug delivery. The influence of several non-dimensional design parameters on the velocity of the swimmer is investigated, including the swimmer aspect ratio, and the amplitude of the traveling wave relative to the swimmer radius. An immersed boundary method based on a finite element method approach is successfully combined with an elastic spring network model to simulate the two-way fluid-structure interaction coupling between the elastic cylindrical tube and the flow of a 3D viscous, incompressible fluid. To gain a deeper insight into the influence of various parameters on the swimmer speed, a reduced 1D fluid-structure interaction model was derived and validated. It was found that fast swimmers are those with large tube aspect ratios, and with the amplitude of the traveling wave which is roughly 50% of the reference swimmer radius. It was shown that the speed of our ;optimal swimmer; is around 1.5 swimmer lengths per second, which is at the top of the class of all currently manufactured micro-swimmers swimming in low Reynolds number flows (Re =10-6), reported in [11].

  6. Numerical investigation on the combustion characteristics of methane/air in a micro-combustor with a hollow hemispherical bluff body

    International Nuclear Information System (INIS)

    Zhang, Li; Zhu, Junchen; Yan, Yunfei; Guo, Hongliang; Yang, Zhongqing

    2015-01-01

    Highlights: • A micro-combustor with a hollow hemisphere bluff body is developed. • Blow-off limit of reactor is expanded 2.5 times by the hollow hemisphere bluff body. • Methane conversion rate of combustor sharply increases at the location of bluff body. • Methane conversion rate is mainly affected by equivalence ratio and inlet velocity. • Recirculation zone expands blow-off limit and increases methane conversion rate. - Abstract: The combustion characteristics of methane in a cube micro-combustor with a hollow hemispherical bluff body were numerically investigated. The blow-off limit, recirculation zone length and methane conversion rate were examined. The results illustrate that the blow-off limit of the micro-combustor with a hollow hemispherical bluff body is 2.5 times higher than that without bluff body, which are 24.5 m/s and 9.5 m/s at the same equivalence ratio (ϕ = 1), respectively. With the use of hollow hemispherical bluff body, methane conversion sharply increases from 0.24% to 17.95% at 3 mm along the inlet-flow direction, where is the location of bluff-body, which is not affected by equivalence ratio and inlet velocity. The recirculation zone size has determined influence on residence time of the mixture gas, which increases with the increase of inlet velocity. Methane conversion rate is determined by equivalence ratio and inlet velocity. Methane conversion rate firstly increases and then decreases when the equivalence ratio and inlet velocity increase, reaching the maximum value (97.84%) at ϕ = 1 and 0.02 m/s. Methane conversion rate sharply increases from 45% to 97.84% when the inlet velocity increases from 0.008 m/s to 0.02 m/s

  7. Massive ordering and alignment of cylindrical micro-objects by photovoltaic optoelectronic tweezers.

    Science.gov (United States)

    Elvira, Iris; Muñoz-Martínez, Juan F; Barroso, Álvaro; Denz, Cornelia; Ramiro, José B; García-Cabañes, Angel; Agulló-López, Fernando; Carrascosa, Mercedes

    2018-01-01

    Optical tools for manipulation and trapping of micro- and nano-objects are a fundamental issue for many applications in nano- and biotechnology. This work reports on the use of one such method, known as photovoltaic optoelectronics tweezers, to orientate and organize cylindrical microcrystals, specifically elongated zeolite L, on the surface of Fe-doped LiNbO 3 crystal plates. Patterns of aligned zeolites have been achieved through the forces and torques generated by the bulk photovoltaic effect. The alignment patterns with zeolites parallel or perpendicular to the substrate surface are highly dependent on the features of light distribution and crystal configuration. Moreover, dielectrophoretic chains of zeolites with lengths up to 100 μm have often been observed. The experimental results of zeolite trapping and alignment have been discussed and compared together with theoretical simulations of the evanescent photovoltaic electric field and the dielectrophoretic potential. They demonstrate the remarkable capabilities of the optoelectronic photovoltaic method to orientate and pattern anisotropic microcrystals. The combined action of patterning and alignment offers a unique tool to prepare functional nanostructures with potential applications in a variety of fields such as nonlinear optics or plasmonics.

  8. Variable volume combustor with nested fuel manifold system

    Science.gov (United States)

    McConnaughhay, Johnie Franklin; Keener, Christopher Paul; Johnson, Thomas Edward; Ostebee, Heath Michael

    2016-09-13

    The present application provides a combustor for use with a gas turbine engine. The combustor may include a number of micro-mixer fuel nozzles, a fuel manifold system in communication with the micro-mixer fuel nozzles to deliver a flow of fuel thereto, and a linear actuator to maneuver the micro-mixer fuel nozzles and the fuel manifold system.

  9. Variable volume combustor with aerodynamic support struts

    Science.gov (United States)

    Ostebee, Heath Michael; Johnson, Thomas Edward; Stewart, Jason Thurman; Keener, Christopher Paul

    2017-03-07

    The present application provides a combustor for use with a gas turbine engine. The combustor may include a number of micro-mixer fuel nozzles and a fuel injection system for providing a flow of fuel to the micro-mixer fuel nozzles. The fuel injection system may include a number of support struts supporting the fuel nozzles and providing the flow of fuel therethrough. The support struts may include an aerodynamic contoured shape so as to distribute evenly a flow of air to the micro-mixer fuel nozzles.

  10. Variable volume combustor with a conical liner support

    Science.gov (United States)

    Johnson, Thomas Edward; McConnaughhay, Johnie Franklin; Keener, Chrisophter Paul; Ostebee, Heath Michael

    2017-06-27

    The present application provides a variable volume combustor for use with a gas turbine engine. The variable volume combustor may include a liner, a number of micro-mixer fuel nozzles positioned within the liner, and a conical liner support supporting the liner.

  11. Combustor and combustor screech mitigation methods

    Science.gov (United States)

    Kim, Kwanwoo; Johnson, Thomas Edward; Uhm, Jong Ho; Kraemer, Gilbert Otto

    2014-05-27

    The present application provides for a combustor for use with a gas turbine engine. The combustor may include a cap member and a number of fuel nozzles extending through the cap member. One or more of the fuel nozzles may be provided in a non-flush position with respect to the cap member.

  12. Variable volume combustor with an air bypass system

    Science.gov (United States)

    Johnson, Thomas Edward; Ziminsky, Willy Steve; Ostebee, Heath Michael; Keener, Christopher Paul

    2017-02-07

    The present application provides a combustor for use with flow of fuel and a flow of air in a gas turbine engine. The combustor may include a number of micro-mixer fuel nozzles positioned within a liner and an air bypass system position about the liner. The air bypass system variably allows a bypass portion of the flow of air to bypass the micro-mixer fuel nozzles.

  13. Study of a solid state micro-dosemeter based on a monolithic silicon telescope: Irradiations with low-energy neutrons and direct comparison with a cylindrical TEPC

    International Nuclear Information System (INIS)

    Agosteo, S.; Colautti, P.; Fanton, I.; Fazzi, A.; Introini, M. V.; Moro, D.; Pola, A.; Varoli, V.

    2011-01-01

    A silicon device based on the monolithic silicon telescope technology coupled to a tissue-equivalent converter was proposed and investigated for solid state microdosimetry. The detector is constituted by a DE stage about 2 μm in thickness geometrically segmented in a matrix of micrometric diodes and a residual-energy measurement stage E about 500 μm in thickness. Each thin diode has a cylindrical sensitive volume 9 μm in nominal diameter, similar to that of a cylindrical tissue-equivalent proportional counter (TEPC). The silicon device and a cylindrical TEPC were irradiated in the same experimental conditions with quasi-monoenergetic neutrons of energy between 0.64 and 2.3 MeV at the INFN-Legnaro National Laboratories (LNLINFN, Legnaro (Italy)). The aim was to study the capability of the silicon-based system of reproducing microdosimetric spectra similar to those measured by a reference micro-dosemeter. The TEPC was set in order to simulate a tissue site about 2 μm in diameter. The spectra of the energy imparted to the ΔE stage of the silicon telescope were corrected for tissue-equivalence through an optimized procedure that exploits the information from the residual energy measurement stage E. A geometrical correction based on parametric criteria for shape-equivalence was also applied. The agreement between the dose distributions of lineal energy and the corresponding mean values is satisfactory at each neutron energy considered. (authors)

  14. Modeling and simulation of three dimensional manipulations of biological micro/nanoparticles by applying cylindrical contact mechanics models by means of AFM

    International Nuclear Information System (INIS)

    Korayem, M. H.; Saraee, M. B.; Mahmoodi, Z.; Dehghani, S.

    2015-01-01

    This paper has attempted to investigate the effective forces in 3D manipulation of biological micro/nano particles. Most of the recent researches have only examined 2D spherical geometries but in this paper, the cylindrical geometries, which are much closer to the real geometries, were considered. For achieving a more accurate modeling, manipulation dynamics was also considered to be three dimensional which have been done for the first time. Because of the sensibility to the amount of endurable applied forces, manipulation process of biological micro/nano particles has some restrictions. Therefore, applied forces exerted on the particles in all different directions were simulated in order to restrict all those possible damages cause by operator of the AFM. Those data from simulated forces will bring a more accurate and sensible understanding for the operator to operate. For the validation of results, the proposed model was compared with the model presented for manipulation of gold nanoparticle and then, by reducing the effective parameters in the 3D manipulation, the results were compared with those obtained for the 2D cylindrical model and with the experimental results of spherical nanoparticle in the 2D manipulation

  15. Design and fabrication of a meso-scale stirling engine and combustor.

    Energy Technology Data Exchange (ETDEWEB)

    Echekki, Tarek (Sandia National Laboratories, Livermore, CA); Haroldsen, Brent L. (Sandia National Laboratories, Livermore, CA); Krafcik, Karen L. (Sandia National Laboratories, Livermore, CA); Morales, Alfredo Martin (Sandia National Laboratories, Livermore, CA); Mills, Bernice E. (Sandia National Laboratories, Livermore, CA); Liu, Shiling (Sandia National Laboratories, Livermore, CA); Lee, Jeremiah C. (Sandia National Laboratories, Livermore, CA); Karpetis, Adionos N. (Sandia National Laboratories, Livermore, CA); Chen, Jacqueline H. (Sandia National Laboratories, Livermore, CA); Ceremuga, Joseph T. (Sandia National Laboratories, Livermore, CA); Raber, Thomas N. (Sandia National Laboratories, Livermore, CA); Hekmuuaty, Michelle A. (Sandia National Laboratories, Livermore, CA)

    2005-05-01

    Power sources capable of supplying tens of watts are needed for a wide variety of applications including portable electronics, sensors, micro aerial vehicles, and mini-robotics systems. The utility of these devices is often limited by the energy and power density capabilities of batteries. A small combustion engine using liquid hydrocarbon fuel could potentially increase both power and energy density by an order of magnitude or more. This report describes initial development work on a meso-scale external combustion engine based on the Stirling cycle. Although other engine designs perform better at macro-scales, we believe the Stirling engine cycle is better suited to small-scale applications. The ideal Stirling cycle requires efficient heat transfer. Consequently, unlike other thermodynamic cycles, the high heat transfer rates that are inherent with miniature devices are an advantage for the Stirling cycle. Furthermore, since the Stirling engine uses external combustion, the combustor and engine can be scaled and optimized semi-independently. Continuous combustion minimizes issues with flame initiation and propagation. It also allows consideration of a variety of techniques to promote combustion that would be difficult in a miniature internal combustion engine. The project included design and fabrication of both the engine and the combustor. Two engine designs were developed. The first used a cylindrical piston design fabricated with conventional machining processes. The second design, based on the Wankel rotor geometry, was fabricated by through-mold electroforming of nickel in SU8 and LIGA micromolds. These technologies provided the requisite precision and tight tolerances needed for efficient micro-engine operation. Electroformed nickel is ideal for micro-engine applications because of its high strength and ductility. A rotary geometry was chosen because its planar geometry was more compatible with the fabrication process. SU8 lithography provided rapid

  16. A Micro-Cylindrical Ion Trap (µ-CIT) Micro-Mass Spectrometer Instrument System (µ-MSIS) for NASA Planetary Exploration

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of this follow-on early stage innovation activity is to advance the development of new, extremely small, low power, and low cost "micro" mass spectrometer...

  17. Dual-Mode Combustor

    Science.gov (United States)

    Trefny, Charles J (Inventor); Dippold, Vance F (Inventor)

    2013-01-01

    A new dual-mode ramjet combustor used for operation over a wide flight Mach number range is described. Subsonic combustion mode is usable to lower flight Mach numbers than current dual-mode scramjets. High speed mode is characterized by supersonic combustion in a free-jet that traverses the subsonic combustion chamber to a variable nozzle throat. Although a variable combustor exit aperture is required, the need for fuel staging to accommodate the combustion process is eliminated. Local heating from shock-boundary-layer interactions on combustor walls is also eliminated.

  18. Variable volume combustor with aerodynamic fuel flanges for nozzle mounting

    Science.gov (United States)

    McConnaughhay, Johnie Franklin; Keener, Christopher Paul; Johnson, Thomas Edward; Ostebee, Heath Michael

    2016-09-20

    The present application provides a combustor for use with a gas turbine engine. The combustor may include a number of micro-mixer fuel nozzles and a fuel injection system for providing a flow of fuel to the micro-mixer fuel nozzles. The fuel injection system may include a number of support struts supporting the fuel nozzles and for providing the flow of fuel therethrough. The fuel injection system also may include a number of aerodynamic fuel flanges connecting the micro-mixer fuel nozzles and the support struts.

  19. Simulation of Main Plasma Parameters of a Cylindrical Asymmetric Capacitively Coupled Plasma Micro-Thruster using Computational Fluid Dynamics

    Directory of Open Access Journals (Sweden)

    Amelia eGreig

    2015-01-01

    Full Text Available Computational fluid dynamics (CFD simulations of a radio-frequency (13.56 MHz electro-thermal capacitively coupled plasma (CCP micro-thruster have been performed using the commercial CFD-ACE+ package. Standard operating conditions of a 10 W, 1.5 Torr argon discharge were used to compare with previously obtained experimental results for validation. Results show that the driving force behind plasma production within the thruster is ion-induced secondary electrons ejected from the surface of the discharge tube, accelerated through the sheath to electron temperatures up to 33.5 eV. The secondary electron coefficient was varied to determine the effect on the discharge, with results showing that full breakdown of the discharge did not occur for coefficients coefficients less than or equal to 0.01.

  20. Combustor nozzles in gas turbine engines

    Science.gov (United States)

    Johnson, Thomas Edward; Keener, Christopher Paul; Stewart, Jason Thurman; Ostebee, Heath Michael

    2017-09-12

    A micro-mixer nozzle for use in a combustor of a combustion turbine engine, the micro-mixer nozzle including: a fuel plenum defined by a shroud wall connecting a periphery of a forward tube sheet to a periphery of an aft tubesheet; a plurality of mixing tubes extending across the fuel plenum for mixing a supply of compressed air and fuel, each of the mixing tubes forming a passageway between an inlet formed through the forward tubesheet and an outlet formed through the aft tubesheet; and a wall mixing tube formed in the shroud wall.

  1. Steam reformer with catalytic combustor

    Science.gov (United States)

    Voecks, Gerald E. (Inventor)

    1990-01-01

    A steam reformer is disclosed having an annular steam reforming catalyst bed formed by concentric cylinders and having a catalytic combustor located at the center of the innermost cylinder. Fuel is fed into the interior of the catalytic combustor and air is directed at the top of the combustor, creating a catalytic reaction which provides sufficient heat so as to maintain the catalytic reaction in the steam reforming catalyst bed. Alternatively, air is fed into the interior of the catalytic combustor and a fuel mixture is directed at the top. The catalytic combustor provides enhanced radiant and convective heat transfer to the reformer catalyst bed.

  2. Ceramic combustor mounting

    Science.gov (United States)

    Hoffman, Melvin G.; Janneck, Frank W.

    1982-01-01

    A combustor for a gas turbine engine includes a metal engine block including a wall portion defining a housing for a combustor having ceramic liner components. A ceramic outlet duct is supported by a compliant seal on the metal block and a reaction chamber liner is stacked thereon and partly closed at one end by a ceramic bypass swirl plate which is spring loaded by a plurality of circumferentially spaced, spring loaded guide rods and wherein each of the guide rods has one end thereof directed exteriorly of a metal cover plate on the engine block to react against externally located biasing springs cooled by ambient air and wherein the rod spring support arrangement maintains the stacked ceramic components together so that a normal force is maintained on the seal between the outlet duct and the engine block under all operating conditions. The support arrangement also is operative to accommodate a substantial difference in thermal expansion between the ceramic liner components of the combustor and the metal material of the engine block.

  3. Gas turbine topping combustor

    Science.gov (United States)

    Beer, J.; Dowdy, T.E.; Bachovchin, D.M.

    1997-06-10

    A combustor is described for burning a mixture of fuel and air in a rich combustion zone, in which the fuel bound nitrogen in converted to molecular nitrogen. The fuel rich combustion is followed by lean combustion. The products of combustion from the lean combustion are rapidly quenched so as to convert the fuel bound nitrogen to molecular nitrogen without forming NOx. The combustor has an air radial swirler that directs the air radially inward while swirling it in the circumferential direction and a radial fuel swirler that directs the fuel radially outward while swirling it in the same circumferential direction, thereby promoting vigorous mixing of the fuel and air. The air inlet has a variable flow area that is responsive to variations in the heating value of the fuel, which may be a coal-derived fuel gas. A diverging passage in the combustor in front of a bluff body causes the fuel/air mixture to recirculate with the rich combustion zone. 14 figs.

  4. A study of air breathing rockets. 3: Supersonic mode combustors

    Science.gov (United States)

    Masuya, G.; Chinzel, N.; Kudo, K.; Murakami, A.; Komuro, T.; Ishii, S.

    An experimental study was made on supersonic mode combustors of an air breathing rocket engine. Supersonic streams of room-temperature air and hot fuel-rich rocket exhaust were coaxially mixed and burned in a concially diverging duct of 2 deg half-angle. The effect of air inlet Mach number and excess air ratio was investigated. Axial wall pressure distribution was measured to calculate one dimensional change of Mach number and stagnation temperature. Calculated results showed that supersonic combustion occurred in the duct. At the exit of the duct, gas sampling and Pitot pressure measurement was made, from which radial distributions of various properties were deduced. The distribution of mass fraction of elements from rocket exhaust showed poor mixing performance in the supersonic mode combustors compared with the previously investigated cylindrical subsonic mode combustors. Secondary combustion efficiency correlated well with the centerline mixing parameter, but not with Annushkin's non-dimensional combustor length. No major effect of air inlet Mach number or excess air ratio was seen within the range of conditions under which the experiment was conducted.

  5. Concentric catalytic combustor

    Science.gov (United States)

    Bruck, Gerald J [Oviedo, FL; Laster, Walter R [Oviedo, FL

    2009-03-24

    A catalytic combustor (28) includes a tubular pressure boundary element (90) having a longitudinal flow axis (e.g., 56) separating a first portion (94) of a first fluid flow (e.g., 24) from a second portion (95) of the first fluid flow. The pressure boundary element includes a wall (96) having a plurality of separate longitudinally oriented flow paths (98) annularly disposed within the wall and conducting respective portions (100, 101) of a second fluid flow (e.g., 26) therethrough. A catalytic material (32) is disposed on a surface (e.g., 102, 103) of the pressure boundary element exposed to at least one of the first and second portions of the first fluid flow.

  6. Effect of ramp-cavity on hydrogen fueled scramjet combustor

    Directory of Open Access Journals (Sweden)

    J.V.S. Moorthy

    2014-03-01

    Full Text Available Sustained combustion and optimization of combustor are the two challenges being faced by combustion scientists working in the area of supersonic combustion. Thorough mixing, lower stagnation pressure losses, positive thrust and sustained combustion are the key issues in the field of supersonic combustion. Special fluid mechanism is required to achieve good mixing. To induce such mechanisms in supersonic inflows, the fuel injectors should be critically shaped incurring less flow losses. Present investigations are focused on the effect of fuel injection scheme on a model scramjet combustor performance. Ramps at supersonic flow generate axial vortices that help in macro-mixing of fuel with air. Interaction of shocks generated by ramps with the fuel stream generates boro-clinic torque at the air & liquid fuel interface, enhancing micro-mixing. Recirculation zones present in cavities increase the residence time of the combustible mixture. Making use of the advantageous features of both, a ramp-cavity combustor is designed. The combustor has two sections. First, constant height section consists of a backward facing step followed by ramps and cavities on both the top and bottom walls. The ramps are located alternately on top and bottom walls. The complete combustor width is utilized for the cavities. The second section of the combustor is diverging area section. This is provided to avoid thermal choking. In the present work gaseous hydrogen is considered as fuel. This study was mainly focused on the mixing characteristics of four different fuel injection locations. It was found that injecting fuel upstream of the ramp was beneficial from fuel spread point of view.

  7. Scale and material effects on flame characteristics in small heat recirculation combustors of a counter-current channel type

    International Nuclear Information System (INIS)

    Lee, Min Jung; Cho, Sang Moon; Choi, Byung Il; Kim, Nam Il

    2010-01-01

    Small energy sources have been interested with the recent development of small-scale mechanical systems. With the purpose of developing a basic model of micro-combustors of heat recirculation, small combustors of a counter-current channel type were fabricated, and the premixed flame stabilization characteristics were investigated experimentally. Each combustor consists of a combustion space and a pair of counter-current channels for heat recirculation. The channel gap was less than the ordinary quenching distance of a stoichiometric methane-air premixed flame. Depending on the flame locations and structures, flame stabilization was classified into four modes: an ordinary mode, a channel mode, a radiation mode, and a well-stirred reaction mode. Base-scale combustors of stainless steel were initially examined. Additional half-scale combustors of stainless steel and quartz were fabricated and their flame stabilization conditions were compared. Consequently, a change of the material of the combustor significantly affected the flame stabilization compared to the effects of a scale-down design. A half-scale quartz combustor had a wide range of flame stabilization conditions. Surface temperatures and the composition of the emission gas were measured. At a higher flow rate, the combustor temperature increases and the light emission from the middle wall is enhanced to extend the flame stabilization conditions. The combustion efficiency and the composition of emitted gas were feasible. These results provide useful information for the design of small-scale combustors.

  8. Combustor and method for distributing fuel in the combustor

    Science.gov (United States)

    Uhm, Jong Ho; Ziminsky, Willy Steve; Johnson, Thomas Edward; York, William David

    2016-04-26

    A combustor includes a tube bundle that extends radially across at least a portion of the combustor. The tube bundle includes an upstream surface axially separated from a downstream surface. A plurality of tubes extends from the upstream surface through the downstream surface, and each tube provides fluid communication through the tube bundle. A baffle extends axially inside the tube bundle between adjacent tubes. A method for distributing fuel in a combustor includes flowing a fuel into a fuel plenum defined at least in part by an upstream surface, a downstream surface, a shroud, and a plurality of tubes that extend from the upstream surface to the downstream surface. The method further includes impinging the fuel against a baffle that extends axially inside the fuel plenum between adjacent tubes.

  9. Radial midframe baffle for can-annular combustor arrangement having tangentially oriented combustor cans

    Science.gov (United States)

    Rodriguez, Jose L.

    2015-09-15

    A can-annular gas turbine engine combustion arrangement (10), including: a combustor can (12) comprising a combustor inlet (38) and a combustor outlet circumferentially and axially offset from the combustor inlet; an outer casing (24) defining a plenum (22) in which the combustor can is disposed; and baffles (70) configured to divide the plenum into radial sectors (72) and configured to inhibit circumferential motion of compressed air (16) within the plenum.

  10. Fuel and Combustor Concerns for Future Commercial Combustors

    Science.gov (United States)

    Chang, Clarence T.

    2017-01-01

    Civil aircraft combustor designs will move from rich-burn to lean-burn due to the latter's advantage in low NOx and nvPM emissions. However, the operating range of lean-burn is narrower, requiring premium mixing performance from the fuel injectors. As the OPR increases, the corresponding combustor inlet temperature increase can benefit greatly with fuel composition improvements. Hydro-treatment can improve coking resistance, allowing finer fuel injection orifices to speed up mixing. Selective cetane number control across the fuel carbon-number distribution may allow delayed ignition at high power while maintaining low-power ignition characteristics.

  11. Assessment of Combustor Working Environments

    Directory of Open Access Journals (Sweden)

    Leiyong Jiang

    2012-01-01

    Full Text Available In order to assess the remaining life of gas turbine critical components, it is vital to accurately define the aerothermodynamic working environments and service histories. As a part of a major multidisciplinary collaboration program, a benchmark modeling on a practical gas turbine combustor is successfully carried out, and the two-phase, steady, turbulent, compressible, reacting flow fields at both cruise and takeoff are obtained. The results show the complicated flow features inside the combustor. The airflow over each flow element of the combustor can or liner is not evenly distributed, and considerable variations, ±25%, around the average values, are observed. It is more important to note that the temperatures at the combustor can and cooling wiggle strips vary significantly, which can significantly affect fatigue life of engine critical components. The present study suggests that to develop an adequate aerothermodynamics tool, it is necessary to carry out a further systematic study, including validation of numerical results, simulations at typical engine operating conditions, and development of simple correlations between engine operating conditions and component working environments. As an ultimate goal, the cost and time of gas turbine engine fleet management must be significantly reduced.

  12. Cylindrical Piezoelectric Fiber Composite Actuators

    Science.gov (United States)

    Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

    2008-01-01

    The use of piezoelectric devices has become widespread since Pierre and Jacques Curie discovered the piezoelectric effect in 1880. Examples of current applications of piezoelectric devices include ultrasonic transducers, micro-positioning devices, buzzers, strain sensors, and clocks. The invention of such lightweight, relatively inexpensive piezoceramic-fiber-composite actuators as macro fiber composite (MFC) actuators has made it possible to obtain strains and displacements greater than those that could be generated by prior actuators based on monolithic piezoceramic sheet materials. MFC actuators are flat, flexible actuators designed for bonding to structures to apply or detect strains. Bonding multiple layers of MFC actuators together could increase force capability, but not strain or displacement capability. Cylindrical piezoelectric fiber composite (CPFC) actuators have been invented as alternatives to MFC actuators for applications in which greater forces and/or strains or displacements may be required. In essence, a CPFC actuator is an MFC or other piezoceramic fiber composite actuator fabricated in a cylindrical instead of its conventional flat shape. Cylindrical is used here in the general sense, encompassing shapes that can have circular, elliptical, rectangular or other cross-sectional shapes in the planes perpendicular to their longitudinal axes.

  13. Alternate-Fueled Combustor-Sector Performance: Part A: Combustor Performance Part B: Combustor Emissions

    Science.gov (United States)

    Shouse, D. T.; Neuroth, C.; Henricks, R. C.; Lynch, A.; Frayne, C.; Stutrud, J. S.; Corporan, E.; Hankins, T.

    2010-01-01

    Alternate aviation fuels for military or commercial use are required to satisfy MIL-DTL-83133F(2008) or ASTM D 7566 (2010) standards, respectively, and are classified as drop-in fuel replacements. To satisfy legacy issues, blends to 50% alternate fuel with petroleum fuels are certified individually on the basis of feedstock. Adherence to alternate fuels and fuel blends requires smart fueling systems or advanced fuel-flexible systems, including combustors and engines without significant sacrifice in performance or emissions requirements. This paper provides preliminary performance (Part A) and emissions and particulates (Part B) combustor sector data for synthetic-parafinic-kerosene- (SPK-) type fuel and blends with JP-8+100 relative to JP-8+100 as baseline fueling.

  14. Numerical study of effect of compressor swirling flow on combustor design in a MTE

    Science.gov (United States)

    Mu, Yong; Wang, Chengdong; Liu, Cunxi; Liu, Fuqiang; Hu, Chunyan; Xu, Gang; Zhu, Junqiang

    2017-08-01

    An effect of the swirling flow on the combustion performance is studied by the computational fluid dynamics (CFD) in a micro-gas turbine with a centrifugal compressor, dump diffuser and forward-flow combustor. The distributions of air mass and the Temperature Pattern Factor (as: Overall Temperature Distribution Factor -OTDF) in outlet are investigated with two different swirling angles of compressed air as 0° and 15° in three combustors. The results show that the influences of swirling flow on the air distribution and OTDF cannot be neglected. Compared with no-swirling flow, the air through outer liner is more, and the air through the inner liner is less, and the pressure loss is bigger under the swirling condition in the same combustor. The Temperature Pattern Factor changes under the different swirling conditions.

  15. Scattering of spermatozoa off cylindrical pillars

    Science.gov (United States)

    Bukatin, Anton; Lushi, Enkeleida; Kantsler, Vasily

    2017-11-01

    The motion of micro-swimmers in structured environments, even though crucial in processes such as in vivo and in vitro egg fertilization, is still not completely understood. We combine microfluidic experiments with mathematical modeling of 3D swimming near convex surfaces to quantify the dynamics of individual sperm cells in the proximity of cylindrical pillars. Our results show that the hydrodynamic and contact forces that account for the shape asymmetry and flagellar motion, are crucial in correctly describing the dynamics observed in the experiments. Last, we discuss how the size of the cylindrical obstacles determines whether the swimmers scatter off or get trapped circling the pillar.

  16. Cylindrical neutron generator

    Science.gov (United States)

    Leung, Ka-Ngo [Hercules, CA

    2008-04-22

    A cylindrical neutron generator is formed with a coaxial RF-driven plasma ion source and target. A deuterium (or deuterium and tritium) plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical neutron generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which contain many slots. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired. The plasma generator may be in the center and the neutron target on the outside, or the plasma generator may be on the outside and the target on the inside. In a nested configuration, several concentric targets and plasma generating regions are nested to increase the neutron flux.

  17. Chaos in an imperfectly premixed model combustor.

    Science.gov (United States)

    Kabiraj, Lipika; Saurabh, Aditya; Karimi, Nader; Sailor, Anna; Mastorakos, Epaminondas; Dowling, Ann P; Paschereit, Christian O

    2015-02-01

    This article reports nonlinear bifurcations observed in a laboratory scale, turbulent combustor operating under imperfectly premixed mode with global equivalence ratio as the control parameter. The results indicate that the dynamics of thermoacoustic instability correspond to quasi-periodic bifurcation to low-dimensional, deterministic chaos, a route that is common to a variety of dissipative nonlinear systems. The results support the recent identification of bifurcation scenarios in a laminar premixed flame combustor (Kabiraj et al., Chaos: Interdiscip. J. Nonlinear Sci. 22, 023129 (2012)) and extend the observation to a practically relevant combustor configuration.

  18. Thermal analysis of cylindrical natural-gas steam reformer for 5 kW PEMFC

    Science.gov (United States)

    Jo, Taehyun; Han, Junhee; Koo, Bonchan; Lee, Dohyung

    2016-11-01

    The thermal characteristics of a natural-gas based cylindrical steam reformer coupled with a combustor are investigated for the use with a 5 kW polymer electrolyte membrane fuel cell. A reactor unit equipped with nickel-based catalysts was designed to activate the steam reforming reaction without the inclusion of high-temperature shift and low-temperature shift processes. Reactor temperature distribution and its overall thermal efficiency depend on various inlet conditions such as the equivalence ratio, the steam to carbon ratio (SCR), and the fuel distribution ratio (FDR) into the reactor and the combustor components. These experiments attempted to analyze the reformer's thermal and chemical properties through quantitative evaluation of product composition and heat exchange between the combustor and the reactor. FDR is critical factor in determining the overall performance as unbalanced fuel injection into the reactor and the combustor deteriorates overall thermal efficiency. Local temperature distribution also influences greatly on the fuel conversion rate and thermal efficiency. For the experiments, the operation conditions were set as SCR was in range of 2.5-4.0 and FDR was in 0.4-0.7 along with equivalence ratio of 0.9-1.1; optimum results were observed for FDR of 0.63 and SCR of 3.0 in the cylindrical steam reformer.

  19. Alternate-Fueled Combustor-Sector Performance. Parts A and B; (A) Combustor Performance; (B) Combustor Emissions

    Science.gov (United States)

    Shouse, D. T.; Hendricks, R. C.; Lynch, A.; Frayne, C. W.; Stutrud, J. S.; Corporan, E.; Hankins, T.

    2012-01-01

    Alternate aviation fuels for military or commercial use are required to satisfy MIL-DTL-83133F(2008) or ASTM D 7566 (2010) standards, respectively, and are classified as "drop-in" fuel replacements. To satisfy legacy issues, blends to 50% alternate fuel with petroleum fuels are certified individually on the basis of processing and assumed to be feedstock agnostic. Adherence to alternate fuels and fuel blends requires "smart fueling systems" or advanced fuel-flexible systems, including combustors and engines, without significant sacrifice in performance or emissions requirements. This paper provides preliminary performance (Part A) and emissions and particulates (Part B) combustor sector data. The data are for nominal inlet conditions at 225 psia and 800 F (1.551 MPa and 700 K), for synthetic-paraffinic-kerosene- (SPK-) type (Fisher-Tropsch (FT)) fuel and blends with JP-8+100 relative to JP-8+100 as baseline fueling. Assessments are made of the change in combustor efficiency, wall temperatures, emissions, and luminosity with SPK of 0%, 50%, and 100% fueling composition at 3% combustor pressure drop. The performance results (Part A) indicate no quantifiable differences in combustor efficiency, a general trend to lower liner and higher core flow temperatures with increased FT fuel blends. In general, emissions data (Part B) show little differences, but with percent increase in FT-SPK-type fueling, particulate emissions and wall temperatures are less than with baseline JP-8. High-speed photography illustrates both luminosity and combustor dynamic flame characteristics.

  20. Scramjet Combustor Characteristics at Hypervelocity Condition over Mach 10 Flight

    Science.gov (United States)

    Takahashi, M.; Komuro, T.; Sato, K.; Kodera, M.; Tanno, H.; Itoh, K.

    2009-01-01

    To investigate possibility of reduction of a scramjet combustor size without thrust performance loss, a two-dimensional constant-area combustor of a previous engine model was replaced with the one with 23% lower-height. With the application of the lower-height combustor, the pressure in the combustor becomes 50% higher and the combustor length for the optimal performance becomes 43% shorter than the original combustor. The combustion tests of the modified engine model were conducted using a large free-piston driven shock tunnel at flow conditions corresponding to the flight Mach number from 9 to 14. CFD was also applied to the engine internal flows. The results showed that the mixing and combustion heat release progress faster to the distance and the combustor performance similar to that of the previous engine was obtained with the modified engine. The reduction of the combustor size without the thrust performance loss is successfully achieved by applying the lower-height combustor.

  1. Experimental clean combustor program, alternate fuels addendum, phase 2

    Science.gov (United States)

    Gleason, C. C.; Bahr, D. W.

    1976-01-01

    The characteristics of current and advanced low-emissions combustors when operated with special test fuels simulating broader range combustion properties of petroleum or coal derived fuels were studied. Five fuels were evaluated; conventional JP-5, conventional No. 2 Diesel, two different blends of Jet A and commercial aromatic mixtures - zylene bottoms and haphthalene charge stock, and a fuel derived from shale oil crude which was refined to Jet A specifications. Three CF6-50 engine size combustor types were evaluated; the standard production combustor, a radial/axial staged combustor, and a double annular combustor. Performance and pollutant emissons characteristics at idle and simulated takeoff conditions were evaluated in a full annular combustor rig. Altitude relight characteristics were evaluated in a 60 degree sector combustor rig. Carboning and flashback characteristics at simulated takeoff conditions were evaluated in a 12 degree sector combustor rig. For the five fuels tested, effects were moderate, but well defined.

  2. Alternate-Fueled Combustor-Sector Performance

    Science.gov (United States)

    Thomas, Anna E.; Saxena, Nikita T.; Shouse, Dale T.; Neuroth, Craig; Hendricks, Robert C.; Lynch, Amy; Frayne, Charles W.; Stutrud, Jeffrey S.; Corporan, Edwin; Hankins, Terry

    2013-01-01

    In order to realize alternative fueling for military and commercial use, the industry has set forth guidelines that must be met by each fuel. These aviation fueling requirements are outlined in MIL-DTL-83133F(2008) or ASTM D 7566 Annex (2011) standards, and are classified as "drop-in" fuel replacements. This report provides combustor performance data for synthetic-paraffinic-kerosene- (SPK-) type (Fischer-Tropsch (FT)) fuel and blends with JP-8+100, relative to JP-8+100 as baseline fueling. Data were taken at various nominal inlet conditions: 75 psia (0.52 MPa) at 500 degF (533 K), 125 psia (0.86 MPa) at 625 degF (603 K), 175 psia (1.21 MPa) at 725 degF (658 K), and 225 psia (1.55 MPa) at 790 degF (694 K). Combustor performance analysis assessments were made for the change in flame temperatures, combustor efficiency, wall temperatures, and exhaust plane temperatures at 3, 4, and 5 percent combustor pressure drop (DP) for fuel:air ratios (F/A) ranging from 0.010 to 0.025. Significant general trends show lower liner temperatures and higher flame and combustor outlet temperatures with increases in FT fueling relative to JP-8+100 fueling. The latter affects both turbine efficiency and blade and vane lives.

  3. Non-linear dynamics in pulse combustor: A review

    Indian Academy of Sciences (India)

    idea of pressure gain combustion (i.e., combustion with gain in total pressure across the combustor as opposed to pressure-loss combustion experienced in constant pressure devices like conventional gas turbine combustors) is gaining popularity for propulsion devices [2]. Thus pulse combustors, which provide a practical ...

  4. Structured cylindrical targets

    International Nuclear Information System (INIS)

    Arnold, R.

    1986-01-01

    A variety of experimental concepts using high-energy heavy-ion beams in cylindrical targets have been studied through numerical simulation. With an accelerator planned for GSl, plasma temperatures of 100 eV can be reached by cylindrical compression, using inhomogeneous hollow-shell targets. Magnetic insulation, using external fields, has been explored as an aid in reaching high core temperatures. Experiments on collision-pumped x-ray laser physics are also discussed. (ii) Two-dimensional PlC code simulations of homogeneous solid targets show hydrodynamic effects not found in previous 1-D calculations. (iii) Preliminary ideas for an experiment on non-equilibrium heavy-ion charge-states using an existing accelerator and a pre-formed plasma target are outlined. (author)

  5. Structured cylindrical targets

    International Nuclear Information System (INIS)

    Arnold, R.; Lackner-Russo, D.; Meyer-ter-Vehn, J.; Hoffmann, I.

    1986-01-01

    A variety of experimental concepts using high-energy heavy-ion beams in cylindrical targets have been studied through numerical simulation. With an accelerator planned for GSl, plasma temperatures of 100 eV can be reached by cylindrical compression, using inhomogenous hollow-shell targets. Magnetic insulation, using external fields, has been explored as an aid in reaching high core temperatures. Experiments on collision-pumped x-ray laser physics are also discussed. (ii) Two-dimensional PlC code simulations of homogeneous solid targets show hydrodynamic effects not found in previous l-D calculations. (iii) Preliminary ideas for an experiment on non-equilibrium heavy-ion charge-states using an existing accelerator and a pre-formed plasma target are outlined. (author)

  6. System and method for controlling a combustor assembly

    Science.gov (United States)

    York, William David; Ziminsky, Willy Steve; Johnson, Thomas Edward; Stevenson, Christian Xavier

    2013-03-05

    A system and method for controlling a combustor assembly are disclosed. The system includes a combustor assembly. The combustor assembly includes a combustor and a fuel nozzle assembly. The combustor includes a casing. The fuel nozzle assembly is positioned at least partially within the casing and includes a fuel nozzle. The fuel nozzle assembly further defines a head end. The system further includes a viewing device configured for capturing an image of at least a portion of the head end, and a processor communicatively coupled to the viewing device, the processor configured to compare the image to a standard image for the head end.

  7. Study of the use of a micro hydro in knockdown container completed with a cylindrical form housing of francis hydraulic turbine to support the development program of energy self-sustainability for remote and isolated areas in Indonesia

    Directory of Open Access Journals (Sweden)

    Kamal Samsul

    2017-01-01

    It shows that the implementation of the unit in a remote area has reduced the total site construction time by 1/3 compared to the predicted one with conventional unit. The performance of the Francis turbine with cylindrical form housing has shown comparable with the conventional one which has volute form housing. The superiority was even more pronounced by introducing a deflection insert in its input flow channel. The insertion was capable to create more distributed flow into the runner. Efficiency of the turbine up to 80% was performed in this research. Local manufacture for turbine usually use many craft work and welding to built a volute form housing for the Francis turbine. The cylindrical form housing here has also proven significantly in reducing the time and price for the turbine manufacturing process.

  8. Pulse combustors for unpulverized solid fuels; Combustor pulsante para solidos nao pulverizados

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Marco Aurelio; Carvalho Junior, Joao Andrade de [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil)

    1988-12-31

    This work presents results of performance evaluation of an experimental pulsating combustor developed to burn unpulverized solid fuels. The fuels tested were sized wood blocks and coal lumps. The results for coal show a clear maximum combustion efficiency as a function of fuel loading within the combustor. For an excess of air of 10%, a maximum combustion efficiency of 94% was obtained. (author) 38 refs., 10 figs., 2 tabs.

  9. Steam Reformer With Fibrous Catalytic Combustor

    Science.gov (United States)

    Voecks, Gerald E.

    1987-01-01

    Proposed steam-reforming reactor derives heat from internal combustion on fibrous catalyst. Supplies of fuel and air to combustor controlled to meet demand for heat for steam-reforming reaction. Enables use of less expensive reactor-tube material by limiting temperature to value safe for material yet not so low as to reduce reactor efficiency.

  10. Alternate-Fueled Combustor-Sector Performance—Part A: Combustor Performance and Part B: Combustor Emissions

    OpenAIRE

    Shouse, D. T.; Neuroth, C.; Hendricks, R. C.; Lynch, A.; Frayne, C. W.; Stutrud, J. S.; Corporan, E.; Hankins, Capt. T.

    2012-01-01

    Alternate aviation fuels for military or commercial use are required to satisfy MIL-DTL-83133F or ASTM D 7566 standards, respectively, and are classified as “drop-in’’ fuel replacements. To satisfy legacy issues, blends to 50% alternate fuel with petroleum fuels are acceptable. Adherence to alternate fuels and fuel blends requires “smart fueling systems’’ or advanced fuel-flexible systems, including combustors and engines, without significant sacrifice in performance or emissions requirements...

  11. MICRO AUTO GASIFICATION SYSTEM: EMISSIONS CHARACTERIZATION

    Science.gov (United States)

    A compact, CONEX-housed waste to energy unit, Micro Auto Gasification System (MAGS), was characterized for air emissions from burning of military waste types. The MAGS unit is a dual chamber gasifier with a secondary diesel-fired combustor. Eight tests were conducted with multipl...

  12. Simulation of the flow inside an annular can combustor

    OpenAIRE

    Alqaraghuli, W; Alkhafagiy, D; Shires, A

    2014-01-01

    In the gas turbine combustion system, the external flows in annuli play one of the key roles in controlling pressure loss, air flow distribution around the combustor liner, and the attendant effects on performance, durability, and stability.  This paper describes a computational fluid dynamics (CFD) simulation of the flow in the outer annulus of a can combustor. Validating this simulation was done with experimental results obtained from analyzing the flow inside a can combustor annulus that w...

  13. Method for controlling incineration in combustor for radioactive wastes

    International Nuclear Information System (INIS)

    Takaoku, Y.; Uehara, A.

    1991-01-01

    This invention relates to a method for controlling incineration in a combustor for low-level radioactive wastes. In particular, it relates to a method for economizing in the consumption of supplemental fuel while maintaining a stable incineration state by controlling the amount of fuel and of radioactive wastes fed to the combustor. The amount of fuel supplied is determined by the outlet gas temperature of the combustor. (L.L.)

  14. Low NOx Fuel Flexible Combustor Integration Project Overview

    Science.gov (United States)

    Walton, Joanne C.; Chang, Clarence T.; Lee, Chi-Ming; Kramer, Stephen

    2015-01-01

    The Integrated Technology Demonstration (ITD) 40A Low NOx Fuel Flexible Combustor Integration development is being conducted as part of the NASA Environmentally Responsible Aviation (ERA) Project. Phase 2 of this effort began in 2012 and will end in 2015. This document describes the ERA goals, how the fuel flexible combustor integration development fulfills the ERA combustor goals, and outlines the work to be conducted during project execution.

  15. Study of the use of a micro hydro in knockdown container completed with a cylindrical form housing of francis hydraulic turbine to support the development program of energy self-sustainability for remote and isolated areas in Indonesia

    Science.gov (United States)

    Kamal, Samsul; Prajitno; Pardadi, Janu

    2017-11-01

    With an intention to reduce the consumption of energy from fossil fuels and the CO2 emission in relation with the climate change solution, Indonesian Government has targeted that the role of the New and Renewable Energy (NRE) resources reaches at least 23% , or about 27 GW , in 2025 and it is expected to increase to the extent of about 134 GW in 2050 within the scenario of mixed energy supply. Geographically Indonesia has many remote and isolated areas with lack of appropriate infrastructure supports. But in the most of the areas, huge potential of new and renewable energy are available such as hydro energy is about 75 GW, biomass energy is about 32 GW and bio fuel is about 32 GW. The total utilization of the energy from small hydro energy up to this year for example is only about 300 MW. The significant obstacle in optimizing the utilization of small hydro energy in the areas is mainly on the infrastructure conditions and the local manufacture capabilities. Difficulties in mobilization of experts, skill worker , parts and constructions material result in very time consuming and costly for site construction. In this research a hydro turbine built in knock down container completed with a Francis turbine in cylindrical form housing is proposed and reported its performance on implementation. The hydro in a knock down container concept comes from the idea to manufacture hydro power solutions in a knock down container, readymade to be transported to installation sites. It can be easily manufactured in a quality controlled and cost effective environment, transported and installed in remote areas, to operate and maintain with minimal amount of equipment. It shows that the implementation of the unit in a remote area has reduced the total site construction time by 1/3 compared to the predicted one with conventional unit. The performance of the Francis turbine with cylindrical form housing has shown comparable with the conventional one which has volute form housing. The

  16. Near-zero emissions combustor system for syngas and biofuels

    International Nuclear Information System (INIS)

    Yongho, Kim; Rosocha, Louis

    2010-01-01

    research necessary to develop a novel, high-efficiency, low-emissions (near-zero, or as low as reasonably achievable), advanced combustion technology for electricity and heat production from biofuels and fuels derived from MSW. For any type of combustion technology, including the advanced technology of this project, two problems of special interest must be addressed: developing and optimizing the combustion chambers and the systems for igniting and sustaining the fuel-burning process. For MSW in particular, there are new challenges over gaseous or liquid fuels because solid fuels must be ground into fine particulates (∼ 10 (micro)m diameter), fed into the advanced combustor, and combusted under plasma-assisted conditions that are quite different than gaseous or liquid fuels. The principal idea of the combustion chamber design is to use so-called reverse vortex gas flow, which allows efficient cooling of the chamber wall and flame stabilization in the central area of the combustor (Tornado chamber). Considerable progress has been made in design ing an advanced, reverse vortex flow combustion chamber for biofuels, although it was not tested on biofuels and a system that could be fully commercialized has never been completed.

  17. Controlled pilot oxidizer for a gas turbine combustor

    Science.gov (United States)

    Laster, Walter R.; Bandaru, Ramarao V.

    2010-07-13

    A combustor (22) for a gas turbine (10) includes a main burner oxidizer flow path (34) delivering a first portion (32) of an oxidizer flow (e.g., 16) to a main burner (28) of the combustor and a pilot oxidizer flow path (38) delivering a second portion (36) of the oxidizer flow to a pilot (30) of the combustor. The combustor also includes a flow controller (42) disposed in the pilot oxidizer flow path for controlling an amount of the second portion delivered to the pilot.

  18. Flame Propagation in a Dump Combustor with Shear Layer Excitation

    Data.gov (United States)

    National Aeronautics and Space Administration — This experimentation looks to investigate the use of fluidic oscillators to attenuate combustion instability in a naturally unstable rocket combustor. Since...

  19. High pressure MHD coal combustors investigation, phase 2

    Science.gov (United States)

    Iwata, H.; Hamberg, R.

    1981-05-01

    A high pressure MHD coal combustor was investigated. The purpose was to acquire basic design and support engineering data through systematic combustion experiments at the 10 and 20 thermal megawatt size and to design a 50 MW/sub t/ combustor. This combustor is to produce an electrically conductive plasma generated by the direct combustion of pulverized coal with hot oxygen enriched vitiated air that is seeded with potassium carbonate. Vitiated air and oxygen are used as the oxidizer, however, preheated air will ultimately be used as the oxidizer in coal fired MHD combustors.

  20. Low pollution combustor designs for CTOL engines - Results of the Experimental Clean Combustor Program

    Science.gov (United States)

    Roberts, R.; Peduzzi, A.; Niedzwiecki, R. W.

    1976-01-01

    The NASA/Pratt & Whitney Aircraft Experimental Clean Combustor Program is a multi-year, major contract effort. Primary program objectives are the generation of combustor technology for development of advanced commercial CTOL engines with lower exhaust emissions than current aircraft and demonstration of this technology in a full-scale JT9D engine in 1976. This paper describes the pollution and performance goals, Phase I and II test results, and the Phase III combustor hardware, pollution sampling techniques, and test plans. Best results were obtained with the Vorbix concept which employs multiple burning zones and improved fuel preparation and distribution. Substantial reductions were achieved in all pollutant categories, meeting the 1979 EPA standards for NOx, THC, and smoke when extrapolated to JT9D cycle conditions. The Vorbix concept additionally demonstrated the capability for acceptable altitude relight and did not appear to have unsolvable durability or exit temperature distribution problems.

  1. Shearfree cylindrical gravitational collapse

    International Nuclear Information System (INIS)

    Di Prisco, A.; Herrera, L.; MacCallum, M. A. H.; Santos, N. O.

    2009-01-01

    We consider diagonal cylindrically symmetric metrics, with an interior representing a general nonrotating fluid with anisotropic pressures. An exterior vacuum Einstein-Rosen spacetime is matched to this using Darmois matching conditions. We show that the matching conditions can be explicitly solved for the boundary values of metric components and their derivatives, either for the interior or exterior. Specializing to shearfree interiors, a static exterior can only be matched to a static interior, and the evolution in the nonstatic case is found to be given in general by an elliptic function of time. For a collapsing shearfree isotropic fluid, only a Robertson-Walker dust interior is possible, and we show that all such cases were included in Cocke's discussion. For these metrics, Nolan and Nolan have shown that the matching breaks down before collapse is complete, and Tod and Mena have shown that the spacetime is not asymptotically flat in the sense of Berger, Chrusciel, and Moncrief. The issues about energy that then arise are revisited, and it is shown that the exterior is not in an intrinsic gravitational or superenergy radiative state at the boundary.

  2. Final analysis and design of a thermal protection system for 8-foot HTST combustor

    Science.gov (United States)

    Moskowitz, S.

    1973-01-01

    The cylindrical shell combustor with T-bar supports in the 8-foot HTST at the NASA-Langley Research Center encountered vibratory fatigue cracking over a period of 50-250 tunnel tests within a limited range of the required operating envelope. A preliminary design study provided several suitable thermal protection system designs for the combustor, one of which was a two-pass regenerative type air-cooled omega-shaped segment liner. A final design layout of the omega segment liner was prepared and analyzed for steady-state and transient conditions. The design of a support system for the fuel spray bar assembly was also included. Detail drawings suitable for fabrication purposes were also prepared. Liner design problems defined during the preliminary study included (1) the ingress of gas into the attachment bulb section of the omega segment, (2) the large thermal gradient along the leg of the omega bulb attachment section and, (3) the local peak metal temperature at the radius between the liner ID and the leg of the bulb attachment. These were resolved during the final design task. Analyses of the final design of the omega segment liner indicated that all design goals were met and the design provided the capability of operating over the required test envelope with a life expectancy substantially above the goal of 1500 cycles.

  3. Single particle behaviour in circulating fluidized bed combustors

    DEFF Research Database (Denmark)

    Erik Weinell, Claus

    1994-01-01

    An investigation of single particle behaviour in a circulating fluidized bed combustor is described, relating to sulphur capture reactions by limestone under alternate oxidizing and reducing conditions present in a circulating fluidized bed combustor, and to the devolatilization and burn out...

  4. Variable volume combustor with pre-nozzle fuel injection system

    Science.gov (United States)

    Keener, Christopher Paul; Johnson, Thomas Edward; McConnaughhay, Johnie Franklin; Ostebee, Heath Michael

    2016-09-06

    The present application provides a combustor for use with a gas turbine engine. The combustor may include a number of fuel nozzles, a pre-nozzle fuel injection system supporting the fuel nozzles, and a linear actuator to maneuver the fuel nozzles and the pre-nozzle fuel injection system.

  5. Combustor nozzle for a fuel-flexible combustion system

    Science.gov (United States)

    Haynes, Joel Meier [Niskayuna, NY; Mosbacher, David Matthew [Cohoes, NY; Janssen, Jonathan Sebastian [Troy, NY; Iyer, Venkatraman Ananthakrishnan [Mason, OH

    2011-03-22

    A combustor nozzle is provided. The combustor nozzle includes a first fuel system configured to introduce a syngas fuel into a combustion chamber to enable lean premixed combustion within the combustion chamber and a second fuel system configured to introduce the syngas fuel, or a hydrocarbon fuel, or diluents, or combinations thereof into the combustion chamber to enable diffusion combustion within the combustion chamber.

  6. Optimization of Cylindrical Hall Thrusters

    International Nuclear Information System (INIS)

    Raitses, Yevgeny; Smirnov, Artem; Granstedt, Erik; Fisch, Nathaniel J.

    2007-01-01

    The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation.

  7. Optimization of Cylindrical Hall Thrusters

    International Nuclear Information System (INIS)

    Raitses, Yevgeny; Smirnov, Artem; Granstedt, Erik; Fi, Nathaniel J.

    2007-01-01

    The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation

  8. System and method for reducing combustion dynamics in a combustor

    Science.gov (United States)

    Uhm, Jong Ho; Ziminsky, Willy Steve; Johnson, Thomas Edward; Srinivasan, Shiva; York, William David

    2016-11-29

    A system for reducing combustion dynamics in a combustor includes an end cap that extends radially across the combustor and includes an upstream surface axially separated from a downstream surface. A combustion chamber is downstream of the end cap, and tubes extend from the upstream surface through the downstream surface. Each tube provides fluid communication through the end cap to the combustion chamber. The system further includes means for reducing combustion dynamics in the combustor. A method for reducing combustion dynamics in a combustor includes flowing a working fluid through tubes that extend axially through an end cap that extends radially across the combustor and obstructing at least a portion of the working fluid flowing through a first set of the tubes.

  9. Rich-burn, flame-assisted fuel cell, quick-mix, lean-burn (RFQL) combustor and power generation

    Science.gov (United States)

    Milcarek, Ryan J.; Ahn, Jeongmin

    2018-03-01

    Micro-tubular flame-assisted fuel cells (mT-FFC) were recently proposed as a modified version of the direct flame fuel cell (DFFC) operating in a dual chamber configuration. In this work, a rich-burn, quick-mix, lean-burn (RQL) combustor is combined with a micro-tubular solid oxide fuel cell (mT-SOFC) stack to create a rich-burn, flame-assisted fuel cell, quick-mix, lean-burn (RFQL) combustor and power generation system. The system is tested for rapid startup and achieves peak power densities after only 35 min of testing. The mT-FFC power density and voltage are affected by changes in the fuel-lean and fuel-rich combustion equivalence ratio. Optimal mT-FFC performance favors high fuel-rich equivalence ratios and a fuel-lean combustion equivalence ratio around 0.80. The electrical efficiency increases by 150% by using an intermediate temperature cathode material and improving the insulation. The RFQL combustor and power generation system achieves rapid startup, a simplified balance of plant and may have applications for reduced NOx formation and combined heat and power.

  10. Stochastic modelling of turbulent combustion for design optimization of gas turbine combustors

    Science.gov (United States)

    Mehanna Ismail, Mohammed Ali

    implementation of time splitting, variable stochastic fluid particle mass control, and a second order time accurate (predictor-corrector) scheme used for solving the stochastic differential equations governing the particles evolution. The model compared well against experimental data found in the literature for two different configurations: bluff body and swirl stabilized combustors. The generalized stochastic reactor is a newly developed model. This model relies on the generalization of the concept of the classical stochastic reactor theory in the sense that it accounts for both finite micro- and macro-mixing processes. (Abstract shortened by UMI.)

  11. Emission control by cyclone combustor technology

    Energy Technology Data Exchange (ETDEWEB)

    Syred, N; Styles, A C; Sahatimehr, A

    1983-09-01

    Recent work carried out on a multi-inlet gas-fired cyclone combustor has shown that NO formation is reduced to negligible proportions when operated at mixture ratios 1.5 < PHI < 2.2 with combustion occurring under fully premixed fuel conditions. Elimination of hot spots, common to partial premixed systems, has been achieved with mean temperatures below 1300 C, thereby reducing NO emissions (1.5 ppm) by preventing the onset of Zeldovich and prompt mechanisms. The low NO levels are therefore dependent on a combination of low flame front temperature (about 1100 C) and premixed combustion conditions. Owing to the operating mode of combustion, heat transfer at the walls plays an important role in flame stability. Insulation of the cyclone chamber by refractory has been found to extend the operating range to higher mixture ratios. Conversely, it is expected that heat removal from the walls would enable the combustor to operate at mixture ratios nearer to stoichiometric, whilst still giving rise to low levels of NO emission. 17 references.

  12. Computational model of a whole tree combustor

    Energy Technology Data Exchange (ETDEWEB)

    Bryden, K.M.; Ragland, K.W. [Univ. of Wisconsin, Madison, WI (United States)

    1993-12-31

    A preliminary computational model has been developed for the whole tree combustor and compared to test results. In the simulation model presented hardwood logs, 15 cm in diameter are burned in a 4 m deep fuel bed. Solid and gas temperature, solid and gas velocity, CO, CO{sub 2}, H{sub 2}O, HC and O{sub 2} profiles are calculated. This deep, fixed bed combustor obtains high energy release rates per unit area due to the high inlet air velocity and extended reaction zone. The lowest portion of the overall bed is an oxidizing region and the remainder of the bed acts as a gasification and drying region. The overfire air region completes the combustion. Approximately 40% of the energy is released in the lower oxidizing region. The wood consumption rate obtained from the computational model is 4,110 kg/m{sup 2}-hr which matches well the consumption rate of 3,770 kg/m{sup 2}-hr observed during the peak test period of the Aurora, MN test. The predicted heat release rate is 16 MW/m{sup 2} (5.0*10{sup 6} Btu/hr-ft{sup 2}).

  13. Fluid Mechanics of Lean Blowout Precursors in Gas Turbine Combustors

    Directory of Open Access Journals (Sweden)

    T. M. Muruganandam

    2012-03-01

    Full Text Available Understanding of lean blowout (LBO phenomenon, along with the sensing and control strategies could enable the gas turbine combustor designers to design combustors with wider operability regimes. Sensing of precursor events (temporary extinction-reignition events based on chemiluminescence emissions from the combustor, assessing the proximity to LBO and using that data for control of LBO has already been achieved. This work describes the fluid mechanic details of the precursor dynamics and the blowout process based on detailed analysis of near blowout flame behavior, using simultaneous chemiluminescence and droplet scatter observations. The droplet scatter method represents the regions of cold reactants and thus help track unburnt mixtures. During a precursor event, it was observed that the flow pattern changes significantly with a large region of unburnt mixture in the combustor, which subsequently vanishes when a double/single helical vortex structure brings back the hot products back to the inlet of the combustor. This helical pattern is shown to be the characteristic of the next stable mode of flame in the longer combustor, stabilized by double helical vortex breakdown (VBD mode. It is proposed that random heat release fluctuations near blowout causes VBD based stabilization to shift VBD modes, causing the observed precursor dynamics in the combustor. A complete description of the evolution of flame near the blowout limit is presented. The description is consistent with all the earlier observations by the authors about precursor and blowout events.

  14. Cylindrical acoustic levitator/concentrator

    Science.gov (United States)

    Kaduchak, Gregory; Sinha, Dipen N.

    2002-01-01

    A low-power, inexpensive acoustic apparatus for levitation and/or concentration of aerosols and small liquid/solid samples having particulates up to several millimeters in diameter in air or other fluids is described. It is constructed from a commercially available, hollow cylindrical piezoelectric crystal which has been modified to tune the resonance frequency of the breathing mode resonance of the crystal to that of the interior cavity of the cylinder. When the resonance frequency of the interior cylindrical cavity is matched to the breathing mode resonance of the cylindrical piezoelectric transducer, the acoustic efficiency for establishing a standing wave pattern in the cavity is high. The cylinder does not require accurate alignment of a resonant cavity. Water droplets having diameters greater than 1 mm have been levitated against the force of gravity using; less than 1 W of input electrical power. Concentration of aerosol particles in air is also demonstrated.

  15. Telescoping cylindrical piezoelectric fiber composite actuator assemblies

    Science.gov (United States)

    Allison, Sidney G. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, legal representative, Christopher L. (Inventor); Fox Chattin, legal representative, Melanie L. (Inventor)

    2010-01-01

    A telescoping actuator assembly includes a plurality of cylindrical actuators in a concentric arrangement. Each cylindrical actuator is at least one piezoelectric fiber composite actuator having a plurality of piezoelectric fibers extending parallel to one another and to the concentric arrangement's longitudinal axis. Each cylindrical actuator is coupled to concentrically-adjacent ones of the cylindrical actuators such that the plurality of cylindrical actuators can experience telescopic movement. An electrical energy source coupled to the cylindrical actuators applies actuation energy thereto to generate the telescopic movement.

  16. An Experimental Investigation of Self-Excited Combustion Dynamics in a Single Element Lean Direct Injection (LDI) Combustor

    Science.gov (United States)

    Gejji, Rohan M.

    the geometric configuration of the combustor, i.e., its acoustic resonance characteristics, with measured pressure fluctuation amplitudes ranged from 5 kPa (0.5% of mean pressure) to 200 kPa ( 20% of mean pressure) depending on combustor geometry. The stability behavior also showed a consistent and pronounced dependence on equivalence ratio and inlet air temperature. Instability amplitude increased with higher equivalence ratio and with lower inlet air temperature. A pronounced effect of fuel nozzle location on the combustion dynamics was also observed. Combustion instabilities with the fuel nozzle at the throat of the venturi throat were stronger than in the configuration with fuel nozzle 2.6 mm upstream of the nozzle. A second set of dynamics data was based on high-response-rate laser-based combustion diagnostics using an optically accessible combustor section. High-frequency measurements of OH*-chemiluminescence and OH-PLIF and velocity fields using PIV were obtained at a relatively stable, low equivalence ratio case and a less stable case at higher equivalence ratio. PIV measurements were performed at 5 kHz for non-reacting flow but glare from the cylindrical quartz chamber limited the field of view to a small region in the combustor. Quantitative and qualitative comparisons were made for five different combinations of geometry and operating condition that yielded discriminating stability behavior in the experiment with simulations that were carried out concurrently. Comparisons were made on the basis of trends and pressure mode data as well as with OH-PLIF measurements for the baseline geometry at equivalence ratios of 0.44 and 0.6. Overall, the ability of the simulation to match experimental data and trends was encouraging. Dynamic Mode Decomposition (DMD) analysis was performed on two sets of computations - a global 2-step chemistry mechanism and an 18-step chemistry mechanism - and the OH-PLIF images to allow comparison of dynamic patterns of heat release and

  17. Filling of charged cylindrical capillaries

    NARCIS (Netherlands)

    Das, Siddhartha; Chanda, Sourayon; Eijkel, J.C.T.; Tas, N.R.; Chakraborty, Suman; Mitra, Sushanta K.

    2014-01-01

    We provide an analytical model to describe the filling dynamics of horizontal cylindrical capillaries having charged walls. The presence of surface charge leads to two distinct effects: It leads to a retarding electrical force on the liquid column and also causes a reduced viscous drag force because

  18. Optics Demonstrations Using Cylindrical Lenses

    Science.gov (United States)

    Ivanov, Dragia; Nikolov, Stefan

    2015-01-01

    In this paper we consider the main properties of cylindrical lenses and propose several demonstrational experiments that can be performed with them. Specifically we use simple glasses full of water to demonstrate some basic geometrical optics principles and phenomena. We also present some less standard experiments that can be performed with such…

  19. Dismantling OPAL's cylindrical magnet core

    CERN Multimedia

    Laurent Guiraud

    2001-01-01

    Lifting a handling device for dismounting the pressure bells, which are inside the cylindrical magnet coil on the central section of OPAL, on the right part of the photo. OPAL was a detector on the LEP accelerator, which ran from 1989 to 2000.

  20. Cylindrical thin-shell wormholes

    International Nuclear Information System (INIS)

    Eiroa, Ernesto F.; Simeone, Claudio

    2004-01-01

    A general formalism for the dynamics of nonrotating cylindrical thin-shell wormholes is developed. The time evolution of the throat is explicitly obtained for thin-shell wormholes whose metric has the form associated with local cosmic strings. It is found that the throat collapses to zero radius, remains static, or expands forever, depending only on the sign of its initial velocity

  1. Mercury emissions from municipal solid waste combustors

    Energy Technology Data Exchange (ETDEWEB)

    1993-05-01

    This report examines emissions of mercury (Hg) from municipal solid waste (MSW) combustion in the United States (US). It is projected that total annual nationwide MSW combustor emissions of mercury could decrease from about 97 tonnes (1989 baseline uncontrolled emissions) to less than about 4 tonnes in the year 2000. This represents approximately a 95 percent reduction in the amount of mercury emitted from combusted MSW compared to the 1989 mercury emissions baseline. The likelihood that routinely achievable mercury emissions removal efficiencies of about 80 percent or more can be assured; it is estimated that MSW combustors in the US could prove to be a comparatively minor source of mercury emissions after about 1995. This forecast assumes that diligent measures to control mercury emissions, such as via use of supplemental control technologies (e.g., carbon adsorption), are generally employed at that time. However, no present consensus was found that such emissions control measures can be implemented industry-wide in the US within this time frame. Although the availability of technology is apparently not a limiting factor, practical implementation of necessary control technology may be limited by administrative constraints and other considerations (e.g., planning, budgeting, regulatory compliance requirements, etc.). These projections assume that: (a) about 80 percent mercury emissions reduction control efficiency is achieved with air pollution control equipment likely to be employed by that time; (b) most cylinder-shaped mercury-zinc (CSMZ) batteries used in hospital applications can be prevented from being disposed into the MSW stream or are replaced with alternative batteries that do not contain mercury; and (c) either the amount of mercury used in fluorescent lamps is decreased to an industry-wide average of about 27 milligrams of mercury per lamp or extensive diversion from the MSW stream of fluorescent lamps that contain mercury is accomplished.

  2. Investigation of bluff-body micro-flameless combustion

    International Nuclear Information System (INIS)

    Hosseini, Seyed Ehsan; Wahid, Mazlan Abdul

    2014-01-01

    Highlights: • The temperature uniformity of the micro-flameless combustion increases when a triangular bluff-body is applied. • The velocity and temperature of exhaust gases are higher in micro-flameless combustion compared to the conventional mode. • The rate of fuel–oxidizer consumption in micro-flameless mode is lower than conventional micro-combustion. - Abstract: Characteristics of lean premixed conventional micro-combustion and lean non-premixed flameless regime of methane/air are investigated in this paper by solving three-dimensional governing equations. At moderate equivalence ratio (∅ = 0.5), standard k–ε and the eddy-dissipation concept are employed to simulate temperature distribution and combustion stability of these models. The effect of bluff-body on the temperature distribution of both conventional and flameless mode is developed. The results show that in the premixed conventional micro-combustion the stability of the flame is increased when a triangular bluff-body is applied. Moreover, micro-flameless combustion is more stable when bluff-body is used. Micro-flameless mode with bluff-body and 7% O 2 concentration (when N 2 is used as diluent) illustrated better performance than other cases. The maximum temperature in premixed conventional micro-combustion and micro-flameless combustion was recorded 2200 K and 1520 K respectively. Indeed, the flue gas temperature of conventional mode and flameless combustion was 1300 K and 1500 K respectively. The fluctuation of temperature in the conventional micro-combustor wall has negative effects on the combustor and reduces the lifetime of micro-combustor. However, in the micro-flameless mode, the wall temperature is moderate and uniform. The rate of fuel–oxidizer consumption in micro-flameless mode takes longer time and the period of cylinders recharging is prolonged

  3. Feasibility study of ultra-low NOx Gas turbine combustor using the RML combustion concept

    International Nuclear Information System (INIS)

    Van, Tien Giap; Hwang, Jeong Jae; Kim, Min Kuk; Ahn, Kook Young

    2016-01-01

    A new combustion concept, the so called RML, was investigated to validate its application as a gas turbine combustor for combustor outlet temperatures over 1973 K. The feasibility study of the RML combustor was conducted with zero dimensional combustion calculations. The emission characteristics of RQL, LEAN, EGR and RML combustors were compared. The calculation results showed that the RQL combustor has lower NOx emissions than the LEAN at high outlet temperature. NOx emissions of the RML combustor at equivalence ratio of the rich chamber of 2.0 can be reduced by 30 % compared with the EGR combustor, and lower than the RQL combustor at a combustor outlet temperature over 1973 K. However, the CO emissions of the RML combustor were higher than those of the LEAN and EGR combustors. Also, the possibility of applying the RML combustor to gas turbines was discussed considering residence time, equivalence ratio of the rich chamber and recirculation rate. Although further research to design and realize the proposed RML combustor is needed, this study verified that the RML concept can be successfully used in a gas turbine combustor

  4. Feasibility study of ultra-low NOx Gas turbine combustor using the RML combustion concept

    Energy Technology Data Exchange (ETDEWEB)

    Van, Tien Giap; Hwang, Jeong Jae; Kim, Min Kuk; Ahn, Kook Young [Environment and Energy Research Division, Korea Institute of Machinery and Materials (KIMM), Daejeon (Korea, Republic of)

    2016-12-15

    A new combustion concept, the so called RML, was investigated to validate its application as a gas turbine combustor for combustor outlet temperatures over 1973 K. The feasibility study of the RML combustor was conducted with zero dimensional combustion calculations. The emission characteristics of RQL, LEAN, EGR and RML combustors were compared. The calculation results showed that the RQL combustor has lower NOx emissions than the LEAN at high outlet temperature. NOx emissions of the RML combustor at equivalence ratio of the rich chamber of 2.0 can be reduced by 30 % compared with the EGR combustor, and lower than the RQL combustor at a combustor outlet temperature over 1973 K. However, the CO emissions of the RML combustor were higher than those of the LEAN and EGR combustors. Also, the possibility of applying the RML combustor to gas turbines was discussed considering residence time, equivalence ratio of the rich chamber and recirculation rate. Although further research to design and realize the proposed RML combustor is needed, this study verified that the RML concept can be successfully used in a gas turbine combustor.

  5. Aerotrace. Measurement of particulates from an engine combustor

    Energy Technology Data Exchange (ETDEWEB)

    Hurley, C D [DRA, Farnborough (United Kingdom)

    1998-12-31

    The effect of gas turbine operating conditions, inlet temperature, pressure and overall air fuel ratio, on particulate number density has been measured. Particulate number density was found to be proportional to combustor inlet pressure and decrease with increasing combustor inlet temperature. The relationship with air fuel ratio is more complex. The mechanism of particulate loss down sample lines has been elucidated and equations are presented to predict particulate losses for stainless steel and PTFE sample lines. (author) 3 refs.

  6. Transient Heat Transfer Properties in a Pulse Detonation Combustor

    Science.gov (United States)

    2011-03-01

    appreciation to my wife Shelly , and my sons Cody, Brandon, and Tyler for their encouragement, support, and understanding during this challenging time...operation frequencies. 56 B. FUTURE WORK A redesign of the cooled combustor chamber is currently in progress and will result in a cast mold. A...water-cooled combustor with casted swept ramps in the combustion chamber that are cooled as well maximizes the amount cooling to the ramps to help

  7. Development of a catalytically assisted combustor for a gas turbine

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa, Yasushi; Fujii, Tomoharu; Sato, Mikio [Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa 240-01 (Japan); Kanazawa, Takaaki; Inoue, Hitoshi [Kansai Electric Power Company, Inc., 3-11-20 Nakoji, Amagasaki, Hyoho 661 (Japan)

    1999-01-01

    A catalytically assisted low NO{sub x} combustor has been developed which has the advantage of catalyst durability. This combustor is composed of a burner section and a premixed combustion section behind the burner section. The burner system consists of six catalytic combustor segments and six premixing nozzles, which are arranged alternately and in parallel. Fuel flow rate for the catalysts and the premixing nozzles are controlled independently. The catalytic combustion temperature is maintained under 1000C, additional premixed gas is injected from the premixing nozzles into the catalytic combustion gas, and lean premixed combustion at 1300C is carried out in the premixed combustion section. This system was designed to avoid catalytic deactivation at high temperature and thermal or mechanical shock fracture of the honeycomb monolith. In order to maintain the catalyst temperature under 1000C, the combustion characteristics of catalysts at high pressure were investigated using a bench scale reactor and an improved catalyst was selected for the combustor test. A combustor for a 20MW class multi-can type gas turbine was designed and tested under high pressure conditions using LNG fuel. Measurements of NO{sub x}, CO and unburned hydrocarbon were made and other measurements were made to evaluate combustor performance under various combustion temperatures and pressures. As a result of the tests, it was proved that NO{sub x} emission was lower than 10ppm converted at 16% O{sub 2}, combustion efficiency was almost 100% at 1300C of combustor outlet temperature and 13.5ata of combustor inlet pressure

  8. Aerotrace. Measurement of particulates from an engine combustor

    Energy Technology Data Exchange (ETDEWEB)

    Hurley, C.D. [DRA, Farnborough (United Kingdom)

    1997-12-31

    The effect of gas turbine operating conditions, inlet temperature, pressure and overall air fuel ratio, on particulate number density has been measured. Particulate number density was found to be proportional to combustor inlet pressure and decrease with increasing combustor inlet temperature. The relationship with air fuel ratio is more complex. The mechanism of particulate loss down sample lines has been elucidated and equations are presented to predict particulate losses for stainless steel and PTFE sample lines. (author) 3 refs.

  9. Hypersonic Combustor Model Inlet CFD Simulations and Experimental Comparisons

    Science.gov (United States)

    Venkatapathy, E.; TokarcikPolsky, S.; Deiwert, G. S.; Edwards, Thomas A. (Technical Monitor)

    1995-01-01

    Numerous two-and three-dimensional computational simulations were performed for the inlet associated with the combustor model for the hypersonic propulsion experiment in the NASA Ames 16-Inch Shock Tunnel. The inlet was designed to produce a combustor-inlet flow that is nearly two-dimensional and of sufficient mass flow rate for large scale combustor testing. The three-dimensional simulations demonstrated that the inlet design met all the design objectives and that the inlet produced a very nearly two-dimensional combustor inflow profile. Numerous two-dimensional simulations were performed with various levels of approximations such as in the choice of chemical and physical models, as well as numerical approximations. Parametric studies were conducted to better understand and to characterize the inlet flow. Results from the two-and three-dimensional simulations were used to predict the mass flux entering the combustor and a mass flux correlation as a function of facility stagnation pressure was developed. Surface heat flux and pressure measurements were compared with the computed results and good agreement was found. The computational simulations helped determine the inlet low characteristics in the high enthalpy environment, the important parameters that affect the combustor-inlet flow, and the sensitivity of the inlet flow to various modeling assumptions.

  10. Pollution technology program, can-annular combustor engines

    Science.gov (United States)

    Roberts, R.; Fiorentino, A. J.; Greene, W.

    1976-01-01

    A Pollution Reduction Technology Program to develop and demonstrate the combustor technology necessary to reduce exhaust emissions for aircraft engines using can-annular combustors is described. The program consisted of design, fabrication, experimental rig testing and assessment of results and was conducted in three program elements. The combustor configurations of each program element represented increasing potential for meeting the 1979 Environmental Protection Agency (EPA) emission standards, while also representing increasing complexity and difficulty of development and adaptation to an operational engine. Experimental test rig results indicate that significant reductions were made to the emission levels of the baseline JT8D-17 combustor by concepts in all three program elements. One of the Element I single-stage combustors reduced carbon monoxide to a level near, and total unburned hydrocarbons (THC) and smoke to levels below the 1979 EPA standards with little or no improvement in oxides of nitrogen. The Element II two-stage advanced Vorbix (vortex burning and mixing) concept met the standard for THC and achieved significant reductions in CO and NOx relative to the baseline. Although the Element III prevaporized-premixed concept reduced high power NOx below the Element II results, there was no improvement to the integrated EPA parameter relative to the Vorbix combustor.

  11. Ejector-Enhanced, Pulsed, Pressure-Gain Combustor

    Science.gov (United States)

    Paxson, Daniel E.; Dougherty, Kevin T.

    2009-01-01

    An experimental combination of an off-the-shelf valved pulsejet combustor and an aerodynamically optimized ejector has shown promise as a prototype of improved combustors for gas turbine engines. Despite their name, the constant pressure combustors heretofore used in gas turbine engines exhibit typical pressure losses ranging from 4 to 8 percent of the total pressures delivered by upstream compressors. In contrast, the present ejector-enhanced pulsejet combustor exhibits a pressure rise of about 3.5 percent at overall enthalpy and temperature ratios compatible with those of modern turbomachines. The modest pressure rise translates to a comparable increase in overall engine efficiency and, consequently, a comparable decrease in specific fuel consumption. The ejector-enhanced pulsejet combustor may also offer potential for reducing the emission of harmful exhaust compounds by making it practical to employ a low-loss rich-burn/quench/lean-burn sequence. Like all prior concepts for pressure-gain combustion, the present concept involves an approximation of constant-volume combustion, which is inherently unsteady (in this case, more specifically, cyclic). The consequent unsteadiness in combustor exit flow is generally regarded as detrimental to the performance of downstream turbomachinery. Among other adverse effects, this unsteadiness tends to detract from the thermodynamic benefits of pressure gain. Therefore, it is desirable in any intermittent combustion process to minimize unsteadiness in the exhaust path.

  12. Homotheties of cylindrically symmetric static spacetimes

    International Nuclear Information System (INIS)

    Qadir, A.; Ziad, M.; Sharif, M.

    1998-08-01

    In this note we consider the homotheties of cylindrically symmetric static spacetimes. We find that we can provide a complete list of all metrics that admit non-trivial homothetic motions and are cylindrically symmetric static. (author)

  13. Combustor with two stage primary fuel tube with concentric members and flow regulating

    Science.gov (United States)

    Parker, David Marchant; Whidden, Graydon Lane; Zolyomi, Wendel

    1999-01-01

    A combustor for a gas turbine having a centrally located fuel nozzle and inner, middle and outer concentric cylindrical liners, the inner liner enclosing a primary combustion zone. The combustor has an air inlet that forms two passages for pre-mixing primary fuel and air to be supplied to the primary combustion zone. Each of the pre-mixing passages has a circumferential array of swirl vanes. A plurality of primary fuel tube assemblies extend through both pre-mixing passages, with each primary fuel tube assembly located between a pair of swirl vanes. Each primary fuel tube assembly is comprised of two tubular members. The first member supplies fuel to the first pre-mixing passage, while the second member, which extends through the first member, supplies fuel to the second pre-mixing passage. An annular fuel manifold is divided into first and second chambers by a circumferentially extending baffle. The proximal end of the first member is attached to the manifold itself while the proximal end of the second member is attached to the baffle. The distal end of the first member is attached directly to the second member at around its mid-point. The inlets of the first and second members are in flow communication with the first and second manifold chambers, respectively. Control valves separately regulate the flow of fuel to the two chambers and, therefore, to the two members of the fuel tube assemblies, thereby allowing the flow of fuel to the first and second pre-mixing passages to be separately controlled.

  14. Cylindrical collapse and gravitational waves

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, L [Escuela de FIsica, Faculdad de Ciencias, Universidad Central de Venezuela, Caracas, Venezuela (Venezuela); Santos, N O [Universite Pierre et Marie Curie, CNRS/FRE 2460 LERMA/ERGA, Tour 22-12, 4eme etage, BoIte 142, 4 place Jussieu, 75252 Paris Cedex 05 (France); Laboratorio Nacional de Computacao Cientifica, 25651-070 Petropolis RJ (Brazil); Centro Brasileiro de Pesquisas Fisicas, 22290-180 Rio de Janeiro RJ (Brazil)

    2005-06-21

    We study the matching conditions for a collapsing anisotropic cylindrical perfect fluid, and we show that its radial pressure is non-zero on the surface of the cylinder and proportional to the time-dependent part of the field produced by the collapsing fluid. This result resembles the one that arises for the radiation-though non-gravitational-in the spherically symmetric collapsing dissipative fluid, in the diffusion approximation.

  15. Cracking of anisotropic cylindrical polytropes

    Energy Technology Data Exchange (ETDEWEB)

    Mardan, S.A. [University of the Management and Technology, Department of Mathematics, Lahore (Pakistan); Azam, M. [University of Education, Division of Science and Technology, Lahore (Pakistan)

    2017-06-15

    We study the appearance of cracking in charged anisotropic cylindrical polytropes with generalized polytropic equation. We investigate the existence of cracking in two different kinds of polytropes existing in the literature through two different assumptions: (a) local density perturbation with conformally flat condition, and (b) perturbing polytropic index, charge and anisotropy parameters. We conclude that cracking appears in both kinds of polytropes for a specific range of density and model parameters. (orig.)

  16. Plastic buckling of cylindrical shells

    International Nuclear Information System (INIS)

    Bandyopadhyay, K.; Xu, J.; Shteyngart, S.; Eckert, H.

    1994-01-01

    Cylindrical shells exhibit buckling under axial loads at stresses much less than the respective theoretical critical stresses. This is due primarily to the presence of geometrical imperfections even though such imperfections could be very small (e.g., comparable to thickness). Under internal pressure, the shell regains some of its buckling strength. For a relatively large radius-to-thickness ratio and low internal pressure, the effect can be reasonably estimated by an elastic analysis. However, for low radius-to-thickness ratios and greater pressures, the elastic-plastic collapse controls the failure load. in order to quantify the elastic-plastic buckling capacity of cylindrical shells, an analysis program was carried out by use of the computer code BOSOR5 developed by Bushnell of Lockheed Missiles and Space Company. The analysis was performed for various radius-to-thickness ratios and imperfection amplitudes. The purpose of the analytical program was to compute the buckling strength of underground cylindrical tanks, that are used for storage of nuclear wastes, for realistic geometric imperfections and internal pressure loads. This paper presents the results of the elastic-plastic analyses and compares them with other available information for various pressure loads

  17. Combustion of alternative fuels in vortex trapped combustor

    International Nuclear Information System (INIS)

    Ghenai, Chaouki; Zbeeb, Khaled; Janajreh, Isam

    2013-01-01

    Highlights: ► We model the combustion of alternative fuels in trapped vortex combustor (TVC). ► We test syngas and hydrogen/hydrocarbon mixture fuels. ► We examine the change in combustion performance and emissions of TVC combustor. ► Increasing the hydrogen content of the fuel will increase the temperature and NO x emissions. ► A high combustor efficiency is obtained for fuels with different compositions and LHV. - Abstract: Trapped vortex combustor represents an efficient and compact combustor for flame stability. Combustion stability is achieved through the use of cavities in which recirculation zones of hot products generated by the direct injection of fuel and air are created and acting as a continuous source of ignition for the incoming main fuel–air stream. Computational Fluid Dynamics analysis was performed in this study to test the combustion performance and emissions from the vortex trapped combustor when natural gas fuel (methane) is replaced with renewable and alternative fuels such as hydrogen and synthetic gas (syngas). The flame temperature, the flow field, and species concentrations inside the Vortex Trapped Combustor were obtained. The results show that hydrogen enriched hydrocarbon fuels combustion will result in more energy, higher temperature (14% increase when methane is replaced with hydrogen fuels) and NO x emissions, and lower CO 2 emissions (50% decrease when methane is replaced with methane/hydrogen mixture with 75% hydrogen fraction). The NO x emission increases when the fraction of hydrogen increases for methane/hydrogen fuel mixture. The results also show that the flame for methane combustion fuel is located in the primary vortex region but it is shifted to the secondary vortex region for hydrogen combustion.

  18. Core Noise: Overview of Upcoming LDI Combustor Test

    Science.gov (United States)

    Hultgren, Lennart S.

    2012-01-01

    This presentation is a technical summary of and outlook for NASA-internal and NASA-sponsored external research on core (combustor and turbine) noise funded by the Fundamental Aeronautics Program Fixed Wing Project. The presentation covers: the emerging importance of core noise due to turbofan design trends and its relevance to the NASA N+3 noise-reduction goal; the core noise components and the rationale for the current emphasis on combustor noise; and the current and planned research activities in the combustor-noise area. Two NASA-sponsored research programs, with particular emphasis on indirect combustor noise, "Acoustic Database for Core Noise Sources", Honeywell Aerospace (NNC11TA40T) and "Measurement and Modeling of Entropic Noise Sources in a Single-Stage Low-Pressure Turbine", U. Illinois/U. Notre Dame (NNX11AI74A) are briefly described. Recent progress in the development of CMC-based acoustic liners for broadband noise reduction suitable for turbofan-core application is outlined. Combustor-design trends and the potential impacts on combustor acoustics are discussed. A NASA GRC developed nine-point lean-direct-injection (LDI) fuel injector is briefly described. The modification of an upcoming thermo-acoustic instability evaluation of the GRC injector in a combustor rig to also provide acoustic information relevant to community noise is presented. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The reduction of aircraft noise is critical to enabling the anticipated large increase in future air traffic. The Quiet Performance Research Theme of the Fixed Wing Project aims to develop concepts and technologies to dramatically reduce the perceived community noise attributable to aircraft with minimal impact on weight and performance.

  19. Effect of Structural Heat Conduction on the Performance of Micro-combustors and Micro-thrusters

    Science.gov (United States)

    2005-01-01

    numerical models lends credence to the principles underlying the modified Mallard- Le Chatelier theory, the quantitative discrepancy between the analytical...employs reasoning similar to that used by Mallard and Le Chatelier to predict the velocity of a freely propagating flame but extends it to include the...equation (2-1). 19 2.2.1. Adiabatic theory The thermal theory of Mallard and Le Chatelier applies to freely propagating flame that does not

  20. Alternate-Fueled Combustor-Sector Emissions

    Science.gov (United States)

    Saxena, Nikita T.; Thomas, Anna E.; Shouse, Dale T.; Neuroth, Craig; Hendricks, Robert C.; Lynch, Amy; Frayne, Charles W.; Stutrud, Jeffrey S.; Corporan, Edwin; Hankins, Terry

    2013-01-01

    In order to meet rapidly growing demand for fuel, as well as address environmental concerns, the aviation industry has been testing alternate fuels for performance and technical usability in commercial and military aircraft. In order to make alternate fuels (and blends) a viable option for aviation, the fuel must be able to perform at a similar or higher level than traditional petroleum fuel. They also attempt to curb harmful emissions, and therefore a truly effective alternate fuel would emit at or under the level of currently used fuel. This report analyzes data from gaseous and particulate emissions of an aircraft combustor sector. The data were evaluated at various inlet conditions, including variation in pressure and temperature, fuel-to-air ratios, and percent composition of alternate fuel. Traditional JP-8+100 data were taken as a baseline, and blends of JP-8+100 with synthetic-paraffinic-kerosene (SPK) fuel (Fischer-Tropsch (FT)) were used for comparison. Gaseous and particulate emissions, as well as flame luminosity, were assessed for differences between FT composition of 0, 50, and 100 percent. The data show that SPK fuel (an FT-derived fuel) had slightly lower harmful gaseous emissions, and smoke number information corroborated the hypothesis that SPK-FT fuels are cleaner burning fuels.

  1. Electron emitter pulsed-type cylindrical IEC

    International Nuclear Information System (INIS)

    Miley, G.H.; Gu, Y.; Stubbers, R.; Zich, R.; Anderl, R.; Hartwell, J.

    1997-01-01

    A cylindrical version of the single grid Inertial Electrostatic Confinement (IEC) device (termed the C-device) has been developed for use as a 2.5-MeV D-D fusion neutron source for neutron activation analysis. The C-device employs a hollow-tube type cathode with similar anodes backed up by ''reflector'' dishes. The resulting discharge differs from a conventional hollow cathode discharge, by creating an explicit ion beam which is ''pinched'' in the cathode region. Resulting fusion reactions generate ∼10 6 neutron/s. A pulsed version is under development for applications requiring higher fluxes. Several pulsing techniques are under study, including an electron emitter (e-emitter) assisted discharge in a thorated tungsten wire emitter located behind a slotted area in the reflector dishes. Pulsing is initiated after establishing a low power steady-state discharge by pulsing the e-emitter current using a capacitor switch type circuit. The resulting electron jet, coupled with the discharge by the biased slot array, creates a strong pulse in the pinched ion beam. The pulse length/repetition rate are controlled by the e-emitter pulse circuit. Typical parameters in present studies are ∼30micros, 10Hz and 1-amp ion current. Corresponding neutron measurements are an In-foil type activation counter for time averaged rates. Results for a wide variety of operating conditions are presented

  2. Absorption factor for cylindrical samples

    International Nuclear Information System (INIS)

    Sears, V.F.

    1984-01-01

    The absorption factor for the scattering of X-rays or neutrons in cylindrical samples is calculated by numerical integration for the case in which the absorption coefficients of the incident and scattered beams are not equal. An extensive table of values having an absolute accuracy of 10 -4 is given in a companion report [Sears (1983). Atomic Energy of Canada Limited, Report No. AECL-8176]. In the present paper an asymptotic expression is derived for the absorption factor which can be used with an error of less than 10 -3 for most cases of interest in both neutron inelastic scattering and neutron diffraction in crystals. (Auth.)

  3. Design and evaluation of combustors for reducing aircraft engine pollution

    Science.gov (United States)

    Jones, R. E.; Grobman, J.

    1973-01-01

    Various techniques and test results are briefly described and referenced for detail. The effort arises from the increasing concern for the measurement and control of emissions from gas turbine engines. The greater part of this research is focused on reducing the oxides of nitrogen formed during takeoff and cruise in both advanced CTOL, high pressure ratio engines, and advanced supersonic aircraft engines. The experimental approaches taken to reduce oxides of nitrogen emissions include the use of: multizone combustors incorporating reduced dwell time, fuel-air premixing, air atomization, fuel prevaporization, water injection, and gaseous fuels. In the experiments conducted to date, some of these techniques were more successful than others in reducing oxides of nitrogen emissions. Tests are being conducted on full-annular combustors at pressures up to 6 atmospheres and on combustor segments at pressures up to 30 atmospheres.

  4. Mixing and NO(x) Emission Calculations of Confined Reacting Jet Flows in a Cylindrical Duct

    Science.gov (United States)

    Holdeman, James D. (Technical Monitor); Oechsle, Victor L.

    2003-01-01

    Rapid mixing of cold lateral jets with hot cross-stream flows in confined configurations is of practical interest in gas turbine combustors as it strongly affects combustor exit temperature quality, and gaseous emissions in for example rich-lean combustion. It is therefore important to further improve our fundamental understanding of the important processes of dilution jet mixing especially when the injected jet mass flow rate exceeds that of the cross-stream. The results reported in this report describe some of the main flow characteristics which develop in the mixing process in a cylindrical duct. A 3-dimensional tool has been used to predict the mixing flow field characteristics and NOx emission in a quench section of an RQL combustor, Eighteen configurations have been analyzed in a circular geometry in a fully reacting environment simulating the operating condition of an actual RQL gas turbine combustion liner. The evaluation matrix was constructed by varying three parameters: 1) jet-to-mainstream momentum-flux ratio (J), 2) orifice shape or orifice aspect ratio, and 3) slot slant angle. The results indicate that the mixing flow field significantly varies with the value of the jet penetration and subsequently, slanting elongated slots generally improve the mixing uniformity at high J conditions. Round orifices produce more uniform mixing and low NO(x) emissions at low J due to the strong and adequate jet penetration. No significant correlation was found between the NO(x) production rates and the mixing deviation parameters, however, strong correlation was found between NO(x) formation and jet penetration. In the computational results, most of the NO(x) formation occurred behind the orifice starting at the orifice wake region. Additional NO(x) is formed upstream of the orifice in certain configurations with high J conditions due to the upstream recirculation.

  5. Turbine combustor with fuel nozzles having inner and outer fuel circuits

    Science.gov (United States)

    Uhm, Jong Ho; Johnson, Thomas Edward; Kim, Kwanwoo

    2013-12-24

    A combustor cap assembly for a turbine engine includes a combustor cap and a plurality of fuel nozzles mounted on the combustor cap. One or more of the fuel nozzles would include two separate fuel circuits which are individually controllable. The combustor cap assembly would be controlled so that individual fuel circuits of the fuel nozzles are operated or deliberately shut off to provide for physical separation between the flow of fuel delivered by adjacent fuel nozzles and/or so that adjacent fuel nozzles operate at different pressure differentials. Operating a combustor cap assembly in this fashion helps to reduce or eliminate the generation of undesirable and potentially harmful noise.

  6. Micro combustion in sub-millimeter channels for novel modular thermophotovoltaic power generators

    International Nuclear Information System (INIS)

    Pan, J F; Tang, A K; Duan, L; Li, X C; Yang, W M; Chou, S K; Xue, H

    2010-01-01

    The performance of micro combustion-driven power systems is strongly influenced by the combustor structure. A novel modular thermophotovoltaic (TPV) power generator is presented, which is based on the sub-millimeter parallel plate combustor. It has the potential to achieve a high power density because of the high radiation energy per unit volume due to the high surface-to-volume ratio of the micro-combustor. The work experimentally investigated the ignition limitation for two micro-combustors. It also studied the effects of three major parameters on a sub-millimeter combustor, namely hydrogen to oxygen mixing ratio, hydrogen volumetric flow rate and nozzle geometry. The results show that the combustion efficiency decreases with the increase of the hydrogen flow rate, which is caused by reduced residence time. The average wall temperature with the rectangular nozzle is 25 K higher than that with the circle nozzle. The output electrical power and power density of the modular TPV power generator are projected to be 0.175 W and 0.0722 W cm −3 respectively. We experimentally achieve 0.166 W of electrical power, which is in good agreement with the model prediction

  7. The electrostatic cylindrical sheath in a plasma

    International Nuclear Information System (INIS)

    Wang Chunhua; Sun Xiaoxia; Bai Dongxue

    2004-01-01

    The electrostatic sheath with a cylindrical geometry in an ion-electron plasma is investigated. Assuming a Boltzmann response to electrons and cold ions with bulk flow, it is shown that the radius of the cylindrical geometry do not affect the sheath potential significantly. The authors also found that the sheath potential profile is steeper in the cylindrical sheath compared to the slab sheath. The distinct feature of the cylindrical sheath is that the ion density distribution is not monotonous. The sheath region can be divided into three regions, two ascendant regions and one descendant region. (author)

  8. The Instituto de Investigaciones Electricas fluidized bed combustor; El combustor de lecho fluidizado del Instituto de Investigaciones Electricas

    Energy Technology Data Exchange (ETDEWEB)

    Milan Foressi, Julio [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1991-12-31

    After synthesizing the most important aspects of the combustion technology in fluidized bed, the experimental combustor developed at the Instituto de Investigaciones Electricas (IIE) is described, as well as the test results of the experiences carried out with coal from Rio Escondido, Coahuila. [Espanol] Tras sintetizar los aspectos mas importantes de la tecnologia de combustion en lecho fluidizado, se describe el combustor experimental desarrollado en el Instituto de Investigaciones Electricas (IIE), asi como los resultados de las experiencias realizadas con carbon proveniente de Rio Escondido, Coahuila.

  9. The Instituto de Investigaciones Electricas fluidized bed combustor; El combustor de lecho fluidizado del Instituto de Investigaciones Electricas

    Energy Technology Data Exchange (ETDEWEB)

    Milan Foressi, Julio [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1992-12-31

    After synthesizing the most important aspects of the combustion technology in fluidized bed, the experimental combustor developed at the Instituto de Investigaciones Electricas (IIE) is described, as well as the test results of the experiences carried out with coal from Rio Escondido, Coahuila. [Espanol] Tras sintetizar los aspectos mas importantes de la tecnologia de combustion en lecho fluidizado, se describe el combustor experimental desarrollado en el Instituto de Investigaciones Electricas (IIE), asi como los resultados de las experiencias realizadas con carbon proveniente de Rio Escondido, Coahuila.

  10. Design and fabrication of a 50 MWt prototypical MHD coal-fired combustor

    International Nuclear Information System (INIS)

    Albright, J.; Braswell, R.; Listvinsky, G.; McAllister, M.; Myrick, S.; Ono, D.; Thom, H.

    1992-01-01

    A prototypical 50 MWt coal-fired combustor has been designed and fabricated as part of the Magnetohydrodynamic (MHD) Integrated Topping Cycle (ITC) Program. This is a DOE-funded program to develop a prototypical MHD power train to be tested at the Component Development and Integration Facility (CDIF) in Butte, Montana. The prototypical combustor is an outgrowth of the 50 MWt workhorse combustor which has previously been tested at the CDIF. In addition to meeting established performance criteria of the existing 50 MWt workhorse combustor, the prototypical combustor design is required to be scaleable for use at the 250 MWt retrofit level. This paper presents an overview of the mechanical design of the prototypical combustor and a description of its fabrication. Fabrication of the 50 MWt prototypical coal-fired combustor was completed in February 1992 and hot-fire testing is scheduled to begin in May 1992

  11. Catalyzed Combustion In Micro-Propulsion Devices: Project Status

    Science.gov (United States)

    Sung, C. J.; Schneider, S. J.

    2003-01-01

    In recent years, there has been a tendency toward shrinking the size of spacecraft. New classes of spacecraft called micro-spacecraft have been defined by their mass, power, and size ranges. Spacecraft in the range of 20 to 100 kg represent the class most likely to be utilized by most small sat users in the near future. There are also efforts to develop 10 to 20 kg class spacecraft for use in satellite constellations. More ambitious efforts will be to develop spacecraft less than 10 kg, in which MEMS fabrication technology is required. These new micro-spacecraft will require new micro-propulsion technology. Although micro-propulsion includes electric propulsion approaches, the focus of this proposed program is micro-chemical propulsion which requires the development of microcombustors. As combustors are scaled down, the surface to volume ratio increases. The heat release rate in the combustor scales with volume, while heat loss rate scales with surface area. Consequently, heat loss eventually dominates over heat release when the combustor size becomes smaller, thereby leading to flame quenching. The limitations imposed on chamber length and diameter has an immediate impact on the degree of miniaturization of a micro-combustor. Before micro-combustors can be realized, such a difficulty must be overcome. One viable combustion alternative is to take advantage of surface catalysis. Micro-chemical propulsion for small spacecraft can be used for primary thrust, orbit insertion, trajectory-control, and attitude control. Grouping micro-propulsion devices in arrays will allow their use for larger thrust applications. By using an array composed of hundreds or thousands of micro-thruster units, a particular configuration can be arranged to be best suited for a specific application. Moreover, different thruster sizes would provide for a range of thrust levels (from N s to mN s) within the same array. Several thrusters could be fired simultaneously for thrust levels higher than

  12. Diffusion from cylindrical waste forms

    International Nuclear Information System (INIS)

    Thomas, G.F.

    1985-05-01

    The diffusion of a single component material from a finite cylindrical waste form, initially containing a uniform concentration of the material, is investigated. Under the condition that the cylinder is maintained in a well-stirred bath, expressions for the fractional inventory leached and the leach rate are derived with allowance for the possible permanent immobilization of the diffusant through its decay to a stable product and/or its irreversible reaction with the waste form matrix. The usefulness of the reported results in nuclear waste disposal applications is emphasized. The results reported herein are related to those previously derived at Oak Ridge National Laboratory by Bell and Nestor. A numerical scheme involving the partial decoupling of nested infinite summations and the use of rapidly converging rational approximants is recommended for the efficient implementation of the expressions derived to obtain reliable estimates of the bulk diffusion constant and the rate constant describing the diffusant-waste form interaction from laboratory data

  13. DEVELOPMENT OF A VORTEX CONTAINMENT COMBUSTOR FOR COAL COMBUSTION SYTEMS

    Science.gov (United States)

    The report describes the development of a vortex containment combustor (VCC) for coal combustion systems, designed to solve major problems facing the conversion of oil- and gas-fired boilers to coal (e.g., derating, inorganic impurities in coal, and excessive formation of NOx and...

  14. Multiscale Software Tool for Controls Prototyping in Supersonic Combustors

    National Research Council Canada - National Science Library

    Pindera, M

    2004-01-01

    .... In Phase I we have developed a proof-of-concept version of such a tool. We have developed a model-free direct control strategy with on-line training and demonstrated its capabilities in controlling isolator unstart in a hypersonic combustor...

  15. The mechanism of char ignition in fluidized bed combustors

    NARCIS (Netherlands)

    Siemons, R.V.

    1987-01-01

    Knowledge about ignition processes of coal in fluidized beds is of importance for the start-up and dynamic control of these combustors. Initial experiments in a transparent fluidized bed scale model showed the existence of a considerable induction period for the ignition of char, especially at low

  16. Spiral modes in cold cylindrical systems

    International Nuclear Information System (INIS)

    Robe, H.

    1975-01-01

    The linearized hydrodynamical equations governing the non-axisymmetric free modes of oscillation of cold cylindrical stellar systems are separated in cylindrical coordinates and solved numerically for two models. Short-wavelength unstable modes corresponding to tight spirals do not exist; but there exists an unstable growing mode which has the form of trailing spirals which are quite open. (orig.) [de

  17. DART Core/Combustor-Noise Initial Test Results

    Science.gov (United States)

    Boyle, Devin K.; Henderson, Brenda S.; Hultgren, Lennart S.

    2017-01-01

    Contributions from the combustor to the overall propulsion noise of civilian transport aircraft are starting to become important due to turbofan design trends and advances in mitigation of other noise sources. Future propulsion systems for ultra-efficient commercial air vehicles are projected to be of increasingly higher bypass ratio from larger fans combined with much smaller cores, with ultra-clean burning fuel-flexible combustors. Unless effective noise-reduction strategies are developed, combustor noise is likely to become a prominent contributor to overall airport community noise in the future. The new NASA DGEN Aero0propulsion Research Turbofan (DART) is a cost-efficient testbed for the study of core-noise physics and mitigation. This presentation gives a brief description of the recently completed DART core combustor-noise baseline test in the NASA GRC Aero-Acoustic Propulsion Laboratory (AAPL). Acoustic data was simultaneously acquired using the AAPL overhead microphone array in the engine aft quadrant far field, a single midfield microphone, and two semi-infinite-tube unsteady pressure sensors at the core-nozzle exit. An initial assessment shows that the data is of high quality and compares well with results from a quick 2014 feasibility test. Combustor noise components of measured total-noise signatures were educed using a two-signal source-separation method an dare found to occur in the expected frequency range. The research described herein is aligned with the NASA Ultra-Efficient Commercial Transport strategic thrust and is supported by the NASA Advanced Air Vehicle Program, Advanced Air Transport Technology Project, under the Aircraft Noise Reduction Subproject.

  18. Intrinsic cylindrical and spherical waves

    International Nuclear Information System (INIS)

    Ludlow, I K

    2008-01-01

    Intrinsic waveforms associated with cylindrical and spherical Bessel functions are obtained by eliminating the factors responsible for the inverse radius and inverse square radius laws of wave power per unit area of wavefront. The resulting expressions are Riccati-Bessel functions for both cases and these can be written in terms of amplitude and phase functions of order v and wave variable z. When z is real, it is shown that a spatial phase angle of the intrinsic wave can be defined and this, together with its amplitude function, is systematically investigated for a range of fixed orders and varying z. The derivatives of Riccati-Bessel functions are also examined. All the component functions exhibit different behaviour in the near field depending on the order being less than, equal to or greater than 1/2. Plots of the phase angle can be used to display the locations of the zeros of the general Riccati-Bessel functions and lead to new relations concerning the ordering of the real zeros of Bessel functions and the occurrence of multiple zeros when the argument of the Bessel function is fixed

  19. Diffusion in a cylindrical plasma

    International Nuclear Information System (INIS)

    Reid, J.

    1977-04-01

    Modern plasma containment devices, such as the Tokamak, employ magnetic fields which are toroidal in shape. They are able to contain a plasma for times approaching a second. Magnetohydrodynamics (M.H.D.) is one of the most attractive theoretical methods for understanding their behaviour, but the equations involved are complex non-linear partial differential equations, and analytic methods are not available for their solution. Numerical methods must be used. A model system of equations representing a cylindrical plasma with no axial variation is considered. It is convenient to introduce a flux function psi for the component of the magnetic field directed around the axis of the cylinder, called the poloidal field, and the M.H.D. equations are rewritten in terms of psi. This produces a set of highly coupled equations describing the evolution of the flux function, the axial field and the plasma pressure. Various steps are taken to gain a better understanding of the properties of these equations. (author)

  20. Vortex combustor for low NOX emissions when burning lean premixed high hydrogen content fuel

    Science.gov (United States)

    Steele, Robert C; Edmonds, Ryan G; Williams, Joseph T; Baldwin, Stephen P

    2012-11-20

    A trapped vortex combustor. The trapped vortex combustor is configured for receiving a lean premixed gaseous fuel and oxidant stream, where the fuel includes hydrogen gas. The trapped vortex combustor is configured to receive the lean premixed fuel and oxidant stream at a velocity which significantly exceeds combustion flame speed in a selected lean premixed fuel and oxidant mixture. The combustor is configured to operate at relatively high bulk fluid velocities while maintaining stable combustion, and low NOx emissions. The combustor is useful in gas turbines in a process of burning synfuels, as it offers the opportunity to avoid use of diluent gas to reduce combustion temperatures. The combustor also offers the possibility of avoiding the use of selected catalytic reaction units for removal of oxides of nitrogen from combustion gases exiting a gas turbine.

  1. Experimental study on the heavy-duty gas turbine combustor

    International Nuclear Information System (INIS)

    Antonovsky, V.; Ahn, Kook Young

    2000-01-01

    The results of stand and field testing of a combustion chamber for a heavy-duty 150 MW gas turbine are discussed. The model represented one of 14 identical segments of a tubular multican combustor constructed in the scale 1:1. The model experiments were executed at a pressure smaller than in the real gas turbine. The combustion efficiency, pressure loss factor, pattern factor, liner wall temperature, flame radiation, fluctuating pressure, and NOx emission were measured at partial and full load for both model and on-site testing. The comparison of these items of information, received on similar modes in the stand and field tests, has allowed the development of a method of calculation and the improvement of gas turbine combustors

  2. Systems and methods for preventing flashback in a combustor assembly

    Science.gov (United States)

    Johnson, Thomas Edward; Ziminsky, Willy Steve; Stevenson, Christian Xavier

    2016-04-05

    Embodiments of the present application include a combustor assembly. The combustor assembly may include a combustion chamber, a first plenum, a second plenum, and one or more elongate air/fuel premixing injection tubes. Each of the elongate air/fuel premixing injection tubes may include a first length at least partially disposed within the first plenum and configured to receive a first fluid from the first plenum. Moreover, each of the elongate air/fuel premixing injection tubes may include a second length disposed downstream of the first length and at least partially disposed within the second plenum. The second length may be formed of a porous wall configured to allow a second fluid from the second plenum to enter the second length and create a boundary layer about the porous wall.

  3. System and method for reducing combustion dynamics in a combustor

    Science.gov (United States)

    Uhm, Jong Ho; Johnson, Thomas Edward; Zuo, Baifang; York, William David

    2013-08-20

    A system for reducing combustion dynamics in a combustor includes an end cap having an upstream surface axially separated from a downstream surface, and tube bundles extend through the end cap. A diluent supply in fluid communication with the end cap provides diluent flow to the end cap. Diluent distributors circumferentially arranged inside at least one tube bundle extend downstream from the downstream surface and provide fluid communication for the diluent flow through the end cap. A method for reducing combustion dynamics in a combustor includes flowing fuel through tube bundles that extend axially through an end cap, flowing a diluent through diluent distributors into a combustion chamber, wherein the diluent distributors are circumferentially arranged inside at least one tube bundle and each diluent distributor extends downstream from the end cap, and forming a diluent barrier in the combustion chamber between at least one pair of adjacent tube bundles.

  4. Numerical optimization of laboratory combustor geometry for NO suppression

    International Nuclear Information System (INIS)

    Mazaheri, Karim; Shakeri, Alireza

    2016-01-01

    Highlights: • A five-step kinetics for NO and CO prediction is extracted from GRI-3.0 mechanism. • Accuracy and applicability of this kinetics for numerical optimization were shown. • Optimized geometry for a combustor was determined using the combined process. • NO emission from optimized geometry is found 10.3% lower than the basis geometry. - Abstract: In this article, geometry optimization of a jet stirred reactor (JSR) combustor has been carried out for minimum NO emissions in methane oxidation using a combined numerical algorithm based on computational fluid dynamics (CFD) and differential evolution (DE) optimization. The optimization algorithm is also used to find a fairly accurate reduced mechanism. The combustion kinetics is based on a five-step mechanism with 17 unknowns which is obtained using an optimization DE algorithm for a PSR–PFR reactor based on GRI-3.0 full mechanism. The optimization design variables are the unknowns of the five-step mechanism and the cost function is the concentration difference of pollutants obtained from the 5-step mechanism and the full mechanism. To validate the flow solver and the chemical kinetics, the computed NO at the outlet of the JSR is compared with experiments. To optimize the geometry of a combustor, the JSR combustor geometry is modeled using three parameters (i.e., design variables). An integrated approach using a flow solver and the DE optimization algorithm produces the lowest NO concentrations. Results show that the exhaust NO emission for the optimized geometry is 10.3% lower than the original geometry, while the inlet temperature of the working fluid and the concentration of O_2 are operating constraints. In addition, the concentration of CO pollutant is also much less than the original chamber.

  5. Cylindrical fabric-confined soil structures

    Science.gov (United States)

    Harrison, Richard A.

    A cylindrical fabric-soil structural concept for implementation on the moon and Mars which provides many advantages is proposed. The most efficient use of fabric is to fashion it into cylindrical tubes, creating cylindrical fabric-confined soil structures. The length, diameter, and curvature of the tubes will depend on the intended application. The cylindrical hoop forces provide radial confinement while end caps provide axial confinement. One of the ends is designed to allow passage of the soil into the fabric tube before sealing. Transportation requirements are reduced due to the low mass and volume of the fabric. Construction requirements are reduced due to the self-erection capability via the pneumatic exoskeleton. Maintenance requirements are reduced due to the passive nature of the concept. The structure's natural ductility is well suited for any seismic activity.

  6. Cylindrical-shaped nanotube field effect transistor

    KAUST Repository

    Hussain, Muhammad Mustafa

    2015-12-29

    A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.

  7. Cylindrical-shaped nanotube field effect transistor

    KAUST Repository

    Hussain, Muhammad Mustafa; Fahad, Hossain M.; Smith, Casey E.; Rojas, Jhonathan Prieto

    2015-01-01

    A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.

  8. Micromagnetic simulations of cylindrical magnetic nanowires

    KAUST Repository

    Ivanov, Yurii P.; Chubykalo-Fesenko, O.

    2015-01-01

    This chapter reviews micromagnetic simulations of cylindrical magnetic nanowires and their ordered arrays. It starts with a description of the theoretical background of micromagnetism. The chapter discusses main magnetization reversal modes, domain

  9. Plasma waves in an inhomogeneous cylindrical plasma

    International Nuclear Information System (INIS)

    Pesic, S.S.

    1976-01-01

    The complete dispersion equation governing small amplitude plasma waves propagating in an inhomogeneous cylindrical plasma confined by a helical magnetic field is solved numerically. The efficiency of the wave energy thermalization in the lower hybrid frequency range is studied

  10. Gravitational Instability of Cylindrical Viscoelastic Medium ...

    Indian Academy of Sciences (India)

    similar to that of viscoelastic fluid where both properties work together. They also ... cylindrical gravitational waves provides a strong motivation in this regard. .... which represents the solenoidal character of the magnetic field and the total stress.

  11. Nonintrusive transceiver and method for characterizing temperature and velocity fields in a gas turbine combustor

    Science.gov (United States)

    DeSilva, Upul P.; Claussen, Heiko

    2017-09-05

    An acoustic transceiver is implemented for measuring acoustic properties of a gas in a turbine engine combustor. The transceiver housing defines a measurement chamber and has an opening adapted for attachment to a turbine engine combustor wall. The opening permits propagation of acoustic signals between the gas in the turbine engine combustor and gas in the measurement chamber. An acoustic sensor mounted to the housing receives acoustic signals propagating in the measurement chamber, and an acoustic transmitter mounted to the housing creates acoustic signals within the measurement chamber. An acoustic measurement system includes at least two such transceivers attached to a turbine engine combustor wall and connected to a controller.

  12. Preliminary investigation of the performance of a single tubular combustor at pressure up to 12 atmospheres

    Science.gov (United States)

    Wear, Jerrold D; Butze, Helmut F

    1954-01-01

    The effects of combustor operation at conditions representative of those encountered in high pressure-ratio turbojet engines or at high flight speeds on carbon deposition, exhaust smoke, and combustion efficiency were studied in a single tubular combustor. Carbon deposition and smoke formation tests were conducted over a range of combustor-inlet pressures from 33 to 173 pounds per square inch absolute and combustor reference velocities from 78 to 143 feet per second. Combustion efficiency tests were conducted over a range of pressures from 58 to 117 pounds per square inch absolute and velocities from 89 to 172 feet per second.

  13. Radon progeny distribution in cylindrical diffusion chambers

    International Nuclear Information System (INIS)

    Pressyanov, Dobromir S.

    2008-01-01

    An algorithm to model the diffusion of radioactive decay chain atoms is presented. Exact mathematical solutions in cylindrical geometry are given. They are used to obtain expressions for the concentrations of 222 Rn progeny atoms in the volume and deposited on the wall surface in cylindrical diffusion chambers. The dependence of volume fractions of 222 Rn progeny and chamber sensitivity on the coefficient of diffusion of 222 Rn progeny atoms in air is modeled.

  14. Cylindrical geometry for proportional and drift chambers

    International Nuclear Information System (INIS)

    Sadoulet, B.

    1975-06-01

    For experiments performed around storage rings such as e + e - rings or the ISR pp rings, cylindrical wire chambers are very attractive. They surround the beam pipe completely without any dead region in the azimuth, and fit well with the geometry of events where particles are more or less spherically produced. Unfortunately, cylindrical proportional or drift chambers are difficult to make. Problems are discussed and two approaches to fabricating the cathodes are discussed. (WHK)

  15. Cylindrical dust acoustic waves with transverse perturbation

    International Nuclear Information System (INIS)

    Xue Jukui

    2003-01-01

    The nonlinear dust acoustic waves in dusty plasmas with the combined effects of bounded cylindrical geometry and the transverse perturbation are studied. Using the perturbation method, a cylindrical Kadomtsev-Petviashvili (CKP) equation that describes the dust acoustic waves is deduced for the first time. A particular solution of this CKP equation is also obtained. It is shown that the dust acoustic solitary waves can exist in the CKP equation

  16. Emissions from laboratory combustor tests of manufactured wood products

    Energy Technology Data Exchange (ETDEWEB)

    Wilkening, R.; Evans, M.; Ragland, K. [Univ. of Wisconsin, Madison, WI (United States); Baker, A. [USDA Forest Products Lab., Madison, WI (United States)

    1993-12-31

    Manufactured wood products contain wood, wood fiber, and materials added during manufacture of the product. Manufacturing residues and the used products are burned in a furnace or boiler instead of landfilling. Emissions from combustion of these products contain additional compounds from the combustion of non-wood material which have not been adequately characterized to specify the best combustion conditions, emissions control equipment, and disposal procedures. Total hydrocarbons, formaldehyde, higher aldehydes and carbon monoxide emissions from aspen flakeboard and aspen cubes were measured in a 76 mm i.d. by 1.5 m long fixed bed combustor as a function of excess oxygen, and temperature. Emissions of hydrocarbons, aldehydes and CO from flakeboard and from clean aspen were very sensitive to average combustor temperature and excess oxygen. Hydrocarbon and aldehyde emissions below 10 ppM were achieved with 5% excess oxygen and 1,200{degrees}C average temperature for aspen flakeboard and 1,100{degrees}C for clean aspen at a 0.9 s residence time. When the average temperature decreased below these levels, the emissions increased rapidly. For example, at 950{degrees}C and 5% excess oxygen the formaldehyde emissions were over 1,000 ppM. These laboratory tests reinforce the need to carefully control the temperature and excess oxygen in full-scale wood combustors.

  17. Flame dynamics of a meso-scale heat recirculating combustor

    Energy Technology Data Exchange (ETDEWEB)

    Vijayan, V.; Gupta, A.K. [Department of Mechanical Engineering, University of Maryland, College Park, MD 20742 (United States)

    2010-12-15

    The dynamics of premixed propane-air flame in a meso-scale ceramic combustor has been examined here. The flame characteristics in the combustor were examined by measuring the acoustic emissions and preheat temperatures together with high-speed cinematography. For the small-scale combustor, the volume to surface area ratio is small and hence the walls have significant effect on the global flame structure, flame location and flame dynamics. In addition to the flame-wall thermal coupling there is a coupling between flame and acoustics in the case of confined flames. Flame-wall thermal interactions lead to low frequency flame fluctuations ({proportional_to}100 Hz) depending upon the thermal response of the wall. However, the flame-acoustic interactions can result in a wide range of flame fluctuations ranging from few hundred Hz to few kHz. Wall temperature distribution is one of the factors that control the amount of reactant preheating which in turn effects the location of flame stabilization. Acoustic emission signals and high-speed flame imaging confirmed that for the present case flame-acoustic interactions have more significant effect on flame dynamics. Based on the acoustic emissions, five different flame regimes have been identified; whistling/harmonic mode, rich instability mode, lean instability mode, silent mode and pulsating flame mode. (author)

  18. The Pulsed Cylindrical Magnetron for Deposition

    Science.gov (United States)

    Korenev, Sergey

    2012-10-01

    The magnetron sputtering deposition of films and coatings broadly uses in microelectronics, material science, environmental applications and etc. The rate of target evaporation and time for deposition of films and coatings depends on magnetic field. These parameters link with efficiency of gas molecules ionization by electrons. The cylindrical magnetrons use for deposition of films and coatings on inside of pipes for different protective films and coatings in oil, chemical, environmental applications. The classical forming of magnetic field by permanent magnets or coils for big and long cylindrical magnetrons is complicated. The new concept of pulsed cylindrical magnetron for high rate deposition of films and coating for big and long pipes is presented in this paper. The proposed cylindrical magnetron has azimuthally pulsed high magnetic field, which allows forming the high ionized plasma and receiving high rate of evaporation material of target (central electrode). The structure of proposed pulsed cylindrical magnetron sputtering system is given. The main requirements to deposition system are presented. The preliminary data for forming of plasma and deposition of Ta films and coatings on the metal pipers are discussed. The comparison of classical and proposed cylindrical magnetrons is given. The analysis of potential applications is considered.

  19. Large eddy simulation of soot evolution in an aircraft combustor

    Science.gov (United States)

    Mueller, Michael E.; Pitsch, Heinz

    2013-11-01

    An integrated kinetics-based Large Eddy Simulation (LES) approach for soot evolution in turbulent reacting flows is applied to the simulation of a Pratt & Whitney aircraft gas turbine combustor, and the results are analyzed to provide insights into the complex interactions of the hydrodynamics, mixing, chemistry, and soot. The integrated approach includes detailed models for soot, combustion, and the unresolved interactions between soot, chemistry, and turbulence. The soot model is based on the Hybrid Method of Moments and detailed descriptions of soot aggregates and the various physical and chemical processes governing their evolution. The detailed kinetics of jet fuel oxidation and soot precursor formation is described with the Radiation Flamelet/Progress Variable model, which has been modified to account for the removal of soot precursors from the gas-phase. The unclosed filtered quantities in the soot and combustion models, such as source terms, are closed with a novel presumed subfilter PDF approach that accounts for the high subfilter spatial intermittency of soot. For the combustor simulation, the integrated approach is combined with a Lagrangian parcel method for the liquid spray and state-of-the-art unstructured LES technology for complex geometries. Two overall fuel-to-air ratios are simulated to evaluate the ability of the model to make not only absolute predictions but also quantitative predictions of trends. The Pratt & Whitney combustor is a Rich-Quench-Lean combustor in which combustion first occurs in a fuel-rich primary zone characterized by a large recirculation zone. Dilution air is then added downstream of the recirculation zone, and combustion continues in a fuel-lean secondary zone. The simulations show that large quantities of soot are formed in the fuel-rich recirculation zone, and, furthermore, the overall fuel-to-air ratio dictates both the dominant soot growth process and the location of maximum soot volume fraction. At the higher fuel

  20. Micro Engineering

    DEFF Research Database (Denmark)

    Alting, Leo; Kimura, F.; Hansen, Hans Nørgaard

    2003-01-01

    The paper addresses the questions of how micro products are designed and how they are manufactured. Definitions of micro products and micro engineering are discussed and the presentation is aimed at describing typical issues, possibilities and tools regarding design of micro products. The implica......The paper addresses the questions of how micro products are designed and how they are manufactured. Definitions of micro products and micro engineering are discussed and the presentation is aimed at describing typical issues, possibilities and tools regarding design of micro products...

  1. 40 CFR 60.33b - Emission guidelines for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

    Science.gov (United States)

    2010-07-01

    ... combustor metals, acid gases, organics, and nitrogen oxides. 60.33b Section 60.33b Protection of Environment... Constructed on or Before September 20, 1994 § 60.33b Emission guidelines for municipal waste combustor metals, acid gases, organics, and nitrogen oxides. (a) The emission limits for municipal waste combustor metals...

  2. 40 CFR 62.14103 - Emission limits for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

    Science.gov (United States)

    2010-07-01

    ... combustor metals, acid gases, organics, and nitrogen oxides. 62.14103 Section 62.14103 Protection of... combustor metals, acid gases, organics, and nitrogen oxides. (a) The emission limits for municipal waste combustor metals are specified in paragraphs (a)(1) through (a)(3) of this section. (1) The owner or...

  3. The preliminary design of an annular combustor for a mini gas turbine

    CSIR Research Space (South Africa)

    Meyers, Bronwyn C

    2015-10-01

    Full Text Available This study involves the redesign of the combustor liner for a 200N mini gas turbine engine using first principles and the design methods of the NREC series as shown in Figure 1. The combustor design was performed using five different operating...

  4. Thermo-acoustic cross-talk between cans in a can-annular combustor

    NARCIS (Netherlands)

    Farisco, Federica; Panek, Lukasz; Kok, Jim B.W.

    2017-01-01

    Thermo-acoustic instabilities in gas turbine engines are studied to avoid engine failure. Compared to the engines with annular combustors, the can-annular combustor design should be less vulnerable to acoustic burner-to-burner interaction, since the burners are acoustically coupled only by the

  5. Three-dimensional particle image velocimetry in a generic can-type gas turbine combustor

    CSIR Research Space (South Africa)

    Meyers, BC

    2009-09-01

    Full Text Available The three-dimensional flow field inside a generic can-type, forward flow, experimental combustor was measured. A stereoscopic Particle Image Velocimetry (PIV) system was used to obtain the flow field of the combustor in the non-reacting condition...

  6. Sensitivity of the Numerical Prediction of Turbulent Combustion Dynamics in the LIMOUSINE Combustor

    NARCIS (Netherlands)

    Shahi, Mina; Kok, Jacobus B.W.; Pozarlik, Artur Krzysztof; Roman Casado, J.C.; Sponfeldner, T.

    2014-01-01

    The objective of this study is to investigate the sensitivity and accuracy of the reaction flow-field prediction for the LIMOUSINE combustor with regard to choices in computational mesh and turbulent combustion model. The LIMOUSINE combustor is a partially premixed, bluff body-stabilized natural gas

  7. Mixing and NOx Emission Calculations of Confined Reacting Jet Flows in Cylindrical and Annular Ducts

    Science.gov (United States)

    Oechsle, Victor L.; Connor, Christopher H.; Holdeman, James D. (Technical Monitor)

    2000-01-01

    Rapid mixing of cold lateral jets with hot cross-stream flows in confined configurations is of practical interest in gas turbine combustors as it strongly affects combustor exit temperature quality, and gaseous emissions in for example rich-lean combustion. It is therefore important to further improve our fundamental understanding of the important processes of dilution jet mixing especially when the injected jet mass flow rate exceeds that of the cross-stream. The results reported in this report describe some of the main flow characteristics which develop in the mixing process in a cylindrical duct. A three-dimensional computational fluid dynamics (CFD) code has been used to predict the mixing flow field characteristics and NOx emission in a quench section of a rich-burn/quick-mix/lean-burn (RQL) combustor. Sixty configurations have been analyzed in both circular and annular geometries in a fully reacting environment simulating the operating condition of an actual RQL gas turbine combustion liner. The evaluation matrix was constructed by varying the number of orifices per row and orifice shape. Other parameters such as J (momentum-flux ratio), MR (mass flowrate ratio), DR (density ratio), and mixer sector orifice ACd (effective orifice area) were maintained constant throughout the entire study. The results indicate that the mixing flow field can be correlated with the NOx production if they are referenced with the stoichiometric equivalence ratio value and not the equilibrium value. The mixing flowfields in both circular and annular mixers are different. The penetration of equal jets in both annular and circular geometries is vastly different which significantly affects the performance of the mixing section. In the computational results with the circular mixer, most of the NOx formation occurred behind the orifice starting at the orifice wake region. General trends have been observed in the NOx production as the number of orifices is changed and this appears to be

  8. The pollution reduction technology program for can-annular combustor engines - Description and results

    Science.gov (United States)

    Roberts, R.; Fiorentino, A. J.; Diehl, L.

    1976-01-01

    Pollutant reduction and performance characteristics were determined for three successively more advanced combustor concepts. Program Element I consisted of minor modifications to the current production JT8D combustor and fuel system to evaluate means of improved fuel preparation and changes to the basic airflow distribution. Element II addressed versions of the two-staged Vorbix (vortex burning and mixing) combustor and represented a moderate increase in hardware complexity and difficulty of development. The concept selected for Element III employed vaporized fuel as a means of achieving minimum emission levels and represented the greatest difficulty of development and adaptation to the JT8D engine. Test results indicate that the Element I single-stage combustors were capable of dramatic improvement in idle pollutants. The multistage combustors evaluated in Program Elements II and III simultaneously reduced CO, THC and NOx emissions, but were unable to satisfy the current 1979 EPA standards.

  9. Fuel properties effect on the performance of a small high temperature rise combustor

    Science.gov (United States)

    Acosta, Waldo A.; Beckel, Stephen A.

    1989-01-01

    The performance of an advanced small high temperature rise combustor was experimentally determined at NASA-Lewis. The combustor was designed to meet the requirements of advanced high temperature, high pressure ratio turboshaft engines. The combustor featured an advanced fuel injector and an advanced segmented liner design. The full size combustor was evaluated at power conditions ranging from idle to maximum power. The effect of broad fuel properties was studied by evaluating the combustor with three different fuels. The fuels used were JP-5, a blend of Diesel Fuel Marine/Home Heating Oil, and a blend of Suntec C/Home Heating Oil. The fuel properties effect on the performance of the combustion in terms of pattern factor, liner temperatures, and exhaust emissions are documented.

  10. Parametric Study of Pulse-Combustor-Driven Ejectors at High-Pressure

    Science.gov (United States)

    Yungster, Shaye; Paxson, Daniel E.; Perkins, Hugh D.

    2015-01-01

    Pulse-combustor configurations developed in recent studies have demonstrated performance levels at high-pressure operating conditions comparable to those observed at atmospheric conditions. However, problems related to the way fuel was being distributed within the pulse combustor were still limiting performance. In the first part of this study, new configurations are investigated computationally aimed at improving the fuel distribution and performance of the pulse-combustor. Subsequent sections investigate the performance of various pulse-combustor driven ejector configurations operating at highpressure conditions, focusing on the effects of fuel equivalence ratio and ejector throat area. The goal is to design pulse-combustor-ejector configurations that maximize pressure gain while achieving a thermal environment acceptable to a turbine, and at the same time maintain acceptable levels of NOx emissions and flow non-uniformities. The computations presented here have demonstrated pressure gains of up to 2.8%.

  11. Effect of Fuel Injection and Mixing Characteristics on Pulse-Combustor Performance at High-Pressure

    Science.gov (United States)

    Yungster, Shaye; Paxson, Daniel E.; Perkins, Hugh D.

    2014-01-01

    Recent calculations of pulse-combustors operating at high-pressure conditions produced pressure gains significantly lower than those observed experimentally and computationally at atmospheric conditions. The factors limiting the pressure-gain at high-pressure conditions are identified, and the effects of fuel injection and air mixing characteristics on performance are investigated. New pulse-combustor configurations were developed, and the results show that by suitable changes to the combustor geometry, fuel injection scheme and valve dynamics the performance of the pulse-combustor operating at high-pressure conditions can be increased to levels comparable to those observed at atmospheric conditions. In addition, the new configurations can significantly reduce the levels of NOx emissions. One particular configuration resulted in extremely low levels of NO, producing an emission index much less than one, although at a lower pressure-gain. Calculations at representative cruise conditions demonstrated that pulse-combustors can achieve a high level of performance at such conditions.

  12. Development and testing of pulsed and rotating detonation combustors

    Science.gov (United States)

    St. George, Andrew C.

    Detonation is a self-sustaining, supersonic, shock-driven, exothermic reaction. Detonation combustion can theoretically provide significant improvements in thermodynamic efficiency over constant pressure combustion when incorporated into existing cycles. To harness this potential performance benefit, countless studies have worked to develop detonation combustors and integrate these devices into existing systems. This dissertation consists of a series of investigations on two types of detonation combustors: the pulse detonation combustor (PDC) and the rotating detonation combustor (RDC). In the first two investigations, an array of air-breathing PDCs is integrated with an axial power turbine. The system is initially operated with steady and pulsed cold air flow to determine the effect of pulsed flow on turbine performance. Various averaging approaches are employed to calculate turbine efficiency, but only flow-weighted (e.g., mass or work averaging) definitions have physical significance. Pulsed flow turbine efficiency is comparable to steady flow efficiency at high corrected flow rates and low rotor speeds. At these conditions, the pulse duty cycle expands and the variation of the rotor incidence angle is constrained to a favorable range. The system is operated with pulsed detonating flow to determine the effect of frequency, fill fraction, and rotor speed on turbine performance. For some conditions, output power exceeds the maximum attainable value from steady constant pressure combustion due to a significant increase in available power from the detonation products. However, the turbine component efficiency estimated from classical thermodynamic analysis is four times lower than the steady design point efficiency. Analysis of blade angles shows a significant penalty due to the detonation, fill, and purge processes simultaneously imposed on the rotor. The latter six investigations focus on fundamental research of the RDC concept. A specially-tailored RDC data

  13. Combustion of cork waste in a circulating fluidized bed combustor

    Energy Technology Data Exchange (ETDEWEB)

    Gulyurtlu, I.; Boavida, D.; Miranda, M.; Cabrita, I. [Dept. de Tecnologias de Combustao, ITE-INETI, Lisboa (Portugal); Abelha, P. [Coaltec e Ambiente, Lisboa (Portugal)

    1999-07-01

    There is currently an ongoing joint project between Portugal and Spain, which is being funded by the FAIR programme. The principal objective of the FAIR project is to investigate the application of the fluidised bed combustion (FBC) technology to burn cork wastes with the aim of overcoming the difficulties currently experienced in the cork processing industries. The combustion studies at INETI were carried out using the 300 kW{sub th} circulating fluidised bed facility. The combustor is square in cross section with each side being 0.3 m long. The combustor height is 5 m. The temperatures in the bed, the riser and that of the flue gases leaving the reactor were continuously monitored. The combustion gases leaving the reactor passed through the recycling cyclone first to capture most of particulates elutriated out of the combustor. The solid particles were intermittently collected for analysis to determine the amount of carbon present, which helped the combustion efficiency to be calculated. Instantaneous measurements of O{sub 2}, CO, CO{sub 2}, NO{sub x}, N{sub 2}O and SO{sub 2} present levels in the flue gases were also carried out. The combustion tests were done with both the cork waste dust and granular virgin cork. The difference is that cork dust gets contaminated during the process due to the use of various additives. Most of the combustion took place in the riser where the temperature was at times up to 523 K above that of the bed. The unburned carbon level was low ranging from about 1.5 to 2.% suggesting that most of the particles burned to completion in the riser. (orig.)

  14. Active Combustion Control for Aircraft Gas-Turbine Engines-Experimental Results for an Advanced, Low-Emissions Combustor Prototype

    Science.gov (United States)

    DeLaat, John C.; Kopasakis, George; Saus, Joseph R.; Chang, Clarence T.; Wey, Changlie

    2012-01-01

    Lean combustion concepts for aircraft engine combustors are prone to combustion instabilities. Mitigation of instabilities is an enabling technology for these low-emissions combustors. NASA Glenn Research Center s prior activity has demonstrated active control to suppress a high-frequency combustion instability in a combustor rig designed to emulate an actual aircraft engine instability experience with a conventional, rich-front-end combustor. The current effort is developing further understanding of the problem specifically as applied to future lean-burning, very low-emissions combustors. A prototype advanced, low-emissions aircraft engine combustor with a combustion instability has been identified and previous work has characterized the dynamic behavior of that combustor prototype. The combustor exhibits thermoacoustic instabilities that are related to increasing fuel flow and that potentially prevent full-power operation. A simplified, non-linear oscillator model and a more physics-based sectored 1-D dynamic model have been developed to capture the combustor prototype s instability behavior. Utilizing these models, the NASA Adaptive Sliding Phasor Average Control (ASPAC) instability control method has been updated for the low-emissions combustor prototype. Active combustion instability suppression using the ASPAC control method has been demonstrated experimentally with this combustor prototype in a NASA combustion test cell operating at engine pressures, temperatures, and flows. A high-frequency fuel valve was utilized to perturb the combustor fuel flow. Successful instability suppression was shown using a dynamic pressure sensor in the combustor for controller feedback. Instability control was also shown with a pressure feedback sensor in the lower temperature region upstream of the combustor. It was also demonstrated that the controller can prevent the instability from occurring while combustor operation was transitioning from a stable, low-power condition to

  15. Forced vibrations of rotating circular cylindrical shells

    International Nuclear Information System (INIS)

    Igawa, Hirotaka; Maruyama, Yoshiyuki; Endo, Mitsuru

    1995-01-01

    Forced vibrations of rotating circular cylindrical shells are investigated. Basic equations, including the effect of initial stress due to rotation, are formulated by the finite-element method. The characteristic relations for finite elements are derived from the energy principle by considering the finite strain. The equations of motion can be separated into quasi-static and dynamic ones, i.e., the equations in the steady rotating state and those in the vibration state. Radial concentrated impulses are considered as the external dynamic force. The transient responses of circular cylindrical shells are numerically calculated under various boundary conditions and rotating speeds. (author)

  16. Tearing instability in cylindrical plasma configuration

    International Nuclear Information System (INIS)

    Zelenyj, L.M.

    1979-01-01

    The effect of the neutral-layer cylindrical geometry on the development of the tearing instability has been investigated in detail. The increments of the instability for all the regimes have been found. The influence of cylindrical effects becomes manifesting itself at small, as compared to the layer characteristic thickness, distances from the axis, and, finally, the electron regime of the instability development transforms into an ion one. The results obtained are of interest for studying the plasma stability in the devices of the ''Astron'' type and in magnetospheres of cosmic objects

  17. Micromagnetic simulations of cylindrical magnetic nanowires

    KAUST Repository

    Ivanov, Yurii P.

    2015-05-27

    This chapter reviews micromagnetic simulations of cylindrical magnetic nanowires and their ordered arrays. It starts with a description of the theoretical background of micromagnetism. The chapter discusses main magnetization reversal modes, domain wall types, and state diagrams in cylindrical nanowires of different types and sizes. The results of the hysteresis process in individual nanowires and nanowire arrays also are presented. Modeling results are compared with experimental ones. The chapter also discusses future trends in nanowire applications in relation to simulations, such as current-driven dynamics, spintronics, and spincaloritronics. The main micromagnetic programs are presented and discussed, together with the corresponding links.

  18. Cylindrical concave body of composite fibrous material

    International Nuclear Information System (INIS)

    1979-01-01

    The invention is concerned with a cylindrical concave body of compound fibrous material which is intended to be exposed to high rotation speeds around its own longitudinal axis. The concave body in question has at least one layer of fibrils that are interwoven and enclose an identical angle with the longitudinal axis of the concave body in both directions. The concave body in question also has at least a second layer of fibrils that run in the direction of the circumference and are fitted radially to the outside. The cylindrical concave body of the invention is particularly well suited for application as a rotor tube in a gas ultra-centrifuge

  19. Cylindrical pressure vessel constructed of several layers

    International Nuclear Information System (INIS)

    Yamauchi, Takeshi.

    1976-01-01

    For a cylindrical pressure vessel constructed of several layers whose jacket has at least one circumferential weld joining the individual layers, it is proposed to provide this at least at the first bending line turning point (counting from the weld between the jacket and vessel floor), which the sinusoidally shaped jacket has. The section of the jacket extending in between should be made as a full wall section. The proposal is based on calculations of the bending stiffness of cylindrical jackets, which could not yet be confirmed for jackets having several layers. (UWI) [de

  20. Magnetic guns with cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, David; Beleggia, Marco; Heller, Luděk

    2012-01-01

    The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...... of the magnetostatic interaction energy. For comparison, the forces involved are also calculated numerically using finite elements methods. Based on the conservation of the magnetostatic and kinetic energies, the exit and asymptotic velocities are determined. The derived formulas can be used to optimize the generated...... forces and motion of the inner cylindrical magnet....

  1. Device for improved air and fuel distribution to a combustor

    Science.gov (United States)

    Laster, Walter R.; Schilp, Reinhard

    2016-05-31

    A flow conditioning device (30, 50, 70, 100, 150) for a can annular gas turbine engine, including a plurality of flow elements (32, 34, 52, 54, 72, 74, 102) disposed in a compressed air flow path (42, 60, 80, 114, 122) leading to a combustor (12), configured such that relative adjustment of at least one flow directing element (32, 52, 72, 110) with respect to an adjacent flow directing element (34, 54, 74, 112, 120) during operation of the gas turbine engine is effective to adjust a level of choking of the compressed air flow path (42, 60, 80, 114, 122).

  2. Refractory experience in circulating fluidized bed combustors, Task 7

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, R.Q.

    1989-11-01

    This report describes the results of an investigation into the status of the design and selection of refractory materials for coal-fueled circulating fluidized-bed combustors. The survey concentrated on operating units in the United States manufactured by six different boiler vendors: Babcock and Wilcox, Combustion Engineering, Foster Wheeler, Keeler Dorr-Oliver, Pyropower, and Riley Stoker. Information was obtained from the boiler vendors, refractory suppliers and installers, and the owners/operators of over forty units. This work is in support of DOE's Clean Coal Technology program, which includes circulating fluidized-bed technology as one of the selected concepts being evaluated.

  3. Laser-Based Diagnostic Measurements of Low Emissions Combustor Concepts

    Science.gov (United States)

    Hicks, Yolanda R.

    2011-01-01

    This presentation provides a summary of primarily laser-based measurement techniques we use at NASA Glenn Research Center to characterize fuel injection, fuel/air mixing, and combustion. The report highlights using Planar Laser-Induced Fluorescence, Particle Image Velocimetry, and Phase Doppler Interferometry to obtain fuel injector patternation, fuel and air velocities, and fuel drop sizes and turbulence intensities during combustion. We also present a brief comparison between combustors burning standard JP-8 Jet fuel and an alternative fuels. For this comparison, we used flame chemiluminescence and high speed imaging.

  4. Design of a multipurpose laboratory scale analytical combustor

    International Nuclear Information System (INIS)

    Mohd Fairus Abdul Farid; Sivapalan Kathiravale; Muhd Noor Muhd Yunus; Mohamad Puad Abu; Norasalwa Zakaria; Khaironie Mohd Takip; Rohyiza Ba'an; Mohamad Azman Che Mat Isa

    2005-01-01

    The current method of digestion in order to determine the content of heavy metals and other elements in Municipal Solid Waste (MSW) is either too long or dangerous due to the usage of concentrated acids. As such, a Multi Purpose Portable Lab Scale Combustor was developed. It could also be used as a test rig under the various combustion conditions i.e. excess air combustion, gasification and pyrolysis. Another future of this rig, is to trap and analyse the combustion gasses produced from the different types of combustion processes. The rig can also be used to monitor weight loss against time during a combustion process. (Author)

  5. Biomimetic surface structuring using cylindrical vector femtosecond laser beams

    Science.gov (United States)

    Skoulas, Evangelos; Manousaki, Alexandra; Fotakis, Costas; Stratakis, Emmanuel

    2017-03-01

    We report on a new, single-step and scalable method to fabricate highly ordered, multi-directional and complex surface structures that mimic the unique morphological features of certain species found in nature. Biomimetic surface structuring was realized by exploiting the unique and versatile angular profile and the electric field symmetry of cylindrical vector (CV) femtosecond (fs) laser beams. It is shown that, highly controllable, periodic structures exhibiting sizes at nano-, micro- and dual- micro/nano scales can be directly written on Ni upon line and large area scanning with radial and azimuthal polarization beams. Depending on the irradiation conditions, new complex multi-directional nanostructures, inspired by the Shark’s skin morphology, as well as superhydrophobic dual-scale structures mimicking the Lotus’ leaf water repellent properties can be attained. It is concluded that the versatility and features variations of structures formed is by far superior to those obtained via laser processing with linearly polarized beams. More important, by exploiting the capabilities offered by fs CV fields, the present technique can be further extended to fabricate even more complex and unconventional structures. We believe that our approach provides a new concept in laser materials processing, which can be further exploited for expanding the breadth and novelty of applications.

  6. Thermal performance of a meso-scale liquid-fuel combustor

    International Nuclear Information System (INIS)

    Vijayan, V.; Gupta, A.K.

    2011-01-01

    Research highlights: → Demonstrated successful combustion of liquid fuel-air mixtures in a novel meso-scale combustor. → Flame quenching was eliminated using heat recirculation in a swiss roll type combustor that also extended the flammability limits. → Liquid fuel was rapidly vaporized with the use of hot narrow channel walls that eliminated the need of a fuel atomizer. → Maximum power density of the combustor was estimated to be about 8.5 GW/m3 and heat load in the range of 50-280W. → Overall efficiency of the combustor was estimated in the range of 12 to 20%. - Abstract: Combustion in small scale devices poses significant challenges due to the quenching of reactions from wall heat losses as well as the significantly reduced time available for mixing and combustion. In the case of liquid fuels there are additional challenges related to atomization, vaporization and mixing with the oxidant in the very short time-scale liquid-fuel combustor. The liquid fuel employed here is methanol with air as the oxidizer. The combustor was designed based on the heat recirculating concept wherein the incoming reactants are preheated by the combustion products through heat exchange occurring via combustor walls. The combustor was fabricated from Zirconium phosphate, a ceramic with very low thermal conductivity (0.8 W m -1 K -1 ). The combustor had rectangular shaped double spiral geometry with combustion chamber in the center of the spiral formed by inlet and exhaust channels. Methanol and air were introduced immediately upstream at inlet of the combustor. The preheated walls of the inlet channel also act as a pre-vaporizer for liquid fuel which vaporizes the liquid fuel and then mixes with air prior to the fuel-air mixture reaching the combustion chamber. Rapid pre-vaporization of the liquid fuel by the hot narrow channel walls eliminated the necessity for a fuel atomizer. Self-sustained combustion of methanol-air was achieved in a chamber volume as small as 32.6 mm 3

  7. A three-dimensional computational model of H2–air premixed combustion in non-circular micro-channels for a thermo-photovoltaic (TPV) application

    International Nuclear Information System (INIS)

    Akhtar, Saad; Kurnia, Jundika C.; Shamim, Tariq

    2015-01-01

    Highlights: • Flow and flame behavior in a micro-combustor are studied. • Predictive capabilities of turbulence and chemistry sub-models are evaluated. • Thermal & hydraulic performance is tested for different combustor geometries. • Excellent outer wall prediction by RSM turbulence and EDC chemistry sub-model. • Enhanced heat transfer for triangular and trapezoid combustor geometries. - Abstract: Wall temperature uniformity and enhancement in a micro combustor for thermo photovoltaic (TPV) applications have attracted considerable attention from researchers in recent years because of their direct impact on efficiency and feasibility of desired energy conversion. In this regard, numerous experimental and numerical studies in micro-combustion application have been conducted and reported. However, most previous studies have been focused on geometrical configurations limited to planar and circular channels. It is therefore of interest to investigate the impact of different channel geometries on wall temperature distribution and energy conversion efficiency. This study addresses flow and flame behavior in a micro-combustor. By utilizing the well-established computational fluid dynamics (CFD) approach, the effect of geometrical parameters on the flow behavior and wall temperature is examined and evaluated. In order to improve the productive capability of the computational model, several steady state Reynolds Average Numerical Simulation (RANS) turbulence models alongside with different reaction rate formulations are evaluated. The results indicate that Reynolds Stress Model (RSM) with Eddy Dissipation Concept (EDC) provide the best quantitative prediction. The developed model is employed to investigate the effect of inlet velocity on flame structure and outer wall temperature. Furthermore, the effect of reactor cross sections, including circular, square, rectangular, triangular and trapezoidal, on the wall temperature is also evaluated. The results show that

  8. An investigation on cylindrical imploding turbulent mixing

    International Nuclear Information System (INIS)

    Liao Haidong; Yang Libin; Zhang Xilin; Ouyang Kai; Li Jun

    2001-01-01

    The interfacial instability experiments in cylindrically convergent geometry are performed by imploding jelly liner with high pressure gases; and instability growth were observed with high-speed framing camera. The relevant 2D numerical simulation programs were developed and their results are in good agreement with those of experiments

  9. Wellposedness of a cylindrical shell model

    International Nuclear Information System (INIS)

    McMillan, C.

    1994-01-01

    We consider a well-known model of a thin cylindrical shell with dissipative feedback controls on the boundary in the form of forces, shears, and moments. We show that the resulting closed loop feedback problem generates a s.c. semigroup of contractions in the energy space

  10. Exact relativistic cylindrical solution of disordered radiation

    International Nuclear Information System (INIS)

    Fonseca Teixeira, A.F. da; Wolk, I.; Som, M.M.

    1976-05-01

    A source free disordered distribution of electromagnetic radiation is considered in Einstein' theory, and a time independent exact solution with cylindrical symmetry is obtained. The gravitation and pressure effects of the radiation alone are sufficient to give the distribution an equilibrium. A finite maximum concentration is found on the axis of symmetry, and decreases monotonically to zero outwards. Timelike and null geodesics are discussed

  11. Antibubbles and fine cylindrical sheets of air

    KAUST Repository

    Beilharz, D.

    2015-08-14

    Drops impacting at low velocities onto a pool surface can stretch out thin hemispherical sheets of air between the drop and the pool. These air sheets can remain intact until they reach submicron thicknesses, at which point they rupture to form a myriad of microbubbles. By impacting a higher-viscosity drop onto a lower-viscosity pool, we have explored new geometries of such air films. In this way we are able to maintain stable air layers which can wrap around the entire drop to form repeatable antibubbles, i.e. spherical air layers bounded by inner and outer liquid masses. Furthermore, for the most viscous drops they enter the pool trailing a viscous thread reaching all the way to the pinch-off nozzle. The air sheet can also wrap around this thread and remain stable over an extended period of time to form a cylindrical air sheet. We study the parameter regime where these structures appear and their subsequent breakup. The stability of these thin cylindrical air sheets is inconsistent with inviscid stability theory, suggesting stabilization by lubrication forces within the submicron air layer. We use interferometry to measure the air-layer thickness versus depth along the cylindrical air sheet and around the drop. The air film is thickest above the equator of the drop, but thinner below the drop and up along the air cylinder. Based on microbubble volumes, the thickness of the cylindrical air layer becomes less than 100 nm before it ruptures.

  12. Shear stresses around circular cylindrical openings

    NARCIS (Netherlands)

    Hoogenboom, P.C.J.; Van Weelden, C.; Blom, C.M.B.

    2010-01-01

    In this paper stress concentrations are studied around circular cylindrical openings or voids in a linear elastic continuum. The loading is such that a uniform shear stress occurs in the continuum, which is disturbed by the opening. The shear stress is in the direction of the centre axis of the

  13. On isotropic cylindrically symmetric stellar models

    International Nuclear Information System (INIS)

    Nolan, Brien C; Nolan, Louise V

    2004-01-01

    We attempt to match the most general cylindrically symmetric vacuum spacetime with a Robertson-Walker interior. The matching conditions show that the interior must be dust filled and that the boundary must be comoving. Further, we show that the vacuum region must be polarized. Imposing the condition that there are no trapped cylinders on an initial time slice, we can apply a result of Thorne's and show that trapped cylinders never evolve. This results in a simplified line element which we prove to be incompatible with the dust interior. This result demonstrates the impossibility of the existence of an isotropic cylindrically symmetric star (or even a star which has a cylindrically symmetric portion). We investigate the problem from a different perspective by looking at the expansion scalars of invariant null geodesic congruences and, applying to the cylindrical case, the result that the product of the signs of the expansion scalars must be continuous across the boundary. The result may also be understood in relation to recent results about the impossibility of the static axially symmetric analogue of the Einstein-Straus model

  14. A strong focussing cylindrical electrostatic quadrupole

    International Nuclear Information System (INIS)

    Sheng Yaochang

    1986-01-01

    The construction and performance of small cylindrical electrostatic quadrupole, which is installed in JM-400 pulse electrostatic accelerator, are described. This electrostatic quadrupole is not only used in neutron generator, but also suitable for ion injector as well as for low energy electron accelerator

  15. Cylindrical Induction Melter Modicon Control System

    International Nuclear Information System (INIS)

    Weeks, G.E.

    1998-04-01

    In the last several years an extensive R ampersand D program has been underway to develop a vitrification system to stabilize Americium (Am) and Curium (Cm) inventories at SRS. This report documents the Modicon control system designed for the 3 inch Cylindrical Induction Melter (CIM)

  16. A cylindrical furnace for absorption spectral studies

    Indian Academy of Sciences (India)

    A cylindrical furnace with three heating zones, capable of providing a temperature of 1100°C, has been fabricated to enable recording of absorption spectra of high temperature species. The temperature of the furnace can be controlled to ± 1°C of the set temperature. The salient feature of this furnace is that the material ...

  17. Antibubbles and fine cylindrical sheets of air

    KAUST Repository

    Beilharz, D.; Guyon, A.; Li, E.  Q.; Thoraval, M.-J.; Thoroddsen, Sigurdur T

    2015-01-01

    Drops impacting at low velocities onto a pool surface can stretch out thin hemispherical sheets of air between the drop and the pool. These air sheets can remain intact until they reach submicron thicknesses, at which point they rupture to form a myriad of microbubbles. By impacting a higher-viscosity drop onto a lower-viscosity pool, we have explored new geometries of such air films. In this way we are able to maintain stable air layers which can wrap around the entire drop to form repeatable antibubbles, i.e. spherical air layers bounded by inner and outer liquid masses. Furthermore, for the most viscous drops they enter the pool trailing a viscous thread reaching all the way to the pinch-off nozzle. The air sheet can also wrap around this thread and remain stable over an extended period of time to form a cylindrical air sheet. We study the parameter regime where these structures appear and their subsequent breakup. The stability of these thin cylindrical air sheets is inconsistent with inviscid stability theory, suggesting stabilization by lubrication forces within the submicron air layer. We use interferometry to measure the air-layer thickness versus depth along the cylindrical air sheet and around the drop. The air film is thickest above the equator of the drop, but thinner below the drop and up along the air cylinder. Based on microbubble volumes, the thickness of the cylindrical air layer becomes less than 100 nm before it ruptures.

  18. Design of thermal protection system for 8 foot HTST combustor

    Science.gov (United States)

    Moskowitz, S.

    1973-01-01

    The combustor in the 8-foot high temperature structures tunnel at the NASA-Langley Research Center has encountered cracking over a period of 50-250 tunnel tests within a limited range of the required operating envelope. A program was conducted which analyzed the failed combustor liner hardware and determined that the mechanism of failure was vibratory fatigue. A vibration damper system using wave springs located axially between the liner T-bar and the liner support was designed as an intermediate solution to extend the life of the current two-pass regenerative air-cooled liner. The effects of liner wall thickness, cooling air passage height, stiffener ring geometry, reflective coatings, and liner material selection were investigated for these designs. Preliminary layout design arrangements including the external water-cooling system requirements, weight estimates, installation requirements and preliminary estimates of manufacturing costs were prepared for the most promissing configurations. A state-of-the-art review of thermal barrier coatings and an evaluation of reflective coatings for the gasside surface of air-cooled liners are included.

  19. Coal-fired MHD combustor development project: Phase 3D

    Science.gov (United States)

    1985-05-01

    This fourth quarterly technical progress report of the Coal-Fired MHD Combustor Development Project (Phase 3D) presents the accomplishments during the period February 1 to April 30, 1985. The scope of work covered by this quarterly report encompasses development work on the 50 MW/sub t/ combustor related to test support at the CDIF, assembly and checkout of first and second stage hardware, second stage design verification testing, designs for a continuous slag rejector and low preheat inlet section, and planning for power train testing. Progress includes the following: assembly and checkout of the second first stage, two second stages, and PEM was completed and the hardware was shipped to CDIF and FETS; integration of first and second stage hardware on the FETS Cell No. 2 test stand was completed, cold flow functional tests were performed, and hot fire checkout testing was initiated; assembly of the continuous slag rejector test set-up was 70% completed; the low preheat air inlet section Preliminary Design Review was held (work on the detail design was initiated and is 85% complete); and the Users' Manual was updated to include material for the second stage and final revisions to the power train test plan were made.

  20. Experimental and Computational Study of Trapped Vortex Combustor Sector Rig with High-Speed Diffuser Flow

    Directory of Open Access Journals (Sweden)

    R. C. Hendricks

    2001-01-01

    Full Text Available The Trapped Vortex Combustor (TVC potentially offers numerous operational advantages over current production gas turbine engine combustors. These include lower weight, lower pollutant emissions, effective flame stabilization, high combustion efficiency, excellent high altitude relight capability, and operation in the lean burn or RQL modes of combustion. The present work describes the operational principles of the TVC, and extends diffuser velocities toward choked flow and provides system performance data. Performance data include EINOx results for various fuel-air ratios and combustor residence times, combustion efficiency as a function of combustor residence time, and combustor lean blow-out (LBO performance. Computational fluid dynamics (CFD simulations using liquid spray droplet evaporation and combustion modeling are performed and related to flow structures observed in photographs of the combustor. The CFD results are used to understand the aerodynamics and combustion features under different fueling conditions. Performance data acquired to date are favorable compared to conventional gas turbine combustors. Further testing over a wider range of fuel-air ratios, fuel flow splits, and pressure ratios is in progress to explore the TVC performance. In addition, alternate configurations for the upstream pressure feed, including bi-pass diffusion schemes, as well as variations on the fuel injection patterns, are currently in test and evaluation phases.

  1. Combustion Dynamics in Multi-Nozzle Combustors Operating on High-Hydrogen Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Santavicca, Dom; Lieuwen, Tim

    2013-09-30

    Actual gas turbine combustors for power generation applications employ multi-nozzle combustor configurations. Researchers at Penn State and Georgia Tech have extended previous work on the flame response in single-nozzle combustors to the more realistic case of multi-nozzle combustors. Research at Georgia Tech has shown that asymmetry of both the flow field and the acoustic forcing can have a significant effect on flame response and that such behavior is important in multi-flame configurations. As a result, the structure of the flame and its response to forcing is three-dimensional. Research at Penn State has led to the development of a three-dimensional chemiluminescence flame imaging technique that can be used to characterize the unforced (steady) and forced (unsteady) flame structure of multi-nozzle combustors. Important aspects of the flame response in multi-nozzle combustors which are being studied include flame-flame and flame-wall interactions. Research at Penn State using the recently developed three-dimensional flame imaging technique has shown that spatial variations in local flame confinement must be accounted for to accurately predict global flame response in a multi-nozzle can combustor.

  2. arXiv The new cylindrical GEM inner tracker of BESIII

    CERN Document Server

    Lavezzi, L.; Amoroso, A.; Ferroli, R. Baldini; Bertani, M.; Bettoni, D.; Bianchi, F.; Calcaterra, A.; Canale, N.; Capodiferro, M.; Carassiti, V.; Cerioni, S.; Chai, Jy; Chiozzi, S.; Cibinetto, G.; Cossio, F.; Cotta Ramusino, A.; De Mori, F.; Destefanis, M.; Dong, J.; Evangelisti, F.; Farinelli, R.; Fava, L.; Felici, G.; Fioravanti, E.; Garzia, I.; Gatta, M.; Greco, M.; Leng, Cy; Li, H.; Maggiora, M.; Malaguti, R.; Marcello, S.; Melchiorri, M.; Mezzadri, G.; Mignone, M.; Morello, G.; Pacetti, S.; Patteri, P.; Pellegrino, J.; Pelosi, A.; Rivetti, A.; Rolo,; Savrié, M.; Scodeggio, M.; Soldani, E.; Sosio, S.; Spataro, S.; Tskhadadze, E.; Verma, S.; Wheadon, R.; Yan, L.

    2018-05-03

    The Cylindrical GEM-Inner Tracker (CGEM-IT) is the upgrade of the internal tracking system of the BESIII experiment. It consists of three layers of cylindrically-shaped triple GEMs, with important innovations with respect to the existing GEM detectors, in order to achieve the best performance with the lowest material budget. It will be the first cylindrical GEM running with analog readout inside a 1T magnetic field. The simultaneous measurement of both the deposited charge and the signal time will permit to use a combination of two algorithms to evaluate the spatial position of the charged tracks inside the CGEM-IT: the charge centroid and the micro time projection chamber modes. They are complementary and can cope with the asymmetry of the electron avalanche when running in magnetic field and with non-orthogonal incident tracks. To evaluate the behaviour under different working settings, both planar chambers and the first cylindrical prototype have been tested during various test beams at CERN with 150 GeV/c...

  3. NONEQUILIBRIUM SULFUR CAPTURE & RETENTION IN AN AIR COOLED SLAGGING COAL COMBUSTOR

    Energy Technology Data Exchange (ETDEWEB)

    Bert Zauderer

    2003-04-21

    Calcium oxide injected in a slagging combustor reacts with the sulfur from coal combustion to form sulfur-bearing particles. The reacted particles impact and melt in the liquid slag layer on the combustor wall by the centrifugal force of the swirling combustion gases. Due to the low solubility of sulfur in slag, it must be rapidly drained from the combustor to limit sulfur gas re-evolution. Prior analyses and laboratory scale data indicated that for Coal Tech's 20 MMBtu/hour, air-cooled, slagging coal combustor slag mass flow rates in excess of 400 lb/hr should limit sulfur re-evolution. The objective of this 42-month project was to validate this sulfur-in-slag model in a group of combustor tests. A total of 36 days of testing on the combustor were completed during the period of performance of this project. This was more that double the 16 test days that were required in the original work statement. The extra tests were made possible by cost saving innovations that were made in the operation of the combustor test facility and in additional investment of Coal Tech resources in the test effort. The original project plan called for two groups of tests. The first group of tests involved the injection of calcium sulfate particles in the form of gypsum or plaster of Paris with the coal into the 20 MMBtu/hour-combustor. The second group of tests consisted of the entire two-step process, in which lime or limestone is co-injected with coal and reacts with the sulfur gas released during combustion to form calcium sulfate particles that impact and dissolve in the slag layer. Since this sulfur capture process has been validated in numerous prior tests in this combustor, the primary effort in the present project was on achieving the high slag flow rates needed to retain the sulfur in the slag.

  4. Development of an analytical model to assess fuel property effects on combustor performance

    Science.gov (United States)

    Sutton, R. D.; Troth, D. L.; Miles, G. A.; Riddlebaugh, S. M.

    1987-01-01

    A generalized first-order computer model has been developed in order to analytically evaluate the potential effect of alternative fuels' effects on gas turbine combustors. The model assesses the size, configuration, combustion reliability, and durability of the combustors required to meet performance and emission standards while operating on a broad range of fuels. Predictions predicated on combustor flow-field determinations by the model indicate that fuel chemistry, as defined by hydrogen content, exerts a significant influence on flame retardation, liner wall temperature, and smoke emission.

  5. Flame stabilization and mixing characteristics in a Stagnation Point Reverse Flow combustor

    Science.gov (United States)

    Bobba, Mohan K.

    A novel combustor design, referred to as the Stagnation Point Reverse-Flow (SPRF) combustor, was recently developed that is able to operate stably at very lean fuel-air mixtures and with low NOx emissions even when the fuel and air are not premixed before entering the combustor. The primary objective of this work is to elucidate the underlying physics behind the excellent stability and emissions performance of the SPRF combustor. The approach is to experimentally characterize velocities, species mixing, heat release and flame structure in an atmospheric pressure SPRF combustor with the help of various optical diagnostic techniques: OH PLIF, chemiluminescence imaging, PIV and Spontaneous Raman Scattering. Results indicate that the combustor is primarily stabilized in a region downstream of the injector that is characterized by low average velocities and high turbulence levels; this is also the region where most of the heat release occurs. High turbulence levels in the shear layer lead to increased product entrainment levels, elevating the reaction rates and thereby enhancing the combustor stability. The effect of product entrainment on chemical timescales and the flame structure is illustrated with simple reactor models. Although reactants are found to burn in a highly preheated (1300 K) and turbulent environment due to mixing with hot product gases, the residence times are sufficiently long compared to the ignition timescales such that the reactants do not autoignite. Turbulent flame structure analysis indicates that the flame is primarily in the thin reaction zones regime throughout the combustor, and it tends to become more flamelet like with increasing distance from the injector. Fuel-air mixing measurements in case of non-premixed operation indicate that the fuel is shielded from hot products until it is fully mixed with air, providing nearly premixed performance without the safety issues associated with premixing. The reduction in NOx emissions in the SPRF

  6. Design and preliminary results of a fuel flexible industrial gas turbine combustor

    Science.gov (United States)

    Novick, A. S.; Troth, D. L.; Yacobucci, H. G.

    1981-01-01

    The design characteristics are presented of a fuel tolerant variable geometry staged air combustor using regenerative/convective cooling. The rich/quench/lean variable geometry combustor is designed to achieve low NO(x) emission from fuels containing fuel bound nitrogen. The physical size of the combustor was calculated for a can-annular combustion system with associated operating conditions for the Allison 570-K engine. Preliminary test results indicate that the concept has the potential to meet emission requirements at maximum continuous power operation. However, airflow sealing and improved fuel/air mixing are necessary to meet Department of Energy program goals.

  7. Micro Vision

    OpenAIRE

    Ohba, Kohtaro; Ohara, Kenichi

    2007-01-01

    In the field of the micro vision, there are few researches compared with macro environment. However, applying to the study result for macro computer vision technique, you can measure and observe the micro environment. Moreover, based on the effects of micro environment, it is possible to discovery the new theories and new techniques.

  8. Robotic Hand with Flexible Fingers for Grasping Cylindrical Objects

    OpenAIRE

    柴田, 瑞穂

    2015-01-01

    In this manuscript, a robotic hand for grasping a cylindrical object is proposed. This robotic hand has flexible fingers that can hold a cylindrical object during moving. We introduce a grasping strategy for a cylindrical object in terms of state transition graph. In this strategy the robotic hand picks up the cylindrical object utilizing a suction device before the hand grasp the object. We also design the flexible fingers; then, we investigate the validity of this robotic hand via several e...

  9. Cylindrical continuous martingales and stochastic integration in infinite dimensions

    NARCIS (Netherlands)

    Veraar, M.C.; Yaroslavtsev, I.S.

    2016-01-01

    In this paper we define a new type of quadratic variation for cylindrical continuous local martingales on an infinite dimensional spaces. It is shown that a large class of cylindrical continuous local martingales has such a quadratic variation. For this new class of cylindrical continuous local

  10. Investigation on Surface Roughness in Cylindrical Grinding

    Science.gov (United States)

    Rudrapati, Ramesh; Bandyopadhyay, Asish; Pal, Pradip Kumar

    2011-01-01

    Cylindrical grinding is a complex machining process. And surface roughness is often a key factor in any machining process while considering the machine tool or machining performance. Further, surface roughness is one of the measures of the technological quality of the product and is a factor that greatly influences cost and quality. The present work is related to some aspects of surface finish in the context of traverse-cut cylindrical grinding. The parameters considered have been: infeed, longitudinal feed and work speed. Taguchi quality design is used to design the experiments and to identify the significantly import parameter(s) affecting the surface roughness. By utilization of Response Surface Methodology (RSM), second order differential equation has been developed and attempts have also been made for optimization of the process in the context of surface roughness by using C- programming.

  11. Method of dismantling cylindrical structure by cutting

    International Nuclear Information System (INIS)

    Harada, Minoru; Mitsuo, Kohei; Yokota, Isoya; Nakamura, Kenjiro.

    1989-01-01

    This invention concerns a method of cutting and removing cylindrical structures, for example, iron-reinforced concrete materials such as thermal shielding walls in BWR type power plants into block-like form. That is, in a method of cutting and removing the cylindrical structure from the side of the outer wall, the structural material is cut from above to below successively in the axial direction and the circumferential direction by means abrasive jet by remote operation and cut into blocks each of a predetermined size. The cut out blocks are successively taken out. Cutting of the material from above to below by remote operation and taking out of small blocks causes no hazards to human body. Upon practicing the present invention, it is preferred to use a processing device for slurry and exhaust gases for preventing scattering of activated dismantled pieces or powdery dusts. (K.M.)

  12. Cylindrically converging blast waves in air

    Science.gov (United States)

    Matsuo, H.; Nakamura, Y.

    1981-07-01

    Cylindrically converging shock waves are produced by utilizing the detonation of cylindrical explosive shells. The production and the propagation of shock waves are observed by framing and streak camera photographs, and the trajectory of shock propagations is determined by using an electrical ionization probing system. The effect of the quantity of explosives on the stability, or the axial symmetry, of shock fronts and on the strength of shocks produced is investigated. It has been shown that, for practical purposes, the approximation of shock trajectories by Guderley's formulas would be sufficiently acceptable in an unexpectedly wide region near the implosion center, and that the axial symmetry of the shock front is improved by increasing the quantity of explosives, and thus, strong shocks are produced by merely increasing the quantity of explosives. The reflected diverging shock seems to be very stable. Piezoelectric elements have also been used to detect reflected diverging waves.

  13. Escape and transmission probabilities in cylindrical geometry

    International Nuclear Information System (INIS)

    Bjerke, M.A.

    1980-01-01

    An improved technique for the generation of escape and transmission probabilities in cylindrical geometry was applied to the existing resonance cross section processing code ROLAIDS. The algorithm of Hwang and Toppel, [ANL-FRA-TM-118] (with modifications) was employed. The probabilities generated were found to be as accurate as those given by the method previously applied in ROLAIDS, while requiring much less computer core storage and CPU time

  14. The large cylindrical drift chamber of TASSO

    International Nuclear Information System (INIS)

    Boerner, H.; Fischer, H.M.; Hartmann, H.; Loehr, B.; Wollstadt, M.; Fohrmann, R.; Schmueser, P.; Cassel, D.G.; Koetz, U.; Kowalski, H.

    1980-03-01

    We have built and operated a large cylindrical drift chamber for the TASSO experiment at the DESY storage ring, PETRA. The chamber has a length of 3.5 m, a diameter of 2.5 m, and a total of 2340 drift cells. The cells are arranged in 15 concentric layers such that tracks can be reconstructed in three dimensions. A spatial resolution of 220 μm has been achieved for tracks of normal incidence on the drift cells. (orig.)

  15. Magnetic guns with cylindrical permanent magnets

    Czech Academy of Sciences Publication Activity Database

    Vokoun, David; Beleggia, M.; Heller, Luděk

    2012-01-01

    Roč. 324, č. 9 (2012), s. 1715-1719 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GAP107/11/0391; GA AV ČR IAA100100920 Institutional research plan: CEZ:AV0Z10100520 Keywords : permanent magnet * cylindrical magnet * Earnshaw's theorem * magnetic gun * magnetostatic interaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.826, year: 2012 http://www.sciencedirect.com/science/article/pii/S0304885311008997

  16. Transmission of infrared radiation through cylindrical waveguides

    International Nuclear Information System (INIS)

    Nucara, A.; Dore, P.; Calvani, P.; Cannavo', D.; Marcelli, A.

    1998-01-01

    Measurement of the transmittance of infrared radiation (v -1 ) through cylindrical waveguides are presented and discussed. The experimental results are compared with numerical simulations, obtained through conventional ray tracing programs. Finally, it' estimated the transmittance of a waveguide in the case of an infrared synchrotron radiation source. Are applied the results to the case of the DAΦNE collider, where a synchrotron radiation beamline for the far infrared is under construction

  17. Cylindric-like algebras and algebraic logic

    CERN Document Server

    Ferenczi, Miklós; Németi, István

    2013-01-01

    Algebraic logic is a subject in the interface between logic, algebra and geometry, it has strong connections with category theory and combinatorics. Tarski’s quest for finding structure in logic leads to cylindric-like algebras as studied in this book, they are among the main players in Tarskian algebraic logic. Cylindric algebra theory can be viewed in many ways:  as an algebraic form of definability theory, as a study of higher-dimensional relations, as an enrichment of Boolean Algebra theory, or, as logic in geometric form (“cylindric” in the name refers to geometric aspects). Cylindric-like algebras have a wide range of applications, in, e.g., natural language theory, data-base theory, stochastics, and even in relativity theory. The present volume, consisting of 18 survey papers, intends to give an overview of the main achievements and new research directions in the past 30 years, since the publication of the Henkin-Monk-Tarski monographs. It is dedicated to the memory of Leon Henkin.

  18. The analytic nodal method in cylindrical geometry

    International Nuclear Information System (INIS)

    Prinsloo, Rian H.; Tomasevic, Djordje I.

    2008-01-01

    Nodal diffusion methods have been used extensively in nuclear reactor calculations, specifically for their performance advantage, but also for their superior accuracy. More specifically, the Analytic Nodal Method (ANM), utilising the transverse integration principle, has been applied to numerous reactor problems with much success. In this work, a nodal diffusion method is developed for cylindrical geometry. Application of this method to three-dimensional (3D) cylindrical geometry has never been satisfactorily addressed and we propose a solution which entails the use of conformal mapping. A set of 1D-equations with an adjusted, geometrically dependent, inhomogeneous source, is obtained. This work describes the development of the method and associated test code, as well as its application to realistic reactor problems. Numerical results are given for the PBMR-400 MW benchmark problem, as well as for a 'cylindrisized' version of the well-known 3D LWR IAEA benchmark. Results highlight the improved accuracy and performance over finite-difference core solutions and investigate the applicability of nodal methods to 3D PBMR type problems. Results indicate that cylindrical nodal methods definitely have a place within PBMR applications, yielding performance advantage factors of 10 and 20 for 2D and 3D calculations, respectively, and advantage factors of the order of 1000 in the case of the LWR problem

  19. Flame Interactions and Thermoacoustics in Multiple-Nozzle Combustors

    Science.gov (United States)

    Dolan, Brian

    The first major chapter of original research (Chapter 3) examines thermoacoustic oscillations in a low-emission staged multiple-nozzle lean direct injection (MLDI) combustor. This experimental program investigated a relatively practical combustor sector that was designed and built as part of a commercial development program. The research questions are both practical, such as under what conditions the combustor can be safely operated, and fundamental, including what is most significant to driving the combustion oscillations in this system. A comprehensive survey of operating conditions finds that the low-emission (and low-stability) intermediate and outer stages are necessary to drive significant thermoacoustics. Phase-averaged and time-resolved OH* imaging show that dramatic periodic strengthening and weakening of the reaction zone downstream of the low-emission combustion stages. An acoustic modal analysis shows the pressure wave shapes and identifies the dominant thermoacoustic behavior as the first longitudinal mode for this combustor geometry. Finally, a discussion of the likely significant coupling mechanisms is given. Periodic reaction zone behavior in the low-emission fuel stages is the primary contributor to unsteady heat release. Differences between the fuel stages in the air swirler design, the fuel number of the injectors, the lean blowout point, and the nominal operating conditions all likely contribute to the limit cycle behavior of the low-emission stages. Chapter 4 investigates the effects of interaction between two adjacent swirl-stabilized nozzles using experimental and numerical tools. These studies are more fundamental; while the nozzle hardware is the same as the lean direct injection nozzles used in the MLDI combustion concept, the findings are generally applicable to other swirl-stabilized combustion systems as well. Much of the work utilizes a new experiment where the distance between nozzles was varied to change the level of interaction

  20. MERCURY CONTROL IN MUNICIPAL WASTE COMBUSTORS AND COAL-FIRED UTILITIES

    Science.gov (United States)

    Control of mercury (Hg) emissions from municipal waste combustors (MWCs) and coal-fired utilities has attracted attention due to current and potential regulations. Among several techniques evaluated for Hg control, dry sorbent injection (primarily injection of activated carbon) h...

  1. 40 CFR 60.53a - Standard for municipal waste combustor organics.

    Science.gov (United States)

    2010-07-01

    ... Municipal Waste Combustors for Which Construction is Commenced After December 20, 1989 and on or Before... exceed 30 nanograms per dry standard cubic meter (12 grains per billion dry standard cubic feet), corrected to 7 percent oxygen (dry basis). ...

  2. System and method for reducing combustion dynamics and NO.sub.x in a combustor

    Science.gov (United States)

    Uhm, Jong H.; Johnson, Thomas Edward

    2015-11-20

    A system for reducing combustion dynamics and NO.sub.x in a combustor includes a tube bundle that extends radially across at least a portion of the combustor, wherein the tube bundle comprises an upstream surface axially separated from a downstream surface. A shroud circumferentially surrounds the upstream and downstream surfaces. A plurality of tubes extends through the tube bundle from the upstream surface through the downstream surface, wherein the downstream surface is stepped to produce tubes having different lengths through the tube bundle. A method for reducing combustion dynamics and NO.sub.x in a combustor includes flowing a working fluid through a plurality of tubes radially arranged between an upstream surface and a downstream surface of an end cap that extends radially across at least a portion of the combustor, wherein the downstream surface is stepped.

  3. Thermal Performance of a Scramjet Combustor Operating at Mach 5.6 Flight Conditions

    National Research Council Canada - National Science Library

    Stouffer, Scott

    1997-01-01

    .... The objective of the thermal loads testing was to map the thermal and mechanical loads, including heat transfer, dynamic and static pressures, and skin friction in a scramjet combustor during direct...

  4. Effect of Surface Impulsive Thermal Loads on Fatigue Behavior of Constant Volume Propulsion Engine Combustor Materials

    National Research Council Canada - National Science Library

    Zhu, Dongming

    2004-01-01

    .... In this study, a simulated engine test rig has been established to evaluate thermal fatigue behavior of a candidate engine combustor material, Haynes 188, under superimposed CO2 laser surface impulsive thermal loads (30 to 100 Hz...

  5. Effects of Burning Alternative Fuel in a 5-Cup Combustor Sector

    Science.gov (United States)

    Tacina, K. M.; Chang, C. T.; Lee, C.-M.; He, Z.; Herbon, J.

    2015-01-01

    A goal of NASA's Environmentally Responsible Aviation (ERA) program is to develop a combustor that will reduce the NOx emissions and that can burn both standard and alternative fuels. To meet this goal, NASA partnered with General Electric Aviation to develop a 5-cup combustor sector; this sector was tested in NASA Glenn's Advanced Subsonic Combustion Rig (ASCR). To verify that the combustor sector was fuel-flexible, it was tested with a 50-50 blend of JP-8 and a biofuel made from the camelina sativa plant. Results from this test were compared to results from tests where the fuel was neat JP-8. Testing was done at three combustor inlet conditions: cruise, 30% power, and 7% power. When compared to burning JP-8, burning the 50-50 blend did not significantly affect emissions of NOx, CO, or total hydrocarbons. Furthermore, it did not significantly affect the magnitude and frequency of the dynamic pressure fluctuations.

  6. Large Municipal Waste Combustors (LMWC): New Source Performance Standards (NSPS) and Emissions Guidelines

    Science.gov (United States)

    Learn about the NSPS, emission guidelines and compliance times for large municipal waste combustors (MWC) by reading the rule summary, rule history and the federal register citations and supporting documents

  7. An Engineering Model for Prediction of Waste Incineration in a Dump Combustor

    National Research Council Canada - National Science Library

    Arunajatesan, S

    1997-01-01

    An engineering model that can be used to obtain predictions of axial distributions of temperature and species concentrations in complex flows has been formulated and applied to waste incineration in a dump combustor...

  8. Flow structures in a lean-premixed swirl-stabilized combustor with microjet air injection

    KAUST Repository

    LaBry, Zachary A.; Shanbhogue, Santosh J.; Speth, Raymond L.; Ghoniem, Ahmed F.

    2011-01-01

    The major challenge facing the development of low-emission combustors is combustion instability. By lowering flame temperatures, lean-premixed combustion has the potential to nearly eliminate emissions of thermally generated nitric oxides

  9. Laser-based investigations in gas turbine model combustors

    Science.gov (United States)

    Meier, W.; Boxx, I.; Stöhr, M.; Carter, C. D.

    2010-10-01

    Dynamic processes in gas turbine (GT) combustors play a key role in flame stabilization and extinction, combustion instabilities and pollutant formation, and present a challenge for experimental as well as numerical investigations. These phenomena were investigated in two gas turbine model combustors for premixed and partially premixed CH4/air swirl flames at atmospheric pressure. Optical access through large quartz windows enabled the application of laser Raman scattering, planar laser-induced fluorescence (PLIF) of OH, particle image velocimetry (PIV) at repetition rates up to 10 kHz and the simultaneous application of OH PLIF and PIV at a repetition rate of 5 kHz. Effects of unmixedness and reaction progress in lean premixed GT flames were revealed and quantified by Raman scattering. In a thermo-acoustically unstable flame, the cyclic variation in mixture fraction and its role for the feedback mechanism of the instability are addressed. In a partially premixed oscillating swirl flame, the cyclic variations of the heat release and the flow field were characterized by chemiluminescence imaging and PIV, respectively. Using phase-correlated Raman scattering measurements, significant phase-dependent variations of the mixture fraction and fuel distributions were revealed. The flame structures and the shape of the reaction zones were visualized by planar imaging of OH distribution. The simultaneous OH PLIF/PIV high-speed measurements revealed the time history of the flow field-flame interaction and demonstrated the development of a local flame extinction event. Further, the influence of a precessing vortex core on the flame topology and its dynamics is discussed.

  10. Investigation and demonstration of a rich combustor cold-start device for alcohol-fueled engines

    Energy Technology Data Exchange (ETDEWEB)

    Hodgson, J W; Irick, D K [Univ. of Tennessee, Knoxville, TN (United States)

    1998-04-01

    The authors have completed a study in which they investigated the use of a rich combustor to aid in cold starting spark-ignition engines fueled with either neat ethanol or neat methanol. The rich combustor burns the alcohol fuel outside the engine under fuel-rich conditions to produce a combustible product stream that is fed to the engine for cold starting. The rich combustor approach significantly extends the cold starting capability of alcohol-fueled engines. A design tool was developed that simulates the operation of the combustor and couples it to an engine/vehicle model. This tool allows the user to determine the fuel requirements of the rich combustor as the vehicle executes a given driving mission. The design tool was used to design and fabricate a rich combustor for use on a 2.8 L automotive engine. The system was tested using a unique cold room that allows the engine to be coupled to an electric dynamometer. The engine was fitted with an aftermarket engine control system that permitted the fuel flow to the rich combustor to be programmed as a function of engine speed and intake manifold pressure. Testing indicated that reliable cold starts were achieved on both neat methanol and neat ethanol at temperatures as low as {minus}20 C. Although starts were experienced at temperatures as low as {minus}30 C, these were erratic. They believe that an important factor at the very low temperatures is the balance between the high mechanical friction of the engine and the low energy density of the combustible mixture fed to the engine from the rich combustor.

  11. DEVELOPMENT AND DEMONSTRATION OF AN ULTRA LOW NOx COMBUSTOR FOR GAS TURBINES

    Energy Technology Data Exchange (ETDEWEB)

    NEIL K. MCDOUGALD

    2005-04-30

    Alzeta Corporation has developed surface-stabilized fuel injectors for use with lean premixed combustors which provide extended turndown and ultra-low NOX emission performance. These injectors use a patented technique to form interacting radiant and blue-flame zones immediately above a selectively-perforated porous metal surface. This allows stable operation at low reaction temperatures. This technology is being commercialized under the product name nanoSTAR. Initial tests demonstrated low NOX emissions but, were limited by flashback failure of the injectors. The weld seams required to form cylindrical injectors from flat sheet material were identified as the cause of the failures. The approach for this project was to first develop new fabrication methods to produce injectors without weld seams, verify similar emissions performance to the original flat sheet material and then develop products for microturbines and small gas turbines along parallel development paths. A 37 month project was completed to develop and test a surface stabilized combustion system for gas turbine applications. New fabrication techniques developed removed a technological barrier to the success of the product by elimination of conductive weld seams from the injector surface. The injectors demonstrated ultra low emissions in rig tests conducted under gas turbine operating conditions. The ability for injectors to share a common combustion chamber allowing for deployment in annular combustion liner was also demonstrated. Some further development is required to resolve integration issues related to specific engine constraints, but the nanoSTAR technology has clearly demonstrated its low emissions potential. The overall project conclusions can be summarized: (1) A wet-laid casting method successfully eliminated weld seams from the injector surface without degrading performance. (2) Gas turbine cycle analysis identified several injector designs and control schemes to start and load engines using

  12. Micro-droplet formation via 3D printed micro channel

    Science.gov (United States)

    Jian, Zhen; Zhang, Jiaming; Li, Erqiang; Thoroddsen, Sigurdur T.

    2016-11-01

    Low cost, fast-designed and fast-fabricated 3D micro channel was used to create micro-droplets. Capillary with an outer diameter of 1.5 mm and an inner diameter of 150 μm was inserted into a 3D printed cylindrical channel with a diameter of 2 mm . Flow rate of the two inlets, insert depth, liquid (density, viscosity and surface tension) and solid (roughness, contact angle) properties all play a role in the droplet formation. Different regimes - dripping, jetting, unstable state - were observed in the micro-channel on varying these parameters. With certain parameter combinations, successive formation of micro-droplets with equal size was observed and its size can be much smaller than the smallest channel size. Based on our experimental results, the droplet formation via 3D printed micro T-junction was investigated through direct numerical simulations with a code called Gerris. Reynolds numbers Re = ρUL / μ and Weber numbers We = ρU2 L / σ of the two liquids were introduced to measure the liquid effect. The parameter regime where different physical dynamics occur was studied and the regime transition was observed with certain threshold values. Qualitative and quantitative analysis were performed as well between simulations and experiments.

  13. Experimental results showing the internal three-component velocity field and outlet temperature contours for a model gas turbine combustor

    CSIR Research Space (South Africa)

    Meyers, BC

    2011-09-01

    Full Text Available by the American Institute of Aeronautics and Astronautics Inc. All rights reserved ISABE-2011-1129 EXPERIMENTAL RESULTS SHOWING THE INTERNAL THREE-COMPONENT VELOCITY FIELD AND OUTLET TEMPERATURE CONTOURS FOR A MODEL GAS TURBINE COMBUSTOR BC Meyers*, GC... identifier c Position identifier F Fuel i Index L (Combustor) Liner OP Orifice plate Introduction There are often inconsistencies when comparing experimental and Computational Fluid Dynamics (CFD) simulations for gas turbine combustors [1...

  14. Comparative study of non-premixed and partially-premixed combustion simulations in a realistic Tay model combustor

    OpenAIRE

    Zhang, K.; Ghobadian, A.; Nouri, J. M.

    2017-01-01

    A comparative study of two combustion models based on non-premixed assumption and partially premixed assumptions using the overall models of Zimont Turbulent Flame Speed Closure Method (ZTFSC) and Extended Coherent Flamelet Method (ECFM) are conducted through Reynolds stress turbulence modelling of Tay model gas turbine combustor for the first time. The Tay model combustor retains all essential features of a realistic gas turbine combustor. It is seen that the non-premixed combustion model fa...

  15. Analysis of a cylindrical shell vibrating in a cylindrical fluid region

    International Nuclear Information System (INIS)

    Chung, H.; Turula, P.; Mulcahy, T.M.; Jendrzejczyk, J.A.

    1976-08-01

    Analytical and experimental methods are presented for evaluating the vibration characteristics of cylindrical shells such as the thermal liner of the Fast Flux Test Facility (FFTF) reactor vessel. The NASTRAN computer program is used to calculate the natural frequencies, mode shapes, and response to a harmonic loading of a thin, circular cylindrical shell situated inside a fluid-filled rigid circular cylinder. Solutions in a vacuum are verified with an exact solution method and the SAP IV computer code. Comparisons between analysis and experiment are made, and the accuracy and utility of the fluid-solid interaction package of NASTRAN is assessed

  16. A CFD Analysis of The Performance of Pin-Fin Laminar Flow Micro/Meso Scale Heat Exchangers

    National Research Council Canada - National Science Library

    Dimas, Sotirios

    2005-01-01

    .... A staggered arrangement of cylindrical pin fins in rectangular channel geometry was used. Various configurations were considered consistent with a parallel experimental study being conducted based on a micro-wind tunnel setup...

  17. NONEQUILIBRIUM SULFUR CAPTURE AND RETENTION IN AN AIR COOLED SLAGGING COAL COMBUSTOR

    International Nuclear Information System (INIS)

    Dr. Bert Zauderer

    1999-01-01

    Calcium oxide injected in a slagging combustor reacts with the sulfur from coal combustion to form sulfur-bearing particles. They are deposited on the liquid slag layer on the combustor wall. Due to the low solubility of sulfur in slag, slag must be rapidly drained from the combustor to limit sulfur gas re-evolution. Analysis indicated that slag mass flow rates in excess of 400 lb/hr should limit sulfur re-evolution. The objective of this 42-month project was to perform a series of tests to determine the factors that control the retention of the sulfur in the slag. 36 days of testing on the combustor were completed prior to the end of this reporting period, 12/31/98. This compares with 16 tests required in the original project plan. Combustor tests in early 1997 with high (37%) ash, Indian coal confirmed that high slag mass flow rates of about 500 lb/hr resulted in retention in the slag of up to 20% of the injected sulfur content mineral matter. To further increase the slag flow rate, rice husks, which contain 20% ash, and rice husk char, which contain 70% ash, were co-fired with coal in the combustor. A series of 13 combustor tests were performed in fourth quarter of 1997 and a further 6 tests were performed in January 1998 and in the summer of 1998. The test objective was to achieve slag flow rates between 500 and 1,000 lb/hr. Due to the very low bulk density of rice husk, compared to pulverized coal, almost the entire test effort focused on developing methods for feeding the rice husks into combustor. In the last test of December 1997, a peak mineral matter, injection rate of 592 lb/hr was briefly achieved by injection of coal, rice husk char, gypsum, and limestone into the combustor. However, no significant sulfur concentration was measured in the slag removed from the combustor. The peak injection rate reached with biomass in the 1997 tests was 310 lb/hr with rice husk, and 584 lb/hr with rice husk char

  18. Fast, inexpensive, diffraction limited cylindrical microlenses

    International Nuclear Information System (INIS)

    Synder, J.J.; Reichert, P.

    1991-01-01

    We have developed a technique for fabricating fast, well corrected cylindrical microlenses. With this technique we have made a number of different microlenses with dimensions and focal lengths in the range of few hundred μm, and diffraction limited numerical apertures as high as 0.9. The microlenses are specifically designed for applications where they can increase the radiance or otherwise enhance the optical characteristics of laser diode light. The fabrication method we use is very versatile, and the microlenses produced this way would be very inexpensive in production quantities. 6 refs., 4 figs

  19. History of the small cylindrical melter

    International Nuclear Information System (INIS)

    Allen, T.L.; Iverson, D.C.; Plodinec, M.J.

    1985-08-01

    The small cylindrical melter (SCM) was designed to provide engineering data useful for operation and design of full-scale glass melters for vitrification of high-level radioactive waste. This melter was part of the research and development program for the Defense Waste Processing Facility (DWPF) at the Savannah River Plant (SRP). Extensive corrosion testing of melter materials of construction (Monofrax K3, Inconel 690), simulated radioactive waste glass characterization, and melter component development were conducted in support of the DWPF full-scale melter design. 66 figs., 14 tabs

  20. Acoustic propagation mode in a cylindrical plasma

    International Nuclear Information System (INIS)

    Ishida, Yoshio; Idehara, Toshitaka; Inada, Hideyo

    1975-01-01

    The sound velocity in a cylindrical plasma produced by a high frequency discharge is measured by an interferometer system. The result shows that the acoustic wave guide effect does exist in a neutral gas and in a plasma. It is found that the wave propagates in the mode m=2 in a rigid boundary above the cut-off frequency fsub(c) and in the mode m=0 below fsub(c). Because the mode m=0 is identical to a plane wave, the sound velocity in free space can be evaluated exactly. In the mode m=2, the sound velocity approaches the free space value, when the frequency increases sufficiently. (auth.)

  1. Cylindrical ionization chamber with compressed krypton

    International Nuclear Information System (INIS)

    Kuz'minov, V.V.; Novikov, V.M.; Pomanskii, A.A.; Pritychenko, B.V.; Viyar, J.; Garcia, E.; Morales, A.; Morales, J.; Nunes-Lagos, R.; Puimedon, J.; Saens, K.; Salinas, A.; Sarsa, M.

    1993-01-01

    A cylindrical ionization chamber with a grid is used to search for double positron decay and atomic electron conversion to a positron in 78 Kr. Krypton is the working gas material of the chamber. The spectrometric characteristics of the chamber filled with krypton and xenon are presented. The energy resolution is 2.1% for an energy of 1.84 MeV (the source of γ-quanta is 88 Y) when the chamber is filled with a mixture of Kr+0.2% H 2 under a pressure of 25 atm

  2. Cullet Manufacture Using the Cylindrical Induction Melter

    International Nuclear Information System (INIS)

    Miller, D. H.

    2000-01-01

    The base process for vitrification of the Am/Cm solution stored in F-canyon uses 25SrABS cullet as the glass former. A small portion of the cullet used in the SRTC development work was purchased from Corning while the majority was made in the 5 inch Cylindrical Induction Melter (CIM5). Task 1.01 of TTR-NMSS/SE-006, Additional Am-Cm Process Development Studies, requested that a process for the glass former (cullet) fabrication be specified. This report provides the process details for 25SrAB cullet production thereby satisfying Task 1.01

  3. Stability analysis of cylindrical Vlasov equilibria

    International Nuclear Information System (INIS)

    Short, R.W.

    1979-01-01

    A general method of stability analysis is described which may be applied to a large class of such problems, namely those which are described dynamically by the Vlasov equation, and geometrically by cylindrical symmetry. The method is presented for the simple case of the Vlasov-Poisson (electrostatic) equations, and the results are applied to a calculation of the lower-hybrid-drift instability in a plasma with a rigid rotor distribution function. The method is extended to the full Vlasov-Maxwell (electromagnetic) equations. These results are applied to a calculation of the instability of the extraordinary electromagnetic mode in a relativistic E-layer interacting with a background plasma

  4. Enhanced Performance of Cylindrical Hall Thrusters

    International Nuclear Information System (INIS)

    Raitses, Y.; Smirnov, A.; Fisch, N.J.

    2007-01-01

    The cylindrical thruster differs significantly in its underlying physical mechanisms from the conventional annular Hall thruster. It features high ionization efficiency, quiet operation, ion acceleration in a large volume-to-surface ratio channel, and performance comparable with the state-of-the-art conventional Hall thrusters. Very significant plume narrowing, accompanied by the increase of the energetic ion fraction and improvement of ion focusing, led to 50-60% increase of the thruster anode efficiency. These improvements were achieved by overrunning the discharge current in the magnetized thruster plasma

  5. Waves in inhomogeneous plasma of cylindrical geometry

    International Nuclear Information System (INIS)

    Rebut, P.H.

    1966-01-01

    The conductivity tensor of a hot and inhomogeneous plasma has been calculated for a cylindrical geometry using Vlasov equations. The method used consists in a perturbation method involving the first integrals of the unperturbed movement. The conductivity tensor will be particularly useful for dealing with stability problems. In the case of a cold plasma the wave equation giving the electric fields as a function of the radius is obtained. This equation shows the existence of resonant layers which lead to an absorption analogous to the Landau absorption in a hot plasma. (author) [fr

  6. Results of performance and emission testing when co-firing blends of dRDF/COAL in a 440 MWe cyclone fired combustor

    International Nuclear Information System (INIS)

    Ohlsson, O.O.

    1993-01-01

    Argonne National Laboratory (ANL) together with the University of North Texas (UNT) have developed an improved method for converting refuse (residential, commercial and institutional waste) into an environmentally safe and economical fuel. In this method, recyclable metals, glass, and some plastic products are separated from the refuse. The remaining fraction, consisting primarily of cellulosic materials is then combined with a calcium hydroxide binding additive and formed into cylindrical pellets. These pellets are dense and odorless, can be stored for extended periods of time without biological or chemical degradation, and due to their increased bulk density are more durable and can be more easily conveyed, handled, and transported than other types of waste-derived fuel pellets. Laboratory and pilot-scale research studies, followed by full-scale combustion tests undertaken by DOE, ANL and UNT, in June--July of 1987 have indicated that binder-enhanced dRDF pellets can be successfully cofired with high sulfur coal in spreader-stoker combustors. The results of these combustion tests indicated significant reductions of SO 2 , NO x and CO 2 in the flue gases, and the reduction of heavy metals and organics in the ash residue. Dioxins and furans, both in the flue gas and in the ash residues were below detectable levels. Additional commercial-scale combustion tests have recently been conducted by DOE, NREL, ANL and several industrial participants including Otter Tail Power Company, Reuter, Inc., XL Recycling and Marblehead Lime Company, under a collaborative research and development agreement (CRADA). A large 440 MW e cyclone-fired combustor was tested at Big Stone City, South Dakota on October 26--27, 1992. This paper describes the cyclone-fired combustion tests, the flue gas emission and ash samples that were collected, the analyses that were performed on these samples, and the final test results

  7. Multimode interaction in axially excited cylindrical shells

    Directory of Open Access Journals (Sweden)

    Silva F. M. A.

    2014-01-01

    Full Text Available Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural frequencies. The shell is modelled using the Donnell nonlinear shallow shell theory and the discretized equations of motion are obtained by applying the Galerkin method. For this, a modal solution that takes into account the modal interaction among the relevant modes and the influence of their companion modes (modes with rotational symmetry, which satisfies the boundary and continuity conditions of the shell, is derived. Special attention is given to the 1:1:1:1 internal resonance (four interacting modes. Solving numerically the governing equations of motion and using several tools of nonlinear dynamics, a detailed parametric analysis is conducted to clarify the influence of the internal resonances on the bifurcations, stability boundaries, nonlinear vibration modes and basins of attraction of the structure.

  8. Forced Vibration Analysis for a FGPM Cylindrical Shell

    Directory of Open Access Journals (Sweden)

    Hong-Liang Dai

    2013-01-01

    Full Text Available This article presents an analytical study for forced vibration of a cylindrical shell which is composed of a functionally graded piezoelectric material (FGPM. The cylindrical shell is assumed to have two-constituent material distributions through the thickness of the structure, and material properties of the cylindrical shell are assumed to vary according to a power-law distribution in terms of the volume fractions for constituent materials, the exact solution for the forced vibration problem is presented. Numerical results are presented to show the effect of electric excitation, thermal load, mechanical load and volume exponent on the static and force vibration of the FGPM cylindrical shell. The goal of this investigation is to optimize the FGPM cylindrical shell in engineering, also the present solution can be used in the forced vibration analysis of cylindrical smart elements.

  9. Note: Electrochemical etching of cylindrical nanoprobes using a vibrating electrolyte

    International Nuclear Information System (INIS)

    Wang, Yufeng; Zeng, Yongbin; Qu, Ningsong; Zhu, Di

    2015-01-01

    An electrochemical etching process using a vibrating electrolyte of potassium hydroxide to prepare tungsten cylindrical nanotips is developed. The vibrating electrolyte eases the effects of a diffusion layer and extends the etching area, which aid in the production of cylindrical nanotips. Larger amplitudes and a vibration frequency of 35 Hz are recommended for producing cylindrical nanotips. Nanotips with a tip radius of approximately 43 nm and a conical angle of arctan 0.0216 are obtained

  10. Magnetostatic interactions and forces between cylindrical permanent magnets

    International Nuclear Information System (INIS)

    Vokoun, David; Beleggia, Marco; Heller, Ludek; Sittner, Petr

    2009-01-01

    Permanent magnets of various shapes are often utilized in magnetic actuators, sensors or releasable magnetic fasteners. Knowledge of the magnetic force is required to control devices reliably. Here, we introduce an analytical expression for calculating the attraction force between two cylindrical permanent magnets on the assumption of uniform magnetization. Although the assumption is not fulfilled exactly in cylindrical magnets, we obtain a very good agreement between the calculated and measured forces between two identical cylindrical magnets and within an array of NdFeB cylindrical magnets.

  11. Aerosol sampling of an experimental fluidized bed coal combustor

    International Nuclear Information System (INIS)

    Newton, G.J.; Peele, E.R.; Carpenter, R.L.; Yeh, H.C.

    1977-01-01

    Fluidized bed combustion of coal, lignite or other materials has a potential for widespread use in central electric generating stations in the near future. This technology may allow widespread use of low-grade and/or high sulfur fuels due to its high energy utilization at low combustion temperature and its ability to meet emission criteria by using limestone bed material. Particulate and gaseous products resulting from fuel combustion and fluidization of bed material are discharged and proceed out the exhaust clean-up system. Sampling philosophy, methodology and equipment used to obtain aerosol samples from the exhaust system of the 18-inch fluidized bed combustor (FBC) at the Morgantown Energy Research Center (MERC) are described. Identification of sampling sites led to design of an aerosol sampling train which allowed a known quantity of the effluent streams to be sampled. Depending on the position, a 15 to 25 l/min sample is extracted from the duct, immediately diluted and transferred to a sampling/aging chamber. Transmission and scanning electron microscope samples, two types of cascade impactor samples, vapor-phase and particulate-phase organic samples, spiral duct aerosol centrifuge samples, optical size measurements and filter samples were obtained. Samples are undergoing physical, chemical and biological tests to help establish human health risk estimates for fluidized bed coal combustion and to provide information for use in design and evaluation of control technologies

  12. Estimating the uncertainty in thermochemical calculations for oxygen-hydrogen combustors

    Science.gov (United States)

    Sims, Joseph David

    The thermochemistry program CEA2 was combined with the statistical thermodynamics program PAC99 in a Monte Carlo simulation to determine the uncertainty in several CEA2 output variables due to uncertainty in thermodynamic reference values for the reactant and combustion species. In all, six typical performance parameters were examined, along with the required intermediate calculations (five gas properties and eight stoichiometric coefficients), for three hydrogen-oxygen combustors: a main combustor, an oxidizer preburner and a fuel preburner. The three combustors were analyzed in two different modes: design mode, where, for the first time, the uncertainty in thermodynamic reference values---taken from the literature---was considered (inputs to CEA2 were specified and so had no uncertainty); and data reduction mode, where inputs to CEA2 did have uncertainty. The inputs to CEA2 were contrived experimental measurements that were intended to represent the typical combustor testing facility. In design mode, uncertainties in the performance parameters were on the order of 0.1% for the main combustor, on the order of 0.05% for the oxidizer preburner and on the order of 0.01% for the fuel preburner. Thermodynamic reference values for H2O were the dominant sources of uncertainty, as was the assigned enthalpy for liquid oxygen. In data reduction mode, uncertainties in performance parameters increased significantly as a result of the uncertainties in experimental measurements compared to uncertainties in thermodynamic reference values. Main combustor and fuel preburner theoretical performance values had uncertainties of about 0.5%, while the oxidizer preburner had nearly 2%. Associated experimentally-determined performance values for all three combustors were 3% to 4%. The dominant sources of uncertainty in this mode were the propellant flowrates. These results only apply to hydrogen-oxygen combustors and should not be generalized to every propellant combination. Species for

  13. The effect of inlet conditions on lean premixed gas turbine combustor performance

    Science.gov (United States)

    Vilayanur, Suresh Ravi

    The combustion community is today faced with the goal to reduce NOx at high efficiencies. This requirement has directed attention to the manner by which air and fuel are treated prior to and at the combustor inlet. This dissertation is directed to establishing the role of combustor inlet conditions on combustor performance, and to deriving an understanding of the relationship between inlet conditions and combustion performance. To investigate the complex effect of inlet parameters on combustor performance, (1) a test facility was designed and constructed, (2) hardware was designed and fabricated, (3) a statistically based technique was designed and applied, and (4) detailed in-situ measurements were acquired. Atmospheric tests were performed at conditions representative of industrial combustors: 670 K inlet preheat and an equivalence ratio of 0.47, and make the study immediately relevant to the combustion community. The effects of premixing length, fuel distribution, swirl angle, swirl vane thickness and swirl solidity were investigated. The detailed in-situ measurements were performed to form the database necessary to study the responsible mechanisms. A host of conventional and advanced diagnostics were used for the investigation. In situ measurements included the mapping of the thermal and velocity fields of the combustor, obtaining species concentrations inside the combustor, and quantifying the fuel-air mixing entering the combustor. Acoustic behavior of the combustor was studied, including the application of high speed videography. The results reveal that the principal statistically significant effect on NOx production is the inlet fuel distribution, and the principal statistically significant effect on CO production is the swirl strength. Elevated levels of NOx emission result when the fuel is weighted to the centerline. Eddies shedding off the swirler hub ignite as discrete packets, and due to the elevated concentrations of fuel, reach higher temperatures

  14. An experimental study of the stable and unstable operation of an LPP gas turbine combustor

    Science.gov (United States)

    Dhanuka, Sulabh Kumar

    A study was performed to better understand the stable operation of an LPP combustor and formulate a mechanism behind the unstable operation. A unique combustor facility was developed at the University of Michigan that incorporates the latest injector developed by GE Aircraft Engines and enables operation at elevated pressures with preheated air at flow-rates reflective of actual conditions. The large optical access has enabled the use of a multitude of state-of-the-art laser diagnostics such as PIV and PLIF, and has shed invaluable light not only into the GE injector specifically but also into gas turbine combustors in general. Results from Particle Imaging Velocimetry (PIV) have illustrated the role of velocity, instantaneous vortices, and key recirculation zones that are all critical to the combustor's operation. It was found that considerable differences exist between the iso-thermal and reacting flows, and between the instantaneous and mean flow fields. To image the flame, Planar Laser Induced Fluorescence (PLIF) of the formaldehyde radical was successfully utilized for the first time in a Jet-A flame. Parameters regarding the flame's location and structure have been obtained that assist in interpreting the velocity results. These results have also shown that some of the fuel injected from the main fuel injectors actually reacts in the diffusion flame of the pilot. The unstable operation of the combustor was studied in depth to obtain the stability limits of the combustor, behavior of the flame dynamics, and frequencies of the oscillations. Results from simultaneous pressure and high speed chemiluminescence images have shown that the low frequency dynamics can be characterized as flashback oscillations. The results have also shown that the stability of the combustor can be explained by simple and well established premixed flame stability mechanisms. This study has allowed the development of a model that describes the instability mechanism and accurately

  15. Influence of the burner swirl on the azimuthal instabilities in an annular combustor

    Science.gov (United States)

    Mazur, Marek; Nygård, Håkon; Worth, Nicholas; Dawson, James

    2017-11-01

    Improving our fundamental understanding of thermoacoustic instabilities will aid the development of new low emission gas turbine combustors. In the present investigation the effects of swirl on the self-excited azimuthal combustion instabilities in a multi-burner annular annular combustor are investigated experimentally. Each of the burners features a bluff body and a swirler to stabilize the flame. The combustor is operated with an ethylene-air premixture at powers up to 100 kW. The swirl number of the burners is varied in these tests. For each case, dynamic pressure measurements at different azimuthal positions, as well as overhead imaging of OH* of the entire combustor are conducted simultaneously and at a high sampling frequency. The measurements are then used to determine the azimuthal acoustic and heat release rate modes in the chamber and to determine whether these modes are standing, spinning or mixed. Furthermore, the phase shift between the heat release rate and pressure and the shape of these two signals are analysed at different azimuthal positions. Based on the Rayleigh criterion, these investigations allow to obtain an insight about the effects of the swirl on the instability margins of the combustor. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant agreement n° 677931 TAIAC).

  16. Forced and self-excited oscillations in a natural gas fired lean premixed combustor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Daesik; Park, Sung Wook

    2010-11-15

    An experimental study of the flame response in a premixed gas turbine combustor has been conducted at room temperature and under atmospheric pressure inlet conditions using natural gas. The fuel is premixed with the air upstream of a choked inlet to avoid equivalence ratio fluctuations. Therefore the observed flame response is only the result of the imposed velocity fluctuations, which are produced using a variable-speed siren. Also, a variable length combustor is designed for investigating characteristics of self-excited instabilities. Measurements are made of the velocity fluctuation in the mixing section using hot wire anemometry and of the heat release fluctuation in the combustor using chemiluminescence emission. The results are analyzed to determine the phase and gain of the flame transfer function. The results show that the gain of flame transfer function is closely associated both with inlet flow forcing conditions such as frequency and amplitude of modulation as well as the operating conditions such as equivalence ratio. In order to predict the operating conditions where the combustor goes stable or unstable at given combustor and nozzle designs, time-lag analysis was tried using convection time delay measured from the phase information of the transfer function. The model prediction was in very good agreement with the self-excited instability measurement. However, spatial heat release distribution became more significant in long flames than in short flames and also had an important influence on the system damping procedure. (author)

  17. Combustion Dynamic Characteristics Identification in a 9-point LDI Combustor Under Choked Outlet Boundary Conditions

    Science.gov (United States)

    He, Zhuohui J.; Chang, Clarence T.

    2017-01-01

    Combustion dynamics data were collected at the NASA Glenn Research Center's CE-5 flame tube test facility under combustor outlet choked conditions. Two 9-point Swirl-Venturi Lean Direct Injection (SV-LDI) configurations were tested in a rectangular cuboid combustor geometry. Combustion dynamic data were measured at different engine operational conditions up to inlet air pressure and temperature of 24.13 bar and 828 K, respectively. In this study, the effects of acoustic cavity resonance, precessing vortex core (PVC), and non-uniform thermal expansion on the dynamic noise spectrum are identified by comparing the dynamic data that collected at various combustor inlet conditions along with combustor geometric calculations. The results show that the acoustic cavity resonance noises were seen in the counter-rotating pilot configuration but not in the co-rotating pilot configuration. Dynamic pressure noise band at around 0.9 kHz was only detected at the P'41 location (9.8 cm after fuel injector face) but not at the P'42 location (29 cm after the fuel injector face); the amplitude of this noise band depended on the thermal expansion ratio (T4/T3). The noise band at around 1.8 kHz was found to depend on the inlet air pressure or the air density inside the combustor. The PVC frequency was not observed in these two configurations.

  18. CFD analysis of a scramjet combustor with cavity based flame holders

    Science.gov (United States)

    Kummitha, Obula Reddy; Pandey, Krishna Murari; Gupta, Rajat

    2018-03-01

    Numerical analysis of a scramjet combustor with different cavity flame holders has been carried out using ANSYS 16 - FLUENT tool. In this research article the internal fluid flow behaviour of the scramjet combustor with different cavity based flame holders have been discussed in detail. Two dimensional Reynolds-Averaged Navier-Stokes governing(RANS) equations and shear stress turbulence (SST) k - ω model along with finite rate/eddy dissipation chemistry turbulence have been considered for modelling chemical reacting flows. Due to the advantage of less computational time, global one step reaction mechanism has been used for combustion modelling of hydrogen and air. The performance of the scramjet combustor with two different cavities namely spherical and step cavity has been compared with the standard DLR scramjet. From the comparison of numerical results, it is found that the development of recirculation regions and additional shock waves from the edge of cavity flame holder is increased. And also it is observed that with the cavity flame holder the residence time of air in the scramjet combustor is also increased and achieved stabilized combustion. From this research analysis, it has been found that the mixing and combustion efficiency of scramjet combustor with step cavity design is optimum as compared to other models.

  19. A study of small molecule ingress into planar and cylindrical materials using ion beam analysis

    International Nuclear Information System (INIS)

    Smith, R.W.

    2001-12-01

    Ion beam analysis techniques have been developed to allow profiling of small molecules diffused into materials at depths ranging from 10 -7 to 10 -1 m. A model DPS/PS/DPS triple-layer film and D( 3 He,p) 4 He nuclear reaction analysis was used to test the applicability of a novel data processing program - the IBA DataFurnace - to nuclear reaction data. The same reaction and program were used to depth profile the diffusion of heavy water into cellophane. A scanning 3 He micro-beam technique was developed to profile the diffusion of small molecules into both planar and cylindrical materials. The materials were exposed to liquids containing deuterium labelled molecules. A cross-section was exposed by cutting the material perpendicular to the surface and this was bombarded by a scanning 3 He micro-beam. Nuclear reaction analysis was used to profile the diffusing molecules, particle induced X-ray emission (in most cases) to locate the matrix and Rutherford backscattering for normalisation. Two-dimensional maps showing the molecular distribution over the cross-section were obtained. From these one-dimensional concentration profiles were produced. Water diffusion was studied into a planar and a cylindrical polymer, three different planar fibre optic grade glasses and both a fibre optic pressure sensor and communication fibre. The diffusion of dye into hair was also investigated. These studies have provided information about the diffusion mechanisms that take place, and where relevant diffusion coefficients have been obtained using either a semi-infinite medium Fickian planar diffusion model or a cylindrical Fickian diffusion model. (author)

  20. Focusing properties of cylindrical vector vortex beams

    Science.gov (United States)

    Xiaoqiang, Zhang; Ruishan, Chen; Anting, Wang

    2018-05-01

    In this paper, following Richards and Wolf vectorial diffraction theory, the focusing properties of cylindrical vector vortex beams (CVVB) are investigated, and a diffractive optical element (DOE) is designed to spatially modulate the amplitude of the CVVB. Simulated results show that the CVVB focused by an objective also carry orbital angular momentum (OAM), and the optical fields near the focal region can be modulated by changing the topological charge of the CVVB. We numerically simulate the focus properties of radially and azimuthally polarized beams with topological charge equal to 0, 1, 2 and 10 respectively. As a result, a dark channel with a length about 20 λ can be obtained. These new properties have the potential applications such as particle acceleration, optical trapping and material processing.

  1. Indentation of Ellipsoidal and Cylindrical Elastic Shells

    KAUST Repository

    Vella, Dominic

    2012-10-01

    Thin shells are found in nature at scales ranging from viruses to hens\\' eggs; the stiffness of such shells is essential for their function. We present the results of numerical simulations and theoretical analyses for the indentation of ellipsoidal and cylindrical elastic shells, considering both pressurized and unpressurized shells. We provide a theoretical foundation for the experimental findings of Lazarus etal. [following paper, Phys. Rev. Lett. 109, 144301 (2012)PRLTAO0031-9007] and for previous work inferring the turgor pressure of bacteria from measurements of their indentation stiffness; we also identify a new regime at large indentation. We show that the indentation stiffness of convex shells is dominated by either the mean or Gaussian curvature of the shell depending on the pressurization and indentation depth. Our results reveal how geometry rules the rigidity of shells. © 2012 American Physical Society.

  2. Confined detonations with cylindrical and spherical symmetry

    International Nuclear Information System (INIS)

    Linan, A.; Lecuona, A.

    1979-01-01

    An imploding spherical or cylindrical detonation, starting in the interface of the detonantion with an external inert media, used as a reflector, creates on it a strong shock wave moving outward from the interface. An initially weak shock wave appears in the detonated media that travels toward the center, and it could reach the detonation wave, enforcing it in its process of implosion. To describe the fluid field, the Euler s equations are solved by means of expansions valid for the early stages of the process. Isentropic of the type P/pγ-K for the detonated and compressed inert media are used. For liquid or solid reflectors a more appropriate equation is used. (Author) 8 refs

  3. Unbalanced Cylindrical Magnetron for Accelerating Cavities Coating

    CERN Document Server

    Rosaz, Guillaume; Calatroni, Sergio; Sublet, Alban; Tobarelli, Mauro

    2016-01-01

    We report in this paper the design and qualification of a cylindrical unbalanced magnetron source. The dedicated magnetic assemblies were simulated using a finite element model. A hall-effect magnetic probe was then used to characterize those assemblies and compared to the theoretical magnet profiles. These show a good agreement between the expected and actual values. the qualification of the different magnetic assemblies was then performed by measuring the ion flux density reaching the surface of the sample to be coated using a commercial retarding field energy analyzer. The strongest unbalanced configuration shows an increase from 0.016A.cm^-2 to 0.074A.cm^-2 of the ion flux density reaching the sample surface compared to the standard balanced configuration for a pressure 5.10^-3 mbar and a plasma source power of 300W.

  4. Space charge emission in cylindrical diode

    International Nuclear Information System (INIS)

    Torres-Córdoba, Rafael; Martínez-García, Edgar

    2014-01-01

    In this paper, a mathematical model to describe cylindrical electron current emissions through a physics approximation method is presented. The proposed mathematical approximation consists of analyzing and solving the nonlinear Poisson's equation, with some determined mathematical restrictions. Our findings tackle the problem when charge-space creates potential barrier that disable the steady-state of the beam propagation. In this problem, the potential barrier effects of electron's speed with zero velocity emitted through the virtual cathode happens. The interaction between particles and the virtual cathode have been to find the inter-atomic potentials as boundary conditions from a quantum mechanics perspective. Furthermore, a non-stationary spatial solution of the electrical potential between anode and cathode is presented. The proposed solution is a 2D differential equation that was linearized from the generalized Poisson equation. A single condition was used solely, throughout the radial boundary conditions of the current density formation

  5. Analysis of a cylindrical imploding shock wave

    International Nuclear Information System (INIS)

    Mishkin, E.A.; Fujimoto, Y.

    1978-01-01

    the self-similar solution of the gasdynamic equations of a strong cylindrical shock wave moving through an ideal gas, with γ = csub(p)/csub(v), is considered. These equations are greatly simplified following the transformation of the reduced velocity U 1 (xi) → U 1 = 1/2(γ + 1 ) (U + xi). The requirement of a single maximum pressure, dsub(xi)P = 0, leads to an analytical determination of the self-similarity exponent α(γ). For gases with γ = 2 + 3sup(1/2), this maximum ensues right at the shock front and the pressure distribution then decreases monotonically. The postulate of analyticity by Gelfand and Butler is shown to concur with the requirement dsub(xi)P 0. The saturated density of the gas left in the wake of the shock is computed and - U is shown to be the reduced velocity of sound at P = P sub(m). (author)

  6. Cathode Effects in Cylindrical Hall Thrusters

    Energy Technology Data Exchange (ETDEWEB)

    Granstedt, E.M.; Raitses, Y.; Fisch, N. J.

    2008-09-12

    Stable operation of a cylindrical Hall thruster (CHT) has been achieved using a hot wire cathode, which functions as a controllable electron emission source. It is shown that as the electron emission from the cathode increases with wire heating, the discharge current increases, the plasma plume angle reduces, and the ion energy distribution function shifts toward higher energies. The observed effect of cathode electron emission on thruster parameters extends and clarifies performance improvements previously obtained for the overrun discharge current regime of the same type of thruster, but using a hollow cathode-neutralizer. Once thruster discharge current saturates with wire heating, further filament heating does not affect other discharge parameters. The saturated values of thruster discharge parameters can be further enhanced by optimal placement of the cathode wire with respect to the magnetic field.

  7. Solar heat gain through vertical cylindrical glass

    Energy Technology Data Exchange (ETDEWEB)

    Kassem, M.A.; Kaseb, S.; El-Refaie, M.F. [Cairo Univ., Mechanical Power Engineering Dept., Cairo (Egypt)

    1999-10-01

    Spaces with nonplanar glazed envelopes are frequently encountered in contemporary buildings. Such spaces represent a problem when calculating the solar heat gain in the course of estimating the cooling or heating load; and hence, sizing of cooling or heating systems. The calculation, using the information currently available in the literature, is tedious and/or approximate. In the present work, the computational procedure for evaluating the solar heat gain to a space having a vertical cylindrical glass envelope is established, and, a computer program is coded to carry out the necessary computations and yield the results in a detailed usable form. The program is versatile and allows for the arbitrary variation of all pertinent parameters. (Author)

  8. Solar heat gain through vertical cylindrical glass

    International Nuclear Information System (INIS)

    Kassem, M.A.; Kaseb, S.; El-Refaie, M.F.

    1999-01-01

    Spaces with nonplanar glazed envelopes are frequently encountered in contemporary buildings. Such spaces represent a problem when calculating the solar heat gain in the course of estimating the cooling or heating load; and hence, sizing of cooling or heating systems. The calculation, using the information currently available in the literature, is tedious and/or approximate. In the present work, the computational procedure for evaluating the solar heat gain to a space having a vertical cylindrical glass envelope is established, and, a computer program is coded to carry out the necessary computations and yield the results in a detailed usable form. The program is versatile and allows for the arbitrary variation of all pertinent parameters. (Author)

  9. Solar heat gain through vertical cylindrical glass

    Energy Technology Data Exchange (ETDEWEB)

    Kassem, M.A.; Kaseb, S.; El-Refaie, M.F. [Cairo Univ., Mechanical Power Engineering Dept., Cairo (Egypt)

    1999-07-01

    Spaces with nonplanar glazed envelopes are frequently encountered in contemporary buildings. Such spaces represent a problem when calculating the solar heat gain in the course of estimating the cooling or heating load; and hence, sizing of cooling or heating systems. The calculation, using the information currently available in the literature, is tedious and/or approximate. In the present work, the computational procedure for evaluating the solar heat gain to a space having a vertical cylindrical glass envelope is established, and, a computer program is coded to carry out the necessary computations and yield the results in a detailed usable form. The program is versatile and allows for the arbitrary variation of all pertinent parameters. (Author)

  10. Diffusion coefficient calculations for cylindrical cells

    International Nuclear Information System (INIS)

    Lam-Hime, M.

    1983-03-01

    An accurate and general diffusion coefficient calculation for cylindrical cells is described using isotropic scattering integral transport theory. This method has been particularly applied to large regular lattices of graphite-moderated reactors with annular coolant channels. The cells are divided into homogeneous zones, and a zone-wise flux expansion is used to formulate a collision probability problem. The reflection of neutrons at the cell boundary is accounted for by the conservation of the neutron momentum. The uncorrected diffusion coefficient Benoist's definition is used, and the described formulation does not neglect any effect. Angular correlation terms, energy coupling non-uniformity and anisotropy of the classical flux are exactly taken into account. Results for gas-graphite typical cells are given showing the importance of these approximations

  11. Study of Cylindrical Honeycomb Solar Collector

    Directory of Open Access Journals (Sweden)

    Atish Mozumder

    2014-01-01

    Full Text Available We present the results of our investigation on cylindrical honeycomb solar collector. The honeycomb has been fabricated with transparent cellulose triacetate polymer sheets. Insulation characteristics of the honeycomb were studied by varying the separation between the honeycomb and the absorber plate. The optimal value of the separation was found to be 3.3 mm for which the heat transfer coefficient is 3.06 W m−2 K−1. This supports result of previous similar experiments. Further we test the honeycomb through a field experiment conducted in Delhi (28.6°N, 77°E and found that when the incident angle of the solar radiation is within 20° then the performance of the system with the honeycomb is better than the one without the honeycomb.

  12. Experimental Study of Annulus Flow for Can Combustor with Vibration Influence

    Directory of Open Access Journals (Sweden)

    Rami. Y. Dahham

    2018-01-01

    Full Text Available This paper concentrate on studying the behavior of velocity profile under the influence of different frequency (34, 48, 65 and 80 Hz in each of the upper and lower annulus of Can Combustor.An experimental rig was designed to simulate the annulus flow inside a Can Combustor.The Can Combustor tested in this study is real part collected from Al-Khairat/Iraq gas turbine power station.The velocity profiles are investigated at three positions in the annular for upper and lower region.The axial velocity and turbulence intensity are calculating with different frequency for upper and lower annulus.The results were shown that the increase of frequency lead to increase the velocity profile and large recirculation zone will build in some points.Reynolds number increasing with raise of axial velocity. Also the increasing in vibration level cause non-uniform velocity profile which affect on distribution of cooling effectiveness.

  13. Numerical exploration of mixing and combustion in ethylene fueled scramjet combustor

    Science.gov (United States)

    Dharavath, Malsur; Manna, P.; Chakraborty, Debasis

    2015-12-01

    Numerical simulations are performed for full scale scramjet combustor of a hypersonic airbreathing vehicle with ethylene fuel at ground test conditions corresponding to flight Mach number, altitude and stagnation enthalpy of 6.0, 30 km and 1.61 MJ/kg respectively. Three dimensional RANS equations are solved along with species transport equations and SST-kω turbulence model using Commercial CFD software CFX-11. Both nonreacting (with fuel injection) and reacting flow simulations [using a single step global reaction of ethylene-air with combined combustion model (CCM)] are carried out. The computational methodology is first validated against experimental results available in the literature and the performance parameters of full scale combustor in terms of thrust, combustion efficiency and total pressure loss are estimated from the simulation results. Parametric studies are conducted to study the effect of fuel equivalence ratio on the mixing and combustion behavior of the combustor.

  14. Emission performance and combustion efficiency of a conical fluidized-bed combustor firing various biomass fuels

    International Nuclear Information System (INIS)

    Permchart, W.; Kouprianov, V.I.

    2004-01-01

    This paper summarizes the results of an experimental study on combustion of three distinct biomass fuels (sawdust, rice husk and pre-dried sugar cane bagasse) in a single fluidized-bed combustor (FBC) with a conical bed using silica sand as the inert bed material. Temperature, CO, NO and O 2 concentrations along the combustor height as well as in flue (stack) gas were measured in the experimental tests. The effects of fuel properties and operating conditions (load and excess air) on these variables were investigated. Both CO and NO axial profiles were found to have a maximum whose location divides conventionally the combustor volume into formation (lower) and reduction (upper) regions for these pollutants. Based on CO emission and unburned carbon content in fly ash, the combustion efficiency of the conical FBC was quantified for the selected biomass fuels fired under different operating conditions. (Author)

  15. An emissions audit of a biomass combustor burning treated wood waste

    International Nuclear Information System (INIS)

    Jackson, P.M.; Jones, H.H.; King, P.G.

    1993-01-01

    This report describes the Emissions Audit carried out on a Biomass Combustor burning treated wood waste at the premises of a furniture manufacturer. The Biomass Combustor was tested in two firing modes; continuous fire and modulating fire. Combustion chamber temperatures and gas residence times were not measured. Boiler efficiencies were very good at greater than 75% in both tests. However, analysis of the flue gases indicated that improved efficiencies are possible. The average concentrations of CO (512mgm -3 ) and THC (34mgm -3 ) for Test 1 were high, indicating that combustion was poor. The combustor clearly does not meet the requirements of the Guidance Note for the Combustion of Wood Waste. CO 2 and O 2 concentrations were quite variable showing that combustion conditions were fairly unstable. Improved control of combustion should lead to acceptable emission concentrations. (Author)

  16. Two-stage combustion for reducing pollutant emissions from gas turbine combustors

    Science.gov (United States)

    Clayton, R. M.; Lewis, D. H.

    1981-01-01

    Combustion and emission results are presented for a premix combustor fueled with admixtures of JP5 with neat H2 and of JP5 with simulated partial-oxidation product gas. The combustor was operated with inlet-air state conditions typical of cruise power for high performance aviation engines. Ultralow NOx, CO and HC emissions and extended lean burning limits were achieved simultaneously. Laboratory scale studies of the non-catalyzed rich-burning characteristics of several paraffin-series hydrocarbon fuels and of JP5 showed sooting limits at equivalence ratios of about 2.0 and that in order to achieve very rich sootless burning it is necessary to premix the reactants thoroughly and to use high levels of air preheat. The application of two-stage combustion for the reduction of fuel NOx was reviewed. An experimental combustor designed and constructed for two-stage combustion experiments is described.

  17. Computational simulation of multi-strut central lobed injection of hydrogen in a scramjet combustor

    Directory of Open Access Journals (Sweden)

    Gautam Choubey

    2016-09-01

    Full Text Available Multi-strut injection is an approach to increase the overall performance of Scramjet while reducing the risk of thermal choking in a supersonic combustor. Hence computational simulation of Scramjet combustor at Mach 2.5 through multiple central lobed struts (three struts have been presented and discussed in the present research article. The geometry and model used here is slight modification of the DLR (German Aerospace Center scramjet model. Present results show that the presence of three struts injector improves the performance of scramjet combustor as compared to single strut injector. The combustion efficiency is also found to be highest in case of three strut fuel injection system. In order to validate the results, the numerical data for single strut injection is compared with experimental result which is taken from the literature.

  18. The magnetic properties of the hollow cylindrical ideal remanence magnet

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    2016-01-01

    We consider the magnetic properties of the hollow cylindrical ideal remanence magnet. This magnet is the cylindrical permanent magnet that generates a uniform field in the cylinder bore, using the least amount of magnetic energy to do so. The remanence distribution of this magnet is derived...

  19. Cylindrical and spherical dust-acoustic wave modulations in dusty ...

    Indian Academy of Sciences (India)

    Abstract. The nonlinear wave modulation of planar and non-planar (cylindrical and spherical) dust-acoustic waves (DAW) propagating in dusty plasmas, in the presence of non-extensive distribu- tions for ions and electrons is investigated. By employing multiple scales technique, a cylindrically and spherically modified ...

  20. Coupled dilaton and electromagnetic field in cylindrically symmetric ...

    Indian Academy of Sciences (India)

    The dilaton black hole solutions have attracted considerable attention for the ... theory and study the corresponding cylindrically symmetric spacetime, where .... where Йm and Йe are integration constants to be interpreted later as the ..... feature is apparent for the cylindrically symmetric spacetime in the presence of the dila-.

  1. Ingestion of six cylindrical and four button batteries

    DEFF Research Database (Denmark)

    Nielsen, Simon U; Rasmussen, Morten; Hoegberg, Lotte C G

    2010-01-01

    We report a suicidal ingestion of six cylindrical and four button batteries, in combination with overdosed prescription medicine and smoking of cannabis.......We report a suicidal ingestion of six cylindrical and four button batteries, in combination with overdosed prescription medicine and smoking of cannabis....

  2. Settling of a cylindrical particle in a stagnant fluid

    DEFF Research Database (Denmark)

    Sørensen, Henrik; Rosendahl, Lasse; Yin, Chungen

    The objective of this work is to collect data and develop models for cylindrical particles which could be used in numerical multiphase flow modeling. Trajectories of cylindrical particles settling in stagnant water are filmed from two directions in order to derive detailed information on their mo...

  3. Analysis of radial vibrations of poroelastic circular cylindrical shells ...

    African Journals Online (AJOL)

    DR OKE

    vanished, the considered problem reduces to the problem of radial vibrations of fluid-filled poroelastic circular cylindrical shell. (2). When the .... the volume change of the solid to that of liquid. ..... When the outer fluid density is zero, that is, ρof = 0 then the poroelastic cylindrical shell immersed in an acoustic medium will.

  4. An Experimental Study of Swirling Flows as Applied to Annular Combustors

    Science.gov (United States)

    Seal, Michael Damian, II

    1997-01-01

    This thesis presents an experimental study of swirling flows with direct applications to gas turbine combustors. Two separate flowfields were investigated: a round, swirling jet and a non-combusting annular combustor model. These studies were intended to allow both a further understanding of the behavior of general swirling flow characteristics, such as the recirculation zone, as well as to provide a base for the development of computational models. In order to determine the characteristics of swirling flows the concentration fields of a round, swirling jet were analyzed for varying amount of swirl. The experimental method used was a light scattering concentration measurement technique known as marker nephelometry. Results indicated the formation of a zone of recirculating fluid for swirl ratios (rotational speed x jet radius over mass average axial velocity) above a certain critical value. The size of this recirculation zone, as well as the spread angle of the jet, was found to increase with increase in the amount of applied swirl. The annular combustor model flowfield simulated the cold-flow characteristics of typical current annular combustors: swirl, recirculation, primary air cross jets and high levels of turbulence. The measurements in the combustor model made by the Laser Doppler Velocimetry technique, allowed the evaluation of the mean and rms velocities in the three coordinate directions, one Reynold's shear stress component and the turbulence kinetic energy: The primary cross jets were found to have a very strong effect on both the mean and turbulence flowfields. These cross jets, along with a large step change in area and wall jet inlet flow pattern, reduced the overall swirl in the test section to negligible levels. The formation of the strong recirculation zone is due mainly to the cross jets and the large step change in area. The cross jets were also found to drive a four-celled vortex-type motion (parallel to the combustor longitudinal axis) near the

  5. MICRO AUTO GASIFICATION SYSTEM: EMISSIONS ...

    Science.gov (United States)

    A compact, CONEX-housed waste to energy unit, Micro Auto Gasification System (MAGS), was characterized for air emissions from burning of military waste types. The MAGS unit is a dual chamber gasifier with a secondary diesel-fired combustor. Eight tests were conducted with multiple waste types in a 7-day period at the Kilauea Military Camp in Hawai’i. The emissions characterized were chosen based on regulatory emissions limits as well as their ability to cause adverse health effects on humans: particulate matter (PM), mercury, heavy metals, volatile organic compounds (VOCs), polyaromatic hydrocarbons (PAHs), and polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Three military waste feedstock compositions reflecting the variety of wastes to be encountered in theatre were investigated: standard waste (SW), standard waste with increased plastic content (HP), standard waste without SW food components but added first strike ration (FSR) food and packaging material (termed FSR). A fourth waste was collected from the Kilauea dumpster that served the dining facility and room lodging (KMC). Limited scrubber water and solid ash residue samples were collected to obtain a preliminary characterization of these effluents/residues.Gasifying SW, HP, and KMC resulted in similar PCDD/PCDF stack concentrations, 0.26-0.27 ng TEQ/m3 at 7% O2, while FSR waste generated a notably higher stack concentration of 0.68 ng TEQ/m3 at 7% O2. The PM emission

  6. Shock-tunnel combustor testing for hypersonic vehicles

    Science.gov (United States)

    Loomis, Mark P.

    1994-01-01

    Proposed configurations for the next generation of transatmospheric vehicles will rely on air breathing propulsion systems during all or part of their mission. At flight Mach numbers greater than about 7 these engines will operate in the supersonic combustion ramjet mode (scramjet). Ground testing of these engine concepts above Mach 8 requires high pressure, high enthalpy facilities such as shock tunnels and expansion tubes. These impulse, or short duration facilities have test times on the order of a millisecond, requiring high speed instrumentation and data systems. One such facility ideally suited for scramjet testing is the NASA-Ames 16-Inch shock tunnel, which over the last two years has completed a series of tests for the NASP (National Aero-Space Plane) program at simulated flight Mach numbers ranging from 12-16. The focus of the experimental programs consisted of a series of classified tests involving a near-full scale hydrogen fueled scramjet combustor model in the semi-free jet method of engine testing whereby the compressed forebody flow ahead of the cowl inlet is reproduced (see appendix A). The AIMHYE-1 (Ames Integrated Modular Hypersonic Engine) test entry for the NASP program was completed in April 1993, while AIMHYE-2 was completed in May 1994. The test entries were regarded as successful, resulting in some of the first data of its kind on the performance of a near full scale scramjet engine at Mach 12-16. The data was distributed to NASP team members for use in design system verification and development. Due to the classified nature of the hardware and data, the data reports resulting from this work are classified and have been published as part of the NASP literature. However, an unclassified AIAA paper resulted from the work and has been included as appendix A. It contains an overview of the test program and a description of some of the important issues.

  7. Fuel Flexible, Low Emission Catalytic Combustor for Opportunity Fuel Applications

    Energy Technology Data Exchange (ETDEWEB)

    Eteman, Shahrokh

    2013-06-30

    Limited fuel resources, increasing energy demand and stringent emission regulations are drivers to evaluate process off-gases or process waste streams as fuels for power generation. Often these process waste streams have low energy content and/or highly reactive components. Operability of low energy content fuels in gas turbines leads to issues such as unstable and incomplete combustion. On the other hand, fuels containing higher-order hydrocarbons lead to flashback and auto-ignition issues. Due to above reasons, these fuels cannot be used directly without modifications or efficiency penalties in gas turbine engines. To enable the use of these wide variety of fuels in gas turbine engines a rich catalytic lean burn (RCL®) combustion system was developed and tested in a subscale high pressure (10 atm.) rig. The RCL® injector provided stability and extended turndown to low Btu fuels due to catalytic pre-reaction. Previous work has shown promise with fuels such as blast furnace gas (BFG) with LHV of 85 Btu/ft3 successfully combusted. This program extends on this work by further modifying the combustor to achieve greater catalytic stability enhancement. Fuels containing low energy content such as weak natural gas with a Lower Heating Value (LHV) of 6.5 MJ/m3 (180 Btu/ft3 to natural gas fuels containing higher hydrocarbon (e.g ethane) with LHV of 37.6 MJ/m3 (1010 Btu/ft3) were demonstrated with improved combustion stability; an extended turndown (defined as the difference between catalytic and non-catalytic lean blow out) of greater than 250oF was achieved with CO and NOx emissions lower than 5 ppm corrected to 15% O2. In addition, for highly reactive fuels the catalytic region preferentially pre-reacted the higher order hydrocarbons with no events of flashback or auto-ignition allowing a stable and safe operation with low NOx and CO emissions.

  8. Fast calculation method for computer-generated cylindrical holograms.

    Science.gov (United States)

    Yamaguchi, Takeshi; Fujii, Tomohiko; Yoshikawa, Hiroshi

    2008-07-01

    Since a general flat hologram has a limited viewable area, we usually cannot see the other side of a reconstructed object. There are some holograms that can solve this problem. A cylindrical hologram is well known to be viewable in 360 deg. Most cylindrical holograms are optical holograms, but there are few reports of computer-generated cylindrical holograms. The lack of computer-generated cylindrical holograms is because the spatial resolution of output devices is not great enough; therefore, we have to make a large hologram or use a small object to fulfill the sampling theorem. In addition, in calculating the large fringe, the calculation amount increases in proportion to the hologram size. Therefore, we propose what we believe to be a new calculation method for fast calculation. Then, we print these fringes with our prototype fringe printer. As a result, we obtain a good reconstructed image from a computer-generated cylindrical hologram.

  9. Flow aerodynamics modeling of an MHD swirl combustor - calculations and experimental verification

    International Nuclear Information System (INIS)

    Gupta, A.K.; Beer, J.M.; Louis, J.F.; Busnaina, A.A.; Lilley, D.G.

    1981-01-01

    This paper describes a computer code for calculating the flow dynamics of constant density flow in the second stage trumpet shaped nozzle section of a two stage MHD swirl combustor for application to a disk generator. The primitive pressure-velocity variable, finite difference computer code has been developed to allow the computation of inert nonreacting turbulent swirling flows in an axisymmetric MHD model swirl combustor. The method and program involve a staggered grid system for axial and radial velocities, and a line relaxation technique for efficient solution of the equations. Tue produces as output the flow field map of the non-dimensional stream function, axial and swirl velocity. 19 refs

  10. System for reducing combustion dynamics and NO.sub.x in a combustor

    Science.gov (United States)

    Uhm, Jong Ho; Ziminsky, Willy Steve; Johnson, Thomas Edward; Hughes, Michael John; York, William David

    2016-05-31

    A combustor includes an end cap that extends radially across at least a portion of the combustor. The end cap includes an upstream surface axially separated from a downstream surface. A plurality of tubes extend from the upstream surface through the downstream surface of the end cap to provide fluid communication through the end cap. Each tube in a first set of the plurality of tubes has an inlet proximate to the upstream surface and an outlet downstream from the downstream surface. Each outlet has a first portion that extends a different axial distance from the inlet than a second portion.

  11. Evaluation of Water Injection Effect on NO(x) Formation for a Staged Gas Turbine Combustor

    Science.gov (United States)

    Fan, L.; Yang, S. L.; Kundu, K. P.

    1996-01-01

    NO(x) emission control by water injection on a staged turbine combustor (STC) was modeled using the KIVA-2 code with modification. Water is injected into the rich-burn combustion zone of the combustor by a single nozzle. Parametric study for different water injection patterns was performed. Results show NO(x) emission will decrease after water being injected. Water nozzle location also has significant effect for NO formation and fuel ignition. The chemical kinetic model is also sensitive to the excess water. Through this study, a better understanding of the physics and chemical kinetics is obtained, this will enhance the STC design process.

  12. Converging cylindrical shocks in ideal magnetohydrodynamics

    International Nuclear Information System (INIS)

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.

    2014-01-01

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=√(μ 0 /p 0 ) I/(2 π) where I is the current, μ 0 is the permeability, and p 0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field

  13. Converging cylindrical shocks in ideal magnetohydrodynamics

    KAUST Repository

    Pullin, D. I.

    2014-09-01

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R = √μ0/p0 I/(2π) where I is the current, μ0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then

  14. Converging cylindrical shocks in ideal magnetohydrodynamics

    KAUST Repository

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, Ravi

    2014-01-01

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R = √μ0/p0 I/(2π) where I is the current, μ0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then

  15. Converging cylindrical shocks in ideal magnetohydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Pullin, D. I. [Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, California 91125 (United States); Mostert, W.; Wheatley, V. [School of Mechanical and Mining Engineering, University of Queensland, Queensland 4072 (Australia); Samtaney, R. [Mechanical Engineering, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)

    2014-09-15

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=√(μ{sub 0}/p{sub 0}) I/(2 π) where I is the current, μ{sub 0} is the permeability, and p{sub 0} is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The

  16. Micro Manufacturing

    DEFF Research Database (Denmark)

    Hansen, Hans Nørgaard

    2003-01-01

    Manufacturing deals with systems that include products, processes, materials and production systems. These systems have functional requirements, constraints, design parameters and process variables. They must be decomposed in a systematic manner to achieve the best possible system performance....... If a micro manufacturing system isn’t designed rationally and correctly, it will be high-cost, unreliable, and not robust. For micro products and systems it is a continuously increasing challenge to create the operational basis for an industrial production. As the products through product development...... processes are made applicable to a large number of customers, the pressure in regard to developing production technologies that make it possible to produce the products at a reasonable price and in large numbers is growing. The micro/nano manufacturing programme at the Department of Manufacturing...

  17. Arbitrarily elliptical-cylindrical invisible cloaking

    International Nuclear Information System (INIS)

    Jiang Weixiang; Cui Tiejun; Yu Guanxia; Lin Xianqi; Cheng Qiang; Chin, J Y

    2008-01-01

    Based on the idea of coordinate transformation (Pendry, Schurig and Smith 2006 Science 312 1780), arbitrarily elliptical-cylindrical cloaks are proposed and designed. The elliptical cloak, which is composed of inhomogeneous anisotropic metamaterials in an elliptical-shell region, will deflect incoming electromagnetic (EM) waves and guide them to propagate around the inner elliptical region. Such EM waves will return to their original propagation directions without distorting the waves outside the elliptical cloak. General formulations of the inhomogeneous and anisotropic permittivity and permeability tensors are derived for arbitrarily elliptical axis ratio k, which can also be used for the circular cloak when k = 1. Hence the elliptical cloaks can make a large range of objects invisible, from round objects (when k approaches 1) to long and thin objects (when k is either very large or very small). We also show that the material parameters in elliptical cloaking are singular at only two points, instead of on the whole inner circle for circular cloaking, which are much easier to be realized in actual applications. Full-wave simulations are given to validate the arbitrarily elliptical cloaking

  18. Electrical tensor Green functions for cylindrical waveguides

    International Nuclear Information System (INIS)

    Prijmenko, S.D.; Papkovich, V.G.; Khizhnyak, N.A.

    1988-01-01

    Formation of electrical tensor Green functions for cylindrical waveguides is considered. Behaviour of these functions in the source region is studied. Cases of electrical tensor Green functions for vector potential G E (r-vector, r'-vector) and electric field G e (r-vector, r'-vector) are analysed. When forming G E (r-vector, r'-vector), its dependence on lateral coordinates is taken into account by means of two-dimensional fundamental vector Hansen functions, several methods are used to take into account the dependence on transverse coordinate. When forming G e (r-vector, r'-vector) we use the fact that G E (r-vector, r'-vector) and G e (r-vector, r'-vector) are the generalized functions. It is shown that G e (r-vector, r'-vector) behaviour in the source region is defined by a singular term, which properties are described by the delta-function. Two variants of solving the problem of defining singular and regular sides of tensor function G E (r-vector, r'-vector) are presented. 23 refs

  19. Cylindrical Hall Thrusters with Permanent Magnets

    International Nuclear Information System (INIS)

    Raitses, Yevgeny; Merino, Enrique; Fisch, Nathaniel J.

    2010-01-01

    The use of permanent magnets instead of electromagnet coils for low power Hall thrusters can offer a significant reduction of both the total electric power consumption and the thruster mass. Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) of different overall dimensions were operated in the power range of 50W-300 W. The discharge and plasma plume measurements revealed that the CHT thrusters with permanent magnets and electromagnet coils operate rather differently. In particular, the angular ion current density distribution from the permanent magnet thrusters has an unusual halo shape, with a majority of high energy ions flowing at large angles with respect to the thruster centerline. Differences in the magnetic field topology outside the thruster channel and in the vicinity of the channel exit are likely responsible for the differences in the plume characteristics measured for the CHTs with electromagnets and permanent magnets. It is shown that the presence of the reversing-direction or cusp-type magnetic field configuration inside the thruster channel without a strong axial magnetic field outside the thruster channel does not lead to the halo plasma plume from the CHT.

  20. Parametric Investigation of Miniaturized Cylindrical and Annular Hall Thrusters

    International Nuclear Information System (INIS)

    Smirnov, A.; Raitses, Y.; Fisch, N.J.

    2002-01-01

    Conventional annular Hall thrusters become inefficient when scaled to low power. An alternative approach, a 2.6-cm miniaturized cylindrical Hall thruster with a cusp-type magnetic field distribution, was developed and studied. Its performance was compared to that of a conventional annular thruster of the same dimensions. The cylindrical thruster exhibits discharge characteristics similar to those of the annular thruster, but it has a much higher propellant ionization efficiency. Significantly, a large fraction of multi-charged xenon ions might be present in the outgoing ion flux generated by the cylindrical thruster. The operation of the cylindrical thruster is quieter than that of the annular thruster. The characteristic peak in the discharge current fluctuation spectrum at 50-60 kHz appears to be due to ionization instabilities. In the power range 50-300 W, the cylindrical and annular thrusters have comparable efficiencies (15-32%) and thrusts (2.5-12 mN). For the annular configuration, a voltage less than 200 V was not sufficient to sustain the discharge at low propellant flow rates. The cylindrical thruster can operate at voltages lower than 200 V, which suggests that a cylindrical thruster can be designed to operate at even smaller power

  1. Experimental Investigation of A Twin Shaft Micro Gas-Turbine System

    International Nuclear Information System (INIS)

    Sadig, Hussain; Sulaiman, Shaharin Anwar; Ibrahim, Idris

    2013-01-01

    Due to the fast depletion of fossil fuels and its negative impact on the environment, more attention has been concentrated to find new resources, policies and technologies, which meet the global needs with regard to fuel sustainability and emissions. In this paper, as a step to study the effect of burning low calorific value fuels on gas-turbine performance; a 50 kW slightly pressurized non-premixed tubular combustor along with turbocharger based twin shaft micro gas-turbine was designed and fabricated. A series of tests were conducted to characterize the system using LPG fuel. The tests include the analysis of the temperature profile, pressure and combustor efficiency as well as air fuel ratio and speed of the second turbine. The tests showed a stable operation with acceptable efficiency, air fuel ratio, and temperature gradient for the single and twin shaft turbines.

  2. Effect of thermal exposure on the residual stress relaxation in a hardened cylindrical sample under creep conditions

    Science.gov (United States)

    Radchenko, V. P.; Saushkin, M. N.; Tsvetkov, V. V.

    2016-05-01

    This paper describes the effect of thermal exposure (high-temperature exposure) ( T = 675°C) on the residual creep stress relaxation in a surface hardened solid cylindrical sample made of ZhS6UVI alloy. The analysis is carried out with the use of experimental data for residual stresses after micro-shot peening and exposures to temperatures equal to T = 675°C during 50, 150, and 300 h. The paper presents the technique for solving the boundary-value creep problem for the hardened cylindrical sample with the initial stress-strain state under the condition of thermal exposure. The uniaxial experimental creep curves obtained under constant stresses of 500, 530, 570, and 600 MPa are used to construct the models describing the primary and secondary stages of creep. The calculated and experimental data for the longitudinal (axial) tensor components of residual stresses are compared, and their satisfactory agreement is determined.

  3. Genetic algorithm to optimize the design of main combustor and gas generator in liquid rocket engines

    Science.gov (United States)

    Son, Min; Ko, Sangho; Koo, Jaye

    2014-06-01

    A genetic algorithm was used to develop optimal design methods for the regenerative cooled combustor and fuel-rich gas generator of a liquid rocket engine. For the combustor design, a chemical equilibrium analysis was applied, and the profile was calculated using Rao's method. One-dimensional heat transfer was assumed along the profile, and cooling channels were designed. For the gas-generator design, non-equilibrium properties were derived from a counterflow analysis, and a vaporization model for the fuel droplet was adopted to calculate residence time. Finally, a genetic algorithm was adopted to optimize the designs. The combustor and gas generator were optimally designed for 30-tonf, 75-tonf, and 150-tonf engines. The optimized combustors demonstrated superior design characteristics when compared with previous non-optimized results. Wall temperatures at the nozzle throat were optimized to satisfy the requirement of 800 K, and specific impulses were maximized. In addition, the target turbine power and a burned-gas temperature of 1000 K were obtained from the optimized gas-generator design.

  4. 40 CFR 60.52a - Standard for municipal waste combustor metals.

    Science.gov (United States)

    2010-07-01

    ... Municipal Waste Combustors for Which Construction is Commenced After December 20, 1989 and on or Before... per dry standard cubic meter (0.015 grains per dry standard cubic foot), corrected to 7 percent oxygen (dry basis). (b) On and after the date on which the initial compliance test is completed or is required...

  5. 40 CFR 60.54a - Standard for municipal waste combustor acid gases.

    Science.gov (United States)

    2010-07-01

    ... for Municipal Waste Combustors for Which Construction is Commenced After December 20, 1989 and on or... weight or volume) or 30 parts per million by volume, corrected to 7 percent oxygen (dry basis), whichever... by volume, corrected to 7 percent oxygen (dry basis), whichever is less stringent. ...

  6. Experimental evaluation of sorbents for sulfur control in a coal-fueled gas turbine slagging combustor

    International Nuclear Information System (INIS)

    Cowell, L.H.; Wen, C.S.; LeCren, R.T.

    1992-01-01

    This paper reports on a slagging combustor that has been used to evaluate three calcium-based sorbents for sulfur capture efficiency in order to assess their applicability for use in a oil-fueled gas turbine. Testing is competed in a bench-scale combustor with one-tenth the heat input needed for the full-scale gas turbine. The bench-scale rig is a two-stage combustor featuring a fuel-rich primary zone an a fuel-lean secondary zone. The combustor is operated at 6.5 bars with inlet air preheated to 600 K. Gas temperatures of 1840 K are generated in the primary zone and 1280 K in the secondary zone. Sorbents are either fed into the secondary zone or mixed with the coal-water mixture and fed into the primary zone. Dry powered sorbents are fed into the secondary zone by an auger into one of six secondary air inlet ports. The three sorbents tested in the secondary zone include dolomite, pressure-hydrated dolomitic lime, and hydrated lime. Sorbents have been tested while burning coal-water mixtures with coal sulfur loadings of 0.56 to 3.13 weight percent sulfur. Sorbents are injected into the secondary zone at varying flow rates such that the calcium/sulfur ratio varies from 0.5 to 10.0

  7. Wall heat flux influence on the thermodynamic optimisation of irreversibilities of a circulating fluidised bed combustor

    CSIR Research Space (South Africa)

    Baloyi, J

    2016-07-01

    Full Text Available . The irreversibilities generated were arrived at by computing the entropy generation rates due to the combustion and frictional pressure drop processes. For the combustor where the wall condition was changed from adiabatic to negative heat flux (that is heat leaving...

  8. 40 CFR 62.14105 - Requirements for municipal waste combustor operator training and certification.

    Science.gov (United States)

    2010-07-01

    ... American Society of Mechanical Engineers, Service Center, 22 Law Drive, Post Office Box 2900, Fairfield, NJ..., Service Center, 22 Law Drive, Post Office Box 2900, Fairfield, NJ 07007. You may inspect a copy at the... subpart; (2) A description of basic combustion theory applicable to a municipal waste combustor unit; (3...

  9. The NASA Ames Hypersonic Combustor-Model Inlet CFD Simulations and Experimental Comparisons

    Science.gov (United States)

    Venkatapathy, E.; Tokarcik-Polsky, S.; Deiwert, G. S.; Edwards, Thomas A. (Technical Monitor)

    1995-01-01

    Computations have been performed on a three-dimensional inlet associated with the NASA Ames combustor model for the hypersonic propulsion experiment in the 16-inch shock tunnel. The 3-dimensional inlet was designed to have the combustor inlet flow nearly two-dimensional and of sufficient mass flow necessary for combustion. The 16-inch shock tunnel experiment is a short duration test with test time of the order of milliseconds. The flow through the inlet is in chemical non-equilibrium. Two test entries have been completed and limited experimental results for the inlet region of the combustor-model are available. A number of CFD simulations, with various levels of simplifications such as 2-D simulations, 3-D simulations with and without chemical reactions, simulations with and without turbulent conditions, etc., have been performed. These simulations have helped determine the model inlet flow characteristics and the important factors that affect the combustor inlet flow and the sensitivity of the flow field to these simplifications. In the proposed paper, CFD modeling of the hypersonic inlet, results from the simulations and comparison with available experimental results will be presented.

  10. Characterization of Centrifugally-Loaded Flame Migration for Ultra-Compact Combustors

    Science.gov (United States)

    2011-10-01

    configuration on the flat vane. However, Radtke [38] investigated a curved radial vane geometry and demonstrated increased combustion eciency with the curved...Hancock, R. D., “Ultra-Compact Combustors for Advanced Gas Turbine Engines,” ASME Turbo Expo 2004 , GT-2004-53155, 2004. [38] Radtke , J. T., Eciency

  11. Bed agglomeration in fluidized combustor fueled by wood and rice straw blends

    DEFF Research Database (Denmark)

    Thy, Peter; Jenkins, Brian; Williams, R.B.

    2010-01-01

    Abstract Petrographic techniques have been used to examine bed materials from fluidized bed combustion experiments that utilized wood and rice straw fuel blends. The experiments were conducted using a laboratory-scale combustor with mullite sand beds, firing temperatures of 840 to 1030 °C, and ru...

  12. Overview of experimental measurements in a generic can-type gas turbine combustor

    CSIR Research Space (South Africa)

    Meyers, BC

    2009-11-01

    Full Text Available Due to CFD Shortfalls, experimental data on gas turbine combustors is required to obtain insight into the combustion and flow mechanisms as well as for simulation and model validation and evaluation. The temperature and velocity fields of a generic...

  13. Three-component particle image velocimetry in a generic can-type gas turbine combustor

    CSIR Research Space (South Africa)

    Meyers, Bronwyn C

    2012-11-01

    Full Text Available -1 Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy November 2012/ Vol. 226(7) Three-componentParticle Image Velocimetry in a Generic Can-type Gas Turbine Combustor B C Meyers 1, 2* , G C Snedden 1 , J P...

  14. Flow visualization studies of transverse fuel injection patterns in a nonreacting Mach 2 combustor

    Science.gov (United States)

    Mcdaniel, J. C.

    1987-01-01

    Planar visualization images are recorded of transverse jet mixing in a supersonic combustor flowfield, without chemical reaction, using laser-induced fluorescence from iodine molecules. Digital image processing and three-dimensional display enable complete representations of fuel penetration boundary and shock surfaces corresponding to several injection geometries and pressures.

  15. Co-combustor: the solid waste thermal treatment plant in MINT

    International Nuclear Information System (INIS)

    Norasalwa Zakaria; Mohd Azman Che Mat Isa; Sivapalan Kathiravale; Mohd Fairus Abdul Farid; Mohamad Puad Hj Abu; Rosli Darmawan; Muhd Noor Muhd Yunus

    2005-01-01

    MINT has geared up into the field of solid waste thermal treatment processing back in 1999 when a new unit known as MIREC was established. Since then, a fast progress has taken place including the design and construction of a pilot scale incinerator, named as the Co-Combustor. The Co-combustor was designed and developed based on the gasification principles, which employs combustion in starved air condition. In year 2001, this plant was commissioned. To date, it has been running quite well according to its design values. Several test runs were also performed in order to collect and gather data, which serve as a background or backtrack record for upgrading purposes and optimizing its performance in future. On going research is also conducted on this plant especially on the study of the waste's behaviors under combustion. Besides the typical RND activities, the Co-combustor is also currently being used to burn waste paper especially to dispose restricted and confidential documents. This paper will highlight on the design, performance, application and usage of the co-combustor. The direction for research and development activities for this plant is also discussed in this paper so as to strengthen the knowledge and build up expertise in the field of incineration

  16. Optimum diameter of a circulating fluidised bed combustor with negative wall heat flux

    CSIR Research Space (South Africa)

    Baloyi, J

    2015-07-01

    Full Text Available on irreversibilities in a 7 m circulating fluidised bed combustor with a negative wall heat flux, firing a mixture of air and solid pitch pine wood, was investigated. An analytical expression was derived that predicts the entropy generation rate, thereby...

  17. Thermo-acoustic coupling in can-annular combustors : A numerical investigation

    NARCIS (Netherlands)

    Farisco, Federica; Panek, Lukasz; Kok, Jim B.W.; Pent, Jared; Rajaram, Rajesh

    2015-01-01

    Thermo-acoustic instabilities in modern, high power density gas turbines need to be predicted and understood in order to avoid unexpected damage and engine failure. While the annular combustor design is expected to suffer from the occurrence of transverse waves and burner-to-burner acoustic

  18. A three-dimensional algebraic grid generation scheme for gas turbine combustors with inclined slots

    Science.gov (United States)

    Yang, S. L.; Cline, M. C.; Chen, R.; Chang, Y. L.

    1993-01-01

    A 3D algebraic grid generation scheme is presented for generating the grid points inside gas turbine combustors with inclined slots. The scheme is based on the 2D transfinite interpolation method. Since the scheme is a 2D approach, it is very efficient and can easily be extended to gas turbine combustors with either dilution hole or slot configurations. To demonstrate the feasibility and the usefulness of the technique, a numerical study of the quick-quench/lean-combustion (QQ/LC) zones of a staged turbine combustor is given. Preliminary results illustrate some of the major features of the flow and temperature fields in the QQ/LC zones. Formation of co- and counter-rotating bulk flow and shape temperature fields can be observed clearly, and the resulting patterns are consistent with experimental observations typical of the confined slanted jet-in-cross flow. Numerical solutions show the method to be an efficient and reliable tool for generating computational grids for analyzing gas turbine combustors with slanted slots.

  19. Bed agglomeration in fluidized combustor fueled by wood and rice straw blends

    NARCIS (Netherlands)

    Thy, P.; Jenkins, B.M.; Williams, R.B.; Lesher, C.E.; Bakker, R.R.

    2010-01-01

    Petrographic techniques have been used to examine bed materials from fluidized bed combustion experiments that utilized wood and rice straw fuel blends. The experiments were conducted using a laboratory-scale combustor with mullite sand beds, firing temperatures of 840 to 1030 °C, and run durations

  20. Cylindrical solitons in shallow water of variable depth

    International Nuclear Information System (INIS)

    Carbonaro, P.; Floris, R.; Pantano, P.

    1983-01-01

    The propagation and the interaction of cylindrical solitons in shallow water of variable depth are studied. Starting from the cylindrically symmetric version of the equations describing long waves in a beach, a Korteweg-de Vries equation is derived. Since no exact analytical solution has been found to date for this equation, some remarkable cases in which the equation takes up a tractable form are analyzed. Finally the intercation between cylindrical imploding and expanding waves is considered and the phase shifts caused by the head-on collision are given

  1. Vibrational analysis of submerged cylindrical shells based on elastic foundations

    International Nuclear Information System (INIS)

    Shah, A.G.; Naeem, M.N.

    2014-01-01

    In this study a vibration analysis was performed of an isotropic cylindrical shell submerged in fluid, resting on Winkler and Pasternak elastic foundations for simply supported boundary condition. Love's thin shell theory was exploited for strain- and curvature- displacement relationship. Shell problem was solved by using wave propagation approach. Influence of fluid and Winkler as well as Pasternak elastic foundations were studied on the natural frequencies of submerged isotropic cylindrical shells. Results were validated by comparing with the existing results in literature. Vibration, Submerged cylindrical shell, Love's thin shell theory, Wave propagation method, Winkler and Pasternak foundations. (author)

  2. Simulation Investigation on Combustion Characteristics in a Four-Point Lean Direct Injection Combustor with Hydrogen/Air

    Directory of Open Access Journals (Sweden)

    Jianzhong Li

    2017-06-01

    Full Text Available To investigate the combustion characteristics in multi-point lean direct injection (LDI combustors with hydrogen/air, two swirl–venturi 2 × 2 array four-point LDI combustors were designed. The four-point LDI combustor consists of injector assembly, swirl–venturi array and combustion chamber. The injector, swirler and venturi together govern the rapid mixing of hydrogen and air to form the mixture for combustion. Using clockwise swirlers and anticlockwise swirlers, the co-swirling and count-swirling swirler arrays LDI combustors were achieved. Using Reynolds-Averaged Navier–Stokes (RANS code for steady-state reacting flow computations, the four-point LDI combustors with hydrogen/air were simulated with an 11 species and 23 lumped reaction steps H2/Air reaction mechanism. The axial velocity, turbulence kinetic energy, total pressure drop coefficient, outlet temperature, mass fraction of OH and emission of pollutant NO of four-point LDI combustors, with different equivalence ratios, are here presented and discussed. As the equivalence ratios increased, the total pressure drop coefficient became higher because of increasing heat loss. Increasing equivalence ratios also corresponded with the rise in outlet temperature of the four-point LDI combustors, as well as an increase in the emission index of NO EINO in the four-point LDI combustors. Along the axial distance, the EINO always increased and was at maximum at the exit of the dump. Along the chamber, the EINO gradually increased, maximizing at the exit of chamber. The total temperature of four-point LDI combustors with different equivalence ratios was identical to the theoretical equilibrium temperature. The EINO was an exponential function of the equivalence ratio.

  3. External Cylindrical Nozzle with Controlled Vacuum

    Directory of Open Access Journals (Sweden)

    V. N. Pil'gunov

    2015-01-01

    Full Text Available There is a developed design of the external cylindrical nozzle with a vacuum camera. The paper studies the nozzle controllability of flow rate via regulated connection of the evacuated chamber to the atmosphere through an air throttle. Working capacity of the nozzle with inlet round or triangular orifice are researched. The gap is provided in the nozzle design between the external wall of the inlet orifice and the end face of the straight case in the nozzle case. The presented mathematical model of the nozzle with the evacuated chamber allows us to estimate the expected vacuum amount in the compressed section of a stream and maximum permissible absolute pressure at the inlet orifice. The paper gives experimental characteristics of the fluid flow process through the nozzle for different values of internal diameter of a straight case and an extent of its end face remoteness from an external wall of the inlet orifice. It estimates how geometry of nozzle constructive elements influences on the volume flow rate. It is established that the nozzle capacity significantly depends on the shape of inlet orifice. Triangular orifice nozzles steadily work in the mode of completely filled flow area of the straight case at much more amounts of the limit pressure of the flow. Vacuum depth in the evacuated chamber also depends on the shape of inlet orifice: the greatest vacuum is reached in a nozzle with the triangular orifice which 1.5 times exceeds the greatest vacuum with the round orifice. Possibility to control nozzle capacity through the regulated connection of the evacuated chamber to the atmosphere was experimentally estimated, thus depth of flow rate regulation of the nozzle with a triangular orifice was 45% in comparison with 10% regulation depth of the nozzle with a round orifice. Depth of regulation calculated by a mathematical model appeared to be much more. The paper presents experimental dependences of the flow coefficients of nozzle input orifice

  4. Investigation of Methane Oxy-Fuel Combustion in a Swirl-Stabilised Gas Turbine Model Combustor

    Directory of Open Access Journals (Sweden)

    Mao Li

    2017-05-01

    Full Text Available CO2 has a strong impact on both operability and emission behaviours in gas turbine combustors. In the present study, an atmospheric, preheated, swirl-stabilised optical gas turbine model combustor rig was employed. The primary objectives were to analyse the influence of CO2 on the fundamental characteristics of combustion, lean blowout (LBO limits, CO emission and flame structures. CO2 dilution effects were examined with three preheating temperatures (396.15, 431.15, and 466.15 K. The fundamental combustion characteristics were studied utilising chemical kinetic simulations. To study the influence of CO2 on the operational range of the combustor, equivalence ratio (Ф was varied from stoichiometric conditions to the LBO limits. CO emissions were measured at the exit of the combustor using a water-cooled probe over the entire operational range. The flame structures and locations were characterised by performing CH chemiluminescence imaging. The inverse Abel transformation was used to analyse the CH distribution on the axisymmetric plane of the combustor. Chemical kinetic modelling indicated that the CO2 resulted in a lower reaction rate compared with the CH4/air flame. Fundamental combustion properties such as laminar flame speed, ignition delay time and blowout residence time were found to be affected by CO2. The experimental results revealed that CO2 dilution resulted in a narrower operational range for the equivalence ratio. It was also found that CO2 had a strong inhibiting effect on CO burnout, which led to a higher concentration of CO in the combustion exhaust. CH chemiluminescence showed that the CO2 dilution did not have a significant impact on the flame structure.

  5. Thermal characteristics of various biomass fuels in a small-scale biomass combustor

    International Nuclear Information System (INIS)

    Al-Shemmeri, T.T.; Yedla, R.; Wardle, D.

    2015-01-01

    Biomass combustion is a mature and reliable technology, which has been used for heating and cooking. In the UK, biomass currently qualifies for financial incentives such as the Renewable Heat Incentive (RHI). Therefore, it is vital to select the right type of fuel for a small-scale combustor to address different types of heat energy needs. In this paper, the authors attempt to investigate the performance of a small-scale biomass combustor for heating, and the impact of burning different biomass fuels on useful output energy from the combustor. The test results of moisture content, calorific value and combustion products of various biomass samples were presented. Results from this study are in general agreement with published data as far as the calorific values and moisture contents are concerned. Six commonly available biomass fuels were tested in a small-scale combustion system, and the factors that affect the performance of the system were analysed. In addition, the study has extended to examine the magnitude and proportion of useful heat, dissipated by convection and radiation while burning different biomass fuels in the small-scale combustor. It is concluded that some crucial factors have to be carefully considered before selecting biomass fuels for any particular heating application. - Highlights: • Six biomass materials combustion performance in a small combustor was examined. • Fuel combustion rate and amount of heat release has varied between materials. • Heat release by radiation, convection and flue gasses varied between materials. • Study helps engineers and users of biomass systems to select right materials

  6. Seismic response of flexible cylindrical tanks

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, T A; Boley, B A [comps.

    1977-01-01

    An experimental study of the seismic behavior of thin shell circular cylindrical liquid storage tanks is described. The investigation was planned to evaluate the adequacy of present methods of tank design, and was conducted using the Earthquake Simulator Facility of the University of California, Berkeley. The model tank considered in this paper was 6 ft high by 12 ft in diameter, and was welded from thin sheet aluminum to simulate a steel tank 36 feet in diameter. During testing the tank had an open top, held 60 inches of water, and was subjected to a time scaled El Centro (1940) earthquake, amplified to a peak acceleration of 0.5 g. Both base free and base fixed conditions were studied. Results of the experiments demonstrate that fluid pressures included both impulsive and convective components, and that the wave sloshing followed basic theory quite closely. But it also was apparent that the tank flexibility influenced the hydrodynamic pressures, as indicated by pressure amplification in the clamped tank, and by a total change of pressure history in the unclamped case. Significant out of round distortions of the tank were developed, of a three lobe form or the free base case and with four lobes in the fixed base case. Uplift of the tank base was closely related to the out-of-round deformation of the unanchored tank, whereas initial eccentricities apparently caused the section distortions in the anchored system. Stresses in the tank wall do not follow the expected pattern of response to overturning moment; instead they seem to be mainly associated with the section distortions. At present there is no analytical procedure for predicting these distortions .

  7. Numerical determination of transmission probabilities in cylindrical geometry

    International Nuclear Information System (INIS)

    Queiroz Bogado Leite, S. de.

    1989-11-01

    Efficient methods for numerical calculation of transmission probabilities in cylindrical geometry are presented. Relative errors of the order of 10 -5 or smaller are obtained using analytical solutions and low order quadrature integration schemes. (author) [pt

  8. Cylindrical Field Effect Transistor: A Full Volume Inversion Device

    KAUST Repository

    Fahad, Hossain M.

    2010-01-01

    inversion in the body. However, these devices are still limited by lithographic and processing challenges making them unsuitable for commercial production. This thesis explores a unique device structure called the CFET (Cylindrical Field Effect Transistors

  9. Response of an electrostatic probe for a right cylindrical spacer

    DEFF Research Database (Denmark)

    Rerup, T; Crichton, George C; McAllister, Iain Wilson

    1994-01-01

    During the last decade many experimental studies of surface charge phenomena have been undertaken employing right cylindrical spacers. Measurement of the surface charge was performed using small electrostatic field probes to scan across the dielectric surface. Charges are electrostatically induced...

  10. Analysis of Hall Probe Precise Positioning with Cylindrical Permanent Magnet

    International Nuclear Information System (INIS)

    Belicev, P.; Vorozhtsov, A.S.; Vorozhtsov, S.B.

    2007-01-01

    Precise positioning of a Hall probe for cyclotron magnetic field mapping, using cylindrical permanent magnets, was analyzed. The necessary permanent magnet parameters in order to achieve ±20 μm position precision, were determined. (author)

  11. Improving the performance parameters of metal cylindrical grid shell ...

    African Journals Online (AJOL)

    Improving the performance parameters of metal cylindrical grid shell structures. ... Finite element models are designed taking into account minimization of production and ... The force factors and deformation parameters of the basic circuits of a ...

  12. Rotating solitary wave at the wall of a cylindrical container

    KAUST Repository

    Amaouche, Mustapha; Ait Abderrahmane, Hamid; Vatistas, Georgios H.

    2013-01-01

    This paper deals with the theoretical modeling of a rotating solitary surface wave that was observed during water drainage from a cylindrical reservoir, when shallow water conditions were reached. It represents an improvement of our previous study

  13. A single-electron current in a cylindrical nanolayer

    International Nuclear Information System (INIS)

    Kazaryan, E.M.; Aghekyan, N.G.; Sarkisyan, H.A.

    2012-01-01

    The orbital current and the spin magnetic moment current of an electron in a cylindrical nanolayer are investigated. It is shown that under certain conditions, the main contribution to the total current is specified by the spin magnetic moment current

  14. On cylindrically converging shock waves shaped by obstacles

    Energy Technology Data Exchange (ETDEWEB)

    Eliasson, V; Henshaw, W D; Appelo, D

    2007-07-16

    Motivated by recent experiments, numerical simulations were performed of cylindrically converging shock waves. The converging shocks impinged upon a set of zero to sixteen regularly space obstacles. For more than two obstacles the resulting diffracted shock fronts formed polygonal shaped patterns near the point of focus. The maximum pressure and temperature as a function of number of obstacles were studied. The self-similar behavior of cylindrical, triangular and square-shaped shocks were also investigated.

  15. Cylindrical particle manipulation and negative spinning using a nonparaxial Hermite-Gaussian light-sheet beam

    Science.gov (United States)

    Mitri, F. G.

    2016-10-01

    Based on the angular spectrum decomposition method (ASDM), a nonparaxial solution for the Hermite-Gaussian (HG m ) light-sheet beam of any order m is derived. The beam-shape coefficients (BSCs) are expressed in a compact form and computed using the standard Simpson’s rule for numerical integration. Subsequently, the analysis is extended to evaluate the longitudinal and transverse radiation forces as well as the spin torque on an absorptive dielectric cylindrical particle in 2D without any restriction to a specific range of frequencies. The dynamics of the cylindrical particle are also examined based on Newton’s second law of motion. The numerical results show that a Rayleigh or Mie cylindrical particle can be trapped, pulled or propelled in the optical field depending on its initial position in the cross-sectional plane of the HG m light-sheet. Moreover, negative or positive axial spin torques can arise depending on the choice of the non-dimensional size parameter ka (where k is the wavenumber and a is the radius of the cylinder) and the location of the absorptive cylinder in the beam. This means that the HG m light-sheet beam can induce clockwise or anti-clockwise rotations depending on its shift from the center of the cylinder. In addition, individual vortex behavior can arise in the cross-sectional plane of wave propagation. The present analysis presents an analytical model to predict the optical radiation forces and torque induced by a HG m light-sheet beam on an absorptive cylinder for applications in optical light-sheet tweezers, optical micro-machines, particle manipulation and opto-fluidics to name a few areas of research.

  16. Theory and modeling of cylindrical thermo-acoustic transduction

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Lihong, E-mail: lhtong@ecjtu.edu.cn [School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang, Jiangxi (China); Lim, C.W. [Department of Architecture and Civil Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR (China); Zhao, Xiushao; Geng, Daxing [School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang, Jiangxi (China)

    2016-06-03

    Models both for solid and thinfilm-solid cylindrical thermo-acoustic transductions are proposed and the corresponding acoustic pressure solutions are obtained. The acoustic pressure for an individual carbon nanotube (CNT) as a function of input power is investigated analytically and it is verified by comparing with the published experimental data. Further numerical analysis on the acoustic pressure response and characteristics for varying input frequency and distance are also examined both for solid and thinfilm-solid cylindrical thermo-acoustic transductions. Through detailed theoretical and numerical studies on the acoustic pressure solution for thinfilm-solid cylindrical transduction, it is concluded that a solid with smaller thermal conductivity favors to improve the acoustic performance. In general, the proposed models are applicable to a variety of cylindrical thermo-acoustic devices performing in different gaseous media. - Highlights: • Theory and modeling both for solid and thinfilm-solid cylindrical thermo-acoustic transductions are proposed. • The modeling is verified by comparing with the published experimental data. • Acoustic response characteristics of cylindrical thermo-acoustic transductions are predicted by the proposed model.

  17. Micropatterning on cylindrical surfaces via electrochemical etching using laser masking

    International Nuclear Information System (INIS)

    Cho, Chull Hee; Shin, Hong Shik; Chu, Chong Nam

    2014-01-01

    Highlights: • Various micropatterns were fabricated on the cylindrical surface of a stainless steel shaft. • Selective electrochemical dissolution was achieved via a series process of laser masking and electrochemical etching. • Laser masking characteristics on the non-planar surface were investigated. • A uniform mask layer was formed on the cylindrical surface via synchronized laser line scanning with a rotary system. • The characteristics of electrochemical etching on the non-planar surface were investigated. - Abstract: This paper proposes a method of selective electrochemical dissolution on the cylindrical surfaces of stainless steel shafts. Selective electrochemical dissolution was achieved via electrochemical etching using laser masking. A micropatterned recast layer was formed on the surface via ytterbium-doped pulsed fiber laser irradiation. The micropatterned recast layer could be used as a mask layer during the electrochemical etching process. Laser masking condition to form adequate mask layer on the planar surface for etching cannot be used directly on the non-planar surface. Laser masking condition changes depending on the morphological surface. The laser masking characteristics were investigated in order to form a uniform mask layer on the cylindrical surface. To minimize factors causing non-uniformity in the mask layer on the cylindrical surface, synchronized laser line scanning with a rotary system was applied during the laser masking process. Electrochemical etching characteristics were also investigated to achieve deeper etched depth, without collapsing the recast layer. Consequently, through a series process of laser masking and electrochemical etching, various micropatternings were successfully performed on the cylindrical surfaces

  18. Micro Programming

    OpenAIRE

    Spanjersberg , Herman

    2012-01-01

    International audience; In the 1970s a need arose to perform special arithmetic operations on minicomputers much more quickly than had been possible in the past. This paper tells the story of why micro programming was needed for special arithmetic operations on mini computers in the 1970s and how it was implemented. The paper tells how the laboratory in which the first experiment took place had a PDP-9 minicomputer from Digital Equipment Corporation and how the author, with several colleagues...

  19. Numerical Investigation of Merged and Non-merged Flame of a Twin Cavity Annular Trapped Vortex Combustor

    Directory of Open Access Journals (Sweden)

    Pravendra Kumar

    2016-09-01

    Full Text Available : The present work is focused to characterize numerically the merged and non-merged flame emanating from the cavities in downstream of twin cavity Annular Trapped Vortex Combustor (ATVC.The isotherm corresponding to the auto-ignition temperature is used to locate the merging point of the flame in the mainstream region along the combustor length. In present study, the cavity flame is said to be merged only if this isotherm corresponding to self-ignition temperature of methane is located within 20 percentage of the combustor length from aft wall of cavities. It is interesting to note that on increasing the power loading parameter (PLP in mainstream for a constant power loading parameter ratio (outer to inner cavity, the merging point gets shifted towards the cavity aft-wall. This leads to the reduction of combustor length and subsequent reduction in overall weight of the gas turbine engine.

  20. Experimental study on combustion modes and thrust performance of a staged-combustor of the scramjet with dual-strut

    Science.gov (United States)

    Yang, Qingchun; Chetehouna, Khaled; Gascoin, Nicolas; Bao, Wen

    2016-05-01

    To enable the scramjet operate in a wider flight Mach number, a staged-combustor with dual-strut is introduced to hold more heat release at low flight Mach conditions. The behavior of mode transition was examined using a direct-connect model scramjet experiment along with pressure measurements. The typical operating modes of the staged-combustor are analyzed. Fuel injection scheme has a significant effect on the combustor operating modes, particularly for the supersonic combustion mode. Thrust performances of the combustor with different combustion modes and fuel distributions are reported in this paper. The first-staged strut injection has a better engine performance in the operation of subsonic combustion mode. On the contrast, the second-staged strut injection has a better engine performance in the operation of supersonic combustion mode.

  1. Investigations on the Influence of the In-Stream Pylon and Strut on the Performance of a Scramjet Combustor

    Directory of Open Access Journals (Sweden)

    Hao Ouyang

    2014-01-01

    Full Text Available The influence of the in-stream pylon and strut on the performance of scramjet combustor was experimentally and numerically investigated. The experiments were conducted with a direct-connect supersonic model combustor equipped with multiple cavities. The entrance parameter of combustor corresponds to scramjet flight Mach number 4.0 with a total temperature of 947 K. The research results show that, compared with the scramjet combustor without pylon and strut, the wall pressure and the thrust of the scramjet increase due to the improvement of mixing and combustion effect due to the pylon and strut. The total pressure loss caused by the strut is considerable whereas pylon influence is slight.

  2. Diode Laser Sensor for Gas Temperature and H2O Concentration in a Scramjet Combustor Using Wavelength Modulation Spectroscopy (Postprint)

    National Research Council Canada - National Science Library

    Rieker, Gregory B; Li, Jonathan T; Jeffries, Jay B; Mathur, Tarun; Gruber, Mark R; Carter, Campbell D

    2005-01-01

    A diode laser absorption sensor which probes three spectral features of water vapor in the near infrared region to infer gas temperature and water vapor concentration near the exit of a scramjet combustor is presented...

  3. Development and Modeling of Angled Effusion Cooling for the BR715 Low Emission Staged Combustor Core Demonstrator

    National Research Council Canada - National Science Library

    Gerendas, M

    2003-01-01

    .... The combustor cooling concept chosen was of the angled effusion type. Development of adequate modeling techniques and steady-state and transient rig tests to calibrate the thermal models was the key factor for the success...

  4. CHARACTERIZATION OF CATALYTIC COMBUSTOR TURBULENCE AND ITS INFLUENCE ON VANE AND ENDWALL HEAT TRANSFER AND ENDWALL FILM COOLING

    Energy Technology Data Exchange (ETDEWEB)

    Forrest E. Ames

    2002-10-01

    Endwall heat transfer distributions taken in a large-scale low speed linear cascade facility are documented for mock catalytic and dry low NOx (DLN) combustion systems. Inlet turbulence levels range from about 1.0 percent for the mock Catalytic combustor condition to 14 percent for the mock dry low NOx combustor system. Stanton number contours are presented at both turbulence conditions for Reynolds numbers based on true chord length and exit conditions ranging from 500,000 to 2,000,000. Catalytic combustor endwall heat transfer shows the influence of the complex three-dimensional flow field, while the effects of individual vortex systems are less evident for the mock dry low NOx cases. Turbulence scales have been documented for both cases. Inlet boundary layers are relatively thin for the mock catalytic combustor case while inlet flow approximates a channel flow with high turbulence for the mock DLN combustor case. Inlet boundary layer parameters are presented across the inlet passage for the three Reynolds numbers and both the mock catalytic and DLN combustor inlet cases. Both midspan and 95 percent span pressure contours are included. This research provides a well-documented database taken across a range of Reynolds numbers and turbulence conditions for assessment of endwall heat transfer predictive capabilities.

  5. An Experimental Study on Axial Temperature Distribution of Combustion of Dewatered Poultry Sludge in Fluidized bed combustor

    Directory of Open Access Journals (Sweden)

    Abbas A.H.

    2016-01-01

    Full Text Available A laboratory scale bubbling fluidized bed combustor was designed and fabricated to study the combustion of dewatered poultry sludge at different operational parameters. This paper present a study on the influence of equivalent ratio, secondary to primary air ratio and the fuel feed rate on the temperature distribution along the combustor. The equivalent ratio has been changed between 0.8 to 1.4% under poultry sludge feed rate of 10 kg/h and from 0.8 to 1 under poultry sludge feed rate of 15 kg/h. The secondary to primary air ratio was varied from 0.1 to 0.5 at 0.65 m injection height and 1.25 equivalent ratio. The results showed that these factors had a significant influence on the combustion characteristics of poultry sludge. The temperature distribution along the combustor was found to be strongly dependent on the fuel feed rate and the equivalent ratio and it increased when these two factors increased. However, the secondary air ratio increased the temperature in the lower region of the combustor while no significant effect was observed at the upper region of the combustor. The results suggested that the poultry sludge can be used as a fuel with high thermal combustor efficiency.

  6. Large eddy simulation of combustion characteristics in a kerosene fueled rocket-based combined-cycle engine combustor

    Science.gov (United States)

    Huang, Zhi-wei; He, Guo-qiang; Qin, Fei; Cao, Dong-gang; Wei, Xiang-geng; Shi, Lei

    2016-10-01

    This study reports combustion characteristics of a rocket-based combined-cycle engine combustor operating at ramjet mode numerically. Compressible large eddy simulation with liquid kerosene sprayed and vaporized is used to study the intrinsic unsteadiness of combustion in such a propulsion system. Results for the pressure oscillation amplitude and frequency in the combustor as well as the wall pressure distribution along the flow-path, are validated using experimental data, and they show acceptable agreement. Coupled with reduced chemical kinetics of kerosene, results are compared with the simultaneously obtained Reynolds-Averaged Navier-Stokes results, and show significant differences. A flow field analysis is also carried out for further study of the turbulent flame structures. Mixture fraction is used to determine the most probable flame location in the combustor at stoichiometric condition. Spatial distributions of the Takeno flame index, scalar dissipation rate, and heat release rate reveal that different combustion modes, such as premixed and non-premixed modes, coexisted at different sections of the combustor. The RBCC combustor is divided into different regions characterized by their non-uniform features. Flame stabilization mechanism, i.e., flame propagation or fuel auto-ignition, and their relative importance, is also determined at different regions in the combustor.

  7. Parameterised Model of 2D Combustor Exit Flow Conditions for High-Pressure Turbine Simulations

    Directory of Open Access Journals (Sweden)

    Marius Schneider

    2017-12-01

    Full Text Available An algorithm is presented generating a complete set of inlet boundary conditions for Reynolds-averaged Navier–Stokes computational fluid dynamics (RANS CFD of high-pressure turbines to investigate their interaction with lean and rich burn combustors. The method shall contribute to understanding the sensitivities of turbine aerothermal performance in a systematic approach. The boundary conditions are based on a set of input parameters controlling velocity, temperature, and turbulence fields. All other quantities are derived from operating conditions and additional modelling assumptions. The algorithm is coupled with a CFD solver by applying the generated profiles as inlet boundary conditions. The successive steps to derive consistent flow profiles are described and results are validated against flow fields extracted from combustor CFD.

  8. Large Eddy Simulations and Experimental Investigation of Flow in a Swirl Stabilized Combustor

    KAUST Repository

    Kewlani, Gaurav

    2012-01-09

    Swirling flows are the preferred mode of flame stabilization in lean premixed gas turbine engine combustors. Developing a fundamental understanding of combustion dynamics and flame stability in such systems requires a detailed investigation of the complex interactions between fluid mechanics and combustion. The turbulent reacting flow in a sudden expansion swirl combustor is studied using compressible large eddy simulations (LES) and compared with experimental data measured using PIV. Different vortex breakdown structures are observed, as the mixture equivalence ratio is reduced, that progressively diminish the stability of the flame. Sub-grid scale combustion models such as the artificially thickened flame method and the partially stirred reactor approach, along with appropriate chemical schemes, are implemented to describe the flame. The numerical predictions for average velocity correspond well with experimental results, and higher accuracy is obtained using the more detailed reaction mechanism. Copyright © 2012 American Institute of Aeronautics and Astronautics, Inc.

  9. NOx results from two combustors tested on medium BTU coal gas

    Science.gov (United States)

    Sherlock, T. P.; Carl, D. E.; Vermes, G.; Schwab, J.; Notardonato, J. J.

    1982-01-01

    The results of tests of two combustor configurations using coal gas from a 25 ton/day fluidized bed coal gasifier are reported. The trials were run with a ceramic-lined, staged rich/lean burner and an integral, all metal multiannular swirl burner (MASB) using a range of temperatures and pressures representative of industrial turbine inlet conditions. A lean mixture was examined at 104, 197, and 254 Btu/Scf, yielding NO(x) emissions of 5, 20, and 70 ppmv, respectively. The MASB was employed only with a gas rated at 220-270 Btu/Scf, producing 80 ppmv NO(x) at rated engine conditions. The results are concluded to be transferrable to current machines. Further tests on the effects of gas composition, the scaling of combustors to utility size, and the development of improved wall cooling techniques and variable geometry are indicated.

  10. Ultra low injection angle fuel holes in a combustor fuel nozzle

    Science.gov (United States)

    York, William David

    2012-10-23

    A fuel nozzle for a combustor includes a mixing passage through which fluid is directed toward a combustion area and a plurality of swirler vanes disposed in the mixing passage. Each swirler vane of the plurality of swirler vanes includes at least one fuel hole through which fuel enters the mixing passage in an injection direction substantially parallel to an outer surface of the plurality of swirler vanes thereby decreasing a flameholding tendency of the fuel nozzle. A method of operating a fuel nozzle for a combustor includes flowing a fluid through a mixing passage past a plurality of swirler vanes and injecting a fuel into the mixing passage in an injection direction substantially parallel to an outer surface of the plurality of swirler vanes.

  11. Numerical Simulation of Combustion and Rotor-Stator Interaction in a Turbine Combustor

    Directory of Open Access Journals (Sweden)

    Dragos D. Isvoranu

    2003-01-01

    Full Text Available This article presents the development of a numerical algorithm for the computation of flow and combustion in a turbine combustor. The flow and combustion are modeled by the Reynolds-averaged Navier-Stokes equations coupled with the species-conservation equations. The chemistry model used herein is a two-step, global, finite-rate combustion model for methane and combustion gases. The governing equations are written in the strong conservation form and solved using a fully implicit, finite-difference approximation. The gas dynamics and chemistry equations are fully decoupled. A correction technique has been developed to enforce the conservation of mass fractions. The numerical algorithm developed herein has been used to investigate the flow and combustion in a one-stage turbine combustor.

  12. Experiments and computations on coaxial swirling jets with centerbody in an axisymmetric combustor

    International Nuclear Information System (INIS)

    Chao, Y.C.; Ho, W.C.; Lin, S.K.

    1987-01-01

    Experiments and computations of turbulent, confined, coannular swirling flows have been performed in a model combustor. Numerical results are obtained by means of a revised two-equation model of turbulence. The combustor consists of two confined, concentric, swirling jets and a centerbody at the center of the inlet. Results are reported for cold flow conditions under co- and counter-swirl. The numerical results agree with the experimental data under both conditions. The size of the central recirculation zone is dominated by the strength of the outer swirl. A two-cell recirculation zone may be formed due to the presence of the swirler hub. The mechanism of interaction between the separation bubble at the hub of the swirler and the central recirculation zone due to vortex breakdown is also investigated. 18 references

  13. An evaluation of a pre-charging pulse-jet filter for small combustor particulate control

    Energy Technology Data Exchange (ETDEWEB)

    Quimby, J.M.

    1990-04-01

    The objective of this test program is the performance and economic evaluation of a pre charged-pulse jet filter as the principal particulate control device for a commercial or industrial scale coal fired combustor. Performance factors that will be considered are the effects of particle charge, air/cloth ratio, fabric types, percent humidity and inlet particulate loading on fine particle collection efficiency, and pressure drop. Economic factors that will be considered are capital costs, energy and other operating costs, and maintenance costs. The program will result in a recommendation regarding the relative suitability of the pre charged pulse-jet filter for small combustor particulate control, as compared to other control devices. Fine particle control capability, ease of operation, and overall economics will be taken into consideration in making comparisons.

  14. Analysis and Control of an Unstable Mode in a Combustor with Tuneable End Condition

    Directory of Open Access Journals (Sweden)

    Maria Heckl

    2013-09-01

    Full Text Available A major problem in the development of low-pollution combustion systems are thermo-acoustic instabilities, i.e. large-amplitude oscillations generated by a feedback between the unsteady heat release and acoustic waves. In order to develop robust control strategies, it is necessary to have a predictive model that captures the physics of the phenomenon. The aim of this paper is to present such a model for a dump combustor with a generic heat release law, and fitted at the inlet end with a perforated plate backed by a tuneable cavity. Our model leads to a simple governing equation for one acoustic mode in the combustor, and from this equation stability predictions can be made with a minimum of numerical effort. We will use it to examine the effect of various system parameters.

  15. Diffuse interfacelets in transcritical flows of propellants into high-pressure combustors

    Science.gov (United States)

    Urzay, Javier; Jofre, Lluis

    2017-11-01

    Rocket engines and new generations of high-power jet engines and diesel engines oftentimes involve the injection of one or more reactants at subcritical temperatures into combustor environments at high pressures, and more particularly, at pressures higher than those corresponding to the critical points of the individual components of the mixture, which typically range from 13 to 50 bars for most propellants. This class of trajectories in the thermodynamic space has been traditionally referred to as transcritical. Under particular conditions often found in hydrocarbon-fueled chemical propulsion systems, and despite the prevailing high pressures, the flow in the combustor may contain regions close to the injector where a diffuse interface is formed in between the fuel and oxidizer streams that is sustained by surface-tension forces as a result of the elevation of the critical pressure of the mixture. This talk describes progress towards modeling these effects in the conservation equations. Funded by the US Department of Energy.

  16. Combustion of biomass-derived, low caloric value, fuel gas in a gasturbine combustor

    Energy Technology Data Exchange (ETDEWEB)

    Andries, J; Hoppesteyn, P D.J.; Hein, K R.G. [Technische Univ. Delf (Netherlands)

    1998-09-01

    The use of biomass and biomass/coal mixtures to produce electricity and heat reduces the net emissions of CO{sub 2}, contributes to the restructuring of the agricultural sector, helps to reduce the waste problem and saves finite fossil fuel reserves. Pressurised fluidised bed gasification followed by an adequate gas cleaning system, a gas turbine and a steam turbine, is a potential attractive way to convert biomass and biomass/coal mixtures. To develop and validate mathematical models, which can be used to design and operate Biomass-fired Integrated Gasification Combined Cycle (BIGCC) systems, a Process Development Unit (PPDU) with a maximum thermal capacity of 1.5 MW{sub th}, located at the Laboratory for Thermal Power Engineering of the Delft University of Technology in The Netherlands is being used. The combustor forms an integral part of this facility. Recirculated flue gas is used to cool the wall of the combustor. (orig.)

  17. Power deposition in a cylindrical geometry using B-10 coatings

    International Nuclear Information System (INIS)

    Chung, A.K.; Prelas, M.A.

    1983-01-01

    The transport of charged particles produced by 10 B (n, α) Li and 235 U (n, νn) ff nuclear reactions in a two region cylindrical geometry is predicted. We employed a mean-range straight-flight approximation to calculate the power deposition by the charged particles in a gaseous medium. Our model demonstrated some features in a cylindrical experiment which were suspected but not proven. In the common slab model used by Guyot et al 1 and Romero 2 , the spatial distribution of power deposition is much flatter than it would be in a cylindrical model. A steeper gradient in the power deposition is expected in a cylindrical geometry than in a slab geometry. We also found that for a standard thickness of Boron-10 coating (1.73 μm) used in NPLs, the expected efficiency of a cylindrical geometry (7.5%) is much lower than the 12% efficiency predicted by the slab model. Indeed the use of slab geometry in modeling current NPL experimental devices is not accurate

  18. Sensitivity optimization in whispering gallery mode optical cylindrical biosensors

    Science.gov (United States)

    Khozeymeh, F.; Razaghi, M.

    2018-01-01

    Whispering-gallery-mode resonances propagated in cylindrical resonators have two angular and radial orders of l and i. In this work, the higher radial order whispering-gallery-mode resonances, (i = 1 - 4), at a fixed l are examined. The sensitivity of theses resonances is analysed as a function of the structural parameters of the cylindrical resonator like different radii and refractive index of composed material of the resonator. A practical application where cylindrical resonators are used for the measurement of glucose concentration in water is presented as a biosensor demonstrator. We calculate the wavelength shifts of the WG1-4, in several glucose/water solutions, with concentrations spanning from 0.0% to 9.0.% (weight/weight). Improved sensitivity can be achieved using multi-WGM cylindrical resonators with radius of R = 100 μm and resonator composed material of MgF 2 with refractive index of nc = 1.38. Also the effect of polarization on sensitivity is considered for all four WGMs. The best sensitivity of 83.07 nm/RIU for the fourth WGM with transverse magnetic polarization, is reported. These results propose optimized parameters aimed to fast designing of cylindrical resonators as optical biosensors, where both the sensitivity and the geometries can be optimized.

  19. The decrease of cylindrical pempek quality during boiling

    Science.gov (United States)

    Karneta, R.; Gultom, N. F.

    2017-09-01

    The research objective was to study the effects of temperature and formulation on quality of pempek lenjer during boiling. Treatments in this study were four levels of pempek formulation and five levels of temperature. Data was processed by using analysis of variance (Anova). If test results showed that samples were significantly different or highly significantly different, then further test was conducted by using Honestly Significant Different. The results showed that chemical analysis showed that fish dominant formula of cylindrical pempek had higher water content, protein content, lipid content and ash content than that of tapioca starch dominant formula, but it had lower carbohydrate content and fibre content than that of tapioca starch dominant formula.The higher the temperature at center point of cylindrical pempek, the lower the chemical quality of cylindrical pempek. The effect of formula on physical quality of cylindrical pempek showed that tapioca starch dominant formula had more rubbery texture, more neutral pH and brighter color than that of fish dominant formula.The temperature change had no significant effect on texture and pH of cylindrical pempek, but it had significant effect on lightness, intensity and chromatic color especially after exceeding optimum time of boiling.

  20. Novel spherical hohlraum with cylindrical laser entrance holes and shields

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Ke [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Zheng, Wudi [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

    2014-09-15

    Our recent works [K. Lan et al., Phys. Plasmas 21, 010704 (2014); K. Lan et al., Phys. Plasmas 21, 052704 (2014)] have shown that the octahedral spherical hohlraums are superior to the cylindrical hohlraums in both higher symmetry during the capsule implosion and lower backscatter without supplementary technology. However, both the coupling efficiency from the drive laser energy to the capsule and the capsule symmetry decrease remarkably when larger laser entrance holes (LEHs) are used. In addition, the laser beams injected at angles > 45° transport close to the hohlraum wall, thus the wall blowoff causes the LEH to close faster and results in strong laser plasma interactions inside the spherical hohlraums. In this letter, we propose a novel octahedral hohlraum with LEH shields and cylindrical LEHs to alleviate these problems. From our theoretical study, with the LEH shields, the laser coupling efficiency is significantly increased and the capsule symmetry is remarkably improved in the spherical hohlraums. The cylindrical LEHs take advantage of the cylindrical hohlraum near the LEH and mitigate the influence of the blowoff on laser transport inside a spherical hohlraum. The cylindrical LEHs can also be applied to the rugby and elliptical hohlraums.

  1. Novel spherical hohlraum with cylindrical laser entrance holes and shields

    International Nuclear Information System (INIS)

    Lan, Ke; Zheng, Wudi

    2014-01-01

    Our recent works [K. Lan et al., Phys. Plasmas 21, 010704 (2014); K. Lan et al., Phys. Plasmas 21, 052704 (2014)] have shown that the octahedral spherical hohlraums are superior to the cylindrical hohlraums in both higher symmetry during the capsule implosion and lower backscatter without supplementary technology. However, both the coupling efficiency from the drive laser energy to the capsule and the capsule symmetry decrease remarkably when larger laser entrance holes (LEHs) are used. In addition, the laser beams injected at angles > 45° transport close to the hohlraum wall, thus the wall blowoff causes the LEH to close faster and results in strong laser plasma interactions inside the spherical hohlraums. In this letter, we propose a novel octahedral hohlraum with LEH shields and cylindrical LEHs to alleviate these problems. From our theoretical study, with the LEH shields, the laser coupling efficiency is significantly increased and the capsule symmetry is remarkably improved in the spherical hohlraums. The cylindrical LEHs take advantage of the cylindrical hohlraum near the LEH and mitigate the influence of the blowoff on laser transport inside a spherical hohlraum. The cylindrical LEHs can also be applied to the rugby and elliptical hohlraums

  2. A cylindrical specimen holder for electron cryo-tomography

    International Nuclear Information System (INIS)

    Palmer, Colin M.; Löwe, Jan

    2014-01-01

    The use of slab-like flat specimens for electron cryo-tomography restricts the range of viewing angles that can be used. This leads to the “missing wedge” problem, which causes artefacts and anisotropic resolution in reconstructed tomograms. Cylindrical specimens provide a way to eliminate the problem, since they allow imaging from a full range of viewing angles around the tilt axis. Such specimens have been used before for tomography of radiation-insensitive samples at room temperature, but never for frozen-hydrated specimens. Here, we demonstrate the use of thin-walled carbon tubes as specimen holders, allowing the preparation of cylindrical frozen-hydrated samples of ribosomes, liposomes and whole bacterial cells. Images acquired from these cylinders have equal quality at all viewing angles, and the accessible tilt range is restricted only by the physical limits of the microscope. Tomographic reconstructions of these specimens demonstrate that the effects of the missing wedge are substantially reduced, and could be completely eliminated if a full tilt range was used. The overall quality of these tomograms is still lower than that obtained by existing methods, but improvements are likely in future. - Highlights: • The missing wedge is a serious problem for electron cryo-tomography. • Cylindrical specimens allow the missing wedge to be eliminated. • Carbon nanopipettes can be used as cylindrical holders for tomography of frozen-hydrated specimens. • Cryo-tomography of cylindrical biological samples demonstrates a reduction of deleterious effects associated with the missing wedge

  3. Pulse Combustor Driven Pressure Gain Combustion for High Efficiency Gas Turbine Engines

    KAUST Repository

    Lisanti, Joel

    2017-02-01

    The gas turbine engine is an essential component of the global energy infrastructure which accounts for a significant portion of the total fossil fuel consumption in transportation and electric power generation sectors. For this reason there is significant interest in further increasing the efficiency and reducing the pollutant emissions of these devices. Conventional approaches to this goal, which include increasing the compression ratio, turbine inlet temperature, and turbine/compressor efficiency, have brought modern gas turbine engines near the limits of what may be achieved with the conventionally applied Brayton cycle. If a significant future step increase in gas turbine efficiency is to be realized some deviation from this convention is necessary. The pressure gain gas turbine concept is a well established new combustion technology that promises to provide a dramatic increase in gas turbine efficiency by replacing the isobaric heat addition process found in conventional technology with an isochoric process. The thermodynamic benefit of even a small increase in stagnation pressure across a gas turbine combustor translates to a significant increase in cycle efficiency. To date there have been a variety of methods proposed for achieving stagnation pressure gains across a gas turbine combustor and these concepts have seen a broad spectrum of levels of success. The following chapter provides an introduction to one of the proposed pressure gain methods that may be most easily realized in a practical application. This approach, known as pulse combustor driven pressure gain combustion, utilizes an acoustically resonant pulse combustor to approximate isochoric heat release and thus produce a rise in stagnation pressure.

  4. Flow structures in a lean-premixed swirl-stabilized combustor with microjet air injection

    KAUST Repository

    LaBry, Zachary A.

    2011-01-01

    The major challenge facing the development of low-emission combustors is combustion instability. By lowering flame temperatures, lean-premixed combustion has the potential to nearly eliminate emissions of thermally generated nitric oxides, but the chamber acoustics and heat release rate are highly susceptible to coupling in ways that lead to sustained, high-amplitude pressure oscillations, known as combustion instability. At different operating conditions, different modes of instability are observed, corresponding to particular flame shapes and resonant acoustic modes. Here we show that in a swirl-stabilized combustor, these instability modes also correspond to particular interactions between the flame and the inner recirculation zone. Two stable and two unstable modes are examined. At lean equivalence ratios, a stable conical flame anchors on the upstream edge of the inner recirculation zone and extends several diameters downstream along the wall. At higher equivalence ratios, with the injection of counter-swirling microjet air flow, another stable flame is observed. This flame is anchored along the upstream edge of a stronger recirculation zone, extending less than one diameter downstream along the wall. Without the microjets, a stationary instability coupled to the 1/4 wave mode of the combustor shows weak velocity oscillations and a stable configuration of the inner and outer recirculation zones. Another instability, coupled to the 3/4 wave mode of the combustor, exhibits periodic vortex breakdown in which the core flow alternates between a columnar mode and a vortex breakdown mode. © 2010 Published by Elsevier Inc. on behalf of The Combustion Institute. All rights reserved.

  5. Co-combustion of waste with coal in a circulating fluidised bed combustor

    Energy Technology Data Exchange (ETDEWEB)

    Gulyurtlu, I.; Boavida, D.; Abelha, P.; Lopes, H.; Cabrita, I. [DEECA-INETI, Lisboa (Portugal)

    2002-07-01

    The results of a study of cocombustion of waste with coal is described. Various wastes (biomass, sludge, and refuse derived fuel) were burned with coal in a circulating fluidised bed combustor. Conditions that prevent segregated combustion, reduce production of nitrogen oxides, and attain high combustion efficiency were studied. The effects of variations in air staging in the riser, mixing of air with volatiles, coal/biomass ratio, methods of feeding biomass, and temperature are described. 5 refs., 3 figs., 5 tabs.

  6. Report covering examination of parts from downhole steam generators. [Combustor head and sleeve parts

    Energy Technology Data Exchange (ETDEWEB)

    Pettit, F. S.; Meier, G. H.

    1983-08-01

    Combustor head and sleeve parts were examined by using optical and scanning electron metallography after use in oxygen/diesel and air/diesel downhole steam generators. The degradation of the different alloy components is described in terms of reactions with oxygen, sulfur and carbon in the presence of cyclic stresses, all generated by the combustion process. Recommendations are presented for component materials (alloys and coatings) to extend component lives in the downhole steam generators. 9 references, 22 figures, 3 tables.

  7. Analysis of oxy-fuel combustion power cycle utilizing a pressurized coal combustor

    OpenAIRE

    Gazzino, Marco; Hong, Jongsup; Chaudhry, Gunaranjan; Brisson II, John G; Field, Randall; Ghoniem, Ahmed F

    2009-01-01

    Growing concerns over greenhouse gas emissions have driven extensive research into new power generation cycles that enable carbon dioxide capture and sequestration. In this regard, oxy-fuel combustion is a promising new technology in which fuels are burned in an environment of oxygen and recycled combustion gases. In this paper, an oxy-fuel combustion power cycle that utilizes a pressurized coal combustor is analyzed. We show that this approach recovers more thermal energy from the flue gases...

  8. Flow Field Dynamics in a High-g Ultra-Compact Combustor

    Science.gov (United States)

    2016-12-01

    Aeronautics and Astronautics Graduate School of Engineering and Management Air Force Institute of Technology Air University Air Education and...exceeded 10%, more than double the accepted state -of-the- art value of 5%. By way of a 2D CFD optimization, the ID of the centerbody was modified to create... States . 14. ABSTRACT The Ultra Compact Combustor (UCC) presents a novel solution to the advancement of aircraft gas turbine engine performance. A

  9. Geometrical characterization of micro-optical cylindrical lens arrays using angular resolved diffraction

    DEFF Research Database (Denmark)

    Iversen, Theis Faber Quist; Hanson, Steen Grüner

    2010-01-01

    been shown (Iversen et al 2009 J. Opt. A: Pure Appl. Opt. 11 054014 (6pp), B¨uttner and Zeitner 2002 Appl. Opt. 41 6841 8) that the average radius of curvature of an MLA structure can be extracted by observing the far-field diffraction pattern intensity distribution obtained from illumination....... By scanning the angle of incidence of the coherent illumination and simultaneously observing the diffracted intensity, information about the grating period and the radius of curvature can be extracted. The method is implemented with emphasis on further development for compact, high-speed dedicated systems. We...

  10. Combustion of peanut and tamarind shells in a conical fluidized-bed combustor: a comparative study.

    Science.gov (United States)

    Kuprianov, Vladimir I; Arromdee, Porametr

    2013-07-01

    Combustion of peanut and tamarind shells was studied in the conical fluidized-bed combustor using alumina sand as the bed material to prevent bed agglomeration. Morphological, thermogravimetric and kinetic characteristics were investigated to compare thermal and combustion reactivity between the biomass fuels. The thermogravimetric kinetics of the biomasses was fitted using the Coats-Redfern method. Experimental tests on the combustor were performed at 60 and 45 kg/h fuel feed rates, with excess air within 20-80%. Temperature and gas concentrations were measured along radial and axial directions in the reactor and at stack. The axial temperature and gas concentration profiles inside the combustor exhibited sensible effects of fuel properties and operating conditions on combustion and emission performance. High (≈ 99%) combustion efficiency and acceptable levels of CO, CxHy, and NO emissions are achievable when firing peanut shells at excess air of about 40%, whereas 60% is more preferable for burning tamarind shells. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. The combustion of low calorific value fuels (oil shale) by using fluidized bed combustor

    Energy Technology Data Exchange (ETDEWEB)

    Azzam, S M

    1994-12-31

    The present work reports an experimental data for combustion of oil-shale in a fluidized bed combustor. The experimental set up was designed for the combustion of low calorific value fuel such as oil-shale to facilitate the variation of many parameters over a wide operating range. A cold run was firstly conducted to study the fluidization parameters. Fluidization experiment were made with different sized quartiz particles. Minimum fluidization velocities and other fluidization characteristics were determined at room temperature. Secondary a hot run was started, first studying the combustion of `LPG` in a fluidized bed as a starting process, then studying the combustion if oil-shale with different flow rates. The experimetal results are promising and give rise to hopes that this valuable deposit can be used as a fuel source and can be burned sucessfully in a fluidized bed combustor. This study had prooved that utilization of oil-shale a fuel source is no more a complicated technical problem, this opens the way for power generation using fluidized bed combustors. (author). 17 refs., 32 figs., 3 tabs.

  12. Ignition and Flame Stabilization of a Strut-Jet RBCC Combustor with Small Rocket Exhaust

    Directory of Open Access Journals (Sweden)

    Jichao Hu

    2014-01-01

    Full Text Available A Rocket Based Combined Cycle combustor model is tested at a ground direct connected rig to investigate the flame holding characteristics with a small rocket exhaust using liquid kerosene. The total temperature and the Mach number of the vitiated air flow, at exit of the nozzle are 1505 K and 2.6, respectively. The rocket base is embedded in a fuel injecting strut and mounted in the center of the combustor. The wall of the combustor is flush, without any reward step or cavity, so the strut-jet is used to make sure of the flame stabilization of the second combustion. Mass flow rate of the kerosene and oxygen injected into the rocket is set to be a small value, below 10% of the total fuel when the equivalence ratio of the second combustion is 1. The experiment has generated two different kinds of rocket exhaust: fuel rich and pure oxygen. Experiment result has shown that, with a relative small total mass flow rate of the rocket, the fuel rich rocket plume is not suitable for ignition and flame stabilization, while an oxygen plume condition is suitable. Then the paper conducts a series of experiments to investigate the combustion characteristics under this oxygen pilot method and found that the flame stabilization characteristics are different at different combustion modes.

  13. Emissions control of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans at municipal waste combustors

    International Nuclear Information System (INIS)

    Tseng, S.C.; Jozewicz, W.; Sedman, C.B.

    1991-01-01

    This paper gives the results of an analysis of available emission data of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) from municipal waste combustors (MWCs) to evaluate the effectiveness of various air pollution control devices on PCDD/PCDF removal. The effects of flue gas temperature, recycling fabric filter ash, and process additives such as ammonia and Tesisorb powder were also analyzed. The analysis shows that MWCs equipped with a spray dryer followed by fabric filters can achieve PCDD/PCDF removal efficiencies (REs) of 97% and higher. A RE of 94% has been achieved at a combustor equipped with a Thermal DeNO x system followed by a spray dryer and fabric filters. MWCs equipped with a duct sorbent injection system followed by fabric filters can potentially achieve a RE of 99%. A combustor equipped with a spray dryer followed by electrostatic precipitators (ESPs) has achieved a RE of 64%. Neither a duct sorbent injection system followed by ESPs nor a furnace sorbent injection system followed by ESPs could effectively remove PCDD/PCDF. PCDD/PCDF were not effectively removed from MWCs equipped with ESPs as the only devices to control air pollution

  14. The combustion of low calorific value fuels (oil shale) by using fluidized bed combustor

    International Nuclear Information System (INIS)

    Azzam, S.M.

    1993-01-01

    The present work reports an experimental data for combustion of oil-shale in a fluidized bed combustor. The experimental set up was designed for the combustion of low calorific value fuel such as oil-shale to facilitate the variation of many parameters over a wide operating range. A cold run was firstly conducted to study the fluidization parameters. Fluidization experiment were made with different sized quartiz particles. Minimum fluidization velocities and other fluidization characteristics were determined at room temperature. Secondary a hot run was started, first studying the combustion of 'LPG' in a fluidized bed as a starting process, then studying the combustion if oil-shale with different flow rates. The experimetal results are promising and give rise to hopes that this valuable deposit can be used as a fuel source and can be burned sucessfully in a fluidized bed combustor. This study had prooved that utilization of oil-shale a fuel source is no more a complicated technical problem, this opens the way for power generation using fluidized bed combustors. (author). 17 refs., 32 figs., 3 tabs

  15. Microjet Injection Strategies for Mitigating Dynamics in a Lean Premixed Swirl-Stabilized Combustor

    KAUST Repository

    LaBry, Zachary

    2011-01-04

    Combustion dynamics remain a challenge in the development of low-emission, air-breathing combustors for power generation and aircraft propulsion. In this paper, we presenta parametric study on the use of microjet injectors for suppressing or mitigating the combustion dynamics that energize the thermoacoustic instability in a swirl-stabilized, premixed combustor. Microjet injectors consist of small inlet ports intended to inject flow with high momentum at relatively low mass flow rates into the flame-anchoring region. The microjets were configured to inject flow either axially, into the outer recirculation zone, or radially into the inner recirculation zone. Additionally, different injectors were tested with different relative senses of swirl (signs of angular momentum)with respect to the main flow: co-swirling, not swirling, or counter-swirling. We observed that injecting air or premixed fuel/air into the inner recirculation zone via counter-swirling radial microjets, we were able to reduce the overall sound pressure level in the combustor by over 20 dB in the lean end of the operating range. Other injector configurations were not observed to positively influence the combust or stability. Detailed PIV measurements are used to examine possible mechanisms of how the microjets impact the combustion dynamics, and the technology implications of our experiments are discussed.

  16. Development of a coal fired pulse combustor for residential space heating. Phase I, Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1988-04-01

    This report presents the results of the first phase of a program for the development of a coal-fired residential combustion system. This phase consisted of the design, fabrication, testing, and evaluation of an advanced pulse combustor sized for residential space heating requirements. The objective was to develop an advanced pulse coal combustor at the {approximately} 100,000 Btu/hr scale that can be integrated into a packaged space heating system for small residential applications. The strategy for the development effort included the scale down of the feasibility unit from 1-2 MMBtu/hr to 100,000 Btu/hr to establish a baseline for isolating the effect of scale-down and new chamber configurations separately. Initial focus at the residential scale was concentrated on methods of fuel injection and atomization in a bare metal unit. This was followed by incorporating changes to the advanced chamber designs and testing of refractory-lined units. Multi-fuel capability for firing oil or gas as a secondary fuel was also established. Upon completion of the configuration and component testing, an optimum configuration would be selected for integrated testing of the pulse combustor unit. The strategy also defined the use of Dry Ultrafine Coal (DUC) for Phases 1 and 2 of the development program with CWM firing to be a product improvement activity for a later phase of the program.

  17. Modeling of NO and N2O emissions from biomass circulating fluidized bed combustors

    International Nuclear Information System (INIS)

    Liu, H.; Gibbs, B.M.

    2002-01-01

    In order to correctly model biomass combustion in a circulating fluidized bed (CFB) combustor, it is necessary to examine the four main stages in the combustion of biomass particles. These include drying, devolatilization, volatile combustion and char combustion in a CFB combustor. This paper presents a newly developed model for nitric oxide (NO) and nitrous oxide (N 2 O) emissions from biomass-fired CFB combustors. A typical woody biomass of pinewood chips was selected for the model parameters. The drying and devolatilization of biomass particles was modeled with limited rates according to woody biomass fuels. The partition of fuel nitrogen between volatiles and char was chosen for pinewood based on available data from literature. It was assumed that the volatile nitrogen was composed of ammonia (NH 3 ), hydrogen cyanide (HCN) and nitrogen (N 2 ). The model included 25 chemical reactions, of which 20 belonged to global fuel-nitrogen reaction kinetics. A 12 MW CFB boiler was used to apply the model. Results were compared with experimental values as well as data from literature. The reaction between NO and char was found to be the key reaction that determines NO emissions. The catalytic effect of bed materials on the oxidation of NH 3 and the the homogeneous reaction of NH 3 with nitric oxide was also significant. 25 refs., 2 tabs., 5 figs

  18. Microjet Injection Strategies for Mitigating Dynamics in a Lean Premixed Swirl-Stabilized Combustor

    KAUST Repository

    LaBry, Zachary; Shanbhogue, Santosh; Ghoniem, Ahmed

    2011-01-01

    Combustion dynamics remain a challenge in the development of low-emission, air-breathing combustors for power generation and aircraft propulsion. In this paper, we presenta parametric study on the use of microjet injectors for suppressing or mitigating the combustion dynamics that energize the thermoacoustic instability in a swirl-stabilized, premixed combustor. Microjet injectors consist of small inlet ports intended to inject flow with high momentum at relatively low mass flow rates into the flame-anchoring region. The microjets were configured to inject flow either axially, into the outer recirculation zone, or radially into the inner recirculation zone. Additionally, different injectors were tested with different relative senses of swirl (signs of angular momentum)with respect to the main flow: co-swirling, not swirling, or counter-swirling. We observed that injecting air or premixed fuel/air into the inner recirculation zone via counter-swirling radial microjets, we were able to reduce the overall sound pressure level in the combustor by over 20 dB in the lean end of the operating range. Other injector configurations were not observed to positively influence the combust or stability. Detailed PIV measurements are used to examine possible mechanisms of how the microjets impact the combustion dynamics, and the technology implications of our experiments are discussed.

  19. The development of an ultra-low-emission gas-fired combustor for space heaters

    International Nuclear Information System (INIS)

    Xiong, Tian-yu; Khinkis, M.J.; Coppin, W.P.

    1991-01-01

    An ultra-low-emission as-fired combustor has been developed for relatively low-temperature direct-air heating applications. High-lean premixed cyclonic combustion with a flame stabilizer is employed to achieve ultra-low emissions and high turndown operation. On the basis of analytical studies and cold modeling a 350-kW test combustor was designed and successfully tested. Experimental results obtained using natural gas and ambient air demonstrated that the test combustor can operate steadily at high excess air up to 80% to 100% over a large turndown range up to 40:1. At design operating conditions, NO x emissions as low as 0.6 vppm and CO and total hydrocarbon (THC) emissions below 3 vppm were achieved. Over the full operating range, NO x emissions from 0.3 to 1.0 vppm and CO and THC emissions below 4 vppm were demonstrated. In all tests, concentrations of NO 2 were less than 40% of the total NO 2 emissions from combustion processes required for good indoor air quality (0.5 vppm). This paper presents the concept of high-lean premixed ultra-low-emission cyclonic combustion, design specifications for the combustion system, and the major experimental results, including flame stability, emissions, and turndown performance. 15 refs., 10 figs., 1 tab

  20. The development of an ultra-low-emission gas-fired cyclonic combustor

    International Nuclear Information System (INIS)

    Xiong, Tian-yu; Khinkis, M.J.; Coppin, W.P.

    1991-01-01

    A gas-fired cyclonic combustor has been developed for relatively low-temperature direct-air heating applications that require ultra-low pollutant emissions. High-lean premixed combustion with a flame stabilizer is adopted to achieve ultra-low emissions and high turndown operation. On the basis of analytical studies and cold modeling, a 350-kW test combustor was designed and successfully tested. Experimental results obtained using natural gas and ambient air demonstrated that the test combustor can operate steadily at high excess air up to 80% to 100% over a large turndown range up to 40:1. At design operating conditions, NO x emissions as low as 0.6 vppm and CO and total hydrocarbon (THC) emissions below 3 vppm were achieved. Over the full operating range, NO x emissions from 0.3 to 1.0 vppm and CO and THC emissions below 4 vppm were demonstrated. In all tests, concentrations of NO 2 were less than 40% of the total NO x emissions -- lower than the level of NO 2 emissions from combustion processes required for good indoor air quality (0.5 vppm). This paper presents the concept of high-lean premixed ultra-low-emission cyclonic combustion, design specifications for the combustion system, and the major experimental results, including flame stability, emissions, and turndown performance. 13 refs., 12 figs., 1 tab

  1. Coal-based oxy-fuel system evaluation and combustor development

    Energy Technology Data Exchange (ETDEWEB)

    MacAdam, S.; Biebuyck, C.; Anderson, R.; Pronske, K. [Clean Energy Systems Inc., Rancho Cordova, CA (United States)

    2007-07-01

    The core of the Clean Energy Systems, Inc. (CES) process is an oxy-combustor adapted from rocket engine technology. This combustor burns gaseous or liquid fuels with gaseous oxygen in the presence of water. Fuels include syngas from coal, refinery residues, or biomass; natural gas; landfill gas; glycoal solutions and oil/water emulsions. The combustion is performed at near-stoichiometric conditions in the presence of recycled water to produce a steam/CO{sub 2} mixture at high temperature and pressure. These combustion products power conventional or advanced steam turbines and may use modified gas turbines operating at high-temperatures for expansion at intermediate pressures. The gas exiting the turbines enter a condenser/separator where it is cooled, separating into its components, water and CO{sub 2}. The recovered CO{sub 2} is conditioned and purified as appropriate and sold or sequestered. Most of the water is recycled to the gas generator but excess high-purity water is produced and available for export. The development, evaluation and demonstration of the CES combustor are described. 8 refs., 4 figs., 1 tab.

  2. Effects of porous insert on flame dynamics in a lean premixed swirl-stabilized combustor

    Science.gov (United States)

    Brown, Marcus; Agrawal, Ajay; Allen, James; Kornegay, John

    2016-11-01

    In this study, we investigated different methods of determining the effect a porous insert has on flame dynamics during lean premixed combustion. A metallic porous insert is used to mitigate instabilities in a swirl-stabilized combustor. Thermoacoustic instabilities are seen as negative consequences of lean premixed combustion and eliminating them is the motivation for our research. Three different diagnostics techniques with high-speed Photron SA5 cameras were used to monitor flame characteristics. Particle image velocimetry (PIV) was used to observe vortical structures and recirculation zones within the combustor. Using planar laser induced fluorescence (PLIF), we were able to observe changes in the reaction zones during instabilities. Finally, utilizing a color high-speed camera, visual images depicting a flame's oscillations during the instability were captured. Using these monitoring techniques, we are able to support the claims made in previous studies stating that the porous insert in the combustor significantly reduces the thermoacoustic instability. Funding for this research was provided by the NSF REU site Grant EEC 1358991 and NASA Grant NNX13AN14A.

  3. Analysis of oxy-fuel combustion power cycle utilizing a pressurized coal combustor

    International Nuclear Information System (INIS)

    Hong, Jongsup; Chaudhry, Gunaranjan; Brisson, J.G.; Field, Randall; Gazzino, Marco; Ghoniem, Ahmed F.

    2009-01-01

    Growing concerns over greenhouse gas emissions have driven extensive research into new power generation cycles that enable carbon dioxide capture and sequestration. In this regard, oxy-fuel combustion is a promising new technology in which fuels are burned in an environment of oxygen and recycled combustion gases. In this paper, an oxy-fuel combustion power cycle that utilizes a pressurized coal combustor is analyzed. We show that this approach recovers more thermal energy from the flue gases because the elevated flue gas pressure raises the dew point and the available latent enthalpy in the flue gases. The high-pressure water-condensing flue gas thermal energy recovery system reduces steam bleeding which is typically used in conventional steam cycles and enables the cycle to achieve higher efficiency. The pressurized combustion process provides the purification and compression unit with a concentrated carbon dioxide stream. For the purpose of our analysis, a flue gas purification and compression process including de-SO x , de-NO x , and low temperature flash unit is examined. We compare a case in which the combustor operates at 1.1 bars with a base case in which the combustor operates at 10 bars. Results show nearly 3% point increase in the net efficiency for the latter case.

  4. A Comparison of Combustion Dynamics for Multiple 7-Point Lean Direct Injection Combustor Configurations

    Science.gov (United States)

    Tacina, K. M.; Hicks, Y. R.

    2017-01-01

    The combustion dynamics of multiple 7-point lean direct injection (LDI) combustor configurations are compared. LDI is a fuel-lean combustor concept for aero gas turbine engines in which multiple small fuel-air mixers replace one traditionally-sized fuel-air mixer. This 7-point LDI configuration has a circular cross section, with a center (pilot) fuel-air mixer surrounded by six outer (main) fuel-air mixers. Each fuel-air mixer consists of an axial air swirler followed by a converging-diverging venturi. A simplex fuel injector is inserted through the center of the air swirler, with the fuel injector tip located near the venturi throat. All 7 fuel-air mixers are identical except for the swirler blade angle, which varies with the configuration. Testing was done in a 5-atm flame tube with inlet air temperatures from 600 to 800 F and equivalence ratios from 0.4 to 0.7. Combustion dynamics were measured using a cooled PCB pressure transducer flush-mounted in the wall of the combustor test section.

  5. Study on mechanism of combustion instability in a dump gas turbine combustor

    International Nuclear Information System (INIS)

    Lee, Yeon Joo; Lee, Jong Ho; Jeon, Chong Hwan; Chang, Yonng June

    2002-01-01

    Combustion instabilities are an important concern associated with lean premixed combustion. Laboratory-scale dump combustor was used to understand the underlying mechanisms causing combustion instabilities. Experiments were conducted at atmospheric pressure and sound level meter was used to track the pressure fluctuations inside the combustor. Instability maps and phase-resolved OH chemiluminescence images were obtained at several conditions to investigate the mechanism of combustion instability and relations between pressure wave and heat release rate. It showed that combustion instability was susceptible to occur at higher value of equivalence ratio (>0.6) as the mean velocity was decreased. Instabilities exhibited a longitudinal mode with a dominant frequency of ∼341.8 Hz, which corresponded to a quarter wave mode of combustor. Heat release and pressure waves were in-phase when instabilities occurred. Rayleigh index distribution gave a hint about the location where the strong coherence of pressure and heat release existed. These results also give an insight to the control scheme of combustion instabilities. Emission test revealed that NO x emissions were affected by not only equivalence but also combustion instability

  6. Operability of an Ejector Enhanced Pulse Combustor in a Gas Turbine Environment

    Science.gov (United States)

    Paxson, Daniel E.; Dougherty, Kevin

    2008-01-01

    A pressure-gain combustor comprised of a mechanically valved, liquid fueled pulsejet, an ejector, and an enclosing shroud, was coupled to a small automotive turbocharger to form a self-aspirating, thrust producing gas turbine engine. The system was constructed in order to investigate issues associated with the interaction of pulsed combustion devices and turbomachinery. Installed instrumentation allowed for sensing of distributed low frequency pressure and temperature, high frequency pressure in the shroud, fuel flow rate, rotational speed, thrust, and laboratory noise. The engine ran successfully and reliably, achieving a sustained thrust of 5 to 6 lbf, and maintaining a rotor speed of approximately 90,000 rpm, with a combustor pressure gain of approximately 4 percent. Numerical simulations of the system without pressure-gain combustion indicated that the turbocharger would not operate. Thus, the new combustor represented a substantial improvement in system performance. Acoustic measurements in the shroud and laboratory indicated turbine stage sound pressure level attenuation of 20 dB. This is consistent with published results from detonative combustion experiments. As expected, the mechanical reed valves suffered considerable damage under the higher pressure and thermal loading characteristics of this system. This result underscores the need for development of more robust valve systems for this application. The efficiency of the turbomachinery components did not appear to be significantly affected by unsteadiness associated with pulsed combustion, though the steady component efficiencies were already low, and thus not expected to be particularly sensitive.

  7. NASA One-Dimensional Combustor Simulation--User Manual for S1D_ML

    Science.gov (United States)

    Stueber, Thomas J.; Paxson, Daniel E.

    2014-01-01

    The work presented in this paper is to promote research leading to a closed-loop control system to actively suppress thermo-acoustic instabilities. To serve as a model for such a closed-loop control system, a one-dimensional combustor simulation composed using MATLAB software tools has been written. This MATLAB based process is similar to a precursor one-dimensional combustor simulation that was formatted as FORTRAN 77 source code. The previous simulation process requires modification to the FORTRAN 77 source code, compiling, and linking when creating a new combustor simulation executable file. The MATLAB based simulation does not require making changes to the source code, recompiling, or linking. Furthermore, the MATLAB based simulation can be run from script files within the MATLAB environment or with a compiled copy of the executable file running in the Command Prompt window without requiring a licensed copy of MATLAB. This report presents a general simulation overview. Details regarding how to setup and initiate a simulation are also presented. Finally, the post-processing section describes the two types of files created while running the simulation and it also includes simulation results for a default simulation included with the source code.

  8. Measurement and modelling of a radiofrequency micro-thruster

    International Nuclear Information System (INIS)

    Charles, C; Boswell, R W

    2012-01-01

    A capacitively coupled radiofrequency (rf) (13.56 MHz) cylindrical argon micro-discharge expanding into a larger glass tube is studied by performing optical and electrical measurements over a pressure range 0.3–5 Torr and a rf power range 5–40 W. Measurements of the axial and radial plasma density profiles at the Paschen minimum near 1.5 Torr are used to develop a global model of the discharge and estimate neutral heating from ion–neutral charge exchange collisions for micro-propulsion applications. (fast track communication)

  9. Cylindrical-confinement-induced phase behaviours of diblock copolymer melts

    International Nuclear Information System (INIS)

    Mei-Jiao, Liu; Shi-Ben, Li; Lin-Xi, Zhang; Xiang-Hong, Wang

    2010-01-01

    The phase behaviours of diblock copolymers under cylindrical confinement are studied in two-dimensional space by using the self-consistent field theory. Several phase parameters are adjusted to investigate the cylindrical-confinement-induced phase behaviours of diblock copolymers. A series of lamella-cylinder mixture phases, such as the mixture of broken-lamellae and cylinders and the mixture of square-lamellae and cylinders, are observed by varying the phase parameters, in which the behaviours of these mixture phases are discussed in the corresponding phase diagrams. Furthermore, the free energies of these mixture phases are investigated to illustrate their evolution processes. Our results are compared with the available observations from the experiments and simulations respectively, and they are in good agreement and provide an insight into the phase behaviours under cylindrical confinement. (cross-disciplinary physics and related areas of science and technology)

  10. The cylindrical GEM detector of the KLOE-2 experiment

    International Nuclear Information System (INIS)

    Bencivenni, G.; Ciambrone, P.; De Lucia, E.; Domenici, D.; Felici, G.; Fermani, P.; Morello, G.; Branchini, P.; Cicco, A. Di; Czerwinski, E.

    2017-01-01

    The KLOE-2 experiment started its data taking campaign in November 2014 with an upgraded tracking system at the DAΦNE electron-positron collider at the Frascati National Laboratory of INFN. The new tracking device, the Inner Tracker, operated together with the KLOE-2 Drift Chamber, has been installed to improve track and vertex reconstruction capabilities of the experimental apparatus. The Inner Tracker is a cylindrical GEM detector composed of four cylindrical triple-GEM detectors, each provided with an X-V strips-pads stereo readout. Although GEM detectors are already used in high energy physics experiments, this device is considered a frontier detector due to its fully-cylindrical geometry: KLOE-2 is the first experiment benefiting of this novel detector technology. Alignment and calibration of this detector will be presented together with its operating performance and reconstruction capabilities.

  11. Errors due to the cylindrical cell approximation in lattice calculations

    Energy Technology Data Exchange (ETDEWEB)

    Newmarch, D A [Reactor Development Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

    1960-06-15

    It is shown that serious errors in fine structure calculations may arise through the use of the cylindrical cell approximation together with transport theory methods. The effect of this approximation is to overestimate the ratio of the flux in the moderator to the flux in the fuel. It is demonstrated that the use of the cylindrical cell approximation gives a flux in the moderator which is considerably higher than in the fuel, even when the cell dimensions in units of mean free path tend to zero; whereas, for the case of real cells (e.g. square or hexagonal), the flux ratio must tend to unity. It is also shown that, for cylindrical cells of any size, the ratio of the flux in the moderator to flux in the fuel tends to infinity as the total neutron cross section in the moderator tends to zero; whereas the ratio remains finite for real cells. (author)

  12. Buckling localization in a cylindrical panel under axial compression

    DEFF Research Database (Denmark)

    Tvergaard, Viggo; Needleman, A.

    2000-01-01

    Localization of an initially periodic buckling pattern is investigated for an axially compressed elastic-plastic cylindrical panel of the type occurring between axial stiffeners on cylindrical shells. The phenomenon of buckling localization and its analogy with plastic flow localization in tensile...... test specimens is discussed in general. For the cylindrical panel, it is shown that buckling localization develops shortly after a maximum load has been attained, and this occurs for a purely elastic panel as well as for elastic-plastic panels. In a case where localization occurs after a load maximum......, but where subsequently the load starts to increase again, it is found that near the local load minimum, the buckling pattern switches back to a periodic type of pattern. The inelastic material behavior of the panel is described in terms of J(2) corner theory, which avoids the sometimes unrealistically high...

  13. Tight multilattices calculated by extended-cell cylindrization

    Energy Technology Data Exchange (ETDEWEB)

    Segev, M; Carmona, S

    1983-01-01

    Among the common features of advanced LWR concepts are the tightness of lattices and the symbiotic setting of different fuels. Such symbioses often come in the form of multilattices, whose numerically-repeated unit is a configuration of several pins, typically with one pin type at the center and pins of a second type surrounding the center pin. If this extended-cell (EC) unit is cylindricized, then a simple transport calculation of the unit will be possible. If the lattice of such units is tight, there is further an a priori reason to expect the cylindrization to introduce only a small distortion of the true neutron fluxes in the lattice. A strict numerical validation of the EC cylindrization approximation is impractical, but similar validations can be carried out for regular lattices, viewed as being made up of multicell units whose centers are moderators and whose peripheries are fuel pins. In these comparisons the EC cylindrization approximation gives good results.

  14. Cylindrical optical resonators: fundamental properties and bio-sensing characteristics

    Science.gov (United States)

    Khozeymeh, Foroogh; Razaghi, Mohammad

    2018-04-01

    In this paper, detailed theoretical analysis of cylindrical resonators is demonstrated. As illustrated, these kinds of resonators can be used as optical bio-sensing devices. The proposed structure is analyzed using an analytical method based on Lam's approximation. This method is systematic and has simplified the tedious process of whispering-gallery mode (WGM) wavelength analysis in optical cylindrical biosensors. By this method, analysis of higher radial orders of high angular momentum WGMs has been possible. Using closed-form analytical equations, resonance wavelengths of higher radial and angular order WGMs of TE and TM polarization waves are calculated. It is shown that high angular momentum WGMs are more appropriate for bio-sensing applications. Some of the calculations are done using a numerical non-linear Newton method. A perfect match of 99.84% between the analytical and the numerical methods has been achieved. In order to verify the validity of the calculations, Meep simulations based on the finite difference time domain (FDTD) method are performed. In this case, a match of 96.70% between the analytical and FDTD results has been obtained. The analytical predictions are in good agreement with other experimental work (99.99% match). These results validate the proposed analytical modelling for the fast design of optical cylindrical biosensors. It is shown that by extending the proposed two-layer resonator structure analyzing scheme, it is possible to study a three-layer cylindrical resonator structure as well. Moreover, by this method, fast sensitivity optimization in cylindrical resonator-based biosensors has been possible. Sensitivity of the WGM resonances is analyzed as a function of the structural parameters of the cylindrical resonators. Based on the results, fourth radial order WGMs, with a resonator radius of 50 μm, display the most bulk refractive index sensitivity of 41.50 (nm/RIU).

  15. Far-field potentials in cylindrical and rectangular volume conductors.

    Science.gov (United States)

    Dumitru, D; King, J C; Rogers, W E

    1993-07-01

    The occurrence of a transient dipole is one method of producing a far-field potential. This investigation qualitatively defines the characteristics of the near-field and far-field electrical potentials produced by a transient dipole in both cylindrical and rectangular volume conductors. Most body segments of electrophysiologic interest such as arms, legs, thorax, and neck are roughly cylindrical in shape. A centrally located dipole generator produces a nonzero equipotential region which is found to occur along the cylindrical wall at a distance from the dipole of approximately 1.4 times the cylinder's radius and 1.9 times the cylinder's radius for the center of the cylinder. This distance to the equi-potential zone along the surface wall expands but remains less than 3.0 times the cylindrical radius when the dipole is eccentrically placed. The magnitude of the equipotential region resulting from an asymmetrically placed dipole remains identical to that when the dipole is centrally located. This behavior is found to be very similar in rectangular shallow conducting volumes that model a longitudinal slice of the cylinder, thus allowing a simple experimental model of the cylinder to be utilized. Amplitudes of the equipotential region are inversely proportional to the cylindrical or rectangular volume's cross-sectional area at the location of dipolar imbalance. This study predicts that referential electrode montages, when placed at 3.0 times the radius or greater from a dipolar axially aligned far-field generator in cylindrical homogeneous volume conductors, will record only equipotential far-field effects.

  16. Development of new cylindrical magnetrons for industrial use

    International Nuclear Information System (INIS)

    Clayton, B.

    2000-09-01

    A number of alternative techniques were considered and tested with a view to the construction of a cylindrical sputtering device. This device was required to be capable of depositing tribological coatings inside approximately cylindrical substrates of diameters less than 100mm, in an industrial situation. A cylindrical magnetron device was designed, and constructed as a prototype, using a magnetic assembly inside a cylindrical target with outside diameter (o.d.) 40mm. Two alternative magnetic assemblies were tested, and found to have complimentary advantages. The magnetron characteristics of the device were tested, as were key properties (such as adhesion level and hardness) of the coatings deposited. In all cases good results were obtained. A 22mm o.d. device based on the same design was shown to operate, but with less satisfactory characteristics. In an attempt to improve the miniaturised design, the feasibility of gas cooling (rather than water cooling) the cylindrical magnetron was demonstrated. A system incorporating four 40mm o.d. cylindrical magnetrons was designed, constructed and briefly tested. This was intended to prove the feasibility of using a multi-magnetron system to reduce the cost to coat. Its dimensions and design were tailored to an industrially specified engine block. In use the plasma rings formed on the 40mm magnetron target surfaces during operation were found to be of unequal intensities, especially on the shorter magnetron design used in the four-fold system. In an attempt to tackle this problem, a finite element model of the magnetic field generated by the magnetic assembly was built, run and verified. Changes were made to this model, and a new .magnet assembly was built and tested based on the results obtained. This did not lead to a final solution of the problem, but has set bounds within which the solution must lie. (author)

  17. Start-up and Self-sustain Test of 500 W Ultra-Micro Gas Turbine Generator

    International Nuclear Information System (INIS)

    Seo, Jeong Min; Park, Jun Young; Choi, Bum Seog

    2013-01-01

    This paper provides the performance test for start-up and self-sustaining of 500W ultra-micro gas turbine (UMGT) generator. Each component of UMGT, a centrifugal compressor, a radial turbine, an annular combustor and a shaft is already designed, manufactured and tested to meet design requirements in previous researches. However, they are not tested to work in an integrate system. Currently, integrated test unit with a compressor, a combustor and a turbine, is developed to find the proper condition of start-up and self-sustain. Ignition sequence depending on rotating speed is designed. Performance test for start-up and self-sustain is designed based on the ignition possible condition. An air impingement starter and a hot bulb inginer are applied. LPG is used as main fuel

  18. Energy corrections in pulsed neutron measurements for cylindrical geometry

    International Nuclear Information System (INIS)

    Drozdowicz, K.; Woznicka, U.

    1982-01-01

    A solution of the thermal neutron diffusion equation for a two-region concentric cylindrical system, with a constant neutron flux in the inner medium assumed, is given. The velocity-averaged dynamic parameters for thermal neutrons are used in the method. The corrections due to the diffusion cooling are introduced into the dynamic material buckling and into the velocity distribution of the thermal neutron flux. Detailed relations obtained for a hydrogenous moderator are given. Results of the measurements of the thermal neutron macroscopic absorption cross-sections for the samples in the two-region cylindrical systems are presented. (author)

  19. Confined and interface phonons in combined cylindrical nanoheterosystem

    Directory of Open Access Journals (Sweden)

    O.M.Makhanets

    2006-01-01

    Full Text Available The spectra of all types of phonons existing in a complicated combined nanoheterosystem consisting of three cylindrical quantum dots embedded into the cylindrical quantum wire placed into vacuum are studied within the dielectric continuum model. It is shown that there are confined optical (LO and interface phonons of two types: top surface optical (TSO and side surface optical (SSO modes of vibration in such a nanosystem. The dependences of phonon energies on the quasiwave numbers and geometrical parameters of quantum dots are investigated and analysed.

  20. The magnetic properties of the hollow cylindrical ideal remanence magnet

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    2016-01-01

    We consider the magnetic properties of the hollow cylindrical ideal remanence magnet. This magnet is the cylindrical permanent magnet that generates a uniform field in the cylinder bore, using the least amount of magnetic energy to do so. The remanence distribution of this magnet is derived...... and the generated field is compared to that of a Halbach cylinder of equal dimensions. The ideal remanence magnet is shown in most cases to generate a significantly lower field than the equivalent Halbach cylinder, although the field is generated with higher efficiency. The most efficient Halbach cylinder is shown...... to generate a field exactly twice as large as the equivalent ideal remanence magnet....

  1. Two-dimensional collapse calculations of cylindrical clouds

    International Nuclear Information System (INIS)

    Bastien, P.; Mitalas, R.

    1979-01-01

    A two-dimensional hydrodynamic computer code has been extensively modified and expanded to study the collapse of non-rotating interstellar clouds. The physics and the numerical methods involved are discussed. The results are presented and discussed in terms of the Jeans number. The critical Jeans number for collapse of non-rotating cylindrical clouds whose length is the same as their diameter is 1.00. No evidence for fragmentation has been found for these clouds, but fragmentation seems quite likely for more elongated cylindrical clouds. (author)

  2. Gravitational collapse of a cylindrical null shell in vacuum

    Directory of Open Access Journals (Sweden)

    S. Khakshournia

    2008-03-01

    Full Text Available   Barrabès-Israel null shell formalism is used to study the gravitational collapse of a thin cylindrical null shell in vacuum. In general the lightlike matter shell whose history coincides with a null hypersurface is characterized by a surface energy density. In addition, a gravitational impulsive wave is present on this null hypersurface whose generators admit both the shear and expansion. In the case of imposing the cylindrical flatness the surface energy-momentum tensor of the matter shell on the null hypersurface vanishes and the null hyper- surface is just the history of the gravitational wave .

  3. Analytic descriptions of cylindrical electromagnetic waves in a nonlinear medium

    Science.gov (United States)

    Xiong, Hao; Si, Liu-Gang; Yang, Xiaoxue; Wu, Ying

    2015-01-01

    A simple but highly efficient approach for dealing with the problem of cylindrical electromagnetic waves propagation in a nonlinear medium is proposed based on an exact solution proposed recently. We derive an analytical explicit formula, which exhibiting rich interesting nonlinear effects, to describe the propagation of any amount of cylindrical electromagnetic waves in a nonlinear medium. The results obtained by using the present method are accurately concordant with the results of using traditional coupled-wave equations. As an example of application, we discuss how a third wave affects the sum- and difference-frequency generation of two waves propagation in the nonlinear medium. PMID:26073066

  4. Spherical and cylindrical particle resonator as a cloak system

    Science.gov (United States)

    Minin, I. V.; Minin, O. V.; Eremeev, A. I.; Tseplyaev, I. S.

    2018-05-01

    The concept of dielectric spherical or cylindrical particle in resonant mode as a cloak system is offered. In fundamental modes (modes with the smallest volume correspond to |m| = l, and s = 1) the field is concentrated mostly in the equatorial plane and at the surface of the sphere. Thus under resonance modes, such perturbation due to cuboid particle inserted in the spherical or cylindrical particle has almost no effect on the field forming resonance regardless of the value of internal particle material (defect) as long as this material does not cover the region where resonance takes place.

  5. Experiments on cylindrically converging blast waves in atmospheric air

    Science.gov (United States)

    Matsuo, Hideo; Nakamura, Yuichi

    1980-06-01

    Cylindrically converging blast waves have been produced in normal atmospheric conditions by the detonation of the explosives, pentaerythritoltetranitrate, (PETN), over cylindrical surfaces. The shocks generated in this way are so strong that the fronts propagating through the air become luminous of themselves. The production and the propagation of the shocks have been monitored with a framing camera and a streak camera, and the time-space relations of the shock propagations have been determined using an electrical ionization probing system. The results have shown that the trajectory of the shock fronts near the axis of the cylinder can be approximately represented by the Guderley's formula.

  6. Metallurgical Evaluation of the Five-Inch Cylindrical Induction Melter

    International Nuclear Information System (INIS)

    Imrich, K.J.

    2000-01-01

    A metallurgical evaluation of the 5-inch cylindrical induction melter (CIM) vessel was performed by the Materials Technology Section to evaluate the metallurgical condition after operating for approximately 375 hours at 1400 to 1500 Degrees Celsius during a 2 year period. Results indicate that wall thinning and significant grain growth occurred in the lower portion of the conical section and the drain tube. No through-wall penetrations were found in the cylindrical and conical sections of the CIM vessel and only one leak site was identified in the drain tube. Failure of the drain tube was associated with a localized over heating and intercrystalline fracture

  7. Prediction of soot and thermal radiation in a model gas turbine combustor burning kerosene fuel spray at different swirl levels

    Science.gov (United States)

    Ghose, Prakash; Patra, Jitendra; Datta, Amitava; Mukhopadhyay, Achintya

    2016-05-01

    Combustion of kerosene fuel spray has been numerically simulated in a laboratory scale combustor geometry to predict soot and the effects of thermal radiation at different swirl levels of primary air flow. The two-phase motion in the combustor is simulated using an Eulerian-Lagragian formulation considering the stochastic separated flow model. The Favre-averaged governing equations are solved for the gas phase with the turbulent quantities simulated by realisable k-ɛ model. The injection of the fuel is considered through a pressure swirl atomiser and the combustion is simulated by a laminar flamelet model with detailed kinetics of kerosene combustion. Soot formation in the flame is predicted using an empirical model with the model parameters adjusted for kerosene fuel. Contributions of gas phase and soot towards thermal radiation have been considered to predict the incident heat flux on the combustor wall and fuel injector. Swirl in the primary flow significantly influences the flow and flame structures in the combustor. The stronger recirculation at high swirl draws more air into the flame region, reduces the flame length and peak flame temperature and also brings the soot laden zone closer to the inlet plane. As a result, the radiative heat flux on the peripheral wall decreases at high swirl and also shifts closer to the inlet plane. However, increased swirl increases the combustor wall temperature due to radial spreading of the flame. The high incident radiative heat flux and the high surface temperature make the fuel injector a critical item in the combustor. The injector peak temperature increases with the increase in swirl flow mainly because the flame is located closer to the inlet plane. On the other hand, a more uniform temperature distribution in the exhaust gas can be attained at the combustor exit at high swirl condition.

  8. Modeling the integration of thermoelectrics in anode exhaust combustors for waste heat recovery in fuel cell systems

    Science.gov (United States)

    Maghdouri Moghaddam, Anita

    Recently developed small-scale hydrocarbon-fueled fuel cell systems for portable power under 1 kW have overall system efficiencies typically no higher than 30-35%. This study explores the possibility of using of thermoelectric waste heat recovery in anode exhaust combustors to improve the fuel cell system efficiencies by as much as 4-5% points and further to reduce required battery power during system start-up. Two models were used to explore this. The first model simulated an integrated SOFC system with a simplified catalytic combustor model with TEs integrated between the combustor and air preheating channels for waste heat recovery. This model provided the basis for assessing how much additional power can achieve during SOFC operation as a function of fuel cell operating conditions. Results for the SOFC system indicate that while the TEs may recover as much as 4% of the total fuel energy into the system, their benefit is reduced in part because they reduce the waste heat transferred back to the incoming air stream and thereby lower the SOFC operating temperatures and operating efficiencies. A second model transient model of a TE-integrated catalytic combustor explored the performance of the TEs during transient start-up of the combustor. This model incorporated more detailed catalytic combustion chemistry and enhanced cooling air fin heat transfer to show the dynamic heating of the integrated combustor. This detailed model provided a basis for exploring combustor designs and showed the importance of adequate reactant preheating when burning exhaust from a reformer during start-up for the TEs to produce significant power to reduce the size of system batteries for start-up.

  9. MicroED data collection and processing

    Energy Technology Data Exchange (ETDEWEB)

    Hattne, Johan; Reyes, Francis E.; Nannenga, Brent L.; Shi, Dan; Cruz, M. Jason de la [Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147 (United States); Leslie, Andrew G. W. [Medical Research Council Laboratory of Molecular Biology, Cambridge (United Kingdom); Gonen, Tamir, E-mail: gonent@janelia.hhmi.org [Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147 (United States)

    2015-07-01

    The collection and processing of MicroED data are presented. MicroED, a method at the intersection of X-ray crystallography and electron cryo-microscopy, has rapidly progressed by exploiting advances in both fields and has already been successfully employed to determine the atomic structures of several proteins from sub-micron-sized, three-dimensional crystals. A major limiting factor in X-ray crystallography is the requirement for large and well ordered crystals. By permitting electron diffraction patterns to be collected from much smaller crystals, or even single well ordered domains of large crystals composed of several small mosaic blocks, MicroED has the potential to overcome the limiting size requirement and enable structural studies on difficult-to-crystallize samples. This communication details the steps for sample preparation, data collection and reduction necessary to obtain refined, high-resolution, three-dimensional models by MicroED, and presents some of its unique challenges.

  10. Magnetization curves for general cylindrical samples in a transverse ...

    Indian Academy of Sciences (India)

    complexity associated with the task of determining and studying the movement of the flux- front as the flux ... a volume current density causing the flux-front to move by an appropriate amount. Since the flux-front does ... Let us consider an infinite cylindrical sample with its axis along the z-axis and its cross- section bounded ...

  11. Acoustic characteristics of sand sediment with circular cylindrical pores

    International Nuclear Information System (INIS)

    Roh, Heui-Seol; Lee, Kang-Il; Yoon, Suk-Wang

    2004-01-01

    The acoustic pressure transmission coefficient and the phase velocity are experimentally measured as functions of the frequency and the porosity in sand sediment slabs with circular cylindrical pores filled with water and air. They are also theoretically estimated with the modified Biot-Attenborough (MBA) model, which uses a separate treatment of the viscous and the thermal effects in a non-rigid porous medium with water- and air-filled cylindrical pores. In this study, the fast (first kind) wave and the slow (second kind) wave are not separated in the transmitted signals through a sediment slab without the circular cylindrical pores, but they are separated in the transmitted signals through a sediment slab with pores. Both the phase velocities and the transmission coefficients of the fast wave and the slow wave in the sediment slabs with water- and air-filled cylindrical pores are sensitive to the air and the water porosities. It is proposed that the fast and the slow waves have opposite behaviors for several acoustic characteristics. The generalized tortuosity factor and the dynamic shape factor are introduced from the acoustic characteristics of the fast wave. The experimental results show reasonable agreement with the theoretical results estimated with the MBA model. These results suggest the possibility of predicting the acoustic characteristics of a sediment as functions of arbitrary water and air porosities. This study may also be applicable to understanding acoustic wave propagations in a bubbly liquid sediment for underwater applications and in cancellous bone for the diagnosis of osteoporosis.

  12. An approximate solution for spherical and cylindrical piston problem

    Indian Academy of Sciences (India)

    the growth and decay of shock strengths for spherical and cylindrical pistons starting from a non-zero ... conditions at an appropriate level, a new theory of shock dynamics (NTSD) has been proposed (Ravindran and ..... sive, its packing density etc. which are not included in our mathematical formulation, it may explain the ...

  13. Coupled dilaton and electromagnetic field in cylindrically symmetric ...

    Indian Academy of Sciences (India)

    An exact solution is obtained for coupled dilaton and electromagnetic field in a cylindrically symmetric spacetime where an axial magnetic field as well as a radial electric field both are present. Depending on the choice of the arbitrary constants our solution reduces either to dilatonic gravity with pure electric field or to that ...

  14. ELECTROMAGNETIC FIELDS IN CYLINDRICAL INDUCTION INDUCTOR SYSTEM WITH MASSIVE SHIELD

    Directory of Open Access Journals (Sweden)

    D. Piskun

    2010-12-01

    Full Text Available The processes in a cylindrical induction inductor system with a massive additional non-magnetic shield and a thin ferromagnetic sheet blank are considered and the formula for induced currents and the strength of excited fields have been obtained.

  15. Optical properties of helical cylindrical molecular aggregates : the homogeneous limit

    NARCIS (Netherlands)

    Didraga, C.; Klugkist, J.A.; Knoester, J.

    2002-01-01

    Using a Frenkel exciton model, we study the optical absorption spectrum and linear and circular dichroism (CD) spectra of cylindrical molecular aggregates. We demonstrate that such aggregates can always be described as a stack of molecular rings with nearest-neighbor rings rotated relative to each

  16. Particle Creation in Oscillating Cavities with Cubic and Cylindrical Geometry

    Science.gov (United States)

    Setare, M. R.; Dinani, H. T.

    2008-04-01

    In the present paper we study the creation of massless scalar particles from the quantum vacuum due to the dynamical Casimir effect by oscillating cavities with cubic and cylindrical geometry. To the first order of the amplitude we derive the expressions for the number of the created particles.

  17. Theory of precipitation effects on dead cylindrical fuels

    Science.gov (United States)

    Michael A. Fosberg

    1972-01-01

    Numerical and analytical solutions of the Fickian diffusion equation were used to determine the effects of precipitation on dead cylindrical forest fuels. The analytical solution provided a physical framework. The numerical solutions were then used to refine the analytical solution through a similarity argument. The theoretical solutions predicted realistic rates of...

  18. Magnetoresistance of cylindrical nanowires with artificial pinning site

    KAUST Repository

    Vidal, Enrique Vilanova; Mohammed, H.; Ivanov, I.; Kosel, Jü rgen

    2015-01-01

    New concepts of magnetic memory devices are exploiting the movement of data bits by current induced domain wall motion. This concept has been widely explored with rectangular nanowires (NWs) or stripes both theoretically and experimentally [1]. In the case of cylindrical NWs not much progress has been made on the experimental side, despite its promising advantages like the absence of Walker breakdown [2].

  19. Circumferential buckling instability of a growing cylindrical tube

    KAUST Repository

    Moulton, D.E.; Goriely, A.

    2011-01-01

    A cylindrical elastic tube under uniform radial external pressure will buckle circumferentially to a non-circular cross-section at a critical pressure. The buckling represents an instability of the inner or outer edge of the tube. This is a common

  20. A cylindrical drift chamber with azimuthal and axial position readout

    International Nuclear Information System (INIS)

    Bar-Yam, Z.; Cummings, J.P.; Dowd, J.P.; Eugenio, P.; Hayek, M.; Kern, W.; King, E.; Shenhav, N.; Chung, S.U.; Hackenburg, R.W.; Olchanski, C.; Weygand, D.P.; Willutzki, H.J.; Brabson, B.B.; Crittenden, R.R.; Dzierba, A.R.; Gunter, J.; Lindenbusch, R.; Rust, D.R.; Scott, E.; Smith, P.T.; Sulanke, T.; Teige, S.; Denisov, S.; Dushkin, A.; Kochetkov, V.; Lipaev, V.; Popov, A.; Shein, I.; Soldatov, A.; Anoshina, E.V.; Bodyagin, V.A.; Demianov, A.I.; Gribushin, A.M.; Kodolova, O.L.; Korotkikh, V.L.; Kostin, M.A.; Ostrovidov, A.I.; Sarycheva, L.I.; Sinev, N.B.; Vardanyan, I.N.; Yershov, A.A.; Adams, T.; Bishop, J.M.; Cason, N.M.; Sanjari, A.H.; LoSecco, J.M.; Manak, J.J.; Shephard, W.D.; Stienike, D.L.; Taegar, S.A.; Thompson, D.R.; Brown, D.S.; Pedlar, T.; Seth, K.K.; Wise, J.; Zhao, D.; Adams, G.S.; Napolitano, J.; Nozar, M.; Smith, J.A.; Witkowski, M.

    1997-01-01

    A cylindrical multiwire drift chamber with axial charge-division has been constructed and used in experiment E852 at Brookhaven National Laboratory. It serves as a trigger element and as a tracking device for recoil protons in π - p interactions. We describe the chamber's design considerations, details of its construction, electronics, and performance characteristics. (orig.)

  1. Measurement of cylindrical particles with phase Doppler anemometry.

    Science.gov (United States)

    Mignon, H; Gréhan, G; Gouesbet, G; Xu, T H; Tropea, C

    1996-09-01

    Light scattering from cylindrical particles has been described with geometric optics. The feasibility of determining the particle diameter with a planar phase Doppler anemometer has been examined by simulations and experiments. In particular, the influence of particle orientation on measurability and measurement accuracy has been investigated. Some recommendations for realizing a practical-measurement instrument have been presented.

  2. Formation of vortex breakdown in conical–cylindrical cavities

    International Nuclear Information System (INIS)

    Martins, Diego Alves de Moro; Souza, Francisco José de; Salvo, Ricardo de Vasconcelos

    2014-01-01

    Highlights: • Rotating flows in conical–cylindrical cavities were simulated via an in-house code using unstructured meshes. • The vortex breakdown phenomenon was verified in the geometries analyzed. • The influence of Stewartson and Bödewadt layers was observed in the vortex breakdown formation. • A curve of stability and number of breakdowns was obtained as a function of Reynolds number. • Spiral vortex breakdown was observed in some situations. - Abstract: Numerical simulations in confined rotating flows were performed in this work, in order to verify and characterize the formation of the vortex breakdown phenomenon. Cylindrical and conical–cylindrical geometries, both closed, were used in the simulations. The rotating flow is induced by the bottom wall, which rotates at constant angular velocity. Firstly the numerical results were compared to experimental results available in references, with the purpose to verify the capacity of the computational code to predict the vortex breakdown phenomenon. Further, several simulations varying the parameters which govern the characteristics of the flows analyzed in this work, i.e., the Reynolds number and the aspect ratio, were performed. In these simulations, the limits for the transitional regime and the vortex breakdown formation were verified. Steady and transient cases, with and without turbulence modeling, were simulated. In general, some aspects of the process of vortex breakdown in conical–cylindrical geometries were observed to be different from that in cylinders

  3. Positive column of the discharge in a cylindrical shell

    International Nuclear Information System (INIS)

    Uehara, M.; Maciel, H.S.

    1991-01-01

    A Schottky type theoretical model is presented for the positive column of a discharge on a cylindric shell contained gas, with the discharge current flowing in the longitudinal direction. Some analytical results and the conclusion are presented. (L.C.J.A.). 5 refs

  4. Magnetic forces between arrays of cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, D.; Tomassetti, G.; Beleggia, Marco

    2011-01-01

    procedures. Here, we introduce analytical expressions for calculating the attraction force between two arrays of cylindrical permanent magnets and compare the predictions with experimental data obtained from force measurements with NdFeB magnets. We show that the difference between predicted and measured...

  5. Development of a cylindrical gas-fired furnace for reycling ...

    African Journals Online (AJOL)

    This study presents the development of a cylindrical gas-fired furnace, which could be used for recycling aluminum in small-scale foundries in Nigeria. The crucible, combustion chamber, suspension shaft and bearings were appropriately sized. The furnace chamber was 410 mm high and 510 mm diameter and had a ...

  6. A winning strategy for 3 x n Cylindrical Hex

    DEFF Research Database (Denmark)

    Huneke, S. C.; Hayward, R.; Toft, Bjarne

    2014-01-01

    For Cylindrical Hex on a board with circumference 3, we give a winning strategy for the end-to-end player. This is the first known winning strategy for odd circumference at least 3, answering a question of David Gale. (C) 2014 Elsevier B.V. All rights reserved....

  7. Magnetoresistance of cylindrical nanowires with artificial pinning site

    KAUST Repository

    Vidal, Enrique Vilanova

    2015-05-01

    New concepts of magnetic memory devices are exploiting the movement of data bits by current induced domain wall motion. This concept has been widely explored with rectangular nanowires (NWs) or stripes both theoretically and experimentally [1]. In the case of cylindrical NWs not much progress has been made on the experimental side, despite its promising advantages like the absence of Walker breakdown [2].

  8. Dynamics of a Liquid Dielectric Attracted by a Cylindrical Capacitor

    Science.gov (United States)

    Nardi, Rafael; Lemos, Nivaldo A.

    2007-01-01

    The dynamics of a liquid dielectric attracted by a vertical cylindrical capacitor are studied. Contrary to what might be expected from the standard calculation of the force exerted by the capacitor, the motion of the dielectric is different depending on whether the charge or the voltage of the capacitor is held constant. The problem turns out to…

  9. static analysis of circular cylindrical shell under hydrostatic and ring

    African Journals Online (AJOL)

    DEPT OF AGRICULTURAL ENGINEERING

    (Golzan et al, 2008). Circular cylindrical shells are used in a large variety of civil engineering structures, e.g. off-shore platforms, chimneys, silos, pipelines, bridge arches or wind turbine towers (Winterstetter et al, 2002). This work is concerned with the analysis of circular cylindri- cal shell subjected to hydrostatic pressure in.

  10. Flow-induced vibrations of circular cylindrical structures

    International Nuclear Information System (INIS)

    Chen, S.

    1977-06-01

    The problems of flow-induced vibrations of circular cylindrical structures are reviewed. First, the general method of analysis and classification of structural responses are presented. Then, the presentation is broken up along the lines with stationary fluid, parallel flow, and cross flow. Finally, design considerations and future research needs are pointed out. 234 references

  11. Simulation of cylindrical Pierce diodes with radial flow

    International Nuclear Information System (INIS)

    Alves, M.V.; Gnavi, G.; Gratton, F.T.; Buenos Aires Univ.

    1996-01-01

    In this paper we study the electron instability and the non linear behaviour of cylindrical Pierce's diodes by particle simulation. We ignore here the ion contribution (ions are fixed at a 1/r density and given a very large mass) to give perspicuity to the electron dynamics, and to facilitate comparison with existing theory. (author). 8 refs., 10 figs

  12. A Clustering Method for Data in Cylindrical Coordinates

    Directory of Open Access Journals (Sweden)

    Kazuhisa Fujita

    2017-01-01

    Full Text Available We propose a new clustering method for data in cylindrical coordinates based on the k-means. The goal of the k-means family is to maximize an optimization function, which requires a similarity. Thus, we need a new similarity to obtain the new clustering method for data in cylindrical coordinates. In this study, we first derive a new similarity for the new clustering method by assuming a particular probabilistic model. A data point in cylindrical coordinates has radius, azimuth, and height. We assume that the azimuth is sampled from a von Mises distribution and the radius and the height are independently generated from isotropic Gaussian distributions. We derive the new similarity from the log likelihood of the assumed probability distribution. Our experiments demonstrate that the proposed method using the new similarity can appropriately partition synthetic data defined in cylindrical coordinates. Furthermore, we apply the proposed method to color image quantization and show that the methods successfully quantize a color image with respect to the hue element.

  13. Optical Properties of Helical Cylindrical Molecular Aggregates : The Homogeneous Limit

    NARCIS (Netherlands)

    Didraga, Cătălin; Klugkist, Joost A.; Knoester, Jasper

    2002-01-01

    Using a Frenkel exciton model, we study the optical absorption spectrum and linear and circular dichroism (CD) spectra of cylindrical molecular aggregates. We demonstrate that such aggregates can always be described as a stack of molecular rings with nearest-neighbor rings rotated relative to each

  14. Dynamic shear-bending buckling experiments of cylindrical shells

    International Nuclear Information System (INIS)

    Hagiwara, Y.; Akiyama, H.

    1995-01-01

    Dynamic experimental studies of the plastic shear/bending buckling of cylindrical shells were performed. They clarified the inelastic response reduction and the seismic margin of FBR reactor vessels. The test results were incorporated into the draft of the seismic buckling design guidelines of FBR. (author). 15 refs., 3 figs

  15. Rothe's method for parabolic equations on non-cylindrical domains

    Czech Academy of Sciences Publication Activity Database

    Dasht, J.; Engström, J.; Kufner, Alois; Persson, L.E.

    2006-01-01

    Roč. 1, č. 1 (2006), s. 59-80 ISSN 0973-2306 Institutional research plan: CEZ:AV0Z10190503 Keywords : parabolic equations * non-cylindrical domains * Rothe's method * time-discretization Subject RIV: BA - General Mathematics

  16. Static Solutions of Einstein's Equations with Cylindrical Symmetry

    Science.gov (United States)

    Trendafilova, C. S.; Fulling, S. A.

    2011-01-01

    In analogy with the standard derivation of the Schwarzschild solution, we find all static, cylindrically symmetric solutions of the Einstein field equations for vacuum. These include not only the well-known cone solution, which is locally flat, but others in which the metric coefficients are powers of the radial coordinate and the spacetime is…

  17. Numerical study of the effect of inlet geometry on combustion instabilities in a lean premixed swirl combustor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Eon [Dept. of Mechanical Engineering, Inha University, Incheon (Korea, Republic of); Park, Seul Hyun [Dept. of Mechanical Systems Engineering, Chosun University, Gwangju (Korea, Republic of); Hwang, Cheol Hong [Dept. of Fire and Disaster Prevention, Daejeon University, Daejeon (Korea, Republic of)

    2016-11-15

    The effects of flow structure and flame dynamics on combustion instabilities in a lean premixed swirl combustor were numerically investigated using Large eddy simulation (LES) by varying the inlet geometry of combustor. The dynamic ksgs-equation and G-equation flamelet models were respectively employed as the LES subgrid models of turbulence and combustion. The divergent half angle (α) in the combustor inlet was varied systematically from 30° to 90° to quantify the effect of inlet geometry on the combustion instabilities. This variation caused considerable deformation in recirculation zones in terms of their size and location, leading to significant changes in flame dynamics. Analysis of unsteady pressure distributions in the combustor showed that the largest damping caused by combustion instabilities takes place at α = 45°, and the amplitude of acoustic pressure oscillation is largest at α = 30°. Examination of local Rayleigh parameters indicated that controlling flame-vortex interactions by modifying inlet geometry can change the local characteristics of combustion instabilities in terms of their amplification and suppression, and thus serve as a useful approach to reduce the instabilities in a lean premixed swirl combustor. These phenomena were studied in detail through unsteady analysis associated with flow and flame dynamics.

  18. Experimental and Modeling Investigation of the Effect of Air Preheat on the Formation of NOx in an RQL Combustor

    Science.gov (United States)

    Samuelsen, G. S.; Brouwer, J.; Vardakas, M. A.; Holderman, J. D.

    2012-01-01

    The Rich-burn/Quick-mix/Lean-burn (RQL) combustor concept has been proposed to minimize the formation of oxides of nitrogen (NOx) in gas turbine systems. The success of this low-NOx combustor strategy is dependent upon the links between the formation of NOx, inlet air preheat temperature, and the mixing of the jet air and fuel-rich streams. Chemical equilibrium and kinetics modeling calculations and experiments were performed to further understand NOx emissions in an RQL combustor. The results indicate that as the temperature at the inlet to the mixing zone increases (due to preheating and/or operating conditions) the fuel-rich zone equivalence ratio must be increased to achieve minimum NOx formation in the primary zone of the combustor. The chemical kinetics model illustrates that there is sufficient residence time to produce NOx at concentrations that agree well with the NOx measurements. Air preheat was found to have very little effect on mixing, but preheating the air did increase NOx emissions significantly. By understanding the mechanisms governing NOx formation and the temperature dependence of key reactions in the RQL combustor, a strategy can be devised to further reduce NOx emissions using the RQL concept.

  19. Numerical study of the effect of inlet geometry on combustion instabilities in a lean premixed swirl combustor

    International Nuclear Information System (INIS)

    Lee, Chang Eon; Park, Seul Hyun; Hwang, Cheol Hong

    2016-01-01

    The effects of flow structure and flame dynamics on combustion instabilities in a lean premixed swirl combustor were numerically investigated using Large eddy simulation (LES) by varying the inlet geometry of combustor. The dynamic ksgs-equation and G-equation flamelet models were respectively employed as the LES subgrid models of turbulence and combustion. The divergent half angle (α) in the combustor inlet was varied systematically from 30° to 90° to quantify the effect of inlet geometry on the combustion instabilities. This variation caused considerable deformation in recirculation zones in terms of their size and location, leading to significant changes in flame dynamics. Analysis of unsteady pressure distributions in the combustor showed that the largest damping caused by combustion instabilities takes place at α = 45°, and the amplitude of acoustic pressure oscillation is largest at α = 30°. Examination of local Rayleigh parameters indicated that controlling flame-vortex interactions by modifying inlet geometry can change the local characteristics of combustion instabilities in terms of their amplification and suppression, and thus serve as a useful approach to reduce the instabilities in a lean premixed swirl combustor. These phenomena were studied in detail through unsteady analysis associated with flow and flame dynamics

  20. Micro club

    CERN Multimedia

    Micro club

    2014-01-01

    Opération NEMO   Pour finir en beauté les activités spéciales que le CMC a réalisé pendant cette année 2014, pour commémorer le 60ème anniversaire du CERN, et le 30ème du Micro Club, l’ Opération NEMO aura cette année un caractère très particulier. Nous allons proposer 6 fabricants de premier ordre qui offriront chacun deux ou trois produits à des prix exceptionnels. L’opération débute le lundi 17 novembre 2014. Elle se poursuivra  jusqu’au samedi 6 décembre inclus. Les délais de livraison seront de deux à trois semaines, selon les fabricants. Donc les commandes faites la dernière semaine, du 1 au 6 décembre, risquent d’arriver qu'au début du mois de janvier 2015. Liste de fabricants part...

  1. Micro club

    CERN Multimedia

    Micro Club

    2014-01-01

    Jeudi 18 septembre 2014 à 18h30 au Bât. 567 R-029 Le CERN MICRO CLUB organise un Atelier sur la sécurité informatique. La Cyber-sécurité : Ce qui se passe vraiment, comment ne pas en être victime ! Orateur : Sebastian Lopienski Adjoint au Computer Security Officer du Département IT. Sujet : Cet exposé vous présentera les modes de sécurité actuels et les problèmes touchants les applications logicielles des ordinateurs, les réseaux ainsi que leurs utilisateurs. Cela inclus des informations sur les nouveaux types de vulnérabilité, les vecteurs d'attaque récents et une vue d'ensemble sur le monde de la cyber-sécurité en 2014. Biographie : Sebastian Lopienski travaille au CERN depuis 2001. Il est actuellement adjoint au Computer Security Officer et s'occupe de la protection de...

  2. Sound radiation modes of cylindrical surfaces and their application to vibro-acoustics analysis of cylindrical shells

    Science.gov (United States)

    Sun, Yao; Yang, Tiejun; Chen, Yuehua

    2018-06-01

    In this paper, sound radiation modes of baffled cylinders have been derived by constructing the radiation resistance matrix analytically. By examining the characteristics of sound radiation modes, it is found that radiation coefficient of each radiation mode increases gradually with the increase of frequency while modal shapes of sound radiation modes of cylindrical shells show a weak dependence upon frequency. Based on understandings on sound radiation modes, vibro-acoustics behaviors of cylindrical shells have been analyzed. The vibration responses of cylindrical shells are described by modified Fourier series expansions and solved by Rayleigh-Ritz method involving Flügge shell theory. Then radiation efficiency of a resonance has been determined by examining whether the vibration pattern is in correspondence with a sound radiation mode possessing great radiation efficiency. Furthermore, effects of thickness and boundary conditions on sound radiation of cylindrical shells have been investigated. It is found that radiation efficiency of thicker shells is greater than thinner shells while shells with a clamped boundary constraint radiate sound more efficiently than simply supported shells under thin shell assumption.

  3. Exploiting Stretchable Metallic Springs as Compliant Electrodes for Cylindrical Dielectric Elastomer Actuators (DEAs

    Directory of Open Access Journals (Sweden)

    Chien-Hao Liu

    2017-11-01

    Full Text Available In recent years, dielectric elastomer actuators (DEAs have been widely used in soft robots and artificial bio-medical applications. Most DEAs are composed of a thin dielectric elastomer layer sandwiched between two compliant electrodes. DEAs vary in their design to provide bending, torsional, and stretch/contraction motions under the application of high external voltages. Most compliant electrodes are made of carbon powders or thin metallic films. In situations involving large deformations or improper fabrication, the electrodes are susceptible to breakage and increased resistivity. The worst cases result in a loss of conductivity and functional failure. In this study, we developed a method by which to exploit stretchable metallic springs as compliant electrodes for cylindrical DEAs. This design was inspired by the extensibility of mechanical springs. The main advantage of this approach is the fact that the metallic spring-like compliant electrodes remain conductive and do not increase the stiffness as the tube-like DEAs elongate in the axial direction. This can be attributed to a reduction in thickness in the radial direction. The proposed cylindrical structure is composed of highly-stretchable VHB 4905 film folded within a hollow tube and then sandwiched between copper springs (inside and outside to allow for stretching and contraction in the axial direction under the application of high DC voltages. We fabricated a prototype and evaluated the mechanical and electromechanical properties of the device experimentally using a high-voltage source of 9.9 kV. This device demonstrated a non-linear increase in axial stretching with an increase in applied voltage, reaching a maximum extension of 0.63 mm (axial strain of 2.35% at applied voltage of 9.9 kV. Further miniaturization and the incorporation of compressive springs are expected to allow the implementation of the proposed method in soft micro-robots and bio-mimetic applications.

  4. Techniques for enhancing durability and equivalence ratio control in a rich-lean, three-stage ground power gas turbine combustor

    Science.gov (United States)

    Schultz, D. F.

    1982-01-01

    Rig tests of a can-type combustor were performed to demonstrate two advanced ground power engine combustor concepts: steam cooled rich-burn combustor primary zones for enhanced durability; and variable combustor geometry for three stage combustion equivalence ratio control. Both concepts proved to be highly successful in achieving their desired objectives. The steam cooling reduced peak liner temperatures to less than 800 K. This offers the potential of both long life and reduced use of strategic materials for liner fabrication. Three degrees of variable geometry were successfully implemented to control airflow distribution within the combustor. One was a variable blade angle axial flow air swirler to control primary airflow while the other two consisted of rotating bands to control secondary and tertiary or dilution air flow.

  5. Rotation, inversion and perversion in anisotropic elastic cylindrical tubes and membranes

    KAUST Repository

    Goriely, A.; Tabor, M.

    2013-01-01

    Cylindrical tubes and membranes are universal structural elements found in biology and engineering over a wide range of scales.Working in the framework of nonlinear elasticity, we consider the possible deformations of elastic cylindrical shells

  6. Rayleigh/Raman/LIF measurements in a turbulent lean premixed combustor

    Energy Technology Data Exchange (ETDEWEB)

    Nandula, S.P.; Pitz, R.W. [Vanderbilt Univ., Nashville, TN (United States); Barlow, R.S. [Sandia National Labs., Livermore, CA (United States)] [and others

    1995-10-01

    Much of the industrial electrical generation capability being added worldwide is gas-turbine engine based and is fueled by natural gas. These gas-turbine engines use lean premixed (LP) combustion to meet the strict NO{sub x} emission standards, while maintaining acceptable levels of CO. In conventional, diffusion flame gas turbine combustors, large amount of NO{sub x} forms in the hot stoichiometric zones via the Zeldovich (thermal) mechanism. Hence, lean premixed combustors are rapidly becoming the norm, since they are specifically designed to avoid these hot stoichiometric zones and the associated thermal NO, However, considerable research and development are still required to reduce the NO{sub x} levels (25-40 ppmvd adjusted to 15% O{sub 2} with the current technology), to the projected goal of under 10 ppmvd by the turn of the century. Achieving this objective would require extensive experiments in LP natural gas (or CH{sub 4}) flames for understanding the combustion phenomena underlying the formation of the exhaust pollutants. Although LP combustion is an effective way to control NO{sub x}, the downside is that it increases the CO emissions. The formation and destruction of the pollutants (NO{sub x} and CO) are strongly affected by the fluid mechanics, the finite-rate chemistry, and their (turbulence-chemistry) interactions. Hence, a thorough understanding of these interactions is vital for controlling and reducing the pollutant emissions. The present research is contributing to this goal by providing a detailed nonintrusive laser based data set with good spatial and temporal resolutions of the pollutants (NO and CO) along with the major species, temperature, and OH. The measurements reported in this work, along with the existing velocity data on a turbulent LP combustor burning CH{sub 4}, would provide insight into the turbulence-chemistry interactions and their effect on pollutant formation.

  7. Experimental study of slight temperature rise combustion in trapped vortex combustors for gas turbines

    International Nuclear Information System (INIS)

    Zhang, R.C.; Fan, W.J.; Xing, F.; Song, S.W.; Shi, Q.; Tian, G.H.; Tan, W.L.

    2015-01-01

    Interstage turbine combustion used for improving efficiency of gas turbine was a new type of combustion mode. Operating conditions and technical requirements for this type of combustor were different from those of traditional combustor. It was expected to achieve engineering application in both ground-based and aviation gas turbine in the near future. In this study, a number of modifications in a base design were applied and examined experimentally. The trapped-vortex combustion technology was adopted for flame stability under high velocity conditions, and the preheating-fuel injection technology was used to improve the atomization and evaporation performance of liquid fuel. The experimental results indicated that stable and efficient combustion with slight temperature-rise can be achieved under the high velocity conditions of combustor inlet. Under all experimental conditions, the excess air coefficients of ignition and lean blow-out were larger than 7 and 20, respectively; pollutant emission index of NO x and the maximum wall temperature were below 2.5 g/(kg fuel) and 1050 K, respectively. Moreover, the effects of fuel injection and overall configuration on the combustion characteristics were analyzed in detail. The number increase, area increase and depth increase of fuel injectors had different influences on the stability, combustion characteristic and temperature distribution. - Highlights: • The combustion mode of slight temperature-rise (200 K) was achieved. • Effect of fuel and air injection on stability characteristic was investigated. • Impact of overall configuration on combustion performance was analyzed. • The feasibility of scheme was determined.

  8. Experimental study of a high-efficiency low-emission surface combustor-heater

    International Nuclear Information System (INIS)

    Xiong, Tian-yu; Khinkis, M.J.; Fish, F.F.

    1991-01-01

    The surface combustor-heater is a combined combustion/heat-transfer device in which the heat-exchange surfaces are embedded in a stationary bed of refractory material where gaseous fuel is burned. Because of intensive heat radiation from the hot solid particles and enhanced heat convection from the gas flow to the heat-exchange tubes, heat transfer is significantly intensified. Removing heat simultaneously with the combustion process has the benefit of reducing the combustion temperature, which suppresses NO x formation. A basic experimental study was conducted on a 60-kW bench-scale surface combustor-heater with two rows of water-cooled tube coils to evaluate its performance and explore the mechanism of combined convective-radiative heat transfer and its interaction with combustion in the porous matrix. Combustion stability in the porous matrix, heat-transfer rates, emissions, and pressure drop through the unit have been investigated for the variable parameters of operation and unit configurations. Experimental results have demonstrated that high combustion intensity (up to 2.5 MW/m 2 ), high heat-transfer rates (up to 310 kW/m 2 ), high density of energy conversion (up to 8 MW/m 3 ), as well as ultra-low emissions (NO x and CO as low as 15 vppm*) have been achieved. The excellent performance of the test unit and the extensive data obtained from the present experimental study provide the basis for further development of high-efficiency and ultra low-emission water heaters, boilers, and process heaters based on the surface combustor-heater concept. 4 refs., 16 figs

  9. Refractory experience in circulating fluidized bed combustors, Task 7. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, R.Q.

    1989-11-01

    This report describes the results of an investigation into the status of the design and selection of refractory materials for coal-fueled circulating fluidized-bed combustors. The survey concentrated on operating units in the United States manufactured by six different boiler vendors: Babcock and Wilcox, Combustion Engineering, Foster Wheeler, Keeler Dorr-Oliver, Pyropower, and Riley Stoker. Information was obtained from the boiler vendors, refractory suppliers and installers, and the owners/operators of over forty units. This work is in support of DOE`s Clean Coal Technology program, which includes circulating fluidized-bed technology as one of the selected concepts being evaluated.

  10. Application of Chimera Grid Scheme to Combustor Flowfields at all Speeds

    Science.gov (United States)

    Yungster, Shaye; Chen, Kuo-Huey

    1997-01-01

    A CFD method for solving combustor flowfields at all speeds on complex configurations is presented. The approach is based on the ALLSPD-3D code which uses the compressible formulation of the flow equations including real gas effects, nonequilibrium chemistry and spray combustion. To facilitate the analysis of complex geometries, the chimera grid method is utilized. To the best of our knowledge, this is the first application of the chimera scheme to reacting flows. In order to evaluate the effectiveness of this numerical approach, several benchmark calculations of subsonic flows are presented. These include steady and unsteady flows, and bluff-body stabilized spray and premixed combustion flames.

  11. On the sensitivity of a helicopter combustor wall temperature to convective and radiative thermal loads

    International Nuclear Information System (INIS)

    Berger, S.; Richard, S.; Duchaine, F.; Staffelbach, G.; Gicquel, L.Y.M.

    2016-01-01

    Highlights: • Coupling of LES, DOM and conduction is applied to an industrial combustor. • Thermal sensitivity of the combustor to convection and radiation is investigated. • CHT based on LES is feasible in an industrial context with acceptable CPU costs. • Radiation heat fluxes are of the same order of magnitude that the convective ones. • CHT with radiation are globally in good agreement with thermocolor test. - Abstract: The design of aeronautical engines is subject to many constraints that cover performance gain as well as increasingly sensitive environmental issues. These often contradicting objectives are currently being answered through an increase in the local and global temperature in the hot stages of the engine. As a result, hot spots could appear causing a premature aging of the combustion chamber. Today, the characterization of wall temperatures is performed experimentally by complex thermocolor tests in advanced phases of the design process. To limit such expensive experiments and integrate the knowledge of the thermal environment earlier in the design process, efforts are currently performed to provide high fidelity numerical tools able to predict the combustion chamber wall temperature including the main physical phenomena: combustion, convection and mixing of hot products and cold flows, radiative transfers as well as conduction in the solid parts. In this paper, partitioned coupling approaches based on a Large Eddy Simulation (LES) solver, a Discrete Ordinate Method radiation solver and an unsteady conduction code are used to investigate the sensitivity of an industrial combustor thermal environment to convection and radiation. Four computations including a reference adiabatic fluid only simulation, Conjugate Heat Transfer, Radiation-Fluid Thermal Interaction and fully coupled simulations are performed and compared with thermocolor experimental data. From the authors knowledge, such comparative study with LES has never been published. It

  12. Turbomachine combustor nozzle including a monolithic nozzle component and method of forming the same

    Science.gov (United States)

    Stoia, Lucas John; Melton, Patrick Benedict; Johnson, Thomas Edward; Stevenson, Christian Xavier; Vanselow, John Drake; Westmoreland, James Harold

    2016-02-23

    A turbomachine combustor nozzle includes a monolithic nozzle component having a plate element and a plurality of nozzle elements. Each of the plurality of nozzle elements includes a first end extending from the plate element to a second end. The plate element and plurality of nozzle elements are formed as a unitary component. A plate member is joined with the nozzle component. The plate member includes an outer edge that defines first and second surfaces and a plurality of openings extending between the first and second surfaces. The plurality of openings are configured and disposed to register with and receive the second end of corresponding ones of the plurality of nozzle elements.

  13. Characterizing G-Loading, Swirl Direction, and Rayleigh Losses in an Ultra Compact Combustor

    Science.gov (United States)

    2013-07-01

    low Mach numbers to avoid these pressure losses while burning. Radtke [25] used a modified version of the Anthenien et al. [9] rig to study pressure...losses in the combustor due to Rayleigh effects. Radtke saw this increase in Mach number when comparing reacting and non-reacting cases, seen in...Anderson, W., Radtke , J., King, P., Thornburg, H., Zelina, J., Sekar, B., “Effects of Main Swirl Direction on High-g Combustion,” 44th AIAA/ASME/SAE

  14. Synergistic erosion/corrosion of superalloys in PFB coal combustor effluent

    Science.gov (United States)

    Benford, S. M.; Zellars, G. R.; Lowell, C. E.

    1981-01-01

    Two Ni-based superalloys were exposed to the high velocity effluent of a pressurized fluidized bed coal combustor. Targets were 15 cm diameter rotors operating at 40,000 rpm and small flat plate specimens. Above an erosion rate threshold, the targets were eroded to bare metal. The presence of accelerated oxidation at lower erosion rates suggests erosion/corrosion synergism. Various mechanisms which may contribute to the observed oxide growth enhancement include erosive removal of protective oxide layers, oxide and subsurface cracking, and chemical interaction with sulfur in the gas and deposits through damaged surface layers.

  15. Thermo-hydrodynamic design of fluidized bed combustors estimating metal wastage

    CERN Document Server

    Lyczkowski, Robert W; Bouillard, Jacques X; Folga, Stephen M

    2012-01-01

    Thermo-Hydrodynamic Design of Fluidized Bed Combustors: Estimating Metal Wastage is a unique volume that finds that the most sensitive parameters affecting metal wastage are superficial fluidizing velocity, particle diameter, and particle sphericity.  Gross consistencies between disparate data sources using different techniques were found when the erosion rates are compared on the same basis using the concept of renormalization.  The simplified mechanistic models and correlations, when validated, can be used to renormalize any experimental data so they can be compared on a consistent basis using a master equation.

  16. Bed agglomeration in fluidized combustor fueled by wood and rice straw blends

    DEFF Research Database (Denmark)

    Thy, Peter; Jenkins, Brian; Williams, R.B.

    2010-01-01

    Abstract Petrographic techniques have been used to examine bed materials from fluidized bed combustion experiments that utilized wood and rice straw fuel blends. The experiments were conducted using a laboratory-scale combustor with mullite sand beds, firing temperatures of 840 to 1030 °C, and run...... areas between bed particles, ultimately led to bed agglomeration. The interfaces and the presence of gas bubbles in the cement suggest a bonding material with a high surface tension and a liquid state. The cement films originate by filling of irregularities on individual and partially agglomerated bed...

  17. Effects of chemical equilibrium on turbine engine performance for various fuels and combustor temperatures

    Science.gov (United States)

    Tran, Donald H.; Snyder, Christopher A.

    1992-01-01

    A study was performed to quantify the differences in turbine engine performance with and without the chemical dissociation effects for various fuel types over a range of combustor temperatures. Both turbojet and turbofan engines were studied with hydrocarbon fuels and cryogenic, nonhydrocarbon fuels. Results of the study indicate that accuracy of engine performance decreases when nonhydrocarbon fuels are used, especially at high temperatures where chemical dissociation becomes more significant. For instance, the deviation in net thrust for liquid hydrogen fuel can become as high as 20 percent at 4160 R. This study reveals that computer central processing unit (CPU) time increases significantly when dissociation effects are included in the cycle analysis.

  18. Combustor deployments of femtosecond laser written fiber Bragg grating arrays for temperature measurements surpassing 1000°C

    Science.gov (United States)

    Walker, Robert B.; Ding, Huimin; Coulas, David; Mihailov, Stephen J.; Duchesne, Marc A.; Hughes, Robin W.; McCalden, David J.; Burchat, Ryan; Yandon, Robert; Yun, Sangsig; Ramachandran, Nanthan; Charbonneau, Michel

    2017-05-01

    Femtosecond Infrared (fs-IR) laser written fiber Bragg gratings (FBGs), have demonstrated great potential for extreme sensing. Such conditions are inherent to advanced power plant technologies and gas turbine engines, under development to reduce greenhouse gas emissions; and the ability to measure temperature gradients in these harsh environments is currently limited by the lack of sensors and controls capable of withstanding the high temperature, pressure and corrosive conditions present. This paper reviews our fabrication and deployment of hundreds of fs-IR written FBGs, for monitoring temperature gradients of an oxy-fuel fluidized bed combustor and an aerospace gas turbine combustor simulator.

  19. Conformal ZnO nanocomposite coatings on micro-patterned surfaces for superhydrophobicity

    International Nuclear Information System (INIS)

    Steele, Adam; Bayer, Ilker; Moran, Stephen; Cannon, Andrew; King, William P.; Loth, Eric

    2010-01-01

    A conformal coating process is presented to transform surfaces with inherent micro-morphology into superhydrophobic surfaces with hierarchical surface structure using wet chemical spray casting. Nanocomposite coatings composed of zinc oxide nanoparticles and organosilane quaternary nitrogen compound are dispersed in solution for application. The coating is applied to a micro-patterned polydimethylsiloxane substrate with a regular array of cylindrical microposts as well as a surface with random micro-structure for the purpose of demonstrating improved non-wettability and a superhydrophobic state for water droplets. Coating surface morphology is investigated with an environmental scanning electron microscope and surface wettability performance is characterized by static and dynamic contact angle measurements.

  20. A Study on Accuracy Improvement of Dual Micro Patterns Using Magnetic Abrasive Deburring

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Dong-Hyun; Kwak, Jae-Seob [Pukyong Nat’l Univ., Busan (Korea, Republic of)

    2016-11-15

    In recent times, the requirement of a micro pattern on the surface of products has been increasing, and high precision in the fabrication of the pattern is required. Hence, in this study, dual micro patterns were fabricated on a cylindrical workpiece, and deburring was performed by magnetic abrasive deburring (MAD) process. A prediction model was developed, and the MAD process was optimized using the response surface method. When the predicted values were compared with the experimental results, the average prediction error was found to be approximately 7%. Experimental verification shows fabrication of high accuracy dual micro pattern and reliability of prediction model.

  1. Friction Compensation in the Upsetting of Cylindrical Test Specimens

    DEFF Research Database (Denmark)

    Christiansen, Peter; Martins, P. A. F.; Bay, Niels Oluf

    2016-01-01

    This manuscript presents a combined numerical andexperimental methodology for determining the stress-straincurve of metallic materials from the measurements of forceand displacement obtained in the axial compression of cylindrical test specimens with friction between the specimens and the platens....... The methodology is based on minimizing the errorbetween the average surface pressure obtained from the experimental measurements of the force and displacement and thatobtained from the slab method of analysis of metal plasticity.Three different friction models based on Coulomb friction, the constant friction...... model or combined friction models are utilized .Experimental results obtained from cylindrical and Rastegaev test specimens with different lubricants combined with the experimental determination of friction by means of ring compression tests allows compensating the effect of friction...

  2. Design algorithm for generatrix profile of cylindrical crowned rollers

    Directory of Open Access Journals (Sweden)

    Creţu Spiridon

    2017-01-01

    Full Text Available The cross-section of roller profile controls the pressure distribution in the contact area and radically affects the roller bearings basic dynamic load rating and rating lives. Today the most used roller profiles are the logarithmic profile and cylindrical-crowned (ZB profile. The logarithmic profile has a continuous evolution with no discontinuities till the intersection with the end fillet while ZB profile has two more discontinuities at the intersections points between the crowning circle and straight line generatrix. Using a semianalytical method, a numerical study has been carried out to find the optimum ZB profile for rollers incorporated in cylindrical rollers bearings. The basic reference rating life (L10_r has been used as optimization criterion.

  3. Response of cylindrical steel shell under seismic loading

    International Nuclear Information System (INIS)

    Tariq, M.; Amin, K.M.

    2003-01-01

    The seismic response of a cylindrical shell is simulated using the finite element method, and by spectral analysis. For this purpose the fundamental frequency of the cylinder is first calculated and compared with a published result. The mode shapes are also calculated which are later used for spectral analysis. The boundary nodes of the shell are displaced periodically according to a predetermined function of time by employing the acceleration time history of the El Centro earthquake to simulate the seismic loading. However, to conduct spectral analysis, the displacements are first transformed from the time domain to frequency domain using the Fast Fourier transformation. This spectral data is then used to obtain the actual displacement in the first mode under the given seismic loading. The techniques employed here can be used for cylindrical shell structures like rotor of a gas centrifuge, besides other structures that are subjected to seismic loading, besides in other time dependent loading conditions, for example rocket motor vibrations. (author)

  4. Electrostatic resonances and optical responses of cylindrical clusters

    International Nuclear Information System (INIS)

    Choy, C W; Xiao, J J; Yu, K W

    2008-01-01

    We developed a Green function formalism (GFF) for computing the electrostatic resonance in clusters of cylindrical particles. In the GFF, we take advantage of a surface integral equation to avoid matching the complicated boundary conditions on the surfaces of the particles. Numerical solutions of the eigenvalue equation yield a pole spectrum in the spectral representation. The pole spectrum can in turn be used to compute the optical response of these particles. For two cylindrical particles, the results are in excellent agreement with the exact results from the multiple image method and the normal mode expansion method. The results of this work can be extended to investigate the enhanced nonlinear optical responses of metal-dielectric composites, as well as optical switching in plasmonic waveguides.

  5. Study of laminated anisotropic cylindrical shells sensitive to transverse stresses

    International Nuclear Information System (INIS)

    Massard, Thierry

    1979-01-01

    A variational method for the determination of stresses and displacements in a multilayered cylindrical shell is presented. All included materials are linearly anisotropic (monoclinic) - i.e. directional fibres reinforced materials. This study uses a functional which is derived from the potential energy of the structure. The incoming stresses are σ RR , σ Rθ , σ RZ , and the displacements are u θ and u Z . This mixed group is the main variables of the formulation. It is shown that the stationarity conditions of the functional are the equilibrium equations and the associated boundary conditions. An approximate solution can be found using a finite element method which realizes a tridimensional discretization of the structure. The program issued is a specific mean for studying the transverse shear stresses in laminated cylindrical structures. From the results obtained it can be concluded that it meets all requirements for the purposes of this range of problems. (author) [fr

  6. On the dynamics of cylindrical z-pinch

    International Nuclear Information System (INIS)

    Solov'ev, L.S.

    1984-01-01

    The stationary configurations of cylindrical plasma flow in the framework of two-liquid relativistic electromagnetic gas dynamics (REMG)) and nonlinear radial oscillations of the plasma cylinder with longitudinal current in the framework of classical monoliquid MGD are considered. It is shown that at sufficiently high conductivity Z-pinch is stable relative to one-dimensional radial perturbations and its motion represents respectively nonlinear radial oscillations. In case of a rather low conductivity or low particle concentration there is in cross section a stability also in relation to the development of sausage type instability. The performed investigations of cylindrical equilibrium and radial oscillations give a qualitative representation on plasma behaviour in Z-pinch at the initial stage of it compression and expansion as well as on motion in an average plane of the developing sausage type instability

  7. Dynamics of cylindrical domain walls in smectic C liquid crystals

    International Nuclear Information System (INIS)

    Stewart, I W; Wigham, E J

    2009-01-01

    An analysis of the dynamics of cylindrical domain walls in planar aligned samples of smectic C liquid crystals is presented. A circular magnetic field, induced by an electric current, drives a time-dependent reorientation of the corresponding radially dependent director field. Nonlinear approximations to the relevant nonlinear dynamic equation, derived from smectic continuum theory, are solved in a comoving coordinated frame: exact solutions are found for a π-wall and numerical solutions are calculated for π/2-walls. Each calculation begins with an assumed initial state for the director that is a prescribed cylindrical domain wall. Such an initial wall will proceed to expand or contract as its central core propagates radially inwards or outwards, depending on the boundary conditions for the director, the elastic constants, the magnitude of the field and the sign of the magnetic anisotropy of the liquid crystal

  8. The transmission probability method in one-dimensional cylindrical geometry

    International Nuclear Information System (INIS)

    Rubin, I.E.

    1983-01-01

    The collision probability method widely used in solving the problems of neutron transpopt in a reactor cell is reliable for simple cells with small number of zones. The increase of the number of zones and also taking into account the anisotropy of scattering greatly increase the scope of calculations. In order to reduce the time of calculation the transmission probability method is suggested to be used for flux calculation in one-dimensional cylindrical geometry taking into account the scattering anisotropy. The efficiency of the suggested method is verified using the one-group calculations for cylindrical cells. The use of the transmission probability method allows to present completely angular and spatial dependences is neutrons distributions without the increase in the scope of calculations. The method is especially effective in solving the multi-group problems

  9. Fem Formulation of Heat Transfer in Cylindrical Porous Medium

    Science.gov (United States)

    Azeem; Khaleed, H. M. T.; Soudagar, Manzoor Elahi M.

    2017-08-01

    Heat transfer in porous medium can be derived from the fundamental laws of flow in porous region ass given by Henry Darcy. The fluid flow and energy transport inside the porous medium can be described with the help of momentum and energy equations. The heat transfer in cylindrical porous medium differs from its counterpart in radial and axial coordinates. The present work is focused to discuss the finite element formulation of heat transfer in cylindrical porous medium. The basic partial differential equations are derived using Darcy law which is the converted into a set of algebraic equations with the help of finite element method. The resulting equations are solved by matrix method for two solution variables involved in the coupled equations.

  10. Gamma ray absorption of cylindrical fissile material with dual shields

    International Nuclear Information System (INIS)

    Wu Chenyan; Cheng Yiying; Huang Yongyi; Lu Fuquan; Yang Fujia

    2005-01-01

    This work analyzed the gamma ray attenuation effect from the self-absorption and shield attenuation perspectively. An exact mathematical equation was given for the geometric factor of the cylindrical fissile material with dual shields. In addition, several approximation approaches suitable for real situation were discussed, especially in the radial and axial directions of the cylinders, since the G-factors have simple forms. Then the space distribution patterns of the G-factor were analyzed based on numerical result and effective ways to solved the geometric information of the cylindrical fissile material, the radii and the heights, were deduced. This method was checked and verified by numerical calculation. Because of the efficiency of the method, it is ideal for application in real situations, such as nuclear safeguards, which demands speed of detection and accuracy of geometric analysis. (authors)

  11. Microinstabilities in a radially contracting inhomogeneous cylindrical plasma slab

    International Nuclear Information System (INIS)

    Deutsch, R.; Kaeppeler, H.J.

    1980-07-01

    In order to study the development of microinstabilities in a collapsing cylindrical plasma sheath, corresponding to the situations in a z-pinch or a plasma focus, the dispersion relation for electromagnetic perturbations is derived with the aid of a newly established slab-model for an inhomogeneous, radially contracting plasma. In contrast to previously used slab-models, the orientation of the electric field is in direction of the cylinder axis and the azimuthal magnetic field is induced by the current flowing through the cylindrical plasma slab. The Vlasov equation is used together with the Krook collision term in order to include the influence of collisions. The results of this theory presented in this report will be used to calculate the growth of drift instabilities in the compression phase of a plasma focus, and shall serve as a basis for further development of a more general dispersion relation including runaway-effects. (orig.)

  12. Cylindrization of a PWR core for neutronic calculations

    International Nuclear Information System (INIS)

    Santos, Rubens Souza dos

    2005-01-01

    In this work we propose a core cylindrization, starting from a PWR core configuration, through the use of an algorithm that becomes the process automated in the program, independent of the discretization. This approach overcomes the problem stemmed from the use of the neutron transport theory on the core boundary, in addition with the singularities associated with the presence of corners on the outer fuel element core of, existents in the light water reactors (LWR). The algorithm was implemented in a computational program used to identification of the control rod drop accident in a typical PWR core. The results showed that the algorithm presented consistent results comparing with an production code, for a problem with uniform properties. In our conclusions, we suggest, for future works, for analyzing the effect on mesh sizes for the Cylindrical geometry, and to compare the transport theory calculations versus diffusion theory, for the boundary conditions with corners, for typical PWR cores. (author)

  13. A study of aerosol deposition by thermophoresis in cylindrical ducts

    International Nuclear Information System (INIS)

    Montassier, N.

    1990-01-01

    The scope of the study was aerosol deposition in cylindrical ducts, and the deposition due to thermophoresis particularly. The theoretical knowledge on this force and the basis of fluid mechanics are first recalled. An experimental study of thermophoretic deposition of particles in laminar flow was carried out in the particular case of uniform particle concentration and gas temperature at the inlet of the cooled tube. When the gas temperature was equilibrated with the wall temperature and thermophoretic particle deposition along the walls had ceased, the deposition efficiency approached a limit. Our experimental results showed that this limiting efficiency was independent on flow. Finally, for the laminar flow regime, a set of simple equations was developed in order to forecast the thermophoretic deposition of particles of any size along a cylindrical tube [fr

  14. Numerical solutions to critical problem of reflected cylindrical reactor

    International Nuclear Information System (INIS)

    Horie, Junnosuke

    1977-01-01

    The multi-region critical problem can be transformed into an eigenvalue problem in the classical sense by using the method of Kuscer and Corngold and of Wing. This transformation is applied to derive a variational formulation for a reflected reactor. An approximate critical value of the multiplying factor is determined by maximizing the Rayleigh quotient for radially and totally reflected cylindrical reactors. It is shown that this approximate critical value is an upper bound of the true critical value. From the facts that the operator is self-adjoint and the eigenfunction is positive, an expression is derived for the upper and lower bounds of the true eigenvalue, by making use of the approximate distribution. The difference of the upper and lower bounds is an uncertainty of the presumption of the true critical value. It is found that we can compute the bounds to any required precision. The narrow bounds are calculated for two radially and one totally reflected cylindrical reactors. (auth.)

  15. Performance of cylindrical-conical cyclones with different geometrical configurations

    Directory of Open Access Journals (Sweden)

    J.D.A.M. Santana

    2001-09-01

    Full Text Available The present work is a continuation of a study of the influence of geometric characteristics on the performance of reverse-flow cylindrical-conical cyclones. After studying the behavior of the pressure drop in previous work (Arnosti et al., 1998, here performance in terms of collection efficiency in the removal of particulate material is addressed. The independent variables considered in this study were inlet gas velocity (three velocities and the following dimensions of the cyclone: the cylindrical section (three heights and internal height of the gas exit duct (three heights. The tests were performed using an 3³ experimental design. Analysis of the results for overall efficiency was carried out using response surfaces and the statistical parameters were estimated from linear regression.

  16. Pulling cylindrical particles using a soft-nonparaxial tractor beam

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Ding, Weiqiang; Wang, Maoyan

    2017-01-01

    In order to pull objects towards the light source a single tractor beam inevitably needs to be strongly nonparaxial. This stringent requirement makes such a tractor beam somewhat hypothetical. Here we reveal that the cylindrical shape of dielectric particles can effectively mitigate the nonparaxi......In order to pull objects towards the light source a single tractor beam inevitably needs to be strongly nonparaxial. This stringent requirement makes such a tractor beam somewhat hypothetical. Here we reveal that the cylindrical shape of dielectric particles can effectively mitigate...... the nonparaxiality requirements, reducing the incidence angle of the partial plane waves of the light beam down to 45 degrees and even to 30 degrees for respectively dipole and dipole-quadrupole objects. The optical pulling force attributed to the interaction of magnetic dipole and magnetic quadrupole moments...... and sorting of targeted particles....

  17. Vertical load analysis of cylindrical ACS support structures

    International Nuclear Information System (INIS)

    Kennedy, J.M.; Belytschko, T.B.

    1984-01-01

    A new concept in LMFBR design ACS (above-core structures) supports which has generated some interest is to use a single large radius cylinder. The advantages of a single cylinder are reduced cost of fabrication, increased lateral stiffness, which enhances seismic resistance, and easier access to the fuel. However, the performance of these support structures when submitted to vertical loads from the core area may be substantially different, for the buckling and postbuckling behavior of a cylinder differs substantially from that of cylindrical beams. In this paper, a comparative analysis of an old prototypical support by 4 columns is compared with a cylindrical support. It is assumed that the single cylinder replaces the 4 columns in the original design. The dimensions of the two designs are compared

  18. Analytic, high β, flux conserving equilibria for cylindrical tokamaks

    International Nuclear Information System (INIS)

    Sigmar, D.J.; Vahala, G.

    1978-09-01

    Using Grad's theory of generalized differential equations, the temporal evolution from low to high β due to ''adiabatic'' and nonadiabatic (i.e., neutral beam injection) heating of a cylindrical tokamak plasma with circular cross section and peaked current profiles is calculated analytically. The influence of shaping the initial safety factor profile and the beam deposition profile and the effect of minor radius compression on the equilibrium is analyzed

  19. On the accuracy of the asymptotic theory for cylindrical shells

    DEFF Research Database (Denmark)

    Niordson, Frithiof; Niordson, Christian

    1999-01-01

    We study the accuracy of the lowest-order bending theory of shells, derived from an asymptotic expansion of the three-dimensional theory of elasticity, by comparing the results of this shell theory for a cylindrical shell with clamped ends with the results of a solution to the three......-dimensional problem. The results are also compared with those of some commonly used engineering shell theories....

  20. On the accuracy of the asymptotic theory for cylindrical shells

    DEFF Research Database (Denmark)

    Niordson, Frithiof; Niordson, Christian

    1999-01-01

    We study the accuracy of the lowest-order bending theory of shells, derived from an asymptotic expansion of the three-dimensional theory of elasticity, by comparing the results of this theory for a cylindrical shell with clamped ends with the results of a solution to the three-dimensional problem....... The results are also compared with those of some commonly used engineering shell theories....

  1. Analytic, high β, flux conserving equilibria for cylindrical tokamaks

    International Nuclear Information System (INIS)

    Sigmar, D.J.; Vahala, G.

    1978-01-01

    Using Grad's theory of generalized differential equations, the temporal evolution from low to high β due to ''adiabatic'' and nonadiabatic (i.e., neutral beam injection) heating of a cylindrical tokamak plasma with circular cross section and peaked current profiles is calculated analytically. The influence of shaping the initial safety factor profile and the beam deposition profile and the effect of minor radius compression on the equilibrium is analyzed

  2. System of cylindrical drift chambers in a superconducting solenoid

    International Nuclear Information System (INIS)

    Camilleri, L.; Blumenfeld, B.J.; Dimcovski, Z.

    1978-01-01

    A superconducting solenoid at the CERN ISR was equipped with a system of high accuracy cylindrical drift chambers. This detector consists of eight layers of field shaped drift cells with a delay line opposite each sense wire to provide coupled two dimensional readout. The design, construction, and operation of this system are discussed. The resolution and performance of the delay lines and sense wires under ISR running conditions are shown

  3. Fatigue and Model Analysis of the CNC Cylindrical Grinder

    OpenAIRE

    Lin Jui-Chang; Lin Cheng-Jen

    2016-01-01

    The purpose of this study is to lower deviation of workpiece by meeting high stability and rigidity to prevent the resonance in producing procedure of the CNC universal cylindrical grinding machine. Using finite element analysis software ABAQUS in grinder machine tools for numerical simulation of several analyses for the following: structural rigidity analysis, optimized design, vibration frequency analysis and fatigue damage analysis. This work aims on state of the transmission of outer diam...

  4. Electron Raman scattering in a cylindrical quantum dot

    International Nuclear Information System (INIS)

    Zhong Qinghu; Yi Xuehua

    2012-01-01

    Electron Raman scattering (ERS) is investigated in a CdS cylindrical quantum dot (QD). The differential cross section is calculated as a function of the scattering frequency and the size of the QD. Single parabolic conduction and valence bands are assumed, and singularities in the spectrum are found and interpreted. The selection rules for the processes are also studied. The ERS studied here can be used to provide direct information about the electron band structure of these systems. (semiconductor physics)

  5. Stability of cylindrical plasma in the Bessel function model

    International Nuclear Information System (INIS)

    Yamagishi, T.; Gimblett, C.G.

    1988-01-01

    The stability of free boundary ideal and tearing modes in a cylindrical plasma is studied by examining the discontinuity (Δ') of the helical flux function given by the force free Bessel function model at the singular surface. The m = O and m = 1 free boundary tearing modes become strongly unstable when the singular surface is just inside the plasma boundary for a wide range of longitudinal wave numbers. (author)

  6. Effective thermoelastic properties of composites with periodicity in cylindrical coordinates

    KAUST Repository

    Chatzigeorgiou, George

    2012-09-01

    The aim of this work is to study composites that present cylindrical periodicity in the microstructure. The effective thermomechanical properties of these composites are identified using a modified version of the asymptotic expansion homogenization method, which accounts for unit cells with shell shape. The microscale response is also shown. Several numerical examples demonstrate the use of the proposed approach, which is validated by other micromechanics methods. © 2012 Elsevier Ltd. All rights reserved.

  7. The data acquisition system for a SPECT with cylindrical detector

    International Nuclear Information System (INIS)

    Jin Yongjie; Liu Yinong; Li Yuanjing

    1995-01-01

    The data acquisition and position estimation system has been developed for a multi-crystal SPECT with modular cylindrical detector. The electronics screen photon energy determines the detector module stricken by incident photon. The relevant PMT outputs are digitized and passed onto a Pentium PC. Then PMT gain normalization, detector bar identification, energy correction, event coordinates calculation and linearity correction are real-time performed by the PC. The system has been employed in clinical brain imaging

  8. Motion of a compact toroid inside a cylindrical flux conserver

    Energy Technology Data Exchange (ETDEWEB)

    Jarboe, T.R.; Henins, I.; Hoida, H.W.; Linford, R.K.; Marshall, J.; Platts, D.A.; Sherwood, A.R.

    1980-10-13

    Compact toroids have been generated in a cylindrical resistive flux conserver. They are observed to rotate so that their major axis is perpendicular to the axis of the flux conserver. Subsequently they remain stationary and their magnetic fields decay with a time constant of about 100 ..mu..s. This is the first observation of the predicted tipping mode and its saturation when no external fields are present. The compact toroids contain toroidal fields and are initially prolate in shape.

  9. Motion of a compact toroid inside a cylindrical flux conserver

    International Nuclear Information System (INIS)

    Jarboe, T.R.; Henins, I.; Hoida, H.W.; Linford, R.K.; Marshall, J.; Platts, D.A.; Sherwood, A.R.

    1980-01-01

    Compact toroids have been generated in a cylindrical resistive flux conserver. They are observed to rotate so that their major axis is perpendicular to the axis of the flux conserver. Subsequently they remain stationary and their magnetic fields decay with a time constant of about 100 μs. This is the first observation of the predicted tipping mode and its saturation when no external fields are present. The compact toroids contain toroidal fields and are initially prolate in shape

  10. A theoretical study of cylindrical ultrasound transducers for intracavitary hyperthermia

    International Nuclear Information System (INIS)

    Lin, W.-L.; Fan, W.-C.; Yen, J.-Y.; Chen, Y.-Y.; Shieh, M.-J.

    2000-01-01

    Purpose: The purpose of this paper was to examine the heating patterns and penetration depth when a cylindrical ultrasound transducer is employed for intracavitary hyperthermia treatments. Methods and Materials: The present study employs a simulation program based on a simplified power deposition model for infinitely long cylindrical ultrasound transducers. The ultrasound power in the tissue is assumed to be exponentially attenuated according to the penetration depth of the ultrasound beam, and a uniform attenuation for the entire treatment region is also assumed. The distribution of specific absorption rate (SAR) ratio (the ratio of SAR for a point within the tissue to that for a specific point on the cavity surface) is used to determine the heating pattern for a set of given parameters. The parameters considered are the ultrasound attenuation in the tissue, the cavity size, and the transducer eccentricity. Results: Simulation results show that the ultrasound attenuation in the tissue, the cavity size, and the transducer eccentricity are the most influential parameters for the distribution of SAR ratio. A low frequency transducer located in a large cavity can produce a much better penetration. The cavity size is the major parameter affecting the penetration depth for a small cavity size, such as interstitial hyperthermia. The heating pattern can also be dramatically changed by the transducer eccentricity and radiating sector. In addition, for a finite length of cylindrical transducer, lower SAR ratio appears in the regions near the applicator's edges. Conclusion: The distribution of SAR ratio indicates the relationship between the treatable region and the parameters if an appropriate threshold of SAR ratio is taken. The findings of the present study comprehend whether or not a tumor is treatable, as well as select the optimal driving frequency, the appropriate cavity size, and the eccentricity of a cylindrical transducer for a specific treatment

  11. Influence of a cylindrical column of rotating plasma on stability

    International Nuclear Information System (INIS)

    Rossato, L.C.

    1975-01-01

    The kink instability of a cylindrical column of rotating plasma, liable to a perturbation of the form f (r) exp [i(m -kz) + wt], under a condition kr<< m, was studied. It was concluded that as we increase the rotation, the interval of possible instabilities decreases. When the speed of rotation in the outlines of the plasma is equal to the speed of Alfven we will surely have stability. (author)

  12. Heat Flow In Cylindrical Bodies During Laser Surface Transformation Hardening

    Science.gov (United States)

    Sandven, Ole A.

    1980-01-01

    A mathematical model for the transient heat flow in cylindrical specimens is presented. The model predicts the temperature distribution in the vicinity of a moving ring-shaped laser spot around the periphery of the outer surface of a cylinder, or the inner surface of a hollow cylinder. It can be used to predict the depth of case in laser surface transformation hardening. The validity of the model is tested against experimental results obtained on SAE 4140 steel.

  13. Characteristics of the low power cylindrical anode layer ion source

    International Nuclear Information System (INIS)

    Zhao Jie; Tang Deli; Cheng Changming; Geng Shaofei

    2009-01-01

    A low power cylindrical anode layer ion source and its working characteristic, and the beam distribution are introduced. This ion source has two working states, emanative state and collimated state, and the normal parameters of this system are: working voltage 200-1200 V, discharge current 0.1-1.4A, air pressure 1.9 x 10 -2 -1.7 x 10 -1 Pa, gas flow 5-20 sccm. (authors)

  14. A nonlinear resistive MHD-code in cylindrical geometry

    International Nuclear Information System (INIS)

    Jakoby, A.

    1987-11-01

    A computer code has been developed which solves the full compressible resistive magnetohydrodynamic (MHD) equations in cylindrical geometry. The variables are expanded in Fourier series in the poloidal and axial directions while finite differences are used in the radial direction. The time advance is accomplished by using a semi-implicit predictor-corrector-scheme. Applications to the ideal m=1 ideal kink saturation in the nonlinear regime and the subsequent decay of the singular current layer due to resistivity are presented. (orig.)

  15. Theory of semicollisional drift-interchange modes in cylindrical plasmas

    International Nuclear Information System (INIS)

    Hahm, T.S.; Chen, L.

    1985-01-01

    Resistive interchange instabilities in cylindrical plasmas are studied, including the effects of electron diamagnetic drift, perpendicular resistivity, and plasma compression. The analyses are pertinent to the semicollisional regime where the effective ion gyro-radius is larger than the resistive layer width. Both analytical and numerical results show that the modes can be completely stabilized by the perpendicular plasma transport. Ion sound effects, meanwhile, are found to be negligible in the semicollisional regime

  16. Dynamic plastic buckling of cylindrical and spherical shells

    International Nuclear Information System (INIS)

    Jones, N.; Okawa, D.M.

    1975-01-01

    A theoretical analysis is developed to predict the dynamic plastic buckling of a long, impulsively loaded cylindrical shell in order to examine various features of plastic buckling and to assess the importance of several approximations with previous authors have introduced in dynamic plastic buckling studies. The influence of a time-dependent circumferential membrane force, the sharpness of the peaks in the displacement and velocity amplification functions, the restrictions which are implicit when employing the Prandtl-Reuss equations in this class of problems, and the limitations due to elastic unloading are examined in some detail. A summary of all previously published theoretical investigations known to the authors is undertaken for the dynamic plastic behavior of cylindrical shells and rings which are made from rigid-plastic, rigid-visco-plastic, elastic-plastic and elastic-visco-plastic materials and subjected to initial axisymmetric impulsive velocity fields. The theoretical predictions of the dominant motions, critical mode numbers, and threshold impulses are compared and critically reviewed. An experimental investigation was also undertaken into the dynamic plastic buckling of circular rings subjected to uniformly distributed external impulsive velocities. It appears that no experiments have been reported previously on mild steel cylindrical shells with an axial length (L) less than four times the shell radius (R). The experimental values of the average final radial deflections, critical mode numbers and dimensions of the permanent wrinkles in the mild steel and some aliminium 6,061 T6 specimens are compared with all the previously published theoretical predictions and experimental results on cylindrical shells with various axial lengths. (orig./HP) [de

  17. Research on cylindrical indexing cam’s unilateral machining

    Directory of Open Access Journals (Sweden)

    Junhua Chen

    2015-08-01

    Full Text Available The cylindrical cam ridge of the indexer is a spatial curved surface, which is difficult to design and machine. The cylindrical cam has some defects after machining because conventional machining methods have inaccuracies. This article aims at proposing a precise way to machine an indexing cam, using basic motion analysis and analytic geometry approach. Analytical methodology is first applied in the cam’s motion analysis, to obtain an error-free cam follower’s trajectory formula, and then separate the continuous trajectory curve by thousandth resolution, to create a three-dimensional discrete trajectory curve. Planar formulae and spherical formulae can be built on the loci. Based on the machine principle, the cutting cutter’s position and orientation will be taken into account. This article calculates the formula set as presented previously and obtains the ultimate cutter path coordinate value. The new error-free cutter path trajectory is called the unilateral machining trajectory. The earned results will compile into numerical control processing schedule. This processing methodology gives a convenient and precision way to manufacture a cylindrical indexing cam. Experimental results are also well supported.

  18. A Novel Automated Method for Analyzing Cylindrical Computed Tomography Data

    Science.gov (United States)

    Roth, D. J.; Burke, E. R.; Rauser, R. W.; Martin, R. E.

    2011-01-01

    A novel software method is presented that is applicable for analyzing cylindrical and partially cylindrical objects inspected using computed tomography. This method involves unwrapping and re-slicing data so that the CT data from the cylindrical object can be viewed as a series of 2-D sheets in the vertical direction in addition to volume rendering and normal plane views provided by traditional CT software. The method is based on interior and exterior surface edge detection and under proper conditions, is FULLY AUTOMATED and requires no input from the user except the correct voxel dimension from the CT scan. The software is available from NASA in 32- and 64-bit versions that can be applied to gigabyte-sized data sets, processing data either in random access memory or primarily on the computer hard drive. Please inquire with the presenting author if further interested. This software differentiates itself in total from other possible re-slicing software solutions due to complete automation and advanced processing and analysis capabilities.

  19. Overflow Characteristic of Cylindrical Shape Crest Weirs Over Horizontal Bed

    Directory of Open Access Journals (Sweden)

    Emad4 AbdulGabbar

    2013-05-01

    Full Text Available The most common types of weirs are the broad-crested weir, the sharp-crested weir, the circular crested weir and the ogee crested weir. Advantages of the cylindrical weir shape include the stable overflow pattern, the ease to pass floating debris, the simplicity of design compared to ogee crest design and the associated lower costs. In present study, it was investigated the overflow characteristics of circular weirs in laboratory for various cylinder radii of three sizes (11.4, 9.0, 6.3 cm, and the models fixed on the channel bed vertically to the direction of flow. The result shows that the increase in the ratio of head to weir radius ratio (Hw/R value causes an increase in discharge coefficient (Cd value for the same height of weir. It was observed that the cylinder size (i.e. radius of cylindrical weir (R has an effect on the (Cd. The flow magnification factor (qw/qs increases with an increase in (Hw/R value and values of (qw/qs were always higher than one for all values of (Hw/R, this means that weirs of cylindrical shape performed better than those of sharp crest for any value of weir radius tested in this study.

  20. Thermal modeling of cylindrical lithium ion battery during discharge cycle

    International Nuclear Information System (INIS)

    Jeon, Dong Hyup; Baek, Seung Man

    2011-01-01

    Highlights: → Transient and thermo-electric finite element analysis (FEA) of cylindrical lithium ion (Li-ion) battery was presented. → This model provides the thermal behavior of Li-ion battery during discharge cycle. → A LiCoO 2 /C battery at various discharge rates was investigated. → The contribution of heat source due to joule heating was significant at a high discharge rate. → The contribution of heat source due to entropy change was dominant at a low discharge rate. - Abstract: Transient and thermo-electric finite element analysis (FEA) of cylindrical lithium ion (Li-ion) battery was presented. The simplified model by adopting a cylindrical coordinate was employed. This model provides the thermal behavior of Li-ion battery during discharge cycle. The mathematical model solves conservation of energy considering heat generations due to both joule heating and entropy change. A LiCoO 2 /C battery at various discharge rates was investigated. The temperature profile from simulation had similar tendency with experiment. The temperature profile was decomposed with contributions of each heat sources and was presented at several discharge rates. It was found that the contribution of heat source due to joule heating was significant at a high discharge rate, whereas that due to entropy change was dominant at a low discharge rate. Also the effect of cooling condition and the LiNiCoMnO 2 /C battery were analyzed for the purpose of temperature reduction.