High-Fidelity Aerodynamic Design with Transition Prediction, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — To enhance aerodynamic design capabilities, Desktop Aeronautics proposes to significantly improve upon the integration (performed in Phase 1) of a new sweep/taper...

Design Of An Aerodynamic Measurement System For Unmanned Aerial Vehicle Airfoils

Directory of Open Access Journals (Sweden)

L. Velázquez-Araque

2012-10-01

Full Text Available This paper presents the design and validation of a measurement system for aerodynamic characteristics of unmanned aerial vehicles. An aerodynamic balance was designed in order to measure the lift, drag forces and pitching moment for different airfoils. During the design process, several aspects were analyzed in order to produce an efficient design, for instance the range of changes of the angle of attack with and a small increment and the versatility of being adapted to different type of airfoils, since it is a wire balance it was aligned and calibrated as well. Wind tunnel tests of a two dimensional NACA four digits family airfoil and four different modifications of this airfoil were performed to validate the aerodynamic measurement system. The modification of this airfoil was made in order to create a blowing outlet with the shape of a step on the suction surface. Therefore, four different locations along the cord line for this blowing outlet were analyzed. This analysis involved the aerodynamic performance which meant obtaining lift, drag and pitching moment coefficients curves as a function of the angle of attack experimentally for the situation where the engine of the aerial vehicle is turned off, called the no blowing condition, by means of wind tunnel tests. The experiments were performed in a closed circuit wind tunnel with an open test section. Finally, results of the wind tunnel tests were compared with numerical results obtained by means of computational fluid dynamics as well as with other experimental references and found to be in good agreement.

An interactive version of PropID for the aerodynamic design of horizontal axis wind turbines

Energy Technology Data Exchange (ETDEWEB)

Ninham, C.P.; Selig, M.S. [Univ. of Illinois, Urbana-Champaign, IL (United States)

1997-12-31

The original PROP code developed by AeroVironment, Inc. and its various versions have been in use for wind turbine performance predictions for over ten years. Due to its simplicity, rapid execution times and relatively accurate predictions, it has become an industry standard in the US. The Europeans have similar blade-element/momentum methods in use for design. Over the years, PROP has continued to be improved (in its accuracy and capability), e.g., PROPSH, PROPPC, PROP93, and PropID. The latter version incorporates a unique inverse design capability that allows the user to specify the desired aerodynamic characteristics from which the corresponding blade geometry is determined. Through this approach, tedious efforts related to manually adjusting the chord, twist, pitch and rpm to achieve desired aerodynamic/performance characteristics can be avoided, thereby making it possible to perform more extensive trade studies in an effort to optimize performance. Past versions of PropID did not have supporting graphics software. The more current version to be discussed includes a Matlab-based graphical user interface (GUI) and additional features that will be discussed in this paper.

Development of aerodynamic bearing support for application in air cycle machines

Directory of Open Access Journals (Sweden)

Šimek J.

2014-06-01

Full Text Available Air cycle machines (ACM are used in environmental control system of aircrafts to manage pressurization of the cabin. The aim of this work is to gain theoretical and experimental data enabling replacement of rolling bearings, which require lubrication and have limited operating speed, with aerodynamic bearing support. Aerodynamic bearings do not pollute process air and at the same time allow achieving higher operating speed, thus enabling to reduce machine mass and dimensions. A test stand enabling the verification of aerodynamic bearing support properties for prospective ACM was designed, manufactured and tested with operating speeds up to 65 000 rpm. Some interesting features of the test stand design and the test results are presented. A smaller test stand with operating speed up to 100 000 rpm is in design stage.

Tactical missile aerodynamics

Science.gov (United States)

Hemsch, Michael J. (Editor); Nielsen, Jack N. (Editor)

1986-01-01

The present conference on tactical missile aerodynamics discusses autopilot-related aerodynamic design considerations, flow visualization methods' role in the study of high angle-of-attack aerodynamics, low aspect ratio wing behavior at high angle-of-attack, supersonic airbreathing propulsion system inlet design, missile bodies with noncircular cross section and bank-to-turn maneuvering capabilities, 'waverider' supersonic cruise missile concepts and design methods, asymmetric vortex sheding phenomena from bodies-of-revolution, and swept shock wave/boundary layer interaction phenomena. Also discussed are the assessment of aerodynamic drag in tactical missiles, the analysis of supersonic missile aerodynamic heating, the 'equivalent angle-of-attack' concept for engineering analysis, the vortex cloud model for body vortex shedding and tracking, paneling methods with vorticity effects and corrections for nonlinear compressibility, the application of supersonic full potential method to missile bodies, Euler space marching methods for missiles, three-dimensional missile boundary layers, and an analysis of exhaust plumes and their interaction with missile airframes.

The space shuttle ascent vehicle aerodynamic challenges configuration design and data base development

Science.gov (United States)

Dill, C. C.; Young, J. C.; Roberts, B. B.; Craig, M. K.; Hamilton, J. T.; Boyle, W. W.

1985-01-01

The phase B Space Shuttle systems definition studies resulted in a generic configuration consisting of a delta wing orbiter, and two solid rocket boosters (SRB) attached to an external fuel tank (ET). The initial challenge facing the aerodynamic community was aerodynamically optimizing, within limits, this configuration. As the Shuttle program developed and the sensitivities of the vehicle to aerodynamics were better understood the requirements of the aerodynamic data base grew. Adequately characterizing the vehicle to support the various design studies exploded the size of the data base to proportions that created a data modeling/management challenge for the aerodynamicist. The ascent aerodynamic data base originated primarily from wind tunnel test results. The complexity of the configuration rendered conventional analytic methods of little use. Initial wind tunnel tests provided results which included undesirable effects from model support tructure, inadequate element proximity, and inadequate plume simulation. The challenge to improve the quality of test results by determining the extent of these undesirable effects and subsequently develop testing techniques to eliminate them was imposed on the aerodynamic community. The challenges to the ascent aerodynamics community documented are unique due to the aerodynamic complexity of the Shuttle launch. Never before was such a complex vehicle aerodynamically characterized. The challenges were met with innovative engineering analyses/methodology development and wind tunnel testing techniques.

Multidisciplinary Aerodynamic Design of a Rotor Blade for an Optimum Rotor Speed Helicopter

Directory of Open Access Journals (Sweden)

Jiayi Xie

2017-06-01

Full Text Available The aerodynamic design of rotor blades is challenging, and is crucial for the development of helicopter technology. Previous aerodynamic optimizations that focused only on limited design points find it difficult to balance flight performance across the entire flight envelope. This study develops a global optimum envelope (GOE method for determining blade parameters—blade twist, taper ratio, tip sweep—for optimum rotor speed helicopters (ORS-helicopters, balancing performance improvements in hover and various freestream velocities. The GOE method implements aerodynamic blade design by a bi-level optimization, composed of a global optimization step and a secondary optimization step. Power loss as a measure of rotor performance is chosen as the objective function, referred to as direct power loss (DPL in this study. A rotorcraft comprehensive code for trim simulation with a prescribed wake method is developed. With the application of the GOE method, a DPL reduction of as high as 16.7% can be achieved in hover, and 24% at high freestream velocity.

A comparison of two closely-related approaches to aerodynamic design optimization

Science.gov (United States)

Shubin, G. R.; Frank, P. D.

1991-01-01

Two related methods for aerodynamic design optimization are compared. The methods, called the implicit gradient approach and the variational (or optimal control) approach, both attempt to obtain gradients necessary for numerical optimization at a cost significantly less than that of the usual black-box approach that employs finite difference gradients. While the two methods are seemingly quite different, they are shown to differ (essentially) in that the order of discretizing the continuous problem, and of applying calculus, is interchanged. Under certain circumstances, the two methods turn out to be identical. We explore the relationship between these methods by applying them to a model problem for duct flow that has many features in common with transonic flow over an airfoil. We find that the gradients computed by the variational method can sometimes be sufficiently inaccurate to cause the optimization to fail.

Computerized method and system for designing an aerodynamic focusing lens stack

Science.gov (United States)

Gard, Eric [San Francisco, CA; Riot, Vincent [Oakland, CA; Coffee, Keith [Diablo Grande, CA; Woods, Bruce [Livermore, CA; Tobias, Herbert [Kensington, CA; Birch, Jim [Albany, CA; Weisgraber, Todd [Brentwood, CA

2011-11-22

A computerized method and system for designing an aerodynamic focusing lens stack, using input from a designer related to, for example, particle size range to be considered, characteristics of the gas to be flowed through the system, the upstream temperature and pressure at the top of a first focusing lens, the flow rate through the aerodynamic focusing lens stack equivalent at atmosphere pressure; and a Stokes number range. Based on the design parameters, the method and system determines the total number of focusing lenses and their respective orifice diameters required to focus the particle size range to be considered, by first calculating for the orifice diameter of the first focusing lens in the Stokes formula, and then using that value to determine, in iterative fashion, intermediate flow values which are themselves used to determine the orifice diameters of each succeeding focusing lens in the stack design, with the results being output to a designer. In addition, the Reynolds numbers associated with each focusing lens as well as exit nozzle size may also be determined to enhance the stack design.

Aerodynamic Shape Optimization Design of Wing-Body Configuration Using a Hybrid FFD-RBF Parameterization Approach

Science.gov (United States)

Liu, Yuefeng; Duan, Zhuoyi; Chen, Song

2017-10-01

Aerodynamic shape optimization design aiming at improving the efficiency of an aircraft has always been a challenging task, especially when the configuration is complex. In this paper, a hybrid FFD-RBF surface parameterization approach has been proposed for designing a civil transport wing-body configuration. This approach is simple and efficient, with the FFD technique used for parameterizing the wing shape and the RBF interpolation approach used for handling the wing body junction part updating. Furthermore, combined with Cuckoo Search algorithm and Kriging surrogate model with expected improvement adaptive sampling criterion, an aerodynamic shape optimization design system has been established. Finally, the aerodynamic shape optimization design on DLR F4 wing-body configuration has been carried out as a study case, and the result has shown that the approach proposed in this paper is of good effectiveness.

Application of computational aerodynamics methods to the design and analysis of transport aircraft

Science.gov (United States)

Da Costa, A. L.

1978-01-01

The application and validation of several computational aerodynamic methods in the design and analysis of transport aircraft is established. An assessment is made concerning more recently developed methods that solve three-dimensional transonic flow and boundary layers on wings. Capabilities of subsonic aerodynamic methods are demonstrated by several design and analysis efforts. Among the examples cited are the B747 Space Shuttle Carrier Aircraft analysis, nacelle integration for transport aircraft, and winglet optimization. The accuracy and applicability of a new three-dimensional viscous transonic method is demonstrated by comparison of computed results to experimental data

Adjoint-Based Aerodynamic Design of Complex Aerospace Configurations

Science.gov (United States)

Nielsen, Eric J.

2016-01-01

An overview of twenty years of adjoint-based aerodynamic design research at NASA Langley Research Center is presented. Adjoint-based algorithms provide a powerful tool for efficient sensitivity analysis of complex large-scale computational fluid dynamics (CFD) simulations. Unlike alternative approaches for which computational expense generally scales with the number of design parameters, adjoint techniques yield sensitivity derivatives of a simulation output with respect to all input parameters at the cost of a single additional simulation. With modern large-scale CFD applications often requiring millions of compute hours for a single analysis, the efficiency afforded by adjoint methods is critical in realizing a computationally tractable design optimization capability for such applications.

Aerodynamic optimization of wind turbine rotor using CFD/AD method

Science.gov (United States)

Cao, Jiufa; Zhu, Weijun; Wang, Tongguang; Ke, Shitang

2018-05-01

The current work describes a novel technique for wind turbine rotor optimization. The aerodynamic design and optimization of wind turbine rotor can be achieved with different methods, such as the semi-empirical engineering methods and more accurate computational fluid dynamic (CFD) method. The CFD method often provides more detailed aerodynamics features during the design process. However, high computational cost limits the application, especially for rotor optimization purpose. In this paper, a CFD-based actuator disc (AD) model is used to represent turbulent flow over a wind turbine rotor. The rotor is modeled as a permeable disc of equivalent area where the forces from the blades are distributed on the circular disc. The AD model is coupled with a Reynolds Averaged Navier-Stokes (RANS) solver such that the thrust and power are simulated. The design variables are the shape parameters comprising the chord, the twist and the relative thickness of the wind turbine rotor blade. The comparative aerodynamic performance is analyzed between the original and optimized reference wind turbine rotor. The results showed that the optimization framework can be effectively and accurately utilized in enhancing the aerodynamic performance of the wind turbine rotor.

Longitudinal aerodynamic characteristics of a wing-winglet model designed at M = 0.8, C sub L = 0.4 using linear aerodynamic theory

Science.gov (United States)

Kuhlman, J. M.

1983-01-01

Wind tunnel test results have been presented herein for a subsonic transport type wing fitted with winglets. Wind planform was chosen to be representative of wings used on current jet transport aircraft, while wing and winglet camber surfaces were designed using two different linear aerodynamic design methods. The purpose of the wind tunnel investigation was to determine the effectiveness of these linear aerodynamic design computer codes in designing a non-planar transport configuration which would cruise efficiently. The design lift coefficient was chosen to be 0.4, at a design Mach number of 0.8. Force and limited pressure data were obtained for the basic wing, and for the wing fitted with the two different winglet designs, at Mach numbers of 0.60, 0.70, 0.75 and 0.80 over an angle of attack range of -2 to +6 degrees, at zero sideslip. The data have been presented without analysis to expedite publication.

Some Features of Aerodynamics of Cyclonic Chamber with Free Exit

Directory of Open Access Journals (Sweden)

A. N. Orekhov

2007-01-01

Full Text Available The paper cites results of an experimental research in aerodynamics of a cyclonic chamber with a free exit that has a large relative length. Distributions of aerodynamic stream characteristics depending on geometry of working volume of the cyclonic chamber are given in the paper. Calculative dependences are proposed in the paper.

Aerodynamics Research Revolutionizes Truck Design

Science.gov (United States)

2008-01-01

During the 1970s and 1980s, researchers at Dryden Flight Research Center conducted numerous tests to refine the shape of trucks to reduce aerodynamic drag and improved efficiency. During the 1980s and 1990s, a team based at Langley Research Center explored controlling drag and the flow of air around a moving body. Aeroserve Technologies Ltd., of Ottawa, Canada, with its subsidiary, Airtab LLC, in Loveland, Colorado, applied the research from Dryden and Langley to the development of the Airtab vortex generator. Airtabs create two counter-rotating vortices to reduce wind resistance and aerodynamic drag of trucks, trailers, recreational vehicles, and many other vehicles.

Design of a wind turbine rotor for maximum aerodynamic efficiency

DEFF Research Database (Denmark)

Johansen, Jeppe; Aagaard Madsen, Helge; Gaunaa, Mac

2009-01-01

The design of a three-bladed wind turbine rotor is described, where the main focus has been highest possible mechanical power coefficient, CP, at a single operational condition. Structural, as well as off-design, issues are not considered, leading to a purely theoretical design for investigating...... maximum aerodynamic efficiency. The rotor is designed assuming constant induction for most of the blade span, but near the tip region, a constant load is assumed instead. The rotor design is obtained using an actuator disc model, and is subsequently verified using both a free-wake lifting line method...

Review of design optimization methods for turbomachinery aerodynamics

Science.gov (United States)

Li, Zhihui; Zheng, Xinqian

2017-08-01

In today's competitive environment, new turbomachinery designs need to be not only more efficient, quieter, and ;greener; but also need to be developed at on much shorter time scales and at lower costs. A number of advanced optimization strategies have been developed to achieve these requirements. This paper reviews recent progress in turbomachinery design optimization to solve real-world aerodynamic problems, especially for compressors and turbines. This review covers the following topics that are important for optimizing turbomachinery designs. (1) optimization methods, (2) stochastic optimization combined with blade parameterization methods and the design of experiment methods, (3) gradient-based optimization methods for compressors and turbines and (4) data mining techniques for Pareto Fronts. We also present our own insights regarding the current research trends and the future optimization of turbomachinery designs.

Application of CAD/CAE class systems to aerodynamic analysis of electric race cars

Science.gov (United States)

Grabowski, L.; Baier, A.; Buchacz, A.; Majzner, M.; Sobek, M.

2015-11-01

Aerodynamics is one of the most important factors which influence on every aspect of a design of a car and car driving parameters. The biggest influence aerodynamics has on design of a shape of a race car body, especially when the main objective of the race is the longest distance driven in period of time, which can not be achieved without low energy consumption and low drag of a car. Designing shape of the vehicle body that must generate the lowest possible drag force, without compromising the other parameters of the drive. In the article entitled „Application of CAD/CAE class systems to aerodynamic analysis of electric race cars” are being presented problems solved by computer analysis of cars aerodynamics and free form modelling. Analysis have been subjected to existing race car of a Silesian Greenpower Race Team. On a basis of results of analysis of existence of Kammback aerodynamic effect innovative car body were modeled. Afterwards aerodynamic analysis were performed to verify existence of aerodynamic effect for innovative shape and to recognize aerodynamics parameters of the shape. Analysis results in the values of coefficients and aerodynamic drag forces. The resulting drag forces Fx, drag coefficients Cx(Cd) and aerodynamic factors Cx*A allowed to compare all of the shapes to each other. Pressure distribution, air velocities and streams courses were useful in determining aerodynamic features of analyzed shape. For aerodynamic tests was used Ansys Fluent CFD software. In a paper the ways of surface modeling with usage of Realize Shape module and classic surface modeling were presented. For shapes modeling Siemens NX 9.0 software was used. Obtained results were used to estimation of existing shapes and to make appropriate conclusions.

Nonlinear Aerodynamics-Structure Time Simulation for HALE Aircraft Design/Analysis, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Time simulation of a nonlinear aerodynamics model (NA) developed at Virginia Tech coupled with a nonlinear structure model (NS) is proposed as a design/analysis...

Aerodynamic and Performance Behavior of a Three-Stage High Efficiency Turbine at Design and Off-Design Operating Points

Directory of Open Access Journals (Sweden)

M. T. Schobeiri

2004-01-01

Full Text Available This article deals with the aerodynamic and performance behavior of a three-stage high pressure research turbine with 3-D curved blades at its design and off-design operating points. The research turbine configuration incorporates six rows beginning with a stator row. Interstage aerodynamic measurements were performed at three stations, namely downstream of the first rotor row, the second stator row, and the second rotor row. Interstage radial and circumferential traversing presented a detailed flow picture of the middle stage. Performance measurements were carried out within a rotational speed range of 75% to 116% of the design speed. The experimental investigations have been carried out on the recently established multi-stage turbine research facility at the Turbomachinery Performance and Flow Research Laboratory, TPFL, of Texas A&M University.

Analysis of New Aerodynamic Design of the Nose Cone Section Using CFD and SPH

Directory of Open Access Journals (Sweden)

Bogdan-Alexandru BELEGA

2015-06-01

Full Text Available A new nose cones concept that promises a gain in performance over existing conventional nose cones is discussed in this paper. It is shown that significant performance gains result from the adaptation of the exhaust flow to the ambient pressure. For this complex work, it was necessary to collect and study the various nose cone shapes and the equations describing them? The paper objective was to identify the types of nose cones with ejector channels and specific aerodynamic characteristics of different types of nose cones. The scope of this paper is to develop some prototype profiles with outstanding aerodynamic qualities and low cost for use in construction projects for missile increasing their range and effect on target. The motivation for such a work is caused by a lack of data on aerodynamics for profiles of some nose cones and especially improved aerodynamic qualities that can be used in designing missiles/ rockets. This design method consists of a geometry creation step in which a three-dimensional geometry is generated, a mathematical model presented and a simple flow analysis (FLUENT Simulation from SolidWorks2012 and ANSYS Simulation with SPH for fluid-structure interaction, step which predicts the air intake mass flow rate. Flow phenomena observed in numerical simulations during different nose cone operations are highlighted, critical design aspects and operation conditions are discussed, and performance characteristics of the selected nose cone are presented.

Aerodynamic Optimization of Vertical Axis Wind Turbine with Trailing Edge Flap

DEFF Research Database (Denmark)

Ertem, Sercan; Ferreira, Carlos Simao; Gaunaa, Mac

2016-01-01

Vertical Axis Wind Turbines (VAWT) are competitive concepts for very large scale (10-20 MW)floating ofshore applications. Rotor circulation control (loading control) opens a wide design space to enhance the aerodynamic and operational features of VAWT. The modied linear derivation of the Actuator...

Application of Reduced Order Transonic Aerodynamic Influence Coefficient Matrix for Design Optimization

Science.gov (United States)

Pak, Chan-gi; Li, Wesley W.

2009-01-01

Supporting the Aeronautics Research Mission Directorate guidelines, the National Aeronautics and Space Administration [NASA] Dryden Flight Research Center is developing a multidisciplinary design, analysis, and optimization [MDAO] tool. This tool will leverage existing tools and practices, and allow the easy integration and adoption of new state-of-the-art software. Today s modern aircraft designs in transonic speed are a challenging task due to the computation time required for the unsteady aeroelastic analysis using a Computational Fluid Dynamics [CFD] code. Design approaches in this speed regime are mainly based on the manual trial and error. Because of the time required for unsteady CFD computations in time-domain, this will considerably slow down the whole design process. These analyses are usually performed repeatedly to optimize the final design. As a result, there is considerable motivation to be able to perform aeroelastic calculations more quickly and inexpensively. This paper will describe the development of unsteady transonic aeroelastic design methodology for design optimization using reduced modeling method and unsteady aerodynamic approximation. The method requires the unsteady transonic aerodynamics be represented in the frequency or Laplace domain. Dynamically linear assumption is used for creating Aerodynamic Influence Coefficient [AIC] matrices in transonic speed regime. Unsteady CFD computations are needed for the important columns of an AIC matrix which corresponded to the primary modes for the flutter. Order reduction techniques, such as Guyan reduction and improved reduction system, are used to reduce the size of problem transonic flutter can be found by the classic methods, such as Rational function approximation, p-k, p, root-locus etc. Such a methodology could be incorporated into MDAO tool for design optimization at a reasonable computational cost. The proposed technique is verified using the Aerostructures Test Wing 2 actually designed

Creation of a Rapid High-Fidelity Aerodynamics Module for a Multidisciplinary Design Environment

Science.gov (United States)

Srinivasan, Muktha; Whittecar, William; Edwards, Stephen; Mavris, Dimitri N.

2012-01-01

In the traditional aerospace vehicle design process, each successive design phase is accompanied by an increment in the modeling fidelity of the disciplinary analyses being performed. This trend follows a corresponding shrinking of the design space as more and more design decisions are locked in. The correlated increase in knowledge about the design and decrease in design freedom occurs partly because increases in modeling fidelity are usually accompanied by significant increases in the computational expense of performing the analyses. When running high fidelity analyses, it is not usually feasible to explore a large number of variations, and so design space exploration is reserved for conceptual design, and higher fidelity analyses are run only once a specific point design has been selected to carry forward. The designs produced by this traditional process have been recognized as being limited by the uncertainty that is present early on due to the use of lower fidelity analyses. For example, uncertainty in aerodynamics predictions produces uncertainty in trajectory optimization, which can impact overall vehicle sizing. This effect can become more significant when trajectories are being shaped by active constraints. For example, if an optimal trajectory is running up against a normal load factor constraint, inaccuracies in the aerodynamic coefficient predictions can cause a feasible trajectory to be considered infeasible, or vice versa. For this reason, a trade must always be performed between the desired fidelity and the resources available. Apart from this trade between fidelity and computational expense, it is very desirable to use higher fidelity analyses earlier in the design process. A large body of work has been performed to this end, led by efforts in the area of surrogate modeling. In surrogate modeling, an up-front investment is made by running a high fidelity code over a Design of Experiments (DOE); once completed, the DOE data is used to create a

Design, aerodynamics and autonomy of the DelFly

International Nuclear Information System (INIS)

De Croon, G C H E; Groen, M A; De Wagter, C; Remes, B; Ruijsink, R; Van Oudheusden, B W

2012-01-01

One of the major challenges in robotics is to develop a fly-like robot that can autonomously fly around in unknown environments. In this paper, we discuss the current state of the DelFly project, in which we follow a top-down approach to ever smaller and more autonomous ornithopters. The presented findings concerning the design, aerodynamics and autonomy of the DelFly illustrate some of the properties of the top-down approach, which allows the identification and resolution of issues that also play a role at smaller scales. A parametric variation of the wing stiffener layout produced a 5% more power-efficient wing. An experimental aerodynamic investigation revealed that this could be associated with an improved stiffness of the wing, while further providing evidence of the vortex development during the flap cycle. The presented experiments resulted in an improvement in the generated lift, allowing the inclusion of a yaw rate gyro, pressure sensor and microcontroller onboard the DelFly. The autonomy of the DelFly is expanded by achieving (1) an improved turning logic to obtain better vision-based obstacle avoidance performance in environments with varying texture and (2) successful onboard height control based on the pressure sensor.

Application of surrogate-based global optimization to aerodynamic design

CERN Document Server

Pérez, Esther

2016-01-01

Aerodynamic design, like many other engineering applications, is increasingly relying on computational power. The growing need for multi-disciplinarity and high fidelity in design optimization for industrial applications requires a huge number of repeated simulations in order to find an optimal design candidate. The main drawback is that each simulation can be computationally expensive – this becomes an even bigger issue when used within parametric studies, automated search or optimization loops, which typically may require thousands of analysis evaluations. The core issue of a design-optimization problem is the search process involved. However, when facing complex problems, the high-dimensionality of the design space and the high-multi-modality of the target functions cannot be tackled with standard techniques. In recent years, global optimization using meta-models has been widely applied to design exploration in order to rapidly investigate the design space and find sub-optimal solutions. Indeed, surrogat...

Quiet Clean Short-haul Experimental Engine (QCSEE). The aerodynamic and mechanical design of the QCSEE over-the-wing fan

Science.gov (United States)

1976-01-01

The aerodynamic and mechanical design of a fixed-pitch 1.36 pressure ratio fan for the over-the-wing (OTW) engine is presented. The fan has 28 blades. Aerodynamically, the fan blades were designed for a composite blade, but titanium blades were used in the experimental fan as a cost savings measure.

Design and aerodynamic performance evaluation of a high-work mixed flow turbine stage

Science.gov (United States)

Neri, Remo N.; Elliott, Thomas J.; Marsh, David N.; Civinskas, Kestutis C.

1994-01-01

As axial and radial turbine designs have been pushed to their aerothermodynamic and mechanical limits, the mixed-flow turbine (MFT) concept has been projected to offer performance and durability improvements, especially when ceramic materials are considered. The objective of this NASA/U.S. Army sponsored mixed-flow turbine (AMFT) program was to determine the level of performance attainable with MFT technology within the mechanical constraints of 1997 projected ceramic material properties. The MFT geometry is similar to a radial turbine, exhibiting a large radius change from inlet to exit, but differing in that the inlet flowpath is not purely radial, nor axial, but mixed; it is the inlet geometry that gives rise to the name 'mixed-flow'. The 'mixed' orientation of the turbine inlet offers several advantages over radial designs by allowing a nonzero inlet blade angle yet maintaining radial-element blades. The oblique inlet not only improves the particle-impact survivability of the design, but improves the aerodynamic performance by reducing the incidence at the blade inlet. The difficulty, however, of using mixed-flow geometry lies in the scarcity of detailed data and documented design experience. This paper reports the design of a MFT stage designed with the intent to maximize aerodynamic performance by optimizing design parameters such as stage reaction, rotor incidence, flowpath shape, blade shape, vane geometry, and airfoil counts using 2-D, 3-D inviscid, and 3-D viscous computational fluid dynamics code. The aerodynamic optimization was accomplished while maintaining mechanical integrity with respect to vibration and stress levels in the rotor. A full-scale cold-flow rig test was performed with metallic hardware fabricated to the specifications of the hot ceramic geometry to evaluate the stage performance.

Integrated optimization on aerodynamics-structure coupling and flight stability of a large airplane in preliminary design

Directory of Open Access Journals (Sweden)

Xiaozhe WANG

2018-06-01

Full Text Available The preliminary phase is significant during the whole design process of a large airplane because of its enormous potential in enhancing the overall performance. However, classical sequential designs can hardly adapt to modern airplanes, due to their repeated iterations, long periods, and massive computational burdens. Multidisciplinary analysis and optimization demonstrates the capability to tackle such complex design issues. In this paper, an integrated optimization method for the preliminary design of a large airplane is proposed, accounting for aerodynamics, structure, and stability. Aeroelastic responses are computed by a rapid three-dimensional flight load analysis method combining the high-order panel method and the structural elasticity correction. The flow field is determined by the viscous/inviscid iteration method, and the cruise stability is evaluated by the linear small-disturbance theory. Parametric optimization is carried out using genetic algorithm to seek the minimal weight of a simplified plate-beam wing structure in the cruise trim condition subject to aeroelastic, aerodynamic, and stability constraints, and the optimal wing geometry shape, front/rear spar positions, and structural sizes are obtained simultaneously. To reduce the computational burden of the static aeroelasticity analysis in the optimization process, the Kriging method is employed to predict aerodynamic influence coefficient matrices of different aerodynamic shapes. The multidisciplinary analyses guarantee computational accuracy and efficiency, and the integrated optimization considers the coupling effect sufficiently between different disciplines to improve the overall performance, avoiding the limitations of sequential approaches utilized currently. Keywords: Aeroelasticity, Integrated optimization, Multidisciplinary analysis, Large airplane, Preliminary design

Aerodynamic Aspects of Wind Energy Conversion

DEFF Research Database (Denmark)

Sørensen, Jens Nørkær

2011-01-01

This article reviews the most important aerodynamic research topics in the field of wind energy. Wind turbine aerodynamics concerns the modeling and prediction of aerodynamic forces, such as performance predictions of wind farms, and the design of specific parts of wind turbines, such as rotor...

Wind Turbine Blade Design System - Aerodynamic and Structural Analysis

Science.gov (United States)

Dey, Soumitr

2011-12-01

The ever increasing need for energy and the depletion of non-renewable energy resources has led to more advancement in the "Green Energy" field, including wind energy. An improvement in performance of a Wind Turbine will enhance its economic viability, which can be achieved by better aerodynamic designs. In the present study, a design system that has been under development for gas turbine turbomachinery has been modified for designing wind turbine blades. This is a very different approach for wind turbine blade design, but will allow it to benefit from the features inherent in the geometry flexibility and broad design space of the presented system. It starts with key overall design parameters and a low-fidelity model that is used to create the initial geometry parameters. The low-fidelity system includes the axisymmetric solver with loss models, T-Axi (Turbomachinery-AXIsymmetric), MISES blade-to-blade solver and 2D wing analysis code XFLR5. The geometry parameters are used to define sections along the span of the blade and connected to the CAD model of the wind turbine blade through CAPRI (Computational Analysis PRogramming Interface), a CAD neutral API that facilitates the use of parametric geometry definition with CAD. Either the sections or the CAD geometry is then available for CFD and Finite Element Analysis. The GE 1.5sle MW wind turbine and NERL NASA Phase VI wind turbine have been used as test cases. Details of the design system application are described, and the resulting wind turbine geometry and conditions are compared to the published results of the GE and NREL wind turbines. A 2D wing analysis code XFLR5, is used for to compare results from 2D analysis to blade-to-blade analysis and the 3D CFD analysis. This kind of comparison concludes that, from hub to 25% of the span blade to blade effects or the cascade effect has to be considered, from 25% to 75%, the blade acts as a 2d wing and from 75% to the tip 3D and tip effects have to be taken into account

A CFD-based aerodynamic design procedure for hypersonic wind-tunnel nozzles

Science.gov (United States)

Korte, John J.

1993-01-01

A new procedure which unifies the best of current classical design practices, computational fluid dynamics (CFD), and optimization procedures is demonstrated for designing the aerodynamic lines of hypersonic wind-tunnel nozzles. The new procedure can be used to design hypersonic wind tunnel nozzles with thick boundary layers where the classical design procedure has been shown to break down. An efficient CFD code, which solves the parabolized Navier-Stokes (PNS) equations using an explicit upwind algorithm, is coupled to a least-squares (LS) optimization procedure. A LS problem is formulated to minimize the difference between the computed flow field and the objective function, consisting of the centerline Mach number distribution and the exit Mach number and flow angle profiles. The aerodynamic lines of the nozzle are defined using a cubic spline, the slopes of which are optimized with the design procedure. The advantages of the new procedure are that it allows full use of powerful CFD codes in the design process, solves an optimization problem to determine the new contour, can be used to design new nozzles or improve sections of existing nozzles, and automatically compensates the nozzle contour for viscous effects as part of the unified design procedure. The new procedure is demonstrated by designing two Mach 15, a Mach 12, and a Mach 18 helium nozzles. The flexibility of the procedure is demonstrated by designing the two Mach 15 nozzles using different constraints, the first nozzle for a fixed length and exit diameter and the second nozzle for a fixed length and throat diameter. The computed flow field for the Mach 15 least squares parabolized Navier-Stokes (LS/PNS) designed nozzle is compared with the classically designed nozzle and demonstrates a significant improvement in the flow expansion process and uniform core region.

Optimized aerodynamic design process for subsonic transport wing fitted with winglets. [wind tunnel model

Science.gov (United States)

Kuhlman, J. M.

1979-01-01

The aerodynamic design of a wind-tunnel model of a wing representative of that of a subsonic jet transport aircraft, fitted with winglets, was performed using two recently developed optimal wing-design computer programs. Both potential flow codes use a vortex lattice representation of the near-field of the aerodynamic surfaces for determination of the required mean camber surfaces for minimum induced drag, and both codes use far-field induced drag minimization procedures to obtain the required spanloads. One code uses a discrete vortex wake model for this far-field drag computation, while the second uses a 2-D advanced panel wake model. Wing camber shapes for the two codes are very similar, but the resulting winglet camber shapes differ widely. Design techniques and considerations for these two wind-tunnel models are detailed, including a description of the necessary modifications of the design geometry to format it for use by a numerically controlled machine for the actual model construction.

Vortex-flow aerodynamics - An emerging design capability

Science.gov (United States)

Campbell, J. F.

1981-01-01

Promising current theoretical and simulational developments in the field of leading edge vortex-generating delta, arrow ogival wings are reported, along with the history of theory and experiment leading to them. The effects of wing slenderness, leading edge nose radius, Mach number and incidence variations, and planform on the onset of vortex generation and redistribution of aerodynamic loads are considered. The range of design possibilities in this field are consequential for the future development of strategic aircraft, supersonic transports and commercial cargo aircraft which will possess low-speed, high-lift capability by virtue of leading edge vortex generation and control without recourse to heavy and expensive leading edge high-lift devices and compound airfoils. Attention is given to interactive graphics simulation devices recently developed.

Machine learning paradigms in design optimization: Applications in turbine aerodynamic design

Science.gov (United States)

Goel, Sanjay

Mechanisms of incorporating machine learning paradigms in design optimization have been investigated in the current research. The primary focus of the work is on machine learning algorithms which use computational models that are analogous to the hypothesized principles of natural or biological learning. Examples from structural and aerodynamic optimization have been used to demonstrate the potential of the proposed schemes. The first strategy examined in the current work seeks to improve the convergence of optimization problems by pruning the search space of weak variables. Such variables are identified by learning from a database of existing designs using neural networks. By using clustering techniques, different sets of weak variables are identified in different regions of the design space. Parameter sensitivity information obtained in the process of identifying weak variables provides accurate heuristics for formulating design rules. The impact of this methodology on obtaining converged designs has been investigated for a turbine design problem. Optimization results from a three-stage power turbine and an aircraft engine turbine are presented in this thesis. The second scheme is an evolutionary design optimization technique which gets progressively 'smarter' during the optimization process by learning from computed domain knowledge. This technique employs adaptive learning mechanisms (classifiers) which recognize the influence of the design variables on the problem solution and then generalize them to dynamically create or change design rules during optimization. This technique, when applied to a constrained optimization problem, shows progressive improvement in convergence of search, as successive generations of rules evolve by learning from the environment. To investigate this methodology, a truss optimization problem is solved with an objective of minimizing the truss weight subject to stress constraints in the truss members. A distinct convergent trend is

A review on design of experiments and surrogate models in aircraft real-time and many-query aerodynamic analyses

Science.gov (United States)

Yondo, Raul; Andrés, Esther; Valero, Eusebio

2018-01-01

Full scale aerodynamic wind tunnel testing, numerical simulation of high dimensional (full-order) aerodynamic models or flight testing are some of the fundamental but complex steps in the various design phases of recent civil transport aircrafts. Current aircraft aerodynamic designs have increase in complexity (multidisciplinary, multi-objective or multi-fidelity) and need to address the challenges posed by the nonlinearity of the objective functions and constraints, uncertainty quantification in aerodynamic problems or the restrained computational budgets. With the aim to reduce the computational burden and generate low-cost but accurate models that mimic those full order models at different values of the design variables, Recent progresses have witnessed the introduction, in real-time and many-query analyses, of surrogate-based approaches as rapid and cheaper to simulate models. In this paper, a comprehensive and state-of-the art survey on common surrogate modeling techniques and surrogate-based optimization methods is given, with an emphasis on models selection and validation, dimensionality reduction, sensitivity analyses, constraints handling or infill and stopping criteria. Benefits, drawbacks and comparative discussions in applying those methods are described. Furthermore, the paper familiarizes the readers with surrogate models that have been successfully applied to the general field of fluid dynamics, but not yet in the aerospace industry. Additionally, the review revisits the most popular sampling strategies used in conducting physical and simulation-based experiments in aircraft aerodynamic design. Attractive or smart designs infrequently used in the field and discussions on advanced sampling methodologies are presented, to give a glance on the various efficient possibilities to a priori sample the parameter space. Closing remarks foster on future perspectives, challenges and shortcomings associated with the use of surrogate models by aircraft industrial

The DelFly design, aerodynamics, and artificial intelligence of a flapping wing robot

CERN Document Server

de Croon, G C H E; Remes, B D W; Ruijsink, R; De Wagter, C

2016-01-01

This book introduces the topics most relevant to autonomously flying flapping wing robots: flapping-wing design, aerodynamics, and artificial intelligence. Readers can explore these topics in the context of the "Delfly", a flapping wing robot designed at Delft University in The Netherlands. How are tiny fruit flies able to lift their weight, avoid obstacles and predators, and find food or shelter? The first step in emulating this is the creation of a micro flapping wing robot that flies by itself. The challenges are considerable: the design and aerodynamics of flapping wings are still active areas of scientific research, whilst artificial intelligence is subject to extreme limitations deriving from the few sensors and minimal processing onboard. This book conveys the essential insights that lie behind success such as the DelFly Micro and the DelFly Explorer. The DelFly Micro, with its 3.07 grams and 10 cm wing span, is still the smallest flapping wing MAV in the world carrying a camera, whilst the DelFly Expl...

Method of test signal design for estimating the aircraft aerodynamic parameters

Science.gov (United States)

Belokon', S. A.; Zolotukhin, Yu. N.; Filippov, M. N.

2017-07-01

A method of test signal design is proposed for studying the aircraft aerodynamic characteristics with the use of the technology of dynamically scaled free-flight models. Simultaneous excitation of all input channels in a prescribed frequency band by a set of mutually orthogonal signals is applied to increase the efficiency. A modified method of calculating the set of mutually orthogonal sinusoidal signals with a small normalized peak factor is presented. Results of simulating the aircraft motion in the MATLAB/Simulink environment with the use of the developed method of test signal design are reported.

Axial Turbine Aerodynamic Design of Small Heavy-Duty Gas Turbines

International Nuclear Information System (INIS)

Kim, Joung Seok; Lee, Wu Sang; Ryu, Je Wook

2013-01-01

This study describes the aerodynamic design procedure for the axial turbines of a small heavy-duty gas turbine engine being developed by Docosan Heavy Industries. The design procedure mainly consists of three parts: namely, flow path design, airfoil design, and 3a performance calculation. To design the optimized flow path, through flow calculations as well as the loss estimation are widely used to evaluate the effect of geometric variables, for example, shape of meridional plane, mean radius, blades axial gap, and had angle. During the airfoil design procedure, the optimum number of blades is calculated by empirical correlations based on the in/outlet flow angles, and then 2a airfoil planar sections are designed carefully, followed by 2a B2 NS calculations. The designed planar sections are stacked along the span wise direction, leading to a 3a surfaced airfoil shape. To consider the 3a effect on turbine performance, 3a multistage Euler calculation, single row, and multistage NS calculations are performed

Aerodynamic analysis of Pegasus - Computations vs reality

Science.gov (United States)

Mendenhall, Michael R.; Lesieutre, Daniel J.; Whittaker, C. H.; Curry, Robert E.; Moulton, Bryan

1993-01-01

Pegasus, a three-stage, air-launched, winged space booster was developed to provide fast and efficient commercial launch services for small satellites. The aerodynamic design and analysis of Pegasus was conducted without benefit of wind tunnel tests using only computational aerodynamic and fluid dynamic methods. Flight test data from the first two operational flights of Pegasus are now available, and they provide an opportunity to validate the accuracy of the predicted pre-flight aerodynamic characteristics. Comparisons of measured and predicted flight characteristics are presented and discussed. Results show that the computational methods provide reasonable aerodynamic design information with acceptable margins. Post-flight analyses illustrate certain areas in which improvements are desired.

Design and manufacturing of skins based on composite corrugated laminates for morphing aerodynamic surfaces

Science.gov (United States)

Airoldi, Alessandro; Fournier, Stephane; Borlandelli, Elena; Bettini, Paolo; Sala, Giuseppe

2017-04-01

The paper discusses the approaches for the design and manufacturing of morphing skins based on rectangular-shaped composite corrugated laminates and proposes a novel solution to prevent detrimental effects of corrugation on aerodynamic performances. Additionally, more complex corrugated shapes are presented and analysed. The manufacturing issues related to the production of corrugated laminates are discussed and tests are performed to compare different solutions and to assess the validity of analytical and numerical predictions. The solution presented to develop an aerodynamically efficient skin consists in the integration of an elastomeric cover in the corrugated laminate. The related manufacturing process is presented and assessed, and a fully nonlinear numerical model is developed and characterized to study the behaviour of this skin concept in different load conditions. Finally, configurations based on combinations of individual rectangular-shaped corrugated panels are considered. Their structural properties are numerically investigated by varying geometrical parameters. Performance indices are defined to compare structural stiffness contributions in non-morphing directions with the ones of conventional panels of the same weight. Numerical studies also show that the extension of the concept to complex corrugated shapes may improve both the design flexibility and some specific performances with respect to rectangular shaped corrugations. The overall results validate the design approaches and manufacturing processes to produce corrugated laminates and indicate that the solution for the integration of an elastomeric cover is a feasible and promising method to enhance the aerodynamic efficiency of corrugated skins.

Aerodynamical study of a photovoltaic solar tracker

OpenAIRE

Gutiérrez Castillo, José Leonardo

2016-01-01

Investigate the aerodynamic features of ground-mounted solar trackers under atmospheric boundary layer flows. Study and identify the aerodynamical interactions of solar trackers when they are displayed as an array. State of the art. Literature review about CFD applied to solar panels. Analytic approach of the problem. Application of CFD analysis. Validation of the results. Discussion of the results. Improvements proposal.

Aerodynamic multi-objective integrated optimization based on principal component analysis

Directory of Open Access Journals (Sweden)

Jiangtao HUANG

2017-08-01

Full Text Available Based on improved multi-objective particle swarm optimization (MOPSO algorithm with principal component analysis (PCA methodology, an efficient high-dimension multi-objective optimization method is proposed, which, as the purpose of this paper, aims to improve the convergence of Pareto front in multi-objective optimization design. The mathematical efficiency, the physical reasonableness and the reliability in dealing with redundant objectives of PCA are verified by typical DTLZ5 test function and multi-objective correlation analysis of supercritical airfoil, and the proposed method is integrated into aircraft multi-disciplinary design (AMDEsign platform, which contains aerodynamics, stealth and structure weight analysis and optimization module. Then the proposed method is used for the multi-point integrated aerodynamic optimization of a wide-body passenger aircraft, in which the redundant objectives identified by PCA are transformed to optimization constraints, and several design methods are compared. The design results illustrate that the strategy used in this paper is sufficient and multi-point design requirements of the passenger aircraft are reached. The visualization level of non-dominant Pareto set is improved by effectively reducing the dimension without losing the primary feature of the problem.

Aerodynamic Optimization of a Wind Turbine Blade Designed for Egypt's Saharan Environment Using a Genetic Algorithm

Directory of Open Access Journals (Sweden)

Khaled Yassin

2015-08-01

Full Text Available This work aims to optimize the aerodynamic parameters (airfoil chord lengths and twist angles smoothed using Bezier curves of the NREL 5MW wind turbine and a wind turbine designed for site-specific wind conditions to increase the wind turbine's annual energy production (AEP under this site conditions. This optimization process is carried out using a Genetic Algorithm (GA developed in MATLAB and coupled with NREL's FAST Modularization Framework. The results shows that after optimizing the NREL 5MW wind turbine design, the AEP was improved by 5.9% of the baseline design AEP while a site-specific designed wind turbine using Schmitz equations shows 1.2% improvement in AEP. These results shows that optimization of wind turbine blade aerodynamic parameters for site-specific wind conditions leads to improvement in AEP and hence decreasing cost of energy generated by wind turbines.

Introduction to wind turbine aerodynamics

CERN Document Server

Schaffarczyk, Alois Peter

2014-01-01

Wind-Turbine Aerodynamics is a self-contained textbook which shows how to come from the basics of fluid mechanics to modern wind turbine blade design. It presents a fundamentals of fluid dynamics and inflow conditions, and gives a extensive introduction into theories describing the aerodynamics of wind turbines. After introducing experiments the book applies the knowledge to explore the impact on blade design.The book is an introduction for professionals and students of very varying levels.

Distributed Aerodynamic Sensing and Processing Toolbox

Science.gov (United States)

Brenner, Martin; Jutte, Christine; Mangalam, Arun

2011-01-01

A Distributed Aerodynamic Sensing and Processing (DASP) toolbox was designed and fabricated for flight test applications with an Aerostructures Test Wing (ATW) mounted under the fuselage of an F-15B on the Flight Test Fixture (FTF). DASP monitors and processes the aerodynamics with the structural dynamics using nonintrusive, surface-mounted, hot-film sensing. This aerodynamic measurement tool benefits programs devoted to static/dynamic load alleviation, body freedom flutter suppression, buffet control, improvement of aerodynamic efficiency through cruise control, supersonic wave drag reduction through shock control, etc. This DASP toolbox measures local and global unsteady aerodynamic load distribution with distributed sensing. It determines correlation between aerodynamic observables (aero forces) and structural dynamics, and allows control authority increase through aeroelastic shaping and active flow control. It offers improvements in flutter suppression and, in particular, body freedom flutter suppression, as well as aerodynamic performance of wings for increased range/endurance of manned/ unmanned flight vehicles. Other improvements include inlet performance with closed-loop active flow control, and development and validation of advanced analytical and computational tools for unsteady aerodynamics.

Design of low noise airfoil with high aerodynamic performance for use on small wind turbines

Institute of Scientific and Technical Information of China (English)

Taehyung; KIM; Seungmin; LEE; Hogeon; KIM; Soogab; LEE

2010-01-01

Wind power is one of the most reliable renewable energy sources and internationally installed capacity is increasing radically every year.Although wind power has been favored by the public in general,the problem with the impact of wind turbine noise on people living in the vicinity of the turbines has been increased.Low noise wind turbine design is becoming more and more important as noise is spreading more adverse effect of wind turbine to public.This paper demonstrates the design of 10 kW class wind turbines,each of three blades,a rotor diameter 6.4 m,a rated rotating speed 200 r/min and a rated wind speed 10 m/s.The optimized airfoil is dedicated for the 75% spanwise position because the dominant source of a wind turbine blade is trailing edge noise from the outer 25% of the blade.Numerical computations are performed for incompressible flow and for Mach number at 0.145 and for Reynolds numbers at 1.02×106 with a lift performance,which is resistant to surface contamination and turbulence intensity.The objectives in the design process are to reduce noise emission,while sustaining high aerodynamic efficiency.Dominant broadband noise sources are predicted by semi-empirical formulas composed of the groundwork by Brooks et al.and Lowson associated with typical wind turbine operation conditions.During the airfoil redesign process,the aerodynamic performance is analyzed to reduce the wind turbine power loss.The results obtained from the design process show that the design method is capable of designing airfoils with reduced noise using a commercial 10 kW class wind turbine blade airfoil as a basis.Therefore,the new optimized airfoil showing 2.9 dB reductions of total sound pressure level(SPL) and higher aerodynamic performance are achieved.

Novel Aerodynamic Design for Formula SAE Vehicles

Science.gov (United States)

Sentongo, Samuel; Carter, Austin; Cecil, Christopher; Feier, Ioan

2017-11-01

This paper identifies and evaluates the design characteristics of a novel airfoil that harnesses the Magnus Effect, applying a moving-surface boundary-layer control (MSBC) method to a Formula SAE Vehicle. The MSBC minimizes adverse pressure gradient and delays boundary layer separation through the use of a conveyor belt that interacts with the airfoil boundary layer. The MSBC allows dynamic control of the aerodynamic coefficients by variation of the belt speed, minimizing drag in high speed straights and maximizing downforce during vehicle cornering. A conveyer belt wing measuring approximately 0.9 x 0.9m in planform was designed and built to test the mechanical setup for such a MSBC wing. This study follows the relationship between inputted power and outputted surface velocity, with the goal being to maximize speed output vs. power input. The greatest hindrance to maximizing speed output is friction among belts, rollers, and stationary members. The maximum belt speed achieved during testing was 5.9 m/s with a power input of 48.8 W, which corresponds to 45.8 N of downforce based on 2D CFD results. Ongoing progress on this project is presented. United States Air Force Academy.

Aerodynamics of magnetic levitation (MAGLEV) trains

Science.gov (United States)

Schetz, Joseph A.; Marchman, James F., III

1996-01-01

High-speed (500 kph) trains using magnetic forces for levitation, propulsion and control offer many advantages for the nation and a good opportunity for the aerospace community to apply 'high tech' methods to the domestic sector. One area of many that will need advanced research is the aerodynamics of such MAGLEV (Magnetic Levitation) vehicles. There are important issues with regard to wind tunnel testing and the application of CFD to these devices. This talk will deal with the aerodynamic design of MAGLEV vehicles with emphasis on wind tunnel testing. The moving track facility designed and constructed in the 6 ft. Stability Wind Tunnel at Virginia Tech will be described. Test results for a variety of MAGLEV vehicle configurations will be presented. The last topic to be discussed is a Multi-disciplinary Design approach that is being applied to MAGLEV vehicle configuration design including aerodynamics, structures, manufacturability and life-cycle cost.

Validation of 3-D Ice Accretion Measurement Methodology for Experimental Aerodynamic Simulation

Science.gov (United States)

Broeren, Andy P.; Addy, Harold E., Jr.; Lee, Sam; Monastero, Marianne C.

2015-01-01

Determining the adverse aerodynamic effects due to ice accretion often relies on dry-air wind-tunnel testing of artificial, or simulated, ice shapes. Recent developments in ice-accretion documentation methods have yielded a laser-scanning capability that can measure highly three-dimensional (3-D) features of ice accreted in icing wind tunnels. The objective of this paper was to evaluate the aerodynamic accuracy of ice-accretion simulations generated from laser-scan data. Ice-accretion tests were conducted in the NASA Icing Research Tunnel using an 18-in. chord, two-dimensional (2-D) straight wing with NACA 23012 airfoil section. For six ice-accretion cases, a 3-D laser scan was performed to document the ice geometry prior to the molding process. Aerodynamic performance testing was conducted at the University of Illinois low-speed wind tunnel at a Reynolds number of 1.8 × 10(exp 6) and a Mach number of 0.18 with an 18-in. chord NACA 23012 airfoil model that was designed to accommodate the artificial ice shapes. The ice-accretion molds were used to fabricate one set of artificial ice shapes from polyurethane castings. The laser-scan data were used to fabricate another set of artificial ice shapes using rapid prototype manufacturing such as stereolithography. The iced-airfoil results with both sets of artificial ice shapes were compared to evaluate the aerodynamic simulation accuracy of the laser-scan data. For five of the six ice-accretion cases, there was excellent agreement in the iced-airfoil aerodynamic performance between the casting and laser-scan based simulations. For example, typical differences in iced-airfoil maximum lift coefficient were less than 3 percent with corresponding differences in stall angle of approximately 1 deg or less. The aerodynamic simulation accuracy reported in this paper has demonstrated the combined accuracy of the laser-scan and rapid-prototype manufacturing approach to simulating ice accretion for a NACA 23012 airfoil. For several

Aerodynamics of Race Cars

Science.gov (United States)

Katz, Joseph

2006-01-01

Race car performance depends on elements such as the engine, tires, suspension, road, aerodynamics, and of course the driver. In recent years, however, vehicle aerodynamics gained increased attention, mainly due to the utilization of the negative lift (downforce) principle, yielding several important performance improvements. This review briefly explains the significance of the aerodynamic downforce and how it improves race car performance. After this short introduction various methods to generate downforce such as inverted wings, diffusers, and vortex generators are discussed. Due to the complex geometry of these vehicles, the aerodynamic interaction between the various body components is significant, resulting in vortex flows and lifting surface shapes unlike traditional airplane wings. Typical design tools such as wind tunnel testing, computational fluid dynamics, and track testing, and their relevance to race car development, are discussed as well. In spite of the tremendous progress of these design tools (due to better instrumentation, communication, and computational power), the fluid dynamic phenomenon is still highly nonlinear, and predicting the effect of a particular modification is not always trouble free. Several examples covering a wide range of vehicle shapes (e.g., from stock cars to open-wheel race cars) are presented to demonstrate this nonlinear nature of the flow field.

aerodynamics and heat transfer

Directory of Open Access Journals (Sweden)

J. N. Rajadas

1998-01-01

Full Text Available A multidisciplinary optimization procedure, with the integration of aerodynamic and heat transfer criteria, has been developed for the design of gas turbine blades. Two different optimization formulations have been used. In the first formulation, the maximum temperature in the blade section is chosen as the objective function to be minimized. An upper bound constraint is imposed on the blade average temperature and a lower bound constraint is imposed on the blade tangential force coefficient. In the second formulation, the blade average and maximum temperatures are chosen as objective functions. In both formulations, bounds are imposed on the velocity gradients at several points along the surface of the airfoil to eliminate leading edge velocity spikes which deteriorate aerodynamic performance. Shape optimization is performed using the blade external and coolant path geometric parameters as design variables. Aerodynamic analysis is performed using a panel code. Heat transfer analysis is performed using the finite element method. A gradient based procedure in conjunction with an approximate analysis technique is used for optimization. The results obtained using both optimization techniques are compared with a reference geometry. Both techniques yield significant improvements with the multiobjective formulation resulting in slightly superior design.

Discrete vortex method simulations of aerodynamic admittance in bridge aerodynamics

DEFF Research Database (Denmark)

Rasmussen, Johannes Tophøj; Hejlesen, Mads Mølholm; Larsen, Allan

, and to determine aerodynamic forces and the corresponding flutter limit. A simulation of the three-dimensional bridge responseto turbulent wind is carried out by quasi steady theory by modelling the bridge girder as a line like structure [2], applying the aerodynamic load coefficients found from the current version......The meshless and remeshed Discrete Vortex Method (DVM) has been widely used in academia and by the industry to model two-dimensional flow around bluff bodies. The implementation “DVMFLOW” [1] is used by the bridge design company COWI to determine and visualise the flow field around bridge sections...

Switchable and Tunable Aerodynamic Drag on Cylinders

Science.gov (United States)

Guttag, Mark; Lopéz Jiménez, Francisco; Upadhyaya, Priyank; Kumar, Shanmugam; Reis, Pedro

We report results on the performance of Smart Morphable Surfaces (Smporhs) that can be mounted onto cylindrical structures to actively reduce their aerodynamic drag. Our system comprises of an elastomeric thin shell with a series of carefully designed subsurface cavities that, once depressurized, lead to a dramatic deformation of the surface topography, on demand. Our design is inspired by the morphology of the giant cactus (Carnegiea gigantea) which possesses an array of axial grooves, thought to help reduce aerodynamic drag, thereby enhancing the structural robustness of the plant under wind loading. We perform systematic wind tunnel tests on cylinders covered with our Smorphs and characterize their aerodynamic performance. The switchable and tunable nature of our system offers substantial advantages for aerodynamic performance when compared to static topographies, due to their operation over a wider range of flow conditions.

DESIGN ASPECTS IN AIRPLANE EVOLUTION

Directory of Open Access Journals (Sweden)

ENUŞ Marilena

2013-11-01

Full Text Available The paper proposes to present a few important aspects from aerodynamics and aerospace technology. It also, presents important points regarding the improvement of airplanes as a result of research in shape modelling, materials, aerodynamics and 3d design. Several examples based on constructive structures are offered. The embodiment design of a traditional airplane is presented in order to offer directions of conceptual development for improving its performance parameters and shapes. The virtual scale models are created by computer in Catia V5, in order to provide the validation of the features and the performance of aerodynamic configuration in the wind tunnel.

Noise aspects at aerodynamic blade optimisation projects

International Nuclear Information System (INIS)

Schepers, J.G.

1997-06-01

The Netherlands Energy Research Foundation (ECN) has often been involved in industrial projects, in which blade geometries are created automatic by means of numerical optimisation. Usually, these projects aim at the determination of the aerodynamic optimal wind turbine blade, i.e. the goal is to design a blade which is optimal with regard to energy yield. In other cases, blades have been designed which are optimal with regard to cost of generated energy. However, it is obvious that the wind turbine blade designs which result from these optimisations, are not necessarily optimal with regard to noise emission. In this paper an example is shown of an aerodynamic blade optimisation, using the ECN-program PVOPT. PVOPT calculates the optimal wind turbine blade geometry such that the maximum energy yield is obtained. Using the aerodynamic optimal blade design as a basis, the possibilities of noise reduction are investigated. 11 figs., 8 refs

Research on design methods and aerodynamics performance of CQUDTU-B21 airfoil

DEFF Research Database (Denmark)

Chen, Jin; Cheng, Jiangtao; Wen, Zhong Shen

2012-01-01

This paper presents the design methods of CQU-DTU-B21 airfoil for wind turbine. Compared with the traditional method of inverse design, the new method is described directly by a compound objective function to balance several conflicting requirements for design wind turbine airfoils, which based...... on design theory of airfoil profiles, blade element momentum (BEM) theory and airfoil Self-Noise prediction model. And then an optimization model with the target of maximum power performance on a 2D airfoil and low noise emission of design ranges for angle of attack has been developed for designing CQU......-DTU-B21 airfoil. To validate the optimization results, the comparison of the aerodynamics performance by XFOIL and wind tunnels test respectively at Re=3×106 is made between the CQU-DTU-B21 and DU93-W-210 which is widely used in wind turbines. © (2012) Trans Tech Publications, Switzerland....

Effects of surface design on aerodynamic forces of iced bridge cables

DEFF Research Database (Denmark)

Koss, Holger

2014-01-01

In recent years the relevance of ice accretion for wind-induced vibration of structural bridge cables has been recognised and became a subject of research in bridge engineering. Full-scale monitoring and observation indicate that light precipitation at moderate low temperatures between zero and -...... influences the accretion of ice to an extent that the aerodynamic forces differ significantly amongst the designs. The experiments were conducted in a wind tunnel facility capable amongst others to simulate in-cloud icing conditions........ The determination of these force coefficients require a proper simulation of the ice layer occurring under the specific climatic conditions, favouring real ice accretion over simplified artificial reproduction. The work presented in this paper was performed to study whether the design of bridge cable surface...

Calculation of aerodynamics of aerosol filter designs for cleaning of heavy liquid metal cooler reactor gas loops

International Nuclear Information System (INIS)

Valery P Melnikov; Pyotr N Martynov; Albert K Papovyants; Ivan V Yagodkin

2005-01-01

Full text of publication follows: One of the basic performances of aerosol filters is the aerodynamic resistance to the flow of gaseous medium to be cleaned. Calculation of the aerodynamics of aerosol filters in reference to the gas loops of reactor installations with heavy liquid metal coolant (HLMC) allows the design of the structural components of filters to be optimized to provide minimum initial resistance values. It is established that owing to various factors aerosol particles of different concentration and disperse composition are present always in the gas spaces of heavy liquid metal cooled reactor gas loops. To prevent the negative effect of aerosols on the equipment of the gas loops, it is reasonable to use filters of multistep design with sections of preliminary and fine cleaning to catch micron and submicron particles, respectively. A computer program and technique have been developed to evaluate the aerodynamics of folded aerosol filters for different parameters of their structural components, taking account of the aerosol spectrum and concentration. The algorithm of the calculation is presented by the example of a two-step design assembled in single vessel; the filter dimensions and pattern of the air flow to be cleaned are determined under the given boundary conditions. The evaluation of the aerodynamic resistance of filters was performed with consideration for local resistances and resistances of all the structural components of the filter (sudden constriction, expansion, the flow in air channels, filtering material and so on). Correlations have been derived for the resistance of air channels, filtering materials of preliminary and fine cleaning sections as a function of such parameters as the section depth (50-500 mm), the height of separators (3,5-20 mm), the filtering surface area (1,5-30 m 2 ). Based on the calculation results, the auto-similarity domain was brought out for the minimal values of filter resistances as a function of the ratio of

Ultra high tip speed (670.6 m/sec) fan stage with composite rotor: Aerodynamic and mechanical design

Science.gov (United States)

Halle, J. E.; Burger, G. D.; Dundas, R. E.

1977-01-01

A highly loaded, single-stage compressor having a tip speed of 670.6 m/sec was designed for the purpose of investigating very high tip speeds and high aerodynamic loadings to obtain high stage pressure ratios at acceptable levels of efficiency. The design pressure ratio is 2.8 at an adiabatic efficiency of 84.4%. Corrected design flow is 83.4 kg/sec; corrected design speed is 15,200 rpm; and rotor inlet tip diameter is 0.853 m. The rotor uses multiple-circular-arc airfoils from 0 to 15% span, precompression airfoils assuming single, strong oblique shocks from 21 to 43% span, and precompression airfoils assuming multiple oblique shocks from 52% span to the tip. Because of the high tip speeds, the rotor blades are designed to be fabricated of composite materials. Two composite materials were investigated: Courtaulds HTS graphite fiber in a Kerimid 601 polyimide matrix and the same fibers in a PMR polyimide matrix. In addition to providing a description of the aerodynamic and mechanical design of the 670.0 m/sec fan, discussion is presented of the results of structural tests of blades fabricated with both types of matrices.

Rotor redesign for a highly loaded 1800 ft/sec tip speed fan. 1: Aerodynamic and mechanical design report

Science.gov (United States)

Norton, J. M.; Tari, U.; Weber, R. M.

1979-01-01

A quasi three dimensional design system and multiple-circular-arc airfoil sections were used to design a fan rotor. An axisymmetric intrablade flow field calculation modeled the shroud of an isolated splitter and radial distribution. The structural analysis indicates that the design is satisfactory for evaluation of aerodynamic performance of the fan stage in a test facility.

Design and aerodynamic analysis of a new Formula Ashenkoff car

OpenAIRE

Mateo Muñoz, Albert

2016-01-01

This project has the objective to learn to use CFD free software OpenFOAM focusing on turbulent problems resolution, with the objective of analyzing the aerodynamics of a formula racing car. We had the opportunity to contact with the company Ashenkoff S.L., whose managers were interested in creating a new prototype, the Ashenkoff K100, and they will borrow us resources to make it. The project will consists on the aerodynamic analysis of this new model using CFD software OpenFOAM. Previo...

ZEUS-DO: A Design Oriented CFD-Based Unsteady Aerodynamic Capability for Flight Vehicle Multidisciplinary Configuration Shape Optimization, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — CFD-based design-oriented (DO) steady/unsteady aerodynamic analysis tools for Aeroelastic / Aeroservoelastic (AE/ASE) evaluation lag significantly behind other...

Aerodynamic Modeling of Transonic Aircraft Using Vortex Lattice Coupled with Transonic Small Disturbance for Conceptual Design

Science.gov (United States)

Chaparro, Daniel; Fujiwara, Gustavo E. C.; Ting, Eric; Nguyen, Nhan

2016-01-01

The need to rapidly scan large design spaces during conceptual design calls for computationally inexpensive tools such as the vortex lattice method (VLM). Although some VLM tools, such as Vorview have been extended to model fully-supersonic flow, VLM solutions are typically limited to inviscid, subcritical flow regimes. Many transport aircraft operate at transonic speeds, which limits the applicability of VLM for such applications. This paper presents a novel approach to correct three-dimensional VLM through coupling of two-dimensional transonic small disturbance (TSD) solutions along the span of an aircraft wing in order to accurately predict transonic aerodynamic loading and wave drag for transport aircraft. The approach is extended to predict flow separation and capture the attenuation of aerodynamic forces due to boundary layer viscosity by coupling the TSD solver with an integral boundary layer (IBL) model. The modeling framework is applied to the NASA General Transport Model (GTM) integrated with a novel control surface known as the Variable Camber Continuous Trailing Edge Flap (VCCTEF).

Center for Computational Wind Turbine Aerodynamics and Atmospheric Turbulence

DEFF Research Database (Denmark)

Sørensen, Jens Nørkær

2014-01-01

In order to design and operate a wind farm optimally it is necessary to know in detail how the wind behaves and interacts with the turbines in a farm. This not only requires knowledge about meteorology, turbulence and aerodynamics, but it also requires access to powerful computers and efficient s...... software. Center for Computational Wind Turbine Aerodynamics and Atmospheric Turbulence was established in 2010 in order to create a world-leading cross-disciplinary flow center that covers all relevant disciplines within wind farm meteorology and aerodynamics.......In order to design and operate a wind farm optimally it is necessary to know in detail how the wind behaves and interacts with the turbines in a farm. This not only requires knowledge about meteorology, turbulence and aerodynamics, but it also requires access to powerful computers and efficient...

Aerodynamic Optimization of an Over-the-Wing-Nacelle-Mount Configuration

OpenAIRE

Sasaki, Daisuke; Nakahashi, Kazuhiro

2011-01-01

An over-the-wing-nacelle-mount airplane configuration is known to prevent the noise propagation from jet engines toward ground. However, the configuration is assumed to have low aerodynamic efficiency due to the aerodynamic interference effect between a wing and a nacelle. In this paper, aerodynamic design optimization is conducted to improve aerodynamic efficiency to be equivalent to conventional under-the-wing-nacelle-mount configuration. The nacelle and wing geometry are modified to achiev...

The impact of aerodynamics on fuel consumption in railway applications

Directory of Open Access Journals (Sweden)

Bogdan TARUS

2012-03-01

Full Text Available The main consequence of on air flow surrounding a moving train resides in the aerodynamic drag and a certain pressure distribution on the frontal and lateral surfaces of the vehicle. The actual value of the aerodynamic drag (if pre-determined may lead to a more accurate design of the whole locomotive power transmission. The aerodynamic drag may be estimated by using two specific experiments: the traction method and the free launch method. While the first one uses highly complex equipment, the second is easier to use due to the relative low number of devices required. The present work’s main goal is to illustrate the importance of aerodynamic design of the railway vehicles, as their performances are influenced by the aerodynamic drag. In order to illustrate the influence of the aerodynamic shape of o locomotive body, we have chosen the latest diesel model available on the local market, the Class 621 EGM locomotives, currently in service at the national passenger railway operator, CFR Călători SA.

Effect of static shape deformation on aerodynamics and aerothermodynamics of hypersonic inflatable aerodynamic decelerator

Science.gov (United States)

Guo, Jinghui; Lin, Guiping; Bu, Xueqin; Fu, Shiming; Chao, Yanmeng

2017-07-01

aerodynamics are revealed, which is critical for the selection of structure material and design of flight control system.

Aerodynamic characteristics of wings designed with a combined-theory method to cruise at a Mach number of 4.5

Science.gov (United States)

Mack, Robert J.

1988-01-01

A wind-tunnel study was conducted to determine the capability of a method combining linear theory and shock-expansion theory to design optimum camber surfaces for wings that will fly at high-supersonic/low-hypersonic speeds. Three force models (a flat-plate reference wing and two cambered and twisted wings) were used to obtain aerodynamic lift, drag, and pitching-moment data. A fourth pressure-orifice model was used to obtain surface-pressure data. All four wing models had the same planform, airfoil section, and centerbody area distribution. The design Mach number was 4.5, but data were also obtained at Mach numbers of 3.5 and 4.0. Results of these tests indicated that the use of airfoil thickness as a theoretical optimum, camber-surface design constraint did not improve the aerodynamic efficiency or performance of a wing as compared with a wing that was designed with a zero-thickness airfoil (linear-theory) constraint.

Aerodynamic Benchmarking of the Deepwind Design

DEFF Research Database (Denmark)

Bedona, Gabriele; Schmidt Paulsen, Uwe; Aagaard Madsen, Helge

2015-01-01

The aerodynamic benchmarking for the DeepWind rotor is conducted comparing different rotor geometries and solutions and keeping the comparison as fair as possible. The objective for the benchmarking is to find the most suitable configuration in order to maximize the power production and minimize...... the blade solicitation and the cost of energy. Different parameters are considered for the benchmarking study. The DeepWind blade is characterized by a shape similar to the Troposkien geometry but asymmetric between the top and bottom parts: this shape is considered as a fixed parameter in the benchmarking...

A large-scale computer facility for computational aerodynamics

International Nuclear Information System (INIS)

Bailey, F.R.; Balhaus, W.F.

1985-01-01

The combination of computer system technology and numerical modeling have advanced to the point that computational aerodynamics has emerged as an essential element in aerospace vehicle design methodology. To provide for further advances in modeling of aerodynamic flow fields, NASA has initiated at the Ames Research Center the Numerical Aerodynamic Simulation (NAS) Program. The objective of the Program is to develop a leading-edge, large-scale computer facility, and make it available to NASA, DoD, other Government agencies, industry and universities as a necessary element in ensuring continuing leadership in computational aerodynamics and related disciplines. The Program will establish an initial operational capability in 1986 and systematically enhance that capability by incorporating evolving improvements in state-of-the-art computer system technologies as required to maintain a leadership role. This paper briefly reviews the present and future requirements for computational aerodynamics and discusses the Numerical Aerodynamic Simulation Program objectives, computational goals, and implementation plans

Aerodynamics of Wind Turbines

DEFF Research Database (Denmark)

Hansen, Martin Otto Laver

Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its second edition, it has been entirely updated and substantially extended to reflect advances in technology, research into rotor aerodynamics and the structural...... response of the wind turbine structure. Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element...... Momentum method is also covered, as are eigenmodes and the dynamic behavior of a turbine. The new material includes a description of the effects of the dynamics and how this can be modeled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Further...

Design and analysis pertaining to the aerodynamic and stability characteristics of a hybrid wing-body cargo aircraft

Directory of Open Access Journals (Sweden)

Ishaan PRAKASH

2017-09-01

Full Text Available Recent trends in aircraft design research have resulted in development of many unconventional configurations mostly aimed at improving aerodynamic efficiency. The blended wing body (BWB is one such configuration that holds potential in this regard. In its current form the BWB although promises a better lift to drag (L/D ratio it is still not able to function to its maximum capability due to design modifications such as twist and reflexed airfoils to overcome stability problems in the absence of a tail. This work aims to maximize the impact of a BWB. A design approach of morphing the BWB with a conventional aft fuselage is proposed. Such a configuration intends to impart full freedom to the main wing and the blended forward fuselage to contribute in lift production while the conventional tail makes up for stability. The aft fuselage, meanwhile, also ensures that the aircraft is compatible with current loading and airdrop operations. This paper is the culmination of obtained models results and inferences from the first phase of the project wherein development of aerodynamic design and analysis methodologies and mission specific optimization have been undertaken.

Design and Execution of the Hypersonic Inflatable Aerodynamic Decelerator Large-Article Wind Tunnel Experiment

Science.gov (United States)

Cassell, Alan M.

2013-01-01

The testing of 3- and 6-meter diameter Hypersonic Inflatable Aerodynamic Decelerator (HIAD) test articles was completed in the National Full-Scale Aerodynamics Complex 40 ft x 80 ft Wind Tunnel test section. Both models were stacked tori, constructed as 60 degree half-angle sphere cones. The 3-meter HIAD was tested in two configurations. The first 3-meter configuration utilized an instrumented flexible aerodynamic skin covering the inflatable aeroshell surface, while the second configuration employed a flight-like flexible thermal protection system. The 6-meter HIAD was tested in two structural configurations (with and without an aft-mounted stiffening torus near the shoulder), both utilizing an instrumented aerodynamic skin.

Aerodynamic potpourri

Science.gov (United States)

Wilson, R. E.

1981-01-01

Aerodynamic developments for vertical axis and horizontal axis wind turbines are given that relate to the performance and aerodynamic loading of these machines. Included are: (1) a fixed wake aerodynamic model of the Darrieus vertical axis wind turbine; (2) experimental results that suggest the existence of a laminar flow Darrieus vertical axis turbine; (3) a simple aerodynamic model for the turbulent windmill/vortex ring state of horizontal axis rotors; and (4) a yawing moment of a rigid hub horizontal axis wind turbine that is related to blade coning.

Bat flight: aerodynamics, kinematics and flight morphology.

Science.gov (United States)

Hedenström, Anders; Johansson, L Christoffer

2015-03-01

Bats evolved the ability of powered flight more than 50 million years ago. The modern bat is an efficient flyer and recent research on bat flight has revealed many intriguing facts. By using particle image velocimetry to visualize wake vortices, both the magnitude and time-history of aerodynamic forces can be estimated. At most speeds the downstroke generates both lift and thrust, whereas the function of the upstroke changes with forward flight speed. At hovering and slow speed bats use a leading edge vortex to enhance the lift beyond that allowed by steady aerodynamics and an inverted wing during the upstroke to further aid weight support. The bat wing and its skeleton exhibit many features and control mechanisms that are presumed to improve flight performance. Whereas bats appear aerodynamically less efficient than birds when it comes to cruising flight, they have the edge over birds when it comes to manoeuvring. There is a direct relationship between kinematics and the aerodynamic performance, but there is still a lack of knowledge about how (and if) the bat controls the movements and shape (planform and camber) of the wing. Considering the relatively few bat species whose aerodynamic tracks have been characterized, there is scope for new discoveries and a need to study species representing more extreme positions in the bat morphospace. © 2015. Published by The Company of Biologists Ltd.

Review of research in feature based design

NARCIS (Netherlands)

Salomons, O.W.; van Houten, Frederikus J.A.M.; Kals, H.J.J.

1993-01-01

Research in feature-based design is reviewed. Feature-based design is regarded as a key factor towards CAD/CAPP integration from a process planning point of view. From a design point of view, feature-based design offers possibilities for supporting the design process better than current CAD systems

Influence of hinge point on flexible flap aerodynamic performance

International Nuclear Information System (INIS)

Zhao, H Y; Ye, Z; Wu, P; Li, C

2013-01-01

Large scale wind turbines lead to increasing blade lengths and weights, which presents new challenges for blade design. This paper selects NREL S809 airfoil, uses the parameterized technology to realize the flexible trailing edge deformation, researches the static aerodynamic characteristics of wind turbine blade airfoil with flexible deformation, and the dynamic aerodynamic characteristics in the process of continuous deformation, analyses the influence of hinge point position on flexible flap aerodynamic performance, in order to further realize the flexible wind turbine blade design and provides some references for the active control scheme. The results show that compared with the original airfoil, proper trailing edge deformation can improve the lift coefficient, reduce the drag coefficient, and thereby more efficiently realize flow field active control. With hinge point moving forward, total aerodynamic performance of flexible flap improves. Positive swing angle can push the transition point backward, thus postpones the occurrence of the transition phenomenon

Experimental study of canard UAV aerodynamics

Directory of Open Access Journals (Sweden)

Panayotov Hristian

2017-01-01

Full Text Available The present paper presents the aerodynamic characteristics of a canard fixed-wing unmanned aircraft TERES-02. A wind tunnel experiment is conducted using a specially designed model of the aircraft. The model is produced through the methods of rapid prototyping using a FDM 3D printer. Aerodynamic corrections are made and thorough analysis and discussion of the results is carried out. The obtained results can be used to determine the accuracy of numerical methods for analysis of aircraft performance.

Recent Development of the Two-Stroke Engine. II - Design Features. 2; Design Features

Science.gov (United States)

Zeman, J.

1945-01-01

Completing the first paper dealing with charging methods and arrangements, the present paper discusses the design forms of two-stroke engines. Features which largely influence piston running are: (a) The shape and surface condition of the sliding parts. (b) The cylinder and piston materials. (c) Heat conditions in the piston, and lubrication. There is little essential difference between four-stroke and two-stroke engines with ordinary pistons. In large engines, for example, are always found separately cast or welded frames in which the stresses are taken up by tie rods. Twin piston and timing piston engines often differ from this design. Examples can be found in many engines of German or foreign make. Their methods of operation will be dealt with in the third part of the present paper, which also includes the bibliography. The development of two-stroke engine design is, of course, mainly concerned with such features as are inherently difficult to master; that is, the piston barrel and the design of the gudgeon pin bearing. Designers of four-stroke engines now-a-days experience approximately the same difficulties, since heat stresses have increased to the point of influencing conditions in the piston barrel. Features which notably affect this are: (a) The material. (b) Prevailing heat conditions.

Aerodynamic tailoring of the Learjet Model 60 wing

Science.gov (United States)

Chandrasekharan, Reuben M.; Hawke, Veronica M.; Hinson, Michael L.; Kennelly, Robert A., Jr.; Madson, Michael D.

1993-01-01

The wing of the Learjet Model 60 was tailored for improved aerodynamic characteristics using the TRANAIR transonic full-potential computational fluid dynamics (CFD) code. A root leading edge glove and wing tip fairing were shaped to reduce shock strength, improve cruise drag and extend the buffet limit. The aerodynamic design was validated by wind tunnel test and flight test data.

Computational Analysis of an effect of aerodynamic pressure on the side view mirror geometry

Science.gov (United States)

Murukesavan, P.; Mu'tasim, M. A. N.; Sahat, I. M.

2013-12-01

This paper describes the evaluation of aerodynamic flow effects on side mirror geometry for a passenger car using ANSYS Fluent CFD simulation software. Results from analysis of pressure coefficient on side view mirror designs is evaluated to analyse the unsteady forces that cause fluctuations to mirror surface and image blurring. The fluctuation also causes drag forces that increase the overall drag coefficient, with an assumption resulting in higher fuel consumption and emission. Three features of side view mirror design were investigated with two input velocity parameters of 17 m/s and 33 m/s. Results indicate that the half-sphere design shows the most effective design with less pressure coefficient fluctuation and drag coefficient.

Desirable airfoil features for smaller-capacity straight-bladed VAWT

Energy Technology Data Exchange (ETDEWEB)

Islam, Mazharul; Ting, D.S.-K.; Fartaj, Amir

2007-05-15

In the small scale wind turbine market, the simple straight-bladed Darrieus type vertical axis wind turbine (SB-VAWT) is very attractive for its simple blade design. A detailed aerodynamic performance analysis was conducted on a smaller capacity fixed-pitch SB-VAWT. Brief analyses of the main aerodynamic challenges of this type of wind turbine were first discussed and subsequently the authors conducted further literature survey and computational analysis to shortlist aerodynamic characteristics of a desirable airfoil for a self-starting and better performing SB-VAWT. The required geometric features of the desirable airfoil to achieve the short listed characteristics were also discussed. It has been found out that conventionally used NACA symmetric airfoils are not suitable for smaller capacity SB-VAWT. Rather, it is advantageous to utilize a high-lift and low-drag asymmetric thick airfoil suitable for low speed operation typically encountered by SB-VAWT. (author)

Modeling Powered Aerodynamics for the Orion Launch Abort Vehicle Aerodynamic Database

Science.gov (United States)

Chan, David T.; Walker, Eric L.; Robinson, Philip E.; Wilson, Thomas M.

2011-01-01

Modeling the aerodynamics of the Orion Launch Abort Vehicle (LAV) has presented many technical challenges to the developers of the Orion aerodynamic database. During a launch abort event, the aerodynamic environment around the LAV is very complex as multiple solid rocket plumes interact with each other and the vehicle. It is further complicated by vehicle separation events such as between the LAV and the launch vehicle stack or between the launch abort tower and the crew module. The aerodynamic database for the LAV was developed mainly from wind tunnel tests involving powered jet simulations of the rocket exhaust plumes, supported by computational fluid dynamic simulations. However, limitations in both methods have made it difficult to properly capture the aerodynamics of the LAV in experimental and numerical simulations. These limitations have also influenced decisions regarding the modeling and structure of the aerodynamic database for the LAV and led to compromises and creative solutions. Two database modeling approaches are presented in this paper (incremental aerodynamics and total aerodynamics), with examples showing strengths and weaknesses of each approach. In addition, the unique problems presented to the database developers by the large data space required for modeling a launch abort event illustrate the complexities of working with multi-dimensional data.

Sensitivity of Key Parameters in Aerodynamic Wind Turbine Rotor Design on Power and Energy Performance

International Nuclear Information System (INIS)

Bak, Christian

2007-01-01

In this paper the influence of different key parameters in aerodynamic wind turbine rotor design on the power efficiency, C p , and energy production has been investigated. The work was divided into an analysis of 2D airfoils/blade sections and of entire rotors. In the analysis of the 2D airfoils it was seen that there was a maximum of the local C p for airfoils with finite maximum C l /C d values. The local speed ratio should be between 2.4 and 3.8 for airfoils with maximum c l /c d between 50 and 200, respectively, to obtain maximum local C p . Also, the investigation showed that Re had a significant impact on CP and especially for Re p for rotors was made with three blades and showed that with the assumption of constant maximum c l /c d along the entire blade, the design tip speed ratio changed from X=6 to X=12 for c l /cd=50 and c l /c d =200, respectively, with corresponding values of maximum c p of 0.46 and 0.525. An analysis of existing rotors re-designed with new airfoils but maintaining the absolute thickness distribution to maintain the stiffness showed that big rotors are more aerodynamic efficient than small rotors caused by higher Re. It also showed that the design tip speed ratio was very dependent on the rotor size and on the assumptions of the airfoil flow being fully turbulent (contaminated airfoil) or free transitional (clean airfoil). The investigations showed that rotors with diameter D=1.75m, should be designed for X around 5.5, whereas rotors with diameter D=126m, should be designed for Xbetween 6.5 and 8.5, depending on the airfoil performance

Aerodynamics and Control of Quadrotors

Science.gov (United States)

Bangura, Moses

Quadrotors are aerial vehicles with a four motor-rotor assembly for generating lift and controllability. Their light weight, ease of design and simple dynamics have increased their use in aerial robotics research. There are many quadrotors that are commercially available or under development. Commercial off-the-shelf quadrotors usually lack the ability to be reprogrammed and are unsuitable for use as research platforms. The open-source code developed in this thesis differs from other open-source systems by focusing on the key performance road blocks in implementing high performance experimental quadrotor platforms for research: motor-rotor control for thrust regulation, velocity and attitude estimation, and control for position regulation and trajectory tracking. In all three of these fundamental subsystems, code sub modules for implementation on commonly available hardware are provided. In addition, the thesis provides guidance on scoping and commissioning open-source hardware components to build a custom quadrotor. A key contribution of the thesis is then a design methodology for the development of experimental quadrotor platforms from open-source or commercial off-the-shelf software and hardware components that have active community support. Quadrotors built following the methodology allows the user access to the operation of the subsystems and, in particular, the user can tune the gains of the observers and controllers in order to push the overall system to its performance limits. This enables the quadrotor framework to be used for a variety of applications such as heavy lifting and high performance aggressive manoeuvres by both the hobby and academic communities. To address the question of thrust control, momentum and blade element theories are used to develop aerodynamic models for rotor blades specific to quadrotors. With the aerodynamic models, a novel thrust estimation and control scheme that improves on existing RPM (revolutions per minute) control of

Innovative Aerodynamic Modeling for Aeroservoelastic Analysis and Design, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — We propose the development of a modern panel code for calculation of steady and unsteady aerodynamic loads needed for dynamic servoelastic (DSE) analysis of flight...

Quiet Clean Short-haul Experimental Engine (QCSEE): The aerodynamic and mechanical design of the QCSEE under-the-wing fan

Science.gov (United States)

1977-01-01

The design, fabrication, and testing of two experimental high bypass geared turbofan engines and propulsion systems for short haul passenger aircraft are described. The aerodynamic and mechanical design of a variable pitch 1.34 pressure ratio fan for the under the wing (UTW) engine are included. The UTW fan was designed to permit rotation of the 18 composite fan blades into the reverse thrust mode of operation through both flat pitch and stall pitch directions.

Theoretical and applied aerodynamics and related numerical methods

CERN Document Server

Chattot, J J

2015-01-01

This book covers classical and modern aerodynamics, theories and related numerical methods, for senior and first-year graduate engineering students, including: -The classical potential (incompressible) flow theories for low speed aerodynamics of thin airfoils and high and low aspect ratio wings. - The linearized theories for compressible subsonic and supersonic aerodynamics. - The nonlinear transonic small disturbance potential flow theory, including supercritical wing sections, the extended transonic area rule with lift effect, transonic lifting line and swept or oblique wings to minimize wave drag. Unsteady flow is also briefly discussed. Numerical simulations based on relaxation mixed-finite difference methods are presented and explained. - Boundary layer theory for all Mach number regimes and viscous/inviscid interaction procedures used in practical aerodynamics calculations. There are also four chapters covering special topics, including wind turbines and propellers, airplane design, flow analogies and h...

Aerodynamic benchmarking of the DeepWind design

DEFF Research Database (Denmark)

Bedon, Gabriele; Schmidt Paulsen, Uwe; Aagaard Madsen, Helge

The aerodynamic benchmarking for the DeepWind rotor is conducted comparing different rotor geometries and solutions and keeping the comparison as fair as possible. The objective for the benchmarking is to find the most suitable configuration in order to maximize the power production and minimize...... the blade solicitation and the cost of energy. Different parameters are considered for the benchmarking study. The DeepWind blade is characterized by a shape similar to the Troposkien geometry but asymmetric between the top and bottom parts. The blade shape is considered as a fixed parameter...

Aerodynamic Shape Optimization Using Hybridized Differential Evolution

Science.gov (United States)

Madavan, Nateri K.

2003-01-01

An aerodynamic shape optimization method that uses an evolutionary algorithm known at Differential Evolution (DE) in conjunction with various hybridization strategies is described. DE is a simple and robust evolutionary strategy that has been proven effective in determining the global optimum for several difficult optimization problems. Various hybridization strategies for DE are explored, including the use of neural networks as well as traditional local search methods. A Navier-Stokes solver is used to evaluate the various intermediate designs and provide inputs to the hybrid DE optimizer. The method is implemented on distributed parallel computers so that new designs can be obtained within reasonable turnaround times. Results are presented for the inverse design of a turbine airfoil from a modern jet engine. (The final paper will include at least one other aerodynamic design application). The capability of the method to search large design spaces and obtain the optimal airfoils in an automatic fashion is demonstrated.

Numerical study on aerodynamic damping of floating vertical axis wind turbines

DEFF Research Database (Denmark)

Cheng, Zhengshun; Aagaard Madsen, Helge; Gao, Zhen

2016-01-01

Harvesting offshore wind energy resources using floating vertical axis wind turbines (VAWTs) has attracted an increasing interest in recent years. Due to its potential impact on fatigue damage, the aerodynamic damping should be considered in the preliminary design of a floating VAWT based...... on the frequency domain method. However, currently the study on aerodynamic damping of floating VAWTs is very limited. Due to the essential difference in aerodynamic load characteristics, the aerodynamic damping of a floating VAWT could be different from that of a floating horizontal axis wind turbine (HAWT...... to four were considered. The aerodynamic damping under steady and turbulent wind conditions were estimated using fully coupled aero-hydro-servo-elastic time domain simulations. It is found that the aerodynamic damping ratio of the considered floating VAWTs ranges from 1.8% to 5.3%. Moreover...

X based interactive computer graphics applications for aerodynamic design and education

Science.gov (United States)

Benson, Thomas J.; Higgs, C. Fred, III

1995-01-01

Six computer applications packages have been developed to solve a variety of aerodynamic problems in an interactive environment on a single workstation. The packages perform classical one dimensional analysis under the control of a graphical user interface and can be used for preliminary design or educational purposes. The programs were originally developed on a Silicon Graphics workstation and used the GL version of the FORMS library as the graphical user interface. These programs have recently been converted to the XFORMS library of X based graphics widgets and have been tested on SGI, IBM, Sun, HP and PC-Lunix computers. The paper will show results from the new VU-DUCT program as a prime example. VU-DUCT has been developed as an educational package for the study of subsonic open and closed loop wind tunnels.

ISOLATED AERODYNAMIC SURFACE CALCULUS

Directory of Open Access Journals (Sweden)

ENUŞ Marilena

2014-07-01

Full Text Available The paper proposes to present a few steps for calculating the dynamics of flight. From an organizational perspective, the paper is structured in three parts. The first part provides essential information that needs to be taken into account when designing an aircraft wing. The second part presents the basic steps in the wing design procedure and finally, the third part contains the diagrams in which one can find the aerodynamic coefficient of a specifying wing.

PREFACE: Aerodynamic sound Aerodynamic sound

Science.gov (United States)

Akishita, Sadao

2010-02-01

The modern theory of aerodynamic sound originates from Lighthill's two papers in 1952 and 1954, as is well known. I have heard that Lighthill was motivated in writing the papers by the jet-noise emitted by the newly commercialized jet-engined airplanes at that time. The technology of aerodynamic sound is destined for environmental problems. Therefore the theory should always be applied to newly emerged public nuisances. This issue of Fluid Dynamics Research (FDR) reflects problems of environmental sound in present Japanese technology. The Japanese community studying aerodynamic sound has held an annual symposium since 29 years ago when the late Professor S Kotake and Professor S Kaji of Teikyo University organized the symposium. Most of the Japanese authors in this issue are members of the annual symposium. I should note the contribution of the two professors cited above in establishing the Japanese community of aerodynamic sound research. It is my pleasure to present the publication in this issue of ten papers discussed at the annual symposium. I would like to express many thanks to the Editorial Board of FDR for giving us the chance to contribute these papers. We have a review paper by T Suzuki on the study of jet noise, which continues to be important nowadays, and is expected to reform the theoretical model of generating mechanisms. Professor M S Howe and R S McGowan contribute an analytical paper, a valuable study in today's fluid dynamics research. They apply hydrodynamics to solve the compressible flow generated in the vocal cords of the human body. Experimental study continues to be the main methodology in aerodynamic sound, and it is expected to explore new horizons. H Fujita's study on the Aeolian tone provides a new viewpoint on major, longstanding sound problems. The paper by M Nishimura and T Goto on textile fabrics describes new technology for the effective reduction of bluff-body noise. The paper by T Sueki et al also reports new technology for the

Australian Aerodynamic Design Codes for Aerial Tow Bodies.

Science.gov (United States)

1987-08-27

HTP -1, which deals with aerial targets, it was recognised that there was a need for a complete and well docL mented approach for their aerodynamic and...circular cables cannot be assessed with the programs in their present form. 10. none of the programs are well documented and user’s manuals are not...National Leader ANL TTCP HTP -1 Weapons Systems Research Laboratory Director Superintendent - Weapons Division - Combat Systems Division Navy Office Navy

Enveloping Aerodynamic Decelerator

Science.gov (United States)

Nock, Kerry T. (Inventor); Aaron, Kim M. (Inventor); McRonald, Angus D. (Inventor); Gates, Kristin L. (Inventor)

2018-01-01

An inflatable aerodynamic deceleration method and system is provided for use with an atmospheric entry payload. The inflatable aerodynamic decelerator includes an inflatable envelope and an inflatant, wherein the inflatant is configured to fill the inflatable envelope to an inflated state such that the inflatable envelope surrounds the atmospheric entry payload, causing aerodynamic forces to decelerate the atmospheric entry payload.

Parameter assessment for virtual Stackelberg game in aerodynamic shape optimization

Science.gov (United States)

Wang, Jing; Xie, Fangfang; Zheng, Yao; Zhang, Jifa

2018-05-01

In this paper, parametric studies of virtual Stackelberg game (VSG) are conducted to assess the impact of critical parameters on aerodynamic shape optimization, including design cycle, split of design variables and role assignment. Typical numerical cases, including the inverse design and drag reduction design of airfoil, have been carried out. The numerical results confirm the effectiveness and efficiency of VSG. Furthermore, the most significant parameters are identified, e.g. the increase of design cycle can improve the optimization results but it will also add computational burden. These studies will maximize the productivity of the effort in aerodynamic optimization for more complicated engineering problems, such as the multi-element airfoil and wing-body configurations.

Engineering models in wind energy aerodynamics : Development, implementation and analysis using dedicated aerodynamic measurements

NARCIS (Netherlands)

Schepers, J.G.

2012-01-01

The subject of aerodynamics is of major importance for the successful deployment of wind energy. As a matter of fact there are two aerodynamic areas in the wind energy technology: Rotor aerodynamics and wind farm aerodynamics. The first subject considers the flow around the rotor and the second

Modulation of leading edge vorticity and aerodynamic forces in flexible flapping wings.

Science.gov (United States)

Zhao, Liang; Deng, Xinyan; Sane, Sanjay P

2011-09-01

In diverse biological flight systems, the leading edge vortex has been implicated as a flow feature of key importance in the generation of flight forces. Unlike fixed wings, flapping wings can translate at higher angles of attack without stalling because their leading edge vorticity is more stable than the corresponding fixed wing case. Hence, the leading edge vorticity has often been suggested as the primary determinant of the high forces generated by flapping wings. To test this hypothesis, it is necessary to modulate the size and strength of the leading edge vorticity independently of the gross kinematics while simultaneously monitoring the forces generated by the wing. In a recent study, we observed that forces generated by wings with flexible trailing margins showed a direct dependence on the flexural stiffness of the wing. Based on that study, we hypothesized that trailing edge flexion directly influences leading edge vorticity, and thereby the magnitude of aerodynamic forces on the flexible flapping wings. To test this hypothesis, we visualized the flows on wings of varying flexural stiffness using a custom 2D digital particle image velocimetry system, while simultaneously monitoring the magnitude of the aerodynamic forces. Our data show that as flexion decreases, the magnitude of the leading edge vorticity increases and enhances aerodynamic forces, thus confirming that the leading edge vortex is indeed a key feature for aerodynamic force generation in flapping flight. The data shown here thus support the hypothesis that camber influences instantaneous aerodynamic forces through modulation of the leading edge vorticity.

Modeling the Aerodynamics and Performances of a Historic Airplane: the Spanish

Directory of Open Access Journals (Sweden)

A. González-Betes

2003-01-01

Full Text Available The process of modeling the aerodynamics and performances of a historic airplane is very similar to the conceptual and preliminary design phases of a new plane, with the advantage of knowing the configuration and that the airplane was airworthy; thus it is unnecessary to outline and assess many different alternatives. However, the drag polar, the real performances, stability features, etc, are still unknown. For various reasons (in particular because of two World Wars, or the Civil War in the Spanish case most details of many historical airplanes have been lost.In the present research work, the situation is as follows. In June 1933 the "Cuatro Vientos", a Spanish-built Bréguet XIX Super TR, flew non-stop from Seville to Cuba; a distance of 7500 km (about 4100 nautical miles in around 40 hours. A few days later, in a far less complicated stage between Havana and Mexico, the airplane was lost with its occupants to a storm in the Yucatan peninsula.The modeling considered in this paper starts by addressing the aerodynamic modifications introduced in the airplane for the extremely long flight. Then, with the help of old and present day aerodynamic data and methods the drag polar is estimated. The available engine data is completed and extrapolated to obtain information on power and fuel consumption. Finally, all this data is integrated to provide a reliable and technically sound reproduction of the Seville-Cuba flight.

Design features to reduce occupational exposure

International Nuclear Information System (INIS)

Adam, J.A.; DiSabatino, A.A. Jr.; Vanasse, R.E.

1975-01-01

Some of the design principles which are important considerations in the evolution of a nuclear power plant design to ensure that occupational radiation exposures can be minimized are discussed. Emphasis is placed on the design features affecting the basic layout and equipment locations within the plant. Examples are provided showing how these design objectives are realized in the Stone and Webster Reference Nuclear Power Plant Design, with particular emphasis on the Annulus Building portion of the reference plant. Design features which are useful in reducing occupational exposure during normal operation are discussed initially, followed by those that chiefly affect exposures during maintenance activity. Finally, those provisions in the design which assist in preventing the spread of radioactive contamination are presented

Aerodynamics of Ventilation in Termite Mounds

Science.gov (United States)

Bailoor, Shantanu; Yaghoobian, Neda; Turner, Scott; Mittal, Rajat

2017-11-01

Fungus-cultivating termites collectively build massive, complex mounds which are much larger than the size of an individual termite and effectively use natural wind and solar energy, as well as the energy generated by the colony's own metabolic activity to maintain the necessary environmental condition for the colony's survival. We seek to understand the aerodynamics of ventilation and thermoregulation of termite mounds through computational modeling. A simplified model accounting for key mound features, such as soil porosity and internal conduit network, is subjected to external draft conditions. The role of surface flow conditions in the generation of internal flow patterns and the ability of the mound to transport gases and heat from the nursery are examined. The understanding gained from our study could be used to guide sustainable bio-inspired passive HVAC system design, which could help optimize energy utilization in commercial and residential buildings. This research is supported by a seed Grant from the Environment, Energy Sustainability and Health Institute of the Johns Hopkins University.

Integrating aerodynamic surface modeling for computational fluid dynamics with computer aided structural analysis, design, and manufacturing

Science.gov (United States)

Thorp, Scott A.

1992-01-01

This presentation will discuss the development of a NASA Geometry Exchange Specification for transferring aerodynamic surface geometry between LeRC systems and grid generation software used for computational fluid dynamics research. The proposed specification is based on a subset of the Initial Graphics Exchange Specification (IGES). The presentation will include discussion of how the NASA-IGES standard will accommodate improved computer aided design inspection methods and reverse engineering techniques currently being developed. The presentation is in viewgraph format.

Estimation of aircraft aerodynamic derivatives using Extended Kalman Filter

OpenAIRE

Curvo, M.

2000-01-01

Design of flight control laws, verification of performance predictions, and the implementation of flight simulations are tasks that require a mathematical model of the aircraft dynamics. The dynamical models are characterized by coefficients (aerodynamic derivatives) whose values must be determined from flight tests. This work outlines the use of the Extended Kalman Filter (EKF) in obtaining the aerodynamic derivatives of an aircraft. The EKF shows several advantages over the more traditional...

Unsteady Aerodynamic Force Sensing from Measured Strain

Science.gov (United States)

Pak, Chan-Gi

2016-01-01

, velocity, and acceleration sensors. This research demonstrates the feasibility of obtaining induced drag and lift forces through the use of distributed sensor technology with measured strain data. An active induced drag control system thus can be designed using the two computed aerodynamic forces, induced drag and lift, to improve the fuel efficiency of an aircraft. Interpolation elements between structural finite element grids and the CFD grids and centroids are successfully incorporated with the unsteady aeroelastic computation scheme. The most critical technology for the success of the proposed approach is the robust on-line parameter estimator, since the least-squares curve fitting method depends heavily on aeroelastic system frequencies and damping factors.

Two-Stage Fan I: Aerodynamic and Mechanical Design

Science.gov (United States)

Messenger, H. E.; Kennedy, E. E.

1972-01-01

A two-stage, highly-loaded fan was designed to deliver an overall pressure ratio of 2.8 with an adiabatic efficiency of 83.9 percent. At the first rotor inlet, design flow per unit annulus area is 42 lbm/sec/sq ft (205 kg/sec/sq m), hub/tip ratio is 0.4 with a tip diameter of 31 inches (0.787 m), and design tip speed is 1450 ft/sec (441.96 m/sec). Other features include use of multiple-circular-arc airfoils, resettable stators, and split casings over the rotor tip sections for casing treatment tests.

Aerodynamic design of horizontal axis wind turbine with innovative local linearization of chord and twist distributions

DEFF Research Database (Denmark)

Tahani, Mojtaba; Kavari, Ghazale; Masdari, Mehran

2017-01-01

This study is aimed to aerodynamically design a 1 mega-Watt horizontal axis wind turbine in order to obtain the maximum power coefficient by linearizing the chord and twist distributions. A new linearization method has been used for chord and twist distributions by crossing tangent line through...... the geometry of the blades determines the power generated by rotor, designing the blade is a very important issue. Herein, calculations are done for different types of airfoil families namely Risø-A1-21, Risø-A1-18, S809, S814 and Du 93-W-210. Hence, the effect of selecting different airfoil families is also...

Numerical study of aerodynamic effects on road vehicles lifting surfaces

Science.gov (United States)

Cernat, Mihail Victor; Cernat Bobonea, Andreea

2017-01-01

The aerodynamic performance analysis of road vehicles depends on the study of engine intake and cooling flow, internal ventilation, tire cooling, and overall external flow as the motion of air around a moving vehicle affects all of its components in one form or another. Due to the complex geometry of these, the aerodynamic interaction between the various body components is significant, resulting in vortex flow and lifting surface shapes. The present study, however focuses on the effects of external aerodynamics only, and in particular on the flow over the lifting surfaces of a common compact car, designed especially for this study.

Numerical study on aerodynamic damping of floating vertical axis wind turbines

Science.gov (United States)

Cheng, Zhengshun; Aagaard Madsen, Helge; Gao, Zhen; Moan, Torgeir

2016-09-01

Harvesting offshore wind energy resources using floating vertical axis wind turbines (VAWTs) has attracted an increasing interest in recent years. Due to its potential impact on fatigue damage, the aerodynamic damping should be considered in the preliminary design of a floating VAWT based on the frequency domain method. However, currently the study on aerodynamic damping of floating VAWTs is very limited. Due to the essential difference in aerodynamic load characteristics, the aerodynamic damping of a floating VAWT could be different from that of a floating horizontal axis wind turbine (HAWT). In this study, the aerodynamic damping of floating VAWTs was studied in a fully coupled manner, and its influential factors and its effects on the motions, especially the pitch motion, were demonstrated. Three straight-bladed floating VAWTs with identical solidity and with a blade number varying from two to four were considered. The aerodynamic damping under steady and turbulent wind conditions were estimated using fully coupled aero-hydro-servo-elastic time domain simulations. It is found that the aerodynamic damping ratio of the considered floating VAWTs ranges from 1.8% to 5.3%. Moreover, the aerodynamic damping is almost independent of the rotor azimuth angle, and is to some extent sensitive to the blade number.

Development of a morphing flap using shape memory alloy actuators: the aerodynamic characteristics of a morphing flap

International Nuclear Information System (INIS)

Ko, Seung-Hee; Bae, Jae-Sung; Rho, Jin-Ho

2014-01-01

The discontinuous contour of a wing with conventional flaps diminishes the aerodynamic performance of an aircraft. A wing with a continuous contour does not experience extreme flow stream fluctuations during flight, and consequently has good aerodynamic characteristics. In this study, a morphing flap using shape memory alloy actuators is proposed, designed and fabricated, and its aerodynamic characteristics are investigated using aerodynamic analyses and wind tunnel tests. The ribs of the morphing flap are designed and fabricated with multiple elements joined together in a way that allows relative rotations of adjacent elements and forms a smooth contour of the morphing flap. The aerodynamic analyses of this multiple-element morphing-flap wing are performed using XFLR pro; its aerodynamic performance is compared with that of a mechanical-flap wing, and is measured through wind-tunnel tests. (papers)

Aerodynamics of wind turbines

CERN Document Server

Hansen, Martin O L

2015-01-01

Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design a classical pitch and torque regulator to control rotational speed and power, while the section on structural dynamics has been extended with a simplified mechanical system explaining the phenomena of forward and backward whirling modes. Readers will also benefit from a new chapter on Vertical Axis W

Viscous-Inviscid Methods in Unsteady Aerodynamic Analysis of Bio-Inspired Morphing Wings

Science.gov (United States)

Dhruv, Akash V.

Flight has been one of the greatest realizations of human imagination, revolutionizing communication and transportation over the years. This has greatly influenced the growth of technology itself, enabling researchers to communicate and share their ideas more effectively, extending the human potential to create more sophisticated systems. While the end product of a sophisticated technology makes our lives easier, its development process presents an array of challenges in itself. In last decade, scientists and engineers have turned towards bio-inspiration to design more efficient and robust aerodynamic systems to enhance the ability of Unmanned Aerial Vehicles (UAVs) to be operated in cluttered environments, where tight maneuverability and controllability are necessary. Effective use of UAVs in domestic airspace will mark the beginning of a new age in communication and transportation. The design of such complex systems necessitates the need for faster and more effective tools to perform preliminary investigations in design, thereby streamlining the design process. This thesis explores the implementation of numerical panel methods for aerodynamic analysis of bio-inspired morphing wings. Numerical panel methods have been one of the earliest forms of computational methods for aerodynamic analysis to be developed. Although the early editions of this method performed only inviscid analysis, the algorithm has matured over the years as a result of contributions made by prominent aerodynamicists. The method discussed in this thesis is influenced by recent advancements in panel methods and incorporates both viscous and inviscid analysis of multi-flap wings. The surface calculation of aerodynamic coefficients makes this method less computationally expensive than traditional Computational Fluid Dynamics (CFD) solvers available, and thus is effective when both speed and accuracy are desired. The morphing wing design, which consists of sequential feather-like flaps installed

Developments of an Interactive Sail Design Method

Directory of Open Access Journals (Sweden)

S. M. Malpede

2000-01-01

Full Text Available This paper presents a new tool for performing the integrated design and analysis of a sail. The features of the system are the geometrical definition of a sail shape, using the Bezier surface method, the creation of a finite element model for the non-linear structural analysis and a fluid-dynamic model for the aerodynamic analysis. The system has been developed using MATLAB(r. Recent sail design efforts have been focused on solving the aeroelastic behavior of the sail. The pressure distribution on a sail changes continuously, by virtue of cloth stretch and flexing. The sail shape determines the pressure distribution and, at the same time, the pressure distribution on the sail stretches and flexes the sail material determining its shape. This characteristic non-linear behavior requires iterative solution strategies to obtain the equilibrium configuration and evaluate the forces involved. The aeroelastic problem is tackled by combining structural with aerodynamic analysis. Firstly, pressure loads for a known sail-shape are computed (aerodynamic analysis. Secondly, the sail-shape is analyzed for the obtained external loads (structural analysis. The final solution is obtained by using an iterative analysis process, which involves both aerodynamic and the structural analysis. When the solution converges, it is possible to make design modifications.

Performance characteristics of aerodynamically optimum turbines for wind energy generators

Science.gov (United States)

Rohrbach, C.; Worobel, R.

1975-01-01

This paper presents a brief discussion of the aerodynamic methodology for wind energy generator turbines, an approach to the design of aerodynamically optimum wind turbines covering a broad range of design parameters, some insight on the effect on performance of nonoptimum blade shapes which may represent lower fabrication costs, the annual wind turbine energy for a family of optimum wind turbines, and areas of needed research. On the basis of the investigation, it is concluded that optimum wind turbines show high performance over a wide range of design velocity ratios; that structural requirements impose constraints on blade geometry; that variable pitch wind turbines provide excellent power regulation and that annual energy output is insensitive to design rpm and solidity of optimum wind turbines.

Experimental and analytical research on the aerodynamics of wind driven turbines. Final report

Energy Technology Data Exchange (ETDEWEB)

Rohrbach, C.; Wainauski, H.; Worobel, R.

1977-12-01

This aerodynamic research program was aimed at providing a reliable, comprehensive data base on a series of wind turbine models covering a broad range of the prime aerodynamic and geometric variables. Such data obtained under controlled laboratory conditions on turbines designed by the same method, of the same size, and tested in the same wind tunnel had not been available in the literature. Moreover, this research program was further aimed at providing a basis for evaluating the adequacy of existing wind turbine aerodynamic design and performance methodology, for assessing the potential of recent advanced theories and for providing a basis for further method development and refinement.

The Aerodynamics of Heavy Vehicles III : Trucks, Buses and Trains

CERN Document Server

Orellano, Alexander

2016-01-01

This volume contains papers presented at the International conference “The Aerodynamics of Heavy Vehicles III: Trucks, Buses and Trains” held in Potsdam, Germany, September 12-17, 2010 by Engineering Conferences International (ECI). Leading scientists and engineers from industry, universities and research laboratories, including truck and high-speed train manufacturers and operators were brought together to discuss computer simulation and experimental techniques to be applied for the design of more efficient trucks, buses and high-speed trains in the future.   This conference was the third in the series after Monterey-Pacific Groove in 2002 and Lake Tahoe in 2007.  The presentations address different aspects of train aerodynamics (cross wind effects, underbody flow, tunnel aerodynamics and aeroacoustics, experimental techniques), truck aerodynamics (drag reduction, flow control, experimental and computational techniques) as well as computational fluid dynamics and bluff body, wake and jet flows.

Comparison of Theodorsen's Unsteady Aerodynamic Forces with Doublet Lattice Generalized Aerodynamic Forces

Science.gov (United States)

Perry, Boyd, III

2017-01-01

This paper identifies the unsteady aerodynamic forces and moments for a typical section contained in the NACA Report No. 496, "General Theory of Aerodynamic Instability and the Mechanism of Flutter," by Theodore Theodorsen. These quantities are named Theodorsen's aerodynamic forces (TAFs). The TAFs are compared to the generalized aerodynamic forces (GAFs) for a very high aspect ratio wing (AR = 20) at zero Mach number computed by the doublet lattice method. Agreement between TAFs and GAFs is very-good-to-excellent. The paper also reveals that simple proportionality relationships that are known to exist between the real parts of some GAFs and the imaginary parts of others also hold for the real and imaginary parts of the corresponding TAFs.

Aerodynamic-structural model of offwind yacht sails

Science.gov (United States)

Mairs, Christopher M.

An aerodynamic-structural model of offwind yacht sails was created that is useful in predicting sail forces. Two sails were examined experimentally and computationally at several wind angles to explore a variety of flow regimes. The accuracy of the numerical solutions was measured by comparing to experimental results. The two sails examined were a Code 0 and a reaching asymmetric spinnaker. During experiment, balance, wake, and sail shape data were recorded for both sails in various configurations. Two computational steps were used to evaluate the computational model. First, an aerodynamic flow model that includes viscosity effects was used to examine the experimental flying shapes that were recorded. Second, the aerodynamic model was combined with a nonlinear, structural, finite element analysis (FEA) model. The aerodynamic and structural models were used iteratively to predict final flying shapes of offwind sails, starting with the design shapes. The Code 0 has relatively low camber and is used at small angles of attack. It was examined experimentally and computationally at a single angle of attack in two trim configurations, a baseline and overtrimmed setting. Experimentally, the Code 0 was stable and maintained large flow attachment regions. The digitized flying shapes from experiment were examined in the aerodynamic model. Force area predictions matched experimental results well. When the aerodynamic-structural tool was employed, the predictive capability was slightly worse. The reaching asymmetric spinnaker has higher camber and operates at higher angles of attack than the Code 0. Experimentally and computationally, it was examined at two angles of attack. Like the Code 0, at each wind angle, baseline and overtrimmed settings were examined. Experimentally, sail oscillations and large flow detachment regions were encountered. The computational analysis began by examining the experimental flying shapes in the aerodynamic model. In the baseline setting, the

Aerodynamic Efficiency Analysis on Modified Drag Generator of Tanker-Ship Using Symmetrical Airfoil

Science.gov (United States)

Moranova, Starida; Rahmat Hadiyatul A., S. T.; Indra Permana S., S. T.

2018-04-01

Time reduction of tanker ship spent in the sea should be applied for solving problems occured in oil and gas distribution, such as the unpunctuality of the distribution and oil spilling. The aerodynamic design for some parts that considered as drag generators is presumed to be one of the solution, utilizing our demand of the increasing speed. This paper suggests two examples of the more-aerodynamic design of a part in the tanker that is considered a drag generator, and reports the value of drag generated from the basic and the suggested aerodynamic designs. The new designs are made by adding the NACA airfoil to the cross section of the drag generator. The scenario is assumed with a 39 km/hour speed of tanker, neglecting the hydrodynamic effects occured in the tanker by cutting it at the waterline which separated the drag between air and water. The results of produced drag in each design are calculated by Computational Fluid Dynamic method.

CONDITIONS OF PHYSICAL MODELING AERODYNAMIC CHARACTERISTICS OF AIRCRAFT WITH CHASSIS HOVERCRAFT

Directory of Open Access Journals (Sweden)

Yu. Yu. Merzlikin

2015-01-01

Full Text Available The features of the physical modeling in the experimental determination of aerodynamics-cal tubes (WT of low-velocity steady and unsteady aerodynamic characteristics at takeoff and landing of aircraft (LA with the chassis air-cushion (ball screw and in studies to determine the stability of equilibrium regimes of movement and shock-absorbing properties of ball screws. Are conscdered the requirements for the experimental facilities, model aircraft with ball screws and re-test of the latest zhimam on the free stream velocity, flow and pressure blowers VР, the frequencies and amplitudes of the oscillations are formulated.

An object-oriented feature-based design system face-based detection of feature interactions

International Nuclear Information System (INIS)

Ariffin Abdul Razak

1999-01-01

This paper presents an object-oriented, feature-based design system which supports the integration of design and manufacture by ensuring that part descriptions fully account for any feature interactions. Manufacturing information is extracted from the feature descriptions in the form of volumes and Tool Access Directions, TADs. When features interact, both volumes and TADs are updated. This methodology has been demonstrated by developing a prototype system in which ACIS attributes are used to record feature information within the data structure of the solid model. The system implemented in the C++ programming language and embedded in a menu-driven X-windows user interface to the ACIS 3D Toolkit. (author)

Design and Experimental Validation of Thick Airfoils for Large Wind Turbines

DEFF Research Database (Denmark)

Hrgovan, Iva; Shen, Wen Zhong; Zhu, Wei Jun

2015-01-01

In this chapter, two new airfoils with thickness to chord ratios of 30 and 36 % are presented, which were designed with an objective of good aerodynamic and structural features. Airfoil design is based on a direct method using shape perturbation function. The optimization algorithm is coupled wit...

Aerodynamic Characteristic of the Active Compliant Trailing Edge Concept

Science.gov (United States)

Nie, Rui; Qiu, Jinhao; Ji, Hongli; Li, Dawei

2016-06-01

This paper introduces a novel Morphing Wing structure known as the Active Compliant Trailing Edge (ACTE). ACTE structures are designed using the concept of “distributed compliance” and wing skins of ACTE are fabricated from high-strength fiberglass composites laminates. Through the relative sliding between upper and lower wing skins which are connected by a linear guide pairs, the wing is able to achieve a large continuous deformation. In order to present an investigation about aerodynamics and noise characteristics of ACTE, a series of 2D airfoil analyses are established. The aerodynamic characteristics between ACTE and conventional deflection airfoil are analyzed and compared, and the impacts of different ACTE structure design parameters on aerodynamic characteristics are discussed. The airfoils mentioned above include two types (NACA0012 and NACA64A005.92). The computing results demonstrate that: compared with the conventional plane flap airfoil, the morphing wing using ACTE structures has the capability to improve aerodynamic characteristic and flow separation characteristic. In order to study the noise level of ACTE, flow field analysis using LES model is done to provide noise source data, and then the FW-H method is used to get the far field noise levels. The simulation results show that: compared with the conventional flap/aileron airfoil, the ACTE configuration is better to suppress the flow separation and lower the overall sound pressure level.

Designing attractive gamification features for collaborative storytelling websites.

Science.gov (United States)

Hsu, Shang Hwa; Chang, Jen-Wei; Lee, Chun-Chia

2013-06-01

Gamification design is considered as the predictor of collaborative storytelling websites' success. Although aforementioned studies have mentioned a broad range of factors that may influence gamification, they neither depicted the actual design features nor relative attractiveness among them. This study aims to identify attractive gamification features for collaborative storytelling websites. We first constructed a hierarchical system structure of gamification design of collaborative storytelling websites and conducted a focus group interview with eighteen frequent users to identify 35gamification features. After that, this study determined the relative attractiveness of these gamification features by administrating an online survey to 6333 collaborative storytelling websites users. The results indicated that the top 10 most attractive gamification features could account for more than 50% of attractiveness among these 35 gamification features. The feature of unpredictable time pressure is important to website users, yet not revealed in previous relevant studies. Implications of the findings were discussed.

Lifting Wing in Constructing Tall Buildings —Aerodynamic Testing

Directory of Open Access Journals (Sweden)

Ian Skelton

2014-05-01

Full Text Available This paper builds on previous research by the authors which determined the global state-of-the-art of constructing tall buildings by surveying the most active specialist tall building professionals around the globe. That research identified the effect of wind on tower cranes as a highly ranked, common critical issue in tall building construction. The research reported here presents a design for a “Lifting Wing,” a uniquely designed shroud which potentially allows the lifting of building materials by a tower crane in higher and more unstable wind conditions, thereby reducing delay on the programmed critical path of a tall building. Wind tunnel tests were undertaken to compare the aerodynamic performance of a scale model of a typical “brick-shaped” construction load (replicating a load profile most commonly lifted via a tower crane against the aerodynamic performance of the scale model of the Lifting Wing in a range of wind conditions. The data indicate that the Lifting Wing improves the aerodynamic performance by a factor of up to 50%.

Fuel Savings and Aerodynamic Drag Reduction from Rail Car Covers

Science.gov (United States)

Storms, Bruce; Salari, Kambiz; Babb, Alex

2008-01-01

The potential for energy savings by reducing the aerodynamic drag of rail cars is significant. A previous study of aerodynamic drag of coal cars suggests that a 25% reduction in drag of empty cars would correspond to a 5% fuel savings for a round trip [1]. Rail statistics for the United States [2] report that approximately 5.7 billion liters of diesel fuel were consumed for coal transportation in 2002, so a 5% fuel savings would total 284 million liters. This corresponds to 2% of Class I railroad fuel consumption nationwide. As part of a DOE-sponsored study, the aerodynamic drag of scale rail cars was measured in a wind tunnel. The goal of the study was to measure the drag reduction of various rail-car cover designs. The cover designs tested yielded an average drag reduction of 43% relative to empty cars corresponding to an estimated round-trip fuel savings of 9%.

Preliminary Aerodynamic Investigation of Fan Rotor Blade Morphing

Science.gov (United States)

Tweedt, Daniel L.

2012-01-01

Various new technologies currently under development may enable controlled blade shape variability, or so-called blade morphing, to be practically employed in aircraft engine fans and compressors in the foreseeable future. The current study is a relatively brief, preliminary computational fluid dynamics investigation aimed at partially demonstrating and quantifying the aerodynamic potential of fan rotor blade morphing. The investigation is intended to provide information useful for near-term planning, as well as aerodynamic solution data sets that can be subsequently analyzed using advanced acoustic diagnostic tools, for the purpose of making fan noise comparisons. Two existing fan system models serve as baselines for the investigation: the Advanced Ducted Propulsor fan with a design tip speed of 806 ft/sec and a pressure ratio of 1.294, and the Source Diagnostic Test fan with a design tip speed of 1215 ft/sec and a pressure ratio of 1.470. Both are 22-in. sub-scale, low-noise research fan/nacelle models that have undergone extensive experimental testing in the 9- by 15-foot Low Speed Wind Tunnel at the NASA Glenn Research Center. The study, restricted to fan rotor blade morphing only, involves a fairly simple blade morphing technique. Specifically, spanwise-linear variations in rotor blade-section setting angle are applied to alter the blade shape; that is, the blade is linearly retwisted from hub to tip. Aerodynamic performance comparisons are made between morphed-blade and corresponding baseline configurations on the basis of equal fan system thrust, where rotor rotational speed for the morphed-blade fan is varied to change the thrust level for that configuration. The results of the investigation confirm that rotor blade morphing could be a useful technology, with the potential to enable significant improvements in fan aerodynamic performance. Even though the study is very limited in scope and confined to simple geometric perturbations of two existing fan

Specialized computer architectures for computational aerodynamics

Science.gov (United States)

Stevenson, D. K.

1978-01-01

In recent years, computational fluid dynamics has made significant progress in modelling aerodynamic phenomena. Currently, one of the major barriers to future development lies in the compute-intensive nature of the numerical formulations and the relative high cost of performing these computations on commercially available general purpose computers, a cost high with respect to dollar expenditure and/or elapsed time. Today's computing technology will support a program designed to create specialized computing facilities to be dedicated to the important problems of computational aerodynamics. One of the still unresolved questions is the organization of the computing components in such a facility. The characteristics of fluid dynamic problems which will have significant impact on the choice of computer architecture for a specialized facility are reviewed.

Study on aerodynamics characteristics an urban concept car for energy-efficient race

Science.gov (United States)

Ambarita, H.; Siregar, M. R.; Kawai, H.

2018-03-01

"Horas Mesin USU" is a prototype of urban concept vehicle designed by University of Sumatera Utara to participate in the energy-efficient competition. This paper deals with a numerical study on aerodynamic characteristics of the Horas Mesin USU. The numerical analyses are carried out by solving the governing equations using CFD FLUENT commercial code. The turbulent flow is closed using k-epsilon turbulence model. In the results, pathline, velocity vector and pressure distribution are plotted. By using the pressure distributions, drag and lift coefficients are calculated. In order to make a comparison, the aerodynamic characteristics of the present design are compared with commercial city car Ford-Fiesta. The averaged drag coefficients of Horas Mesin USU and Ford-Fiesta are 0.24320 and 0.29598, respectively. On the other hand, the averaged lift coefficients of the Horas Mesin USU and Ford-Fiesta are 0.03192202 and 0.09485621, respectively. This fact suggests that Ford-Fiesta has a better aerodynamic performance in comparison with Horas Mesin USU. The flow field analysis shows that there are many modifications can be proposed to improve the aerodynamic performance of the Horas Mesin USU. It is suggested to perform further analysis to improve the aerodynamic performance of Horas Mesin USU.

Analytical Aerodynamic Simulation Tools for Vertical Axis Wind Turbines

International Nuclear Information System (INIS)

Deglaire, Paul

2010-01-01

Wind power is a renewable energy source that is today the fastest growing solution to reduce CO 2 emissions in the electric energy mix. Upwind horizontal axis wind turbine with three blades has been the preferred technical choice for more than two decades. This horizontal axis concept is today widely leading the market. The current PhD thesis will cover an alternative type of wind turbine with straight blades and rotating along the vertical axis. A brief overview of the main differences between the horizontal and vertical axis concept has been made. However the main focus of this thesis is the aerodynamics of the wind turbine blades. Making aerodynamically efficient turbines starts with efficient blades. Making efficient blades requires a good understanding of the physical phenomena and effective simulations tools to model them. The specific aerodynamics for straight bladed vertical axis turbine flow are reviewed together with the standard aerodynamic simulations tools that have been used in the past by blade and rotor designer. A reasonably fast (regarding computer power) and accurate (regarding comparison with experimental results) simulation method was still lacking in the field prior to the current work. This thesis aims at designing such a method. Analytical methods can be used to model complex flow if the geometry is simple. Therefore, a conformal mapping method is derived to transform any set of section into a set of standard circles. Then analytical procedures are generalized to simulate moving multibody sections in the complex vertical flows and forces experienced by the blades. Finally the fast semi analytical aerodynamic algorithm boosted by fast multipole methods to handle high number of vortices is coupled with a simple structural model of the rotor to investigate potential aeroelastic instabilities. Together with these advanced simulation tools, a standard double multiple streamtube model has been developed and used to design several straight bladed

TO THE DEVELOPMENT OF AERODYNAMIC SHAPE OF MEDIUM SIZED PERSPECTIVE HELICOPTER FUSELAGE

Directory of Open Access Journals (Sweden)

2016-01-01

Full Text Available This paper presents the initial stage of work out of the helicopter body aerodynamic configuration. The main pur- pose of this work is to design the model of the fuselage and to minimize its drag.The analysis of experimental data obtained in TsAGI and other research centers was made at the first stage of the work. All features of flow around parts of the fuselage obtained from experimental data were taken into account. The de- pendencies of the fuselage component drag, such as the bow, fairings exhaust pipes of helicopter, sponsons, and tail sectionof the fuselage, on their form are described in this article.At the second stage the fuselage geometry was created in program SolidWorks. All the features of the flow around various fuselage components derived from the experimental data were considered in designing.The third stage is calculating of fuselage model aerodynamic characteristics. The calculations were made in the program ANSYS CFX (TsAGI License №501024. Boundary conditions were chosen so as to correspond to normal at- mospheric conditions at 1,000 meters with velocity of flight is V = 85 m/s. The output of the hot jet from engines is takinginto account in computation. The purpose of this calculation is to find the optimal angle of the engine exhaust pipe whenthe hot spray does not intersect with the tail and stabilizer and creates the maximum of propulsive force. The volume of the grid in computational domain is approximately 13 million cells.Data analysis has shown that the fuselage has a 20% less drag at cruising flight (аf = -4 ° compared to the original model. The hot jets do not intersect with the tail and stabilizers at cruising flight so the fuselage is protected from overheating.

PRINCIPLE "EARLY MATCHING" AERODYNAMIC DESIGN AIRCRAFT WITH LANDING GEAR HOVERCRAFT

Directory of Open Access Journals (Sweden)

V. P. Morozov

2015-01-01

Full Text Available The principle of "early matching" aircraft aerohydrodynamic layouts with air cushion landing gear is suggested. Application of this principle is considered as an example of adaptation to the ball screw base circuit of light transport aircraft. The principle, other than weight, aerodynamic, technological and operational requirements includes additional project activities related to the installation of ball screws.

A Distributed Feature-based Environment for Collaborative Design

Directory of Open Access Journals (Sweden)

Wei-Dong Li

2003-02-01

Full Text Available This paper presents a client/server design environment based on 3D feature-based modelling and Java technologies to enable design information to be shared efficiently among members within a design team. In this environment, design tasks and clients are organised through working sessions generated and maintained by a collaborative server. The information from an individual design client during a design process is updated and broadcast to other clients in the same session through an event-driven and call-back mechanism. The downstream manufacturing analysis modules can be wrapped as agents and plugged into the open environment to support the design activities. At the server side, a feature-feature relationship is established and maintained to filter the varied information of a working part, so as to facilitate efficient information update during the design process.

Optimal Spacecraft Attitude Control Using Aerodynamic Torques

Science.gov (United States)

2007-03-01

His design resembles a badminton shuttlecock and “uses passive aerodynamic drag torques to stabilize pitch and yaw” and active magnetic torque...Ravindran’s and Hughes’ ‘arrow-like’ design. Psiaki notes that “this arrow concept has been modified to become a badminton shuttlecock-type design...panels were placed to the rear of the center-of-mass, similar to a badminton shuttlecock, to provide passive stability about the pitch and yaw axes

Optimization of rotor blades for combined structural, dynamic, and aerodynamic properties

Science.gov (United States)

He, Cheng-Jian; Peters, David A.

1990-01-01

Optimal helicopter blade design with computer-based mathematical programming has received more and more attention in recent years. Most of the research has focused on optimum dynamic characteristics of rotor blades to reduce vehicle vibration. There is also work on optimization of aerodynamic performance and on composite structural design. This research has greatly increased our understanding of helicopter optimum design in each of these aspects. Helicopter design is an inherently multidisciplinary process involving strong interactions among various disciplines which can appropriately include aerodynamics; dynamics, both flight dynamics and structural dynamics; aeroelasticity: vibrations and stability; and even acoustics. Therefore, the helicopter design process must satisfy manifold requirements related to the aforementioned diverse disciplines. In our present work, we attempt to combine several of these important effects in a unified manner. First, we design a blade with optimum aerodynamic performance by proper layout of blade planform and spanwise twist. Second, the blade is designed to have natural frequencies that are placed away from integer multiples of the rotor speed for a good dynamic characteristics. Third, the structure is made as light as possible with sufficient rotational inertia to allow for autorotational landing, with safe stress margins and flight fatigue life at each cross-section, and with aeroelastical stability and low vibrations. Finally, a unified optimization refines the solution.

Analysis of Aerodynamic Load of LSU-03 (LAPAN Surveillance UAV-03) Propeller

Science.gov (United States)

Rahmadi Nuranto, Awang; Jamaludin Fitroh, Ahmad; Syamsudin, Hendri

2018-04-01

The existing propeller of the LSU-03 aircraft is made of wood. To improve structural strength and obtain better mechanical properties, the propeller will be redesigned usingcomposite materials. It is necessary to simulate and analyze the design load. This research paper explainsthe simulation and analysis of aerodynamic load prior to structural design phase of composite propeller. Aerodynamic load calculations are performed using both the Blade Element Theory(BET) and the Computational Fluid Dynamic (CFD)simulation. The result of both methods show a close agreement, the different thrust forces is only 1.2 and 4.1% for two type mesh. Thus the distribution of aerodynamic loads along the surface of the propeller blades of the 3-D CFD simulation results are considered valid and ready to design the composite structure. TheCFD results is directly imported to the structure model using the Direct Import CFD / One-Way Fluid Structure Interaction (FSI) method. Design load of propeller is chosen at the flight condition at speed of 20 km/h at 7000 rpm.

In-flight evaluation of aerodynamic predictions of an air-launched space booster

Science.gov (United States)

Curry, Robert E.; Mendenhall, Michael R.; Moulton, Bryan

1993-01-01

Several analytical aerodynamic design tools that were applied to the Pegasus air-launched space booster were evaluated using flight measurements. The study was limited to existing codes and was conducted with limited computational resources. The flight instrumentation was constrained to have minimal impact on the primary Pegasus missions. Where appropriate, the flight measurements were compared with computational data. Aerodynamic performance and trim data from the first two flights were correlated with predictions. Local measurements in the wing and wing-body interference region were correlated with analytical data. This complex flow region includes the effect of aerothermal heating magnification caused by the presence of a corner vortex and interaction of the wing leading edge shock and fuselage boundary layer. The operation of the first two missions indicates that the aerodynamic design approach for Pegasus was adequate, and data show that acceptable margins were available. Additionally, the correlations provide insight into the capabilities of these analytical tools for more complex vehicles in which design margins may be more stringent.

Atmospheric testing of wind turbine trailing edge aerodynamic brakes

Energy Technology Data Exchange (ETDEWEB)

Miller, L.S. [Wichita State Univ., KS (United States); Migliore, P.G. [National Renewable Energy Lab., Golden, CO (United States); Quandt, G.A.

1997-12-31

An experimental investigation was conducted using an instrumented horizontal-axis wind turbine that incorporated variable span trailing-edge aerodynamic brakes. A primary goal was to directly compare study results with (infinite-span) wind tunnel data and to provide information on how to account for device span effects during turbine design or analysis. Comprehensive measurements were utilized to define effective changes in the aerodynamic coefficients, as a function of angle of attack and control deflection, for three device spans and configurations. Differences in the lift and drag behavior are most pronounced near stall and for device spans of less than 15%. Drag performance is affected only minimally (<70%) for 15% or larger span devices. Interestingly, aerodynamic controls with characteristic vents or openings appear most affected by span reductions and three-dimensional flow.

Influence of unsteady aerodynamics on driving dynamics of passenger cars

Science.gov (United States)

Huemer, Jakob; Stickel, Thomas; Sagan, Erich; Schwarz, Martin; Wall, Wolfgang A.

2014-11-01

Recent approaches towards numerical investigations with computational fluid dynamics methods on unsteady aerodynamic loads of passenger cars identified major differences compared with steady-state aerodynamic excitations. Furthermore, innovative vehicle concepts such as electric-vehicles or hybrid drives further challenge the basic layout of passenger cars. Therefore, the relevance of unsteady aerodynamic loads on cross-wind stability of changing basic vehicle architectures should be analysed. In order to assure and improve handling and ride characteristics at high velocity of the actual range of vehicle layouts, the influence of unsteady excitations on the vehicle response was investigated. For this purpose, a simulation of the vehicle dynamics through multi-body simulation was used. The impact of certain unsteady aerodynamic load characteristics on the vehicle response was quantified and key factors were identified. Through a series of driving simulator tests, the identified differences in the vehicle response were evaluated regarding their significance on the subjective driver perception of cross-wind stability. Relevant criteria for the subjective driver assessment of the vehicle response were identified. As a consequence, a design method for the basic layout of passenger cars and chassis towards unsteady aerodynamic excitations was defined.

Aerodynamic and sound intensity measurements in tracheoesophageal voice

NARCIS (Netherlands)

Grolman, Wilko; Eerenstein, Simone E. J.; Tan, Frédérique M. L.; Tange, Rinze A.; Schouwenburg, Paul F.

2007-01-01

BACKGROUND: In laryngectomized patients, tracheoesophageal voice generally provides a better voice quality than esophageal voice. Understanding the aerodynamics of voice production in patients with a voice prosthesis is important for optimizing prosthetic designs and successful voice rehabilitation.

Development of design tools for reduced aerodynamic noise wind turbines (draw)

NARCIS (Netherlands)

Wagner, S.; Guidati, G.; Ostertag, J.; Bareiss, R.; Wittum, G.; Huurdeman, B.; Braun, K.; Hirsch, C.; Kang, S.; Khodak, A.; Overmeire, M. van; Bladt, G.; Nienhaus, A.; Dassen, A.G.M.; Parchen, R.R.; Looijmans, K.

1997-01-01

The major aim of the present project was the development of new predictïon models for the aerodynamic noise generation at wind turbine blades. These models should be transferred to computer codes and should be sensitive enough to consider even small changes in the airfoil geometry. This accuracy is

Concept definition and aerodynamic technology studies for single-engine V/STOL fighter/attack aircraft

Science.gov (United States)

Nelms, W. P.; Durston, D. A.

1981-01-01

The results obtained in the early stages of a research program to develop aerodynamic technology for single-engine V/STOL fighter/attack aircraft projected for the post-1990 period are summarized. This program includes industry studies jointly sponsored by NASA and the Navy. Four contractors have identified promising concepts featuring a variety of approaches for providing propulsive lift. Vertical takeoff gross weights range from about 10,000 to 13,600 kg (22,000 to 30,000 lb). The aircraft have supersonic capability, are highly maneuverable, and have significant short takeoff overload capability. The contractors have estimated the aerodynamics and identified aerodynamic uncertainties associated with their concepts. Wind-tunnel research programs will be formulated to investigate these uncertainties. A description of the concepts is emphasized.

A Hybrid Metaheuristic-Based Approach for the Aerodynamic Optimization of Small Hybrid Wind Turbine Rotors

Directory of Open Access Journals (Sweden)

José F. Herbert-Acero

2014-01-01

Full Text Available This work presents a novel framework for the aerodynamic design and optimization of blades for small horizontal axis wind turbines (WT. The framework is based on a state-of-the-art blade element momentum model, which is complemented with the XFOIL 6.96 software in order to provide an estimate of the sectional blade aerodynamics. The framework considers an innovative nested-hybrid solution procedure based on two metaheuristics, the virtual gene genetic algorithm and the simulated annealing algorithm, to provide a near-optimal solution to the problem. The objective of the study is to maximize the aerodynamic efficiency of small WT (SWT rotors for a wide range of operational conditions. The design variables are (1 the airfoil shape at the different blade span positions and the radial variation of the geometrical variables of (2 chord length, (3 twist angle, and (4 thickness along the blade span. A wind tunnel validation study of optimized rotors based on the NACA 4-digit airfoil series is presented. Based on the experimental data, improvements in terms of the aerodynamic efficiency, the cut-in wind speed, and the amount of material used during the manufacturing process were achieved. Recommendations for the aerodynamic design of SWT rotors are provided based on field experience.

Mechanical Design Features of PGSFR NSSS

International Nuclear Information System (INIS)

Park, Chang-Gyu; Koo, Gyeong-Hoi; Cho, Jae-Hun; Kim, Sung-Kyun

2016-01-01

The NSSS(Nuclear Steam Supply System) is composed of PHTS(Primary Heat Transport System), IHTS (Intermediate Heat Transport System), and SGS(Steam Generation System). And, DHRS(Decay Heat Removal System) adopts both the active and passive systems for diversity. The structures including components and piping should be designed to ensure the structural integrity for their design life against mechanical and operational loads. In this study, the mechanical design features for the structures and components that make up PGSFR NSSS are described. The mechanical design features of structures and components for a PGSFR NSSS are described. The structures are being designed to maintain the structural integrity for their design lifetime by considering the high temperature operating condition. The decay heat removal system(DHRS) removes all reactor decay heat in two ways; active type(ADHRS) and passive type(PDHRS). ADHRS consists of DHX, blower, FHX, circulation pump, and expansion tank. But PDHRS consists of DHX, AHX, and expansion tank. FHX is a finned-tube-type sodium-to-air heat exchanger whereas AHX is a helical-type sodium-to-air heat exchanger

Mechanical Design Features of PGSFR NSSS

Energy Technology Data Exchange (ETDEWEB)

Park, Chang-Gyu; Koo, Gyeong-Hoi; Cho, Jae-Hun; Kim, Sung-Kyun [KAERI, Daejeon (Korea, Republic of)

2016-05-15

The NSSS(Nuclear Steam Supply System) is composed of PHTS(Primary Heat Transport System), IHTS (Intermediate Heat Transport System), and SGS(Steam Generation System). And, DHRS(Decay Heat Removal System) adopts both the active and passive systems for diversity. The structures including components and piping should be designed to ensure the structural integrity for their design life against mechanical and operational loads. In this study, the mechanical design features for the structures and components that make up PGSFR NSSS are described. The mechanical design features of structures and components for a PGSFR NSSS are described. The structures are being designed to maintain the structural integrity for their design lifetime by considering the high temperature operating condition. The decay heat removal system(DHRS) removes all reactor decay heat in two ways; active type(ADHRS) and passive type(PDHRS). ADHRS consists of DHX, blower, FHX, circulation pump, and expansion tank. But PDHRS consists of DHX, AHX, and expansion tank. FHX is a finned-tube-type sodium-to-air heat exchanger whereas AHX is a helical-type sodium-to-air heat exchanger.

Aerodynamics profile not in stationary flow

Directory of Open Access Journals (Sweden)

А.А. Загорулько

2006-02-01

Full Text Available  Consider the question about influence of unsteady flight on the size of drag and lift coefficients of theaerodynamic profile. Distinctive features of this investigation are obtaining data about aerodynamic drag chancing in process unsteady on high angle at attack and oscillation profile in subsonic and transonic flight. Given analysis of oscillation profile show, that dynamic loops accompany change of lift and dray force. The researches show that it is necessary to clarity the mathematic model of the airplane flight dynamics by introducing numbers, with take into account unsteady effects.

Aerodynamic resistance reduction of electric and hybrid vehicles

Science.gov (United States)

1979-01-01

The generation of an EHV aerodynamic data base was initiated by conducting full-scale wind tunnel tests on 16 vehicles. Zero-yaw drag coefficients ranged from a high of 0.58 for a boxey delivery van and an open roadster to a low of about 0.34 for a current 4-passenger prototype automobile which was designed with aerodynamics as an integrated parameter. Characteristic effects of aspect ratio or fineness ratio which might appear if electric vehicle shape proportions were to vary significantly from current automobiles were identified. Some preliminary results indicate a 5 to 10% variation in drag over the range of interest. Effective drag coefficient wind-weighting factors over J227a driving cycles in the presence of annual mean wind fields were identified. Such coefficients, when properly weighted, were found to be from 5 to 65% greater than the zero-yaw drag coefficient in the cases presented. A vehicle aerodynamics bibliography of over 160 entries, in six general categories is included.

A Comparative Assessment of Aerodynamic Models for Buffeting and Flutter of Long-Span Bridges

Directory of Open Access Journals (Sweden)

Igor Kavrakov

2017-12-01

Full Text Available Wind-induced vibrations commonly represent the leading criterion in the design of long-span bridges. The aerodynamic forces in bridge aerodynamics are mainly based on the quasi-steady and linear unsteady theory. This paper aims to investigate different formulations of self-excited and buffeting forces in the time domain by comparing the dynamic response of a multi-span cable-stayed bridge during the critical erection condition. The bridge is selected to represent a typical reference object with a bluff concrete box girder for large river crossings. The models are viewed from a perspective of model complexity, comparing the influence of the aerodynamic properties implied in the aerodynamic models, such as aerodynamic damping and stiffness, fluid memory in the buffeting and self-excited forces, aerodynamic nonlinearity, and aerodynamic coupling on the bridge response. The selected models are studied for a wind-speed range that is typical for the construction stage for two levels of turbulence intensity. Furthermore, a simplified method for the computation of buffeting forces including the aerodynamic admittance is presented, in which rational approximation is avoided. The critical flutter velocities are also compared for the selected models under laminar flow. Keywords: Buffeting, Flutter, Long-span bridges, Bridge aerodynamics, Bridge aeroelasticity, Erection stage

Progresses in application of computational ?uid dynamic methods to large scale wind turbine aerodynamics?

Institute of Scientific and Technical Information of China (English)

Zhenyu ZHANG; Ning ZHAO; Wei ZHONG; Long WANG; Bofeng XU

2016-01-01

The computational ?uid dynamics (CFD) methods are applied to aerody-namic problems for large scale wind turbines. The progresses including the aerodynamic analyses of wind turbine pro?les, numerical ?ow simulation of wind turbine blades, evalu-ation of aerodynamic performance, and multi-objective blade optimization are discussed. Based on the CFD methods, signi?cant improvements are obtained to predict two/three-dimensional aerodynamic characteristics of wind turbine airfoils and blades, and the vorti-cal structure in their wake ?ows is accurately captured. Combining with a multi-objective genetic algorithm, a 1.5 MW NH-1500 optimized blade is designed with high e?ciency in wind energy conversion.

Energy Harvesting from Aerodynamic Instabilities: Current prospect and Future Trends

Science.gov (United States)

Bashir, M.; Rajendran, P.; Khan, S. A.

2018-01-01

This paper evaluates the layout and advancement of energy harvesting based on aerodynamic instabilities of an aircraft. Vibration and thermoelectric energy harvesters are substantiated as most suitable alternative low-power sources for aerospace applications. Furthermore, the facility associated with the aircraft applications in harvesting the mechanical vibrations and converting it to electric energy has fascinated the researchers. These devices are designed as an alternative to a battery-based solution especially for small aircrafts, wireless structural health monitoring for aircraft systems, and harvester plates employed in UAVs to enhance the endurance and operational flight missions. We will emphasize on various sources of energy harvesting that are designed to come from aerodynamic flow-induced vibrations, specific attention is then given at those technologies that may offer, today or in the near future, a potential benefit to reduce both the cost and emissions of the aviation industry. The advancements achieved in the energy harvesting based on aerodynamic instabilities show very good scope for many piezoelectric harvesters in the field of aerospace, specifically green aviation technology in the future.

The effect of variations in first- and second-order derivatives on airfoil aerodynamic performance

Directory of Open Access Journals (Sweden)

Penghui Yi

2017-01-01

Full Text Available The geometric factors which influence airfoil aerodynamic performance are attributed to variations in local first- and second-order curvature derivatives. Based on a self-developed computational fluid dynamics (CFD program called UCFD, the influence of local profile variations on airfoil aerodynamic performance in different pressure areas is investigated. The results show that variations in first- and second-order derivatives of the airfoil profiles can cause fluctuations in airfoil aerodynamic performance. The greater the variation in local first- and second-order derivatives, the greater the fluctuation amplitude of the airfoil aerodynamic coefficients. Moreover, at the area near the leading edge and the shock-wave position, the surface pressure is more sensitive to changes in first- and second-order derivatives. These results provide a reference for airfoil aerodynamic shape design.

Improved design features of KSNP+ BOP Fluid System

International Nuclear Information System (INIS)

Park, Heung Gyu; Yoon, Kyung Sup

2002-01-01

KOPEC (Korea Power Engineering Co.) in conjunction with the client KHNP (Korea Hydro and Nuclear Power Co.) has been developing the KSNP + (Improved Korean Standard Nuclear Power Plants) design concept since 1998. The main objective of the KSNP + is to enhance safety and economy of KSNP. The design concepts of the KSNP + will be implemented in Shin-Kori Units 1 and 2 Shin-Wolsung Units 1 and 2. This paper provides on an introduction to the improved design features of the KSNP + BOP fluid system consisting of 45 design improvement items. The design improvement concepts of the BOP fluid system have been developed as follows: optimization of system configuration and capacity, simplification of system, and adoption of advanced design features. Improved design features of the BOP fluid system allow additional benefits due to making a contribution to the optimization of plant arrangement and the reduction of operating costs during the plant life time. In conclusion, design improvement to the BOP fluid system have contributed to the KSNP + design concept being more reliable, safe and economically competitive

Compressor performance aerodynamics for the user

CERN Document Server

Gresh, Theodore

2001-01-01

Compressor Performance is a reference book and CD-ROM for compressor design engineers and compressor maintenance engineers, as well as engineering students. The book covers the full spectrum of information needed for an individual to select, operate, test and maintain axial or centrifugal compressors. It includes basic aerodynamic theory to provide the user with the ""how's"" and ""why's"" of compressor design. Maintenance engineers will especially appreciate the troubleshooting guidelines offered. Includes many example problems and reference data such as gas propert

Aerodynamic Noise An Introduction for Physicists and Engineers

CERN Document Server

Bose, Tarit

2013-01-01

Aerodynamic Noise extensively covers the theoretical basis and mathematical modeling of sound, especially the undesirable sounds produced by aircraft. This noise could come from an aircraft’s engine—propellers, fans, combustion chamber, jets—or the vehicle itself—external surfaces—or from sonic booms. The majority of the sound produced is due to the motion of air and its interaction with solid boundaries, and this is the main discussion of the book. With problem sets at the end of each chapter, Aerodynamic Noise is ideal for graduate students of mechanical and aerospace engineering. It may also be useful for designers of cars, trains, and wind turbines.

Transient response of two lobe aerodynamic journal bearing

Directory of Open Access Journals (Sweden)

Saurabh Kumar Yadav

2018-03-01

Full Text Available The dynamic behavior of a rotor-dynamic system is greatly affected by the performance of aerodynamic bearing and the performance of bearing is characterized by the stiffness and damping coefficients. In the present work, stiffness and damping coefficients of bearing are computed and the performance of the bearing is greatly changed with the change in bearing air film profile. The effect of lobe offset factors on the transient performance of aerodynamic bearing is presented. Bifurcation and Poincare diagrams of two lobe journal bearing have been presented for different offset factors. A bearing designer can judge the bearing performance based on bifurcation diagrams.

Dynamic stability of an aerodynamically efficient motorcycle

Science.gov (United States)

Sharma, Amrit; Limebeer, David J. N.

2012-08-01

Motorcycles exhibit two potentially dangerous oscillatory modes known as 'wobble' and 'weave'. The former is reminiscent of supermarket castor shimmy, while the latter is a low frequency 'fish-tailing' motion that involves a combination of rolling, yawing, steering and side-slipping motions. These unwanted dynamic features, which can occur when two-wheeled vehicles are operated at speed, have been studied extensively. The aim of this paper is to use mathematical analysis to identify important stability trends in the on-going design of a novel aerodynamically efficient motorcycle known as the ECOSSE Spirit ES1. A mathematical model of the ES1 is developed using a multi-body dynamics software package called VehicleSim [Anon, VehicleSim Lisp Reference Manual Version 1.0, Mechanical Simulation Corporation, 2008. Available at http://www.carsim.com]. This high-fidelity motorcycle model includes realistic tyre-road contact geometry, a comprehensive tyre model, tyre relaxation and a flexible frame. A parameter set representative of a modern high-performance machine and rider is used. Local stability is investigated via the eigenvalues of the linearised models that are associated with equilibrium points of interest. A comprehensive study of the effects of frame flexibilities, acceleration, aerodynamics and tyre variations is presented, and an optimal passive steering compensator is derived. It is shown that the traditional steering damper cannot be used to stabilise the ES1 over its entire operating speed range. A simple passive compensator, involving an inerter is proposed. Flexibility can be introduced deliberately into various chassis components to change the stability characteristics of the vehicle; the implications of this idea are studied.

Winglet and long duct nacelle aerodynamic development for DC-10 derivatives

Science.gov (United States)

Taylor, A. B.

1978-01-01

Advanced technology for application to the Douglas DC-10 transport is discussed. Results of wind tunnel tests indicate that the winglet offers substantial cruise drag reduction with less wing root bending moment penalty than a wing-tip extension of the same effectiveness and that the long duct nacelle offers substantial drag reduction potential as a result of aerodynamic and propulsion improvements. The aerodynamic design and test of the nacelle and pylon installation are described.

Aerodynamic Limits on Large Civil Tiltrotor Sizing and Efficiency

Science.gov (United States)

Acree, C W.

2014-01-01

The NASA Large Civil Tiltrotor (2nd generation, or LCTR2) is a useful reference design for technology impact studies. The present paper takes a broad view of technology assessment by examining the extremes of what aerodynamic improvements might hope to accomplish. Performance was analyzed with aerodynamically idealized rotor, wing, and airframe, representing the physical limits of a large tiltrotor. The analysis was repeated with more realistic assumptions, which revealed that increased maximum rotor lift capability is potentially more effective in improving overall vehicle efficiency than higher rotor or wing efficiency. To balance these purely theoretical studies, some practical limitations on airframe layout are also discussed, along with their implications for wing design. Performance of a less efficient but more practical aircraft with non-tilting nacelles is presented.

Improved blade element momentum theory for wind turbine aerodynamic computations

DEFF Research Database (Denmark)

Sun, Zhenye; Chen, Jin; Shen, Wen Zhong

2016-01-01

Blade element momentum (BEM) theory is widely used in aerodynamic performance predictions and design applications for wind turbines. However, the classic BEM method is not quite accurate which often tends to under-predict the aerodynamic forces near root and over-predict its performance near tip....... for the MEXICO rotor. Results show that the improved BEM theory gives a better prediction than the classic BEM method, especially in the blade tip region, when comparing to the MEXICO measurements. (C) 2016 Elsevier Ltd. All rights reserved....

Aerodynamics of bridge hangers in smooth and turbulent flow and implications on aeroelastic stability

DEFF Research Database (Denmark)

Demartino, Cristoforo; Ricciardelli, Francesco; Georgakis, Christos T.

2015-01-01

The aerodynamics of circular cylinders featuring geometric imperfections, such as bridge cables, has received much attention in recent years due to the recognition that such imperfections can be the cause of large amplitude vibrations. Bridge cables are usually made of strands or wires protected......, of mechanical damage occurring during transport and installation, as well as of the ageing process due to the exposure to environmental factors. Few experimental works are already available dealing with the effects of imperfections on the aerodynamics of bridge cables. For example, Matteoni and Georgakis...

Main physics features driving design concept and physics design constraints

International Nuclear Information System (INIS)

Fujisawa, Noboru; Sugihara, Masayoshi; Yamamoto, Shin

1987-07-01

Major physics design philosophies are described, which are essential bases for a plasma design and may have significant impacts on a reactor design concept. Those design philosophies are classified into two groups, physics design drivers and physics design constraints. The design drivers are featured by the fact that a designer is free to choose and the choice may be guided by his opinion, such as ignition, a pulse length, an operation scenario, etc.. The design constraints may follow a physical law, such as plasma confinement, β-limit, density limit, and so on. (author)

Ground effect aerodynamics of racing cars

OpenAIRE

Zhang, Xin; Toet, Willem; Zerihan, Jonathan

2006-01-01

We review the progress made during the last thirty years on ground effect aerodynamics associated with race cars, in particular open wheel race cars. Ground effect aerodynamics of race cars is concerned with generating downforce, principally via low pressure on the surfaces nearest to the ground. The “ground effected” parts of an open wheeled car's aerodynamics are the most aerodynamically efficient and contribute less drag than that associated with, for example, an upper rear wing. Whilst dr...

Aerodynamic interaction effects of tip-mounted propellers installed on the horizontal tailplane

NARCIS (Netherlands)

van Arnhem, N.; Sinnige, T.; Stokkermans, T.C.A.; Eitelberg, G.; Veldhuis, L.L.M.

2018-01-01

This paper addresses the effects of propeller installation on the aerodynamic performance of a tailplane featuring tip-mounted propellers. A model of a low aspect ratio tailplane equipped with an elevator and a tip-mounted propeller was installed in a low-speed wind-tunnel. Measurements were

Safety design features of the IRIS

International Nuclear Information System (INIS)

2009-01-01

The International Reactor Innovative and Secure (IRIS) is an advanced, integral, light water cooled reactor of medium generating capacity (335 MW(e)), that features an integral reactor vessel containing all the reactor primary system components, including steam generators, coolant pumps, pressurizer and heaters, and control rod drive mechanisms; in addition to the typical core, internals, control rods and neutron reflector. This integral configuration allows for the use of a small, high design pressure, spherical steel containment which results in a significant reduction in the size of the nuclear island. Other IRIS innovations include a simplified passive safety system concept and equipment features that derive from the 'safety-by-design' philosophy. This design approach allows for elimination of certain accident initiators at the design stage, or when outright elimination is not possible, decreases accident consequences and/or their probability of occurrence. Major design characteristics of the IRIS are given. As part of the IRIS pre-application licensing review by the U.S. Nuclear Regulatory Commission (NRC), the IRIS design team has developed a test plan that will provide the necessary data for safety analysis computer model verification, as well as for verifying the manufacturing feasibility, operability, and durability of new component designs

Unsteady aerodynamic modeling at high angles of attack using support vector machines

Directory of Open Access Journals (Sweden)

Wang Qing

2015-06-01

Full Text Available Accurate aerodynamic models are the basis of flight simulation and control law design. Mathematically modeling unsteady aerodynamics at high angles of attack bears great difficulties in model structure determination and parameter estimation due to little understanding of the flow mechanism. Support vector machines (SVMs based on statistical learning theory provide a novel tool for nonlinear system modeling. The work presented here examines the feasibility of applying SVMs to high angle-of-attack unsteady aerodynamic modeling field. Mainly, after a review of SVMs, several issues associated with unsteady aerodynamic modeling by use of SVMs are discussed in detail, such as selection of input variables, selection of output variables and determination of SVM parameters. The least squares SVM (LS-SVM models are set up from certain dynamic wind tunnel test data of a delta wing and an aircraft configuration, and then used to predict the aerodynamic responses in other tests. The predictions are in good agreement with the test data, which indicates the satisfying learning and generalization performance of LS-SVMs.

Aerodynamic Noise Generated by Shinkansen Cars

Science.gov (United States)

KITAGAWA, T.; NAGAKURA, K.

2000-03-01

The noise value (A -weighted sound pressure level, SLOW) generated by Shinkansen trains, now running at 220-300 km/h, should be less than 75 dB(A) at the trackside. Shinkansen noise, such as rolling noise, concrete support structure noise, and aerodynamic noise are generated by various parts of Shinkansen trains. Among these aerodynamic noise is important because it is the major contribution to the noise generated by the coaches running at high speed. In order to reduce the aerodynamic noise, a number of improvements to coaches have been made. As a result, the aerodynamic noise has been reduced, but it still remains significant. In addition, some aerodynamic noise generated from the lower parts of cars remains. In order to investigate the contributions of these noises, a method of analyzing Shinkansen noise has been developed and applied to the measured data of Shinkansen noise at speeds between 120 and 315 km/h. As a result, the following conclusions have been drawn: (1) Aerodynamic noise generated from the upper parts of cars was reduced considerably by smoothing car surfaces. (2) Aerodynamic noise generated from the lower parts of cars has a major influence upon the wayside noise.

Experimental and analytical research on the aerodynamics of wind driven turbines. Final report

Energy Technology Data Exchange (ETDEWEB)

Rohrbach, C.; Wainauski, H.; Worobel, R.

1977-12-01

The successful development of reliable, cost competitive horizontal axis, propeller-type wind energy conversion systems (WECS) is strongly dependent on the availability of advanced technology for each of the system components. This aerodynamic research program was aimed at providing a reliable, comprehensive data base on a series of wind turbine models covering a broad range of the prime aerodynamic and geometric variables. Such data obtained under controlled laboratory conditions on turbines designed by the same method, of the same size, and tested in the same wind tunnel had not been available in the literature. Moreover, this research program was further aimed at providing a basis for evaluating the adequacy of existing wind turbine aerodynamic design and performance methodology, for assessing the potential of recent advanced theories and for providing a basis for further method development and refinement.

Structural dynamics and aerodynamics measurements of biologically inspired flexible flapping wings

International Nuclear Information System (INIS)

Wu, P; Stanford, B K; Ifju, P G; Saellstroem, E; Ukeiley, L

2011-01-01

Flapping wing flight as seen in hummingbirds and insects poses an interesting unsteady aerodynamic problem: coupling of wing kinematics, structural dynamics and aerodynamics. There have been numerous studies on the kinematics and aerodynamics in both experimental and computational cases with both natural and artificial wings. These studies tend to ignore wing flexibility; however, observation in nature affirms that passive wing deformation is predominant and may be crucial to the aerodynamic performance. This paper presents a multidisciplinary experimental endeavor in correlating a flapping micro air vehicle wing's aeroelasticity and thrust production, by quantifying and comparing overall thrust, structural deformation and airflow of six pairs of hummingbird-shaped membrane wings of different properties. The results show that for a specific spatial distribution of flexibility, there is an effective frequency range in thrust production. The wing deformation at the thrust-productive frequencies indicates the importance of flexibility: both bending and twisting motion can interact with aerodynamic loads to enhance wing performance under certain conditions, such as the deformation phase and amplitude. By measuring structural deformations under the same aerodynamic conditions, beneficial effects of passive wing deformation can be observed from the visualized airflow and averaged thrust. The measurements and their presentation enable observation and understanding of the required structural properties for a thrust effective flapping wing. The intended passive responses of the different wings follow a particular pattern in correlation to their aerodynamic performance. Consequently, both the experimental technique and data analysis method can lead to further studies to determine the design principles for micro air vehicle flapping wings.

Structural dynamics and aerodynamics measurements of biologically inspired flexible flapping wings

Energy Technology Data Exchange (ETDEWEB)

Wu, P; Stanford, B K; Ifju, P G [Department of Mechanical and Aerospace Engineering, MAE-A 231, University of Florida, Gainesville, FL 32611 (United States); Saellstroem, E; Ukeiley, L, E-mail: diccidwp@ufl.edu [Department of Mechanical and Aerospace Engineering, University of Florida, Shalimar, FL 32579 (United States)

2011-03-15

Flapping wing flight as seen in hummingbirds and insects poses an interesting unsteady aerodynamic problem: coupling of wing kinematics, structural dynamics and aerodynamics. There have been numerous studies on the kinematics and aerodynamics in both experimental and computational cases with both natural and artificial wings. These studies tend to ignore wing flexibility; however, observation in nature affirms that passive wing deformation is predominant and may be crucial to the aerodynamic performance. This paper presents a multidisciplinary experimental endeavor in correlating a flapping micro air vehicle wing's aeroelasticity and thrust production, by quantifying and comparing overall thrust, structural deformation and airflow of six pairs of hummingbird-shaped membrane wings of different properties. The results show that for a specific spatial distribution of flexibility, there is an effective frequency range in thrust production. The wing deformation at the thrust-productive frequencies indicates the importance of flexibility: both bending and twisting motion can interact with aerodynamic loads to enhance wing performance under certain conditions, such as the deformation phase and amplitude. By measuring structural deformations under the same aerodynamic conditions, beneficial effects of passive wing deformation can be observed from the visualized airflow and averaged thrust. The measurements and their presentation enable observation and understanding of the required structural properties for a thrust effective flapping wing. The intended passive responses of the different wings follow a particular pattern in correlation to their aerodynamic performance. Consequently, both the experimental technique and data analysis method can lead to further studies to determine the design principles for micro air vehicle flapping wings.

Unsteady Aerodynamics Experiment Phases II-IV Test Configurations and Available Data Campaigns

Energy Technology Data Exchange (ETDEWEB)

Simms, D. A.; Hand, M. M.; Fingersh, L. J.; Jager, D. W.

1999-08-19

The main objective of the Unsteady Aerodynamics Experiment is to provide information needed to quantify the full-scale three-dimensional aerodynamic behavior of horizontal axis wind turbines. To accomplish this, an experimental wind turbine configured to meet specific research objectives was assembled and operated at the National Renewable Energy Laboratory (NREL). The turbine was instrumented to characterize rotating blade aerodynamic performance, machine structural responses, and atmospheric inflow conditions. Comprehensive tests were conducted with the turbine operating in an outdoor field environment under diverse conditions. Resulting data are used to validate aerodynamic and structural dynamics models which are an important part of wind turbine design and engineering codes. Improvements in these models are needed to better characterize aerodynamic response in both the steady-state post-stall and dynamic stall regimes. Much of the effort in the earlier phase of the Unsteady Aerodynamics Experiment focused on developing required data acquisition systems. Complex instrumentation and equipment was needed to meet stringent data requirements while operating under the harsh environmental conditions of a wind turbine rotor. Once the data systems were developed, subsequent phases of experiments were then conducted to collect data for use in answering specific research questions. A description of the experiment configuration used during Phases II-IV of the experiment is contained in this report.

Unsteady Aerodynamics Experiment Phase V: Test Configuration and Available Data Campaigns; TOPICAL

International Nuclear Information System (INIS)

Hand, M. M.; Simms, D. A.; Fingersh, L. J.; Jager, D. W.; Cotrell, J. R.

2001-01-01

The main objective of the Unsteady Aerodynamics Experiment is to provide information needed to quantify the full-scale, three-dimensional, unsteady aerodynamic behavior of horizontal-axis wind turbines (HAWTs). To accomplish this, an experimental wind turbine configured to meet specific research objectives was assembled and operated at the National Renewable Energy Laboratory (NREL). The turbine was instrumented to characterize rotating-blade aerodynamic performance, machine structural responses, and atmospheric inflow conditions. Comprehensive tests were conducted with the turbine operating in an outdoor field environment under diverse conditions. Resulting data are used to validate aerodynamic and structural dynamics models, which are an important part of wind turbine design and engineering codes. Improvements in these models are needed to better characterize aerodynamic response in both the steady-state post-stall and dynamic-stall regimes. Much of the effort in the first phase of the Unsteady Aerodynamics Experiment focused on developing required data acquisition systems. Complex instrumentation and equipment was needed to meet stringent data requirements while operating under the harsh environmental conditions of a wind turbine rotor. Once the data systems were developed, subsequent phases of experiments were then conducted to collect data for use in answering specific research questions. A description of the experiment configuration used during Phase V of the experiment is contained in this report

Details of insect wing design and deformation enhance aerodynamic function and flight efficiency.

Science.gov (United States)

Young, John; Walker, Simon M; Bomphrey, Richard J; Taylor, Graham K; Thomas, Adrian L R

2009-09-18

Insect wings are complex structures that deform dramatically in flight. We analyzed the aerodynamic consequences of wing deformation in locusts using a three-dimensional computational fluid dynamics simulation based on detailed wing kinematics. We validated the simulation against smoke visualizations and digital particle image velocimetry on real locusts. We then used the validated model to explore the effects of wing topography and deformation, first by removing camber while keeping the same time-varying twist distribution, and second by removing camber and spanwise twist. The full-fidelity model achieved greater power economy than the uncambered model, which performed better than the untwisted model, showing that the details of insect wing topography and deformation are important aerodynamically. Such details are likely to be important in engineering applications of flapping flight.

Aerodynamic Simulation Analysis of Unmanned Airborne Electronic Bomb

Science.gov (United States)

Yang, Jiaoying; Guo, Yachao

2017-10-01

For microelectronic bombs for UAVs, on the basis of the use of rotors to lift the insurance on the basis of ammunition, increased tail to increase stability. The aerodynamic simulation of the outer structure of the ammunition was carried out by FLUENT software. The resistance coefficient, the lift coefficient and the pitch moment coefficient under different angle of attack and Mach number were obtained, and the aerodynamic characteristics of the electronic bomb were studied. The pressure line diagram and the velocity line diagram of the flow around the bomb are further analyzed, and the rationality of the external structure is verified, which provides a reference for the subsequent design of the electronic bomb.

Main engineering features driving design concept and engineering design constraints

International Nuclear Information System (INIS)

Saito, Ryusei; Kobayashi, Takeshi; Yamada, Masao

1987-09-01

Major engineering design philosophies are described, which are essential bases for an engineering design and may have significant impacts on a reactor design concept. Those design philosophies are classified into two groups, engineering design drivers and engineering design constraints. The design drivers are featured by the fact that a designer is free to choose and the choice may be guided by his opinion, such as coil system, a mechanical configuration, a tritium breeding scenario, etc.. The design constraints may follow a natural law or engineering limit, such as material strength, coil current density, and so on. (author)

Study on fundamental features of helium turbomachine for high temperature gas-cooled reactor

International Nuclear Information System (INIS)

Wang Jie; Gu Yihua

2004-01-01

The High temperature gas-cooled reactor (HTGR) coupled with helium turbine cycle is considered as one of the leading candidates for future nuclear power plants. The HTGR helium turbine cycle was analyzed and optimized. Then the focal point of investigation was concentrated on the fundamental thermodynamic and aerodynamic features of helium turbomachine. As a result, a helium turbomachine is different from a general combustion gas turbine in two main design features, that is a helium turbomachine has more blade stages and shorter blade length, which are caused by the helium property and the high pressure of a closed cycle, respectively. (authors)

Shape optimization for aerodynamic efficiency and low observability

Science.gov (United States)

Vinh, Hoang; Van Dam, C. P.; Dwyer, Harry A.

1993-01-01

Field methods based on the finite-difference approximations of the time-domain Maxwell's equations and the potential-flow equation have been developed to solve the multidisciplinary problem of airfoil shaping for aerodynamic efficiency and low radar cross section (RCS). A parametric study and an optimization study employing the two analysis methods are presented to illustrate their combined capabilities. The parametric study shows that for frontal radar illumination, the RCS of an airfoil is independent of the chordwise location of maximum thickness but depends strongly on the maximum thickness, leading-edge radius, and leadingedge shape. In addition, this study shows that the RCS of an airfoil can be reduced without significant effects on its transonic aerodynamic efficiency by reducing the leading-edge radius and/or modifying the shape of the leading edge. The optimization study involves the minimization of wave drag for a non-lifting, symmetrical airfoil with constraints on the airfoil maximum thickness and monostatic RCS. This optimization study shows that the two analysis methods can be used effectively to design aerodynamically efficient airfoils with certain desired RCS characteristics.

Fault-tolerant control with mixed aerodynamic surfaces and RCS jets for hypersonic reentry vehicles

Directory of Open Access Journals (Sweden)

Jingjing He

2017-04-01

Full Text Available This paper proposes a fault-tolerant strategy for hypersonic reentry vehicles with mixed aerodynamic surfaces and reaction control systems (RCS under external disturbances and subject to actuator faults. Aerodynamic surfaces are treated as the primary actuator in normal situations, and they are driven by a continuous quadratic programming (QP allocator to generate torque commanded by a nonlinear adaptive feedback control law. When aerodynamic surfaces encounter faults, they may not be able to provide sufficient torque as commanded, and RCS jets are activated to augment the aerodynamic surfaces to compensate for insufficient torque. Partial loss of effectiveness and stuck faults are considered in this paper, and observers are designed to detect and identify the faults. Based on the fault identification results, an RCS control allocator using integer linear programming (ILP techniques is designed to determine the optimal combination of activated RCS jets. By treating the RCS control allocator as a quantization element, closed-loop stability with both continuous and quantized inputs is analyzed. Simulation results verify the effectiveness of the proposed method.

Numerical aerodynamic simulation (NAS)

International Nuclear Information System (INIS)

Peterson, V.L.; Ballhaus, W.F. Jr.; Bailey, F.R.

1984-01-01

The Numerical Aerodynamic Simulation (NAS) Program is designed to provide a leading-edge computational capability to the aerospace community. It was recognized early in the program that, in addition to more advanced computers, the entire computational process ranging from problem formulation to publication of results needed to be improved to realize the full impact of computational aerodynamics. Therefore, the NAS Program has been structured to focus on the development of a complete system that can be upgraded periodically with minimum impact on the user and on the inventory of applications software. The implementation phase of the program is now under way. It is based upon nearly 8 yr of study and should culminate in an initial operational capability before 1986. The objective of this paper is fivefold: 1) to discuss the factors motivating the NAS program, 2) to provide a history of the activity, 3) to describe each of the elements of the processing-system network, 4) to outline the proposed allocation of time to users of the facility, and 5) to describe some of the candidate problems being considered for the first benchmark codes

Flight Test Maneuvers for Efficient Aerodynamic Modeling

Science.gov (United States)

Morelli, Eugene A.

2011-01-01

Novel flight test maneuvers for efficient aerodynamic modeling were developed and demonstrated in flight. Orthogonal optimized multi-sine inputs were applied to aircraft control surfaces to excite aircraft dynamic response in all six degrees of freedom simultaneously while keeping the aircraft close to chosen reference flight conditions. Each maneuver was designed for a specific modeling task that cannot be adequately or efficiently accomplished using conventional flight test maneuvers. All of the new maneuvers were first described and explained, then demonstrated on a subscale jet transport aircraft in flight. Real-time and post-flight modeling results obtained using equation-error parameter estimation in the frequency domain were used to show the effectiveness and efficiency of the new maneuvers, as well as the quality of the aerodynamic models that can be identified from the resultant flight data.

Project Analysis of Aerodynamics Configuration of Re-entry Сapsule-shaped Body Based on Numerical Methods for Newtonian Flow Theory

Directory of Open Access Journals (Sweden)

V. E. Minenko

2015-01-01

Full Text Available The article objective is to review the basic design parameters of space capsule (SC to select a rational shape at the early stages of design.The choice is based on the design parameters such as a volume filling factor (volumetric efficiency of shape, aerodynamic coefficients, margin of stability, and centering characteristics.The aerodynamic coefficients are calculated by a numerical method based on approximate Newton's theory. A proposed engineering technique uses this theory to calculate aerodynamic characteristics of the capsule shapes. The gist of the technique is in using a developed programme to generate capsule shapes and provide numerical calculation of aerodynamic characteristics. The accuracy of the calculation, performed according to proposed technique, tends to the results obtained by analytical integral dependencies according to the Newtonian technique.When considering the stability of the capsule shapes the paper gives a diagram of the aerodynamic forces acting on the SC in the descent phase, and using the aerodynamically-shaped SC "Soyuz" as an example analyses a dangerous moment of flow at adverse angles of attack.After determining a design center-of-mass position to meet the stability requirements it is necessary at the early stage, before starting the SC layout work, to evaluate the complexity of bringing the center-of-mass to the specified point. In this regard have been considered such design parameters of the shape as a volume-centering and surface-centering coefficients.Next, using the above engineering technique are calculated aerodynamic characteristics of capsule shapes similar to the well-known SC "Soyuz", "Zarya 2" and the command module "Apollo".All calculated design parameters are summarized in the table. Currently, among the works cited in foreign publications concerning the contours of winged configuration of the type "Space Shuttle" some papers are close to the proposed technique.Application of the proposed

Program for aerodynamic performance tests of helium gas compressor model of the gas turbine high temperature reactor (GTHTR300)

International Nuclear Information System (INIS)

Takada, Shoji; Takizuka, Takakazu; Kunimoto, Kazuhiko; Yan, Xing; Itaka, Hidehiko; Mori, Eiji

2003-01-01

Research and development program for helium gas compressor aerodynamics was planned for the power conversion system of the Gas Turbine High Temperature Reactor (GTHTR300). The axial compressor with polytropic efficiency of 90% and surge margin more than 30% was designed with 3-dimensional aerodynamic design. Performance and surge margin of the helium gas compressor tends to be lower due to the higher boss ratio which makes the tip clearance wide relative to the blade height, as well as due to a larger number of stages. The compressor was designed on the basis of methods and data for the aerodynamic design of industrial open-cycle gas-turbine. To validate the design of the helium gas compressor of the GTHTR300, aerodynamic performance tests were planned, and a 1/3-scale, 4-stage compressor model was designed. In the tests, the performance data of the helium gas compressor model will be acquired by using helium gas as a working fluid. The maximum design pressure at the model inlet is 0.88 MPa, which allows the Reynolds number to be sufficiently high. The present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan. (author)

Aerodynamics of wind turbines

DEFF Research Database (Denmark)

Hansen, Martin Otto Laver

Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design...... Turbines (VAWT). Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method...... is also covered, as are eigenmodes and the dynamic behaviour of a turbine. The book describes the effects of the dynamics and how this can be modelled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Furthermore, it examines how to calculate...

Stall Recovery in a Centrifuge-Based Flight Simulator With an Extended Aerodynamic Model

NARCIS (Netherlands)

Ledegang, W.D.; Groen, E.L.

2015-01-01

We investigated the performance of 12 airline pilots in recovering from an asymmetrical stall in a flight simulator featuring an extended aerodynamic model of a transport-category aircraft, and a centrifuge-based motion platform capable of generating enhanced buffet motion and g-cueing. All pilots

LMFBR plant design features for sodium spill and fire protection

International Nuclear Information System (INIS)

Palm, R.E.

1982-01-01

Design features have been developed for an LMFBR plant to protect the concrete structures from potential liquid spills and fires and prevent sodium-concrete reactions. The inclusion of these features in the plant design reduces the severity of design basis accident conditions imposed on containment and other critical plant structures. Steel liners are provided in cells containing radioactive sodium systems, and catch pans are located in non-radioactive sodium system cells. The design requirements and descriptions of each of these protective features are presented. The loading conditions, analytical approach and numerical results are also included. Design of concrete cell structures that are subject to high temperature effects from sodium spills is discussed. The structural design considers the influence of high temperature on design properties of concrete and carbon steel materials based on results of a comprehensive test program. The development of these design features and high temperature design considerations for the Clinch River Breeder Reactor Plant (CRBRP) are presented in this paper

Aerodynamic optimization of supersonic compressor cascade using differential evolution on GPU

Energy Technology Data Exchange (ETDEWEB)

Aissa, Mohamed Hasanine; Verstraete, Tom [Von Karman Institute for Fluid Dynamics (VKI) 1640 Sint-Genesius-Rode (Belgium); Vuik, Cornelis [Delft University of Technology 2628 CD Delft (Netherlands)

2016-06-08

Differential Evolution (DE) is a powerful stochastic optimization method. Compared to gradient-based algorithms, DE is able to avoid local minima but requires at the same time more function evaluations. In turbomachinery applications, function evaluations are performed with time-consuming CFD simulation, which results in a long, non affordable, design cycle. Modern High Performance Computing systems, especially Graphic Processing Units (GPUs), are able to alleviate this inconvenience by accelerating the design evaluation itself. In this work we present a validated CFD Solver running on GPUs, able to accelerate the design evaluation and thus the entire design process. An achieved speedup of 20x to 30x enabled the DE algorithm to run on a high-end computer instead of a costly large cluster. The GPU-enhanced DE was used to optimize the aerodynamics of a supersonic compressor cascade, achieving an aerodynamic loss minimization of 20%.

Towards a virtual platform for aerodynamic design, performance assessment and optimization of horizontal axis wind turbines

OpenAIRE

Martínez Valdivieso, Daniel

2017-01-01

This thesis focuses on the study and improvement of the techniques involved on a virtual platform for the simulation of the Aerodynamics of Horizontal Axis Wind Turbines, with the ultimate objective of making Wind Energy more competitive. Navier-Stokes equations govern Aerodynamics, which is an unresolved and very active field of research due to the current inability to capture the relevant the scales both in time and space for nowadays industrial-size machines (with rotors over 100 m...

Design and fabrication of a wind turbine blade | Laryea | Ghana ...

African Journals Online (AJOL)

Dimensions and weights were measured to determine the possibilities of its performance. Factors that affect the spinning of the blade include the weight, blade count and its aerodynamic features. The new blades are assumed to be more reliable and efficient than wholly wood design. The calculated wind speed and power ...

Aerodynamic Classification of Swept-Wing Ice Accretion

Science.gov (United States)

Diebold, Jeff M.; Broeren, Andy P.; Bragg, Michael B.

2013-01-01

The continued design, certification and safe operation of swept-wing airplanes in icing conditions rely on the advancement of computational and experimental simulation methods for higher fidelity results over an increasing range of aircraft configurations and performance, and icing conditions. The current stateof- the-art in icing aerodynamics is mainly built upon a comprehensive understanding of two-dimensional geometries that does not currently exist for fundamentally three-dimensional geometries such as swept wings. The purpose of this report is to describe what is known of iced-swept-wing aerodynamics and to identify the type of research that is required to improve the current understanding. Following the method used in a previous review of iced-airfoil aerodynamics, this report proposes a classification of swept-wing ice accretion into four groups based upon unique flowfield attributes. These four groups are: ice roughness, horn ice, streamwise ice and spanwise-ridge ice. In the case of horn ice it is shown that a further subclassification of "nominally 3D" or "highly 3D" horn ice may be necessary. For all of the proposed ice-shape classifications, relatively little is known about the three-dimensional flowfield and even less about the effect of Reynolds number and Mach number on these flowfields. The classifications and supporting data presented in this report can serve as a starting point as new research explores swept-wing aerodynamics with ice shapes. As further results are available, it is expected that these classifications will need to be updated and revised.

Active aerodynamic drag reduction on morphable cylinders

Science.gov (United States)

Guttag, M.; Reis, P. M.

2017-12-01

We study a mechanism for active aerodynamic drag reduction on morphable grooved cylinders, whose topography can be modified pneumatically. Our design is inspired by the morphology of the Saguaro cactus (Carnegiea gigantea), which possesses an array of axial grooves, thought to help reduce aerodynamic drag, thereby enhancing the structural robustness of the plant under wind loading. Our analog experimental samples comprise a spoked rigid skeleton with axial cavities, covered by a stretched elastomeric film. Decreasing the inner pressure of the sample produces axial grooves, whose depth can be accurately varied, on demand. First, we characterize the relation between groove depth and pneumatic loading through a combination of precision mechanical experiments and finite element simulations. Second, wind tunnel tests are used to measure the aerodynamic drag coefficient (as a function of Reynolds number) of the grooved samples, with different levels of periodicity and groove depths. We focus specifically on the drag crisis and systematically measure the associated minimum drag coefficient and the critical Reynolds number at which it occurs. The results are in agreement with the classic literature of rough cylinders, albeit with an unprecedented level of precision and resolution in varying topography using a single sample. Finally, we leverage the morphable nature of our system to dynamically reduce drag for varying aerodynamic loading conditions. We demonstrate that actively controlling the groove depth yields a drag coefficient that decreases monotonically with Reynolds number and is significantly lower than the fixed sample counterparts. These findings open the possibility for the drag reduction of grooved cylinders to be operated over a wide range of flow conditions.

Modeling of aerodynamics in vortex furnace

Energy Technology Data Exchange (ETDEWEB)

Anufriev, I.; Krasinsky, D. [Russian Academy of Sciences, Novosibirsk (Russian Federation). Inst. of Thermophysics; Salomatov, V.; Anikin, Y.; Sharypov, O. [Russian Academy of Sciences, Novosibirsk (Russian Federation). Inst. of Thermophysics; Novosibirsk State Univ. (Russian Federation); Enkhjargal, Kh. [Mongol Univ. of Science and Technology, Ulan Bator (Mongolia)

2013-07-01

At present, the torch burning technology of pulverized-coal fuel in vortex flow is one of the most prospective and environmentally-friendly combustion technologies of low-grade coals. Appropriate organization of aerodynamics may influence stability of temperature and heat flux distributions, increase slag catching, and reduce toxic emissions. Therefore, from scientific point of view it is interesting to investigate aerodynamics in the devices aiming at justification of design and operating parameters for new steam generators with vortex furnace, and upgrade of existing boiler equipment. The present work is devoted to physical and mathematical modeling of interior aerodynamics of vortex furnace of steam generator of thermal power plants. Research was carried out on the air isothermal model which geometry was similar to one section of the experimental- industrial boiler TPE-427 of Novosibirsk TPS-3. Main elements of vortex furnace structure are combustion chamber, diffuser, and cooling chamber. The model is made from organic glass; on the front wall two rectangular nozzles (through which compressed air is injected) are placed symmetrically at 15 to the horizon. The Laser Doppler Velocimeter LAD-05 was used for non-contact measurement of vortex flow characteristics. Two velocity components in the XY-plane (in different cross- sections of the model) were measured in these experiments. Reynolds number was 3.10{sup 5}. Numerical simulation of 3-D turbulent isothermal flow was performed with the use of CFD package FLUENT. Detailed structure of the flow in vortex furnace model has been obtained in predictions. The distributions of main flow characteristics (pressure, velocity and vorticity fields, turbulent kinetic energy) are presented. The obtained results may be used at designing boilers with vortex furnace. Computations were performed using the supercomputer NKS-160.

Development of multi-element active aerodynamics for the formula sae car

Science.gov (United States)

Merkel, James Patrick

This thesis focuses on the design, development, and implementation of an active aerodynamics system on 2013 Formula SAE car. The aerodynamics package itself consists of five element front and rear wings as well as an under body diffuser. Five element wings produce significant amounts of drag which is a compromise between the cornering ability of the car and the acceleration capability on straights. The active aerodynamics system allows for the wing angle of attack to dynamically change their configuration on track based on sensory data to optimize the wings for any given scenario. The wings are studied using computational fluid dynamics both in their maximum lift configuration as well as a minimum drag configuration. A control system is then developed using an electro mechanical actuation system to articulate the wings between these two states.

In vivo recording of aerodynamic force with an aerodynamic force platform: from drones to birds.

Science.gov (United States)

Lentink, David; Haselsteiner, Andreas F; Ingersoll, Rivers

2015-03-06

Flapping wings enable flying animals and biomimetic robots to generate elevated aerodynamic forces. Measurements that demonstrate this capability are based on experiments with tethered robots and animals, and indirect force calculations based on measured kinematics or airflow during free flight. Remarkably, there exists no method to measure these forces directly during free flight. Such in vivo recordings in freely behaving animals are essential to better understand the precise aerodynamic function of their flapping wings, in particular during the downstroke versus upstroke. Here, we demonstrate a new aerodynamic force platform (AFP) for non-intrusive aerodynamic force measurement in freely flying animals and robots. The platform encloses the animal or object that generates fluid force with a physical control surface, which mechanically integrates the net aerodynamic force that is transferred to the earth. Using a straightforward analytical solution of the Navier-Stokes equation, we verified that the method is accurate. We subsequently validated the method with a quadcopter that is suspended in the AFP and generates unsteady thrust profiles. These independent measurements confirm that the AFP is indeed accurate. We demonstrate the effectiveness of the AFP by studying aerodynamic weight support of a freely flying bird in vivo. These measurements confirm earlier findings based on kinematics and flow measurements, which suggest that the avian downstroke, not the upstroke, is primarily responsible for body weight support during take-off and landing.

Aerodynamic study of sounding rocket flows using Chimera and patched multiblock meshes

Directory of Open Access Journals (Sweden)

João Alves de Oliveira Neto

2011-01-01

Full Text Available Aerodynamic flow simulations over a typical sounding rocket are presented in this paper. The work is inserted in the effort of developing computational tools necessary to simulate aerodynamic flows over configurations of interest for Instituto de Aeronáutica e Espaço of Departamento de Ciência e Tecnologia Aeroespacial. Sounding rocket configurations usually require fairly large fins and, quite frequently, have more than one set of fins. In order to be able to handle such configurations, the present paper presents a novel methodology which combines both Chimera and patched multiblock grids in the discretization of the computational domain. The flows of interest are modeled using the 3-D Euler equations and the work describes the details of discretization procedure, which uses a finite difference approach for structure, body-conforming, multiblock grids. The method is used to calculate the aerodynamics of a sounding rocket vehicle. The results indicate that the present approach can be a powerful aerodynamic analysis and design tool.

TAD- THEORETICAL AERODYNAMICS PROGRAM

Science.gov (United States)

Barrowman, J.

1994-01-01

This theoretical aerodynamics program, TAD, was developed to predict the aerodynamic characteristics of vehicles with sounding rocket configurations. These slender, axisymmetric finned vehicle configurations have a wide range of aeronautical applications from rockets to high speed armament. Over a given range of Mach numbers, TAD will compute the normal force coefficient derivative, the center-of-pressure, the roll forcing moment coefficient derivative, the roll damping moment coefficient derivative, and the pitch damping moment coefficient derivative of a sounding rocket configured vehicle. The vehicle may consist of a sharp pointed nose of cone or tangent ogive shape, up to nine other body divisions of conical shoulder, conical boattail, or circular cylinder shape, and fins of trapezoid planform shape with constant cross section and either three or four fins per fin set. The characteristics computed by TAD have been shown to be accurate to within ten percent of experimental data in the supersonic region. The TAD program calculates the characteristics of separate portions of the vehicle, calculates the interference between separate portions of the vehicle, and then combines the results to form a total vehicle solution. Also, TAD can be used to calculate the characteristics of the body or fins separately as an aid in the design process. Input to the TAD program consists of simple descriptions of the body and fin geometries and the Mach range of interest. Output includes the aerodynamic characteristics of the total vehicle, or user-selected portions, at specified points over the mach range. The TAD program is written in FORTRAN IV for batch execution and has been implemented on an IBM 360 computer with a central memory requirement of approximately 123K of 8 bit bytes. The TAD program was originally developed in 1967 and last updated in 1972.

Aerodynamic properties of turbulent combustion fields

Science.gov (United States)

Hsiao, C. C.; Oppenheim, A. K.

1985-01-01

Flow fields involving turbulent flames in premixed gases under a variety of conditions are modeled by the use of a numerical technique based on the random vortex method to solve the Navier-Stokes equations and a flame propagation algorithm to trace the motion of the front and implement the Huygens principle, both due to Chorin. A successive over-relaxation hybrid method is applied to solve the Euler equation for flows in an arbitrarily shaped domain. The method of images, conformal transformation, and the integral-equation technique are also used to treat flows in special cases, according to their particular requirements. Salient features of turbulent flame propagation in premixed gases are interpreted by relating them to the aerodynamic properties of the flow field. Included among them is the well-known cellular structure of flames stabilized by bluff bodies, as well as the formation of the characteristic tulip shape of flames propagating in ducts. In its rudimentary form, the mechanism of propagation of a turbulent flame is shown to consist of: (1) rotary motion of eddies at the flame front, (2) self-advancement of the front at an appropriate normal burning speed, and (3) dynamic effects of expansion due to exothermicity of the combustion reaction. An idealized model is used to illustrate these fundamental mechanisms and to investigate basic aerodynamic features of flames in premixed gases. The case of a confined flame stabilized behind a rearward-facing step is given particular care and attention. Solutions are shown to be in satisfactory agreement with experimental results, especially with respect to global properties such as the average velocity profiles and reattachment length.

Noise aspects at aerodynamic blade optimisation projects

Energy Technology Data Exchange (ETDEWEB)

Schepers, J.G. [Netherlands Energy Research Foundation, Petten (Netherlands)

1997-12-31

This paper shows an example of an aerodynamic blade optimisation, using the program PVOPT. PVOPT calculates the optimal wind turbine blade geometry such that the maximum energy yield is obtained. Using the aerodynamic optimal blade design as a basis, the possibilities of noise reduction are investigated. The aerodynamic optimised geometry from PVOPT is the `real` optimum (up to the latest decimal). The most important conclusion from this study is, that it is worthwhile to investigate the behaviour of the objective function (in the present case the energy yield) around the optimum: If the optimum is flat, there is a possibility to apply modifications to the optimum configuration with only a limited loss in energy yield. It is obvious that the modified configurations emits a different (and possibly lower) noise level. In the BLADOPT program (the successor of PVOPT) it will be possible to quantify the noise level and hence to assess the reduced noise emission more thoroughly. At present the most promising approaches for noise reduction are believed to be a reduction of the rotor speed (if at all possible), and a reduction of the tip angle by means of low lift profiles, or decreased twist at the outboard stations. These modifications were possible without a significant loss in energy yield. (LN)

Computational Aerodynamic Modeling of Small Quadcopter Vehicles

Science.gov (United States)

Yoon, Seokkwan; Ventura Diaz, Patricia; Boyd, D. Douglas; Chan, William M.; Theodore, Colin R.

2017-01-01

High-fidelity computational simulations have been performed which focus on rotor-fuselage and rotor-rotor aerodynamic interactions of small quad-rotor vehicle systems. The three-dimensional unsteady Navier-Stokes equations are solved on overset grids using high-order accurate schemes, dual-time stepping, low Mach number preconditioning, and hybrid turbulence modeling. Computational results for isolated rotors are shown to compare well with available experimental data. Computational results in hover reveal the differences between a conventional configuration where the rotors are mounted above the fuselage and an unconventional configuration where the rotors are mounted below the fuselage. Complex flow physics in forward flight is investigated. The goal of this work is to demonstrate that understanding of interactional aerodynamics can be an important factor in design decisions regarding rotor and fuselage placement for next-generation multi-rotor drones.

Aerodynamic design applying automatic differentiation and using robust variable fidelity optimization

Science.gov (United States)

Takemiya, Tetsushi

In modern aerospace engineering, the physics-based computational design method is becoming more important, as it is more efficient than experiments and because it is more suitable in designing new types of aircraft (e.g., unmanned aerial vehicles or supersonic business jets) than the conventional design method, which heavily relies on historical data. To enhance the reliability of the physics-based computational design method, researchers have made tremendous efforts to improve the fidelity of models. However, high-fidelity models require longer computational time, so the advantage of efficiency is partially lost. This problem has been overcome with the development of variable fidelity optimization (VFO). In VFO, different fidelity models are simultaneously employed in order to improve the speed and the accuracy of convergence in an optimization process. Among the various types of VFO methods, one of the most promising methods is the approximation management framework (AMF). In the AMF, objective and constraint functions of a low-fidelity model are scaled at a design point so that the scaled functions, which are referred to as "surrogate functions," match those of a high-fidelity model. Since scaling functions and the low-fidelity model constitutes surrogate functions, evaluating the surrogate functions is faster than evaluating the high-fidelity model. Therefore, in the optimization process, in which gradient-based optimization is implemented and thus many function calls are required, the surrogate functions are used instead of the high-fidelity model to obtain a new design point. The best feature of the AMF is that it may converge to a local optimum of the high-fidelity model in much less computational time than the high-fidelity model. However, through literature surveys and implementations of the AMF, the author xx found that (1) the AMF is very vulnerable when the computational analysis models have numerical noise, which is very common in high-fidelity models

Uncertainty quantification-based robust aerodynamic optimization of laminar flow nacelle

Science.gov (United States)

Xiong, Neng; Tao, Yang; Liu, Zhiyong; Lin, Jun

2018-05-01

The aerodynamic performance of laminar flow nacelle is highly sensitive to uncertain working conditions, especially the surface roughness. An efficient robust aerodynamic optimization method on the basis of non-deterministic computational fluid dynamic (CFD) simulation and Efficient Global Optimization (EGO)algorithm was employed. A non-intrusive polynomial chaos method is used in conjunction with an existing well-verified CFD module to quantify the uncertainty propagation in the flow field. This paper investigates the roughness modeling behavior with the γ-Ret shear stress transport model including modeling flow transition and surface roughness effects. The roughness effects are modeled to simulate sand grain roughness. A Class-Shape Transformation-based parametrical description of the nacelle contour as part of an automatic design evaluation process is presented. A Design-of-Experiments (DoE) was performed and surrogate model by Kriging method was built. The new design nacelle process demonstrates that significant improvements of both mean and variance of the efficiency are achieved and the proposed method can be applied to laminar flow nacelle design successfully.

Developments of an Interactive Sail Design Method

OpenAIRE

S. M. Malpede; M. Vezza

2000-01-01

This paper presents a new tool for performing the integrated design and analysis of a sail. The features of the system are the geometrical definition of a sail shape, using the Bezier surface method, the creation of a finite element model for the non-linear structural analysis and a fluid-dynamic model for the aerodynamic analysis. The system has been developed using MATLAB(r). Recent sail design efforts have been focused on solving the aeroelastic behavior of the sail. The pressure dis...

ON THE IMPACT OF FLIGHT SAFETY CERTIFICATION REQUIREMENTS ON THE AERODYNAMIC EFFICIENCY OF COMMERCIAL AIRPLANES

Directory of Open Access Journals (Sweden)

Vladimir I. Shevyakov

2018-01-01

Full Text Available The article considers the issue of aerodynamics efficiency implementation taking into account certification requirements for flight safety. Aerodynamics efficiency means high aerodynamic performance (depending on the airplane size, aerodynamic performance in cruise flight, high aerodynamic performance at takeoff, as well as lift performance at landing.The author estimated the impact on aerodynamics efficiency of both the requirements for aerodynamics performance and requirements for aircraft systems, noncompliance with which may result in significant change of expected operating conditions. It was shown that the use of supercritical wing profiles may result in flight mode limitations due to failure of the required buffeting capacities. It does not allow engaging all the advantages of aerodynamics layout and requires special design solutions to prevent such cases.There were reviewed certification requirements for flight level pressure altitude accuracy and icing conditions warning sysytem. The research presented the methods of aerodynamic efficiency increase by meeting the requirements for reduced vertical separation minima flights and in icing conditions, including requirements for air data probes. Reduced vertical separation minima flight requirements are met by means of efficient air data probes location. Theoretical methods of flow calculation determine areas on the airplane skin surface where static probes minimize errors depending on angle-of-attack and sideslip. It was shown that if certification requirements are not met and in case of flight out of reduced vertical separation minima area, aerodynamics efficiency is significantly reduced and fuel consumption can be increased by 10% and higher. Suggested approaches implementation allows increasing commercial airplanes competitiveness.

Experimental Research of Influence of a Relative Particles Positioning in a Gas Stream on Characteristics of their Aerodynamic Traces

Directory of Open Access Journals (Sweden)

Volkov Roman S.

2016-01-01

Full Text Available The cycle of experimental studies on determination of length of aerodynamic traces of the particles which are flowed round by an air stream is executed. When carrying out researches, panoramic optical methods for diagnostics of multiphase flows of PIV and PTV were used. Velocities of an air flow were varied in the range of 1-3 m/s. The sizes of particles changed from 1mm to 5 mm. The defining influence of the sizes of particles and velocities of an air stream on length of aerodynamic traces is established. Influence of a relative positioning of particles on features of formation of an aerodynamic trace is shown.

Wind Turbine Aerodynamics from an Aerospace Perspective

NARCIS (Netherlands)

van Garrel, Arne; ten Pas, Sebastiaan; Venner, Cornelis H.; van Muijden, Jaap

2018-01-01

The current challenges in wind turbine aerodynamics simulations share a number of similarities with the challenges that the aerospace industry has faced in the past. Some of the current challenges in the aerospace aerodynamics community are also relevant for today’s wind turbine aerodynamics

Challenges of Aircraft Design Integration

Science.gov (United States)

2003-03-01

predicted by the conceptual stick model and the full FEM of the Challenger wing without winglets . Advanced aerodynamic wing design methods To design wings...Piperni, E. Laurendeau Advanced Aerodynamics Bombardier Aerospace 400 CMte Vertu Road Dorval, Quebec, Canada, H4S 1Y9 Fassi.Kafyeke @notes.canadair.ca Tel...514) 855-7186 Abstract The design of a modern airplane brings together many disciplines: structures, aerodynamics , controls, systems, propulsion

The influence of aerodynamic coefficients on the elements of classic projectile paths

Directory of Open Access Journals (Sweden)

Damir D. Jerković

2011-04-01

Full Text Available The article deals with the results of the research on the influence of aerodynamic coefficient values on the trajectory elements and the stability parameters of classic axisymmetric projectiles. It presents the characteristic functions of aerodynamic coefficients with regard to aerodynamic parameters and the projectile body shape. The trajectory elements of the model of classic axisymmetric projectiles and the analyses of their changes were presented with respect to the aerodynamic coefficient values. Introduction Classic axisymmetric projectiles fly through atmosphere using muzzle velocity as initial energy resource, so the aerodynamic force and moment have the most significant influence on the motion of projectiles. The aerodynamic force and moment components represented as aerodynamic coefficients depend on motion velocity i. e. flow velocity, the flow features produced by projectile shape and position in the flow, and angular velocity (rate of the body. The functional dependence of aerodynamic coefficients on certain influential parameters, such as angle of attack and angular velocity components is expressed by the derivative of aerodynamic coefficients. The determination of aerodynamic coefficients and derivatives enables complete definition of the aerodynamic force and moment acting on the classic projectile. The projectile motion problem is considered in relation to defining the projectile stability parameters and the conditions under which the stability occurs. The comparative analyses of aerodynamic coefficient values obtained by numerical methods, semi empirical calculations and experimental research give preliminary evaluation of the quality of the determined values. The flight simulation of the motion of a classic axisymetric projectile, which has the shape defined by the aerodynamic coefficient values, enables the comparative analyses of the trajectory elements and stability characteristics. The model of the classic projectile

Aerodynamic and aeroacoustic performance of airfoils with morphing structures

OpenAIRE

Ai, Qing; Azarpeyvand, Mahdi; Lachenal, Xavier; Weaver, Paul M.

2016-01-01

Aerodynamic and aeroacoustic performance of airfoils fitted with morphing trailing edges are investigated using a coupled structure/fluid/noise model. The control of the flow over the surface of an airfoil using shape optimization techniques can significantly improve the load distribution along the chord and span lengths whilst minimising noise generation. In this study, a NACA 63-418 airfoil is fitted with a morphing flap and various morphing profiles are considered with two features that di...

Engineering features of the INTOR conceptual design

International Nuclear Information System (INIS)

Shannon, T.E.

1981-01-01

The INTOR engineering design has been strongly influenced by considerations for assembly and maintenance. A maintenance philosophy was established at the outset of the conceptual design to insure that the tokamak configuration would be developed to accommodate maintenance requirements. The main features of the INTOR design are summarized in this paper with primary emphasis on the impact of maintenance considerations

NASA Iced Aerodynamics and Controls Current Research

Science.gov (United States)

Addy, Gene

2009-01-01

This slide presentation reviews the state of current research in the area of aerodynamics and aircraft control with ice conditions by the Aviation Safety Program, part of the Integrated Resilient Aircraft Controls Project (IRAC). Included in the presentation is a overview of the modeling efforts. The objective of the modeling is to develop experimental and computational methods to model and predict aircraft response during adverse flight conditions, including icing. The Aircraft icing modeling efforts includes the Ice-Contaminated Aerodynamics Modeling, which examines the effects of ice contamination on aircraft aerodynamics, and CFD modeling of ice-contaminated aircraft aerodynamics, and Advanced Ice Accretion Process Modeling which examines the physics of ice accretion, and works on computational modeling of ice accretions. The IRAC testbed, a Generic Transport Model (GTM) and its use in the investigation of the effects of icing on its aerodynamics is also reviewed. This has led to a more thorough understanding and models, both theoretical and empirical of icing physics and ice accretion for airframes, advanced 3D ice accretion prediction codes, CFD methods for iced aerodynamics and better understanding of aircraft iced aerodynamics and its effects on control surface effectiveness.

Design features of APWR in Japan

International Nuclear Information System (INIS)

Yamaguchi, H.; Aeba, Y.; Weiss, E.H.

1999-01-01

Development of the Advanced Pressurized Water Reactor (APWR) was executed in the Improvement and Standardization Program which was organized by the Ministry of International Trade and Industry, Japanese utilities (Hokkaido, Kansai, Shikoku, Kyushu Electric Power Companies and the Japan Atomic Power Company) and manufacturers (Mitsubishi Heavy Industries and Westinghouse Electric). Improvements in terms of safety, reliability, operability, maintainability and economy have been incorporated based on comprehensive evaluations of both the advanced technologies available today, and the experience associated with construction and operation of current PWR plants. The main design improvement features applied in APWR include a core design that contributes to effective use of uranium resource, safety enhancement in the engineered safeguard system, and reliability enhancement in the reactor internal structures. This paper briefly describes the main features of the APWR design focusing on the following two items: the radial reflector, which enhances reliability of the reactor internal structures as well as neutron economy in the core region; and an advanced accumulator, which enhances Emergency Core Cooling System (ECCS) reliability and contributes to system simplification due to passive low pressure injection function. (author)

The Oxford Probe: an open access five-hole probe for aerodynamic measurements

Science.gov (United States)

Hall, B. F.; Povey, T.

2017-03-01

The Oxford Probe is an open access five-hole probe designed for experimental aerodynamic measurements. The open access probe can be manufactured by the end user via additive manufacturing (metal or plastic). The probe geometry, drawings, calibration maps, and software are available under a creative commons license. The purpose is to widen access to aerodynamic measurement techniques in education and research environments. There are many situations in which the open access probe will allow results of comparable accuracy to a well-calibrated commercial probe. We discuss the applications and limitations of the probe, and compare the calibration maps for 16 probes manufactured in different materials and at different scales, but with the same geometrical design.

The Oxford Probe: an open access five-hole probe for aerodynamic measurements

International Nuclear Information System (INIS)

Hall, B F; Povey, T

2017-01-01

The Oxford Probe is an open access five-hole probe designed for experimental aerodynamic measurements. The open access probe can be manufactured by the end user via additive manufacturing (metal or plastic). The probe geometry, drawings, calibration maps, and software are available under a creative commons license. The purpose is to widen access to aerodynamic measurement techniques in education and research environments. There are many situations in which the open access probe will allow results of comparable accuracy to a well-calibrated commercial probe. We discuss the applications and limitations of the probe, and compare the calibration maps for 16 probes manufactured in different materials and at different scales, but with the same geometrical design. (paper)

Structural health monitoring feature design by genetic programming

International Nuclear Information System (INIS)

Harvey, Dustin Y; Todd, Michael D

2014-01-01

Structural health monitoring (SHM) systems provide real-time damage and performance information for civil, aerospace, and other high-capital or life-safety critical structures. Conventional data processing involves pre-processing and extraction of low-dimensional features from in situ time series measurements. The features are then input to a statistical pattern recognition algorithm to perform the relevant classification or regression task necessary to facilitate decisions by the SHM system. Traditional design of signal processing and feature extraction algorithms can be an expensive and time-consuming process requiring extensive system knowledge and domain expertise. Genetic programming, a heuristic program search method from evolutionary computation, was recently adapted by the authors to perform automated, data-driven design of signal processing and feature extraction algorithms for statistical pattern recognition applications. The proposed method, called Autofead, is particularly suitable to handle the challenges inherent in algorithm design for SHM problems where the manifestation of damage in structural response measurements is often unclear or unknown. Autofead mines a training database of response measurements to discover information-rich features specific to the problem at hand. This study provides experimental validation on three SHM applications including ultrasonic damage detection, bearing damage classification for rotating machinery, and vibration-based structural health monitoring. Performance comparisons with common feature choices for each problem area are provided demonstrating the versatility of Autofead to produce significant algorithm improvements on a wide range of problems. (paper)

AIAA Applied Aerodynamics Conference, 10th, Palo Alto, CA, June 22-24, 1992, Technical Papers. Pts. 1 AND 2

International Nuclear Information System (INIS)

Anon.

1992-01-01

Consideration is given to vortex physics and aerodynamics; supersonic/hypersonic aerodynamics; STOL/VSTOL/rotors; missile and reentry vehicle aerodynamics; CFD as applied to aircraft; unsteady aerodynamics; supersonic/hypersonic aerodynamics; low-speed/high-lift aerodynamics; airfoil/wing aerodynamics; measurement techniques; CFD-solvers/unstructured grid; airfoil/drag prediction; high angle-of-attack aerodynamics; and CFD grid methods. Particular attention is given to transonic-numerical investigation into high-angle-of-attack leading-edge vortex flow, prediction of rotor unsteady airloads using vortex filament theory, rapid synthesis for evaluating the missile maneuverability parameters, transonic calculations of wing/bodies with deflected control surfaces; the static and dynamic flow field development about a porous suction surface wing; the aircraft spoiler effects under wind shear; multipoint inverse design of an infinite cascade of airfoils, turbulence modeling for impinging jet flows; numerical investigation of tail buffet on the F-18 aircraft; the surface grid generation in a parameter space; and the flip flop nozzle extended to supersonic flows

Feature-based component model for design of embedded systems

Science.gov (United States)

Zha, Xuan Fang; Sriram, Ram D.

2004-11-01

An embedded system is a hybrid of hardware and software, which combines software's flexibility and hardware real-time performance. Embedded systems can be considered as assemblies of hardware and software components. An Open Embedded System Model (OESM) is currently being developed at NIST to provide a standard representation and exchange protocol for embedded systems and system-level design, simulation, and testing information. This paper proposes an approach to representing an embedded system feature-based model in OESM, i.e., Open Embedded System Feature Model (OESFM), addressing models of embedded system artifacts, embedded system components, embedded system features, and embedded system configuration/assembly. The approach provides an object-oriented UML (Unified Modeling Language) representation for the embedded system feature model and defines an extension to the NIST Core Product Model. The model provides a feature-based component framework allowing the designer to develop a virtual embedded system prototype through assembling virtual components. The framework not only provides a formal precise model of the embedded system prototype but also offers the possibility of designing variation of prototypes whose members are derived by changing certain virtual components with different features. A case study example is discussed to illustrate the embedded system model.

Shape optimization of turbine blades with the integration of aerodynamics and heat transfer

Directory of Open Access Journals (Sweden)

Rajadas J. N.

1998-01-01

Full Text Available A multidisciplinary optimization procedure, with the integration of aerodynamic and heat transfer criteria, has been developed for the design of gas turbine blades. Two different optimization formulations have been used. In the first formulation, the maximum temperature in the blade section is chosen as the objective function to be minimized. An upper bound constraint is imposed on the blade average temperature and a lower bound constraint is imposed on the blade tangential force coefficient. In the second formulation, the blade average and maximum temperatures are chosen as objective functions. In both formulations, bounds are imposed on the velocity gradients at several points along the surface of the airfoil to eliminate leading edge velocity spikes which deteriorate aerodynamic performance. Shape optimization is performed using the blade external and coolant path geometric parameters as design variables. Aerodynamic analysis is performed using a panel code. Heat transfer analysis is performed using the finite element method. A gradient based procedure in conjunction with an approximate analysis technique is used for optimization. The results obtained using both optimization techniques are compared with a reference geometry. Both techniques yield significant improvements with the multiobjective formulation resulting in slightly superior design.

AIAA Applied Aerodynamics Conference, 8th, Portland, OR, Aug. 20-22, 1990, Technical Papers. Parts 1 ampersand 2

International Nuclear Information System (INIS)

Anon.

1990-01-01

The present conference discusses topics in CFD methods and their validation, vortices and vortical flows, STOL/VSTOL aerodynamics, boundary layer transition and separation, wing airfoil aerodynamics, laminar flow, supersonic and hypersonic aerodynamics, CFD for wing airfoil and nacelle applications, wind tunnel testing, flight testing, missile aerodynamics, unsteady flow, configuration aerodynamics, and multiple body/interference flows. Attention is given to the numerical simulation of vortical flows over close-coupled canard-wing configuration, propulsive lift augmentation by side fences, road-vehicle aerodynamics, a shock-capturing method for multidimensional flow, transition-detection studies in a cryogenic environment, a three-dimensional Euler analysis of ducted propfan flowfields, multiple vortex and shock interaction at subsonic and supersonic speeds, and a Navier-Stokes simulation of waverider flowfields. Also discussed are the induced drag of crescent-shaped wings, the preliminary design aerodynamics of missile inlets, finite wing lift prediction at high angles-of-attack, optimal supersonic/hypersonic bodies, and adaptive grid embedding for the two-dimensional Euler equations

Aerodynamic drag on intermodal railcars

Science.gov (United States)

Kinghorn, Philip; Maynes, Daniel

2014-11-01

The aerodynamic drag associated with transport of commodities by rail is becoming increasingly important as the cost of diesel fuel increases. This study aims to increase the efficiency of intermodal cargo trains by reducing the aerodynamic drag on the load carrying cars. For intermodal railcars a significant amount of aerodynamic drag is a result of the large distance between loads that often occurs and the resulting pressure drag resulting from the separated flow. In the present study aerodynamic drag data have been obtained through wind tunnel testing on 1/29 scale models to understand the savings that may be realized by judicious modification to the size of the intermodal containers. The experiments were performed in the BYU low speed wind tunnel and the test track utilizes two leading locomotives followed by a set of five articulated well cars with double stacked containers. The drag on a representative mid-train car is measured using an isolated load cell balance and the wind tunnel speed is varied from 20 to 100 mph. We characterize the effect that the gap distance between the containers and the container size has on the aerodynamic drag of this representative rail car and investigate methods to reduce the gap distance.

Unsteady Aerodynamics of Deformable Thin Airfoils

OpenAIRE

Walker, William Paul

2009-01-01

Unsteady aerodynamic theories are essential in the analysis of bird and insect flight. The study of these types of locomotion is vital in the development of flapping wing aircraft. This paper uses potential flow aerodynamics to extend the unsteady aerodynamic theory of Theodorsen and Garrick (which is restricted to rigid airfoil motion) to deformable thin airfoils. Frequency-domain lift, pitching moment and thrust expressions are derived for an airfoil undergoing harmonic oscillations and def...

Extension of a nonlinear systems theory to general-frequency unsteady transonic aerodynamic responses

Science.gov (United States)

Silva, Walter A.

1993-01-01

A methodology for modeling nonlinear unsteady aerodynamic responses, for subsequent use in aeroservoelastic analysis and design, using the Volterra-Wiener theory of nonlinear systems is presented. The methodology is extended to predict nonlinear unsteady aerodynamic responses of arbitrary frequency. The Volterra-Wiener theory uses multidimensional convolution integrals to predict the response of nonlinear systems to arbitrary inputs. The CAP-TSD (Computational Aeroelasticity Program - Transonic Small Disturbance) code is used to generate linear and nonlinear unit impulse responses that correspond to each of the integrals for a rectangular wing with a NACA 0012 section with pitch and plunge degrees of freedom. The computed kernels then are used to predict linear and nonlinear unsteady aerodynamic responses via convolution and compared to responses obtained using the CAP-TSD code directly. The results indicate that the approach can be used to predict linear unsteady aerodynamic responses exactly for any input amplitude or frequency at a significant cost savings. Convolution of the nonlinear terms results in nonlinear unsteady aerodynamic responses that compare reasonably well with those computed using the CAP-TSD code directly but at significant computational cost savings.

Design of a wind tunnel scale model of an adaptive wind turbine blade for active aerodynamic load control experiments

NARCIS (Netherlands)

Hulskamp, A.W.; Beukers, A.; Bersee, H.E.N.; Van Wingerden, J.W.; Barlas, T.

2007-01-01

Within wind energy research there is a drive towards the development of a “smart rotor”; a rotor of which the loading can be measured and controlled through the application of a sensor system, a control system and an aerodynamic device. Most promising solutions from an aerodynamic point of view are

Aerodynamics/ACEE: Aircraft energy efficiency

Science.gov (United States)

1981-01-01

An overview is presented of a 10 year program managed by NASA which seeks to make possible the most efficient use of energy for aircraft propulsion and lift as well as provide a technology that can be used by U.S. manufacturers of air transports and engines. Supercritical wings, winglets, vortex drag reduction, high lift, active control, laminar flow control, and aerodynamics by computer are among the topics discussed. Wind tunnel models in flight verification of advanced technology, and the design, construction and testing of various aircraft structures are also described.

Comparative Analysis of Uninhibited and Constrained Avian Wing Aerodynamics

Science.gov (United States)

Cox, Jordan A.

The flight of birds has intrigued and motivated man for many years. Bird flight served as the primary inspiration of flying machines developed by Leonardo Da Vinci, Otto Lilienthal, and even the Wright brothers. Avian flight has once again drawn the attention of the scientific community as unmanned aerial vehicles (UAV) are not only becoming more popular, but smaller. Birds are once again influencing the designs of aircraft. Small UAVs operating within flight conditions and low Reynolds numbers common to birds are not yet capable of the high levels of control and agility that birds display with ease. Many researchers believe the potential to improve small UAV performance can be obtained by applying features common to birds such as feathers and flapping flight to small UAVs. Although the effects of feathers on a wing have received some attention, the effects of localized transient feather motion and surface geometry on the flight performance of a wing have been largely overlooked. In this research, the effects of freely moving feathers on a preserved red tailed hawk wing were studied. A series of experiments were conducted to measure the aerodynamic forces on a hawk wing with varying levels of feather movement permitted. Angle of attack and air speed were varied within the natural flight envelope of the hawk. Subsequent identical tests were performed with the feather motion constrained through the use of externally-applied surface treatments. Additional tests involved the study of an absolutely fixed geometry mold-and-cast wing model of the original bird wing. Final tests were also performed after applying surface coatings to the cast wing. High speed videos taken during tests revealed the extent of the feather movement between wing models. Images of the microscopic surface structure of each wing model were analyzed to establish variations in surface geometry between models. Recorded aerodynamic forces were then compared to the known feather motion and surface

The 1/3-scale aerodynamics performance test of helium compressor for GTHTR300 turbo machine of JAERI (step 1)

International Nuclear Information System (INIS)

Takada, Shoji; Takizuka, Takakazu; Kunitomi, Kazuhiko; Xing, Yan

2003-01-01

A program for research and development on aerodynamics in a helium gas compressor was planned for the power conversion system of the Gas Turbine High Temperature Reactor (GTHTR300). The three-dimensional aerodynamic design of the compressor achieved a high polytropic efficiency of 90%, keeping a sufficient surge margin over 30%. To validate the design of the helium gas compressor of GTHTR300, aerodynamic performance tests were planned, and a 1/3-scale, 4-stage compressor model was designed. In the tests, the performance data of the helium gas compressor model will be acquired by using helium gas as a working fluid. The maximum design pressure at the model inlet is 0.88 MPa, which allows the Reynolds number to be sufficiently high. The present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan. (author)

Membrane wing aerodynamics for micro air vehicles

Science.gov (United States)

Lian, Yongsheng; Shyy, Wei; Viieru, Dragos; Zhang, Baoning

2003-10-01

The aerodynamic performance of a wing deteriorates considerably as the Reynolds number decreases from 10 6 to 10 4. In particular, flow separation can result in substantial change in effective airfoil shape and cause reduced aerodynamic performance. Lately, there has been growing interest in developing suitable techniques for sustained and robust flight of micro air vehicles (MAVs) with a wingspan of 15 cm or smaller, flight speed around 10 m/ s, and a corresponding Reynolds number of 10 4-10 5. This paper reviews the aerodynamics of membrane and corresponding rigid wings under the MAV flight conditions. The membrane wing is observed to yield desirable characteristics in delaying stall as well as adapting to the unsteady flight environment, which is intrinsic to the designated flight speed. Flow structures associated with the low Reynolds number and low aspect ratio wing, such as pressure distribution, separation bubble and tip vortex are reviewed. Structural dynamics in response to the surrounding flow field is presented to highlight the multiple time-scale phenomena. Based on the computational capabilities for treating moving boundary problems, wing shape optimization can be conducted in automated manners. To enhance the lift, the effect of endplates is evaluated. The proper orthogonal decomposition method is also discussed as an economic tool to describe the flow structure around a wing and to facilitate flow and vehicle control.

Preliminary Structural Sensitivity Study of Hypersonic Inflatable Aerodynamic Decelerator Using Probabilistic Methods

Science.gov (United States)

Lyle, Karen H.

2014-01-01

Acceptance of new spacecraft structural architectures and concepts requires validated design methods to minimize the expense involved with technology validation via flighttesting. This paper explores the implementation of probabilistic methods in the sensitivity analysis of the structural response of a Hypersonic Inflatable Aerodynamic Decelerator (HIAD). HIAD architectures are attractive for spacecraft deceleration because they are lightweight, store compactly, and utilize the atmosphere to decelerate a spacecraft during re-entry. However, designers are hesitant to include these inflatable approaches for large payloads or spacecraft because of the lack of flight validation. In the example presented here, the structural parameters of an existing HIAD model have been varied to illustrate the design approach utilizing uncertainty-based methods. Surrogate models have been used to reduce computational expense several orders of magnitude. The suitability of the design is based on assessing variation in the resulting cone angle. The acceptable cone angle variation would rely on the aerodynamic requirements.

Analysis of VAWT aerodynamics and design using the Actuator Cylinder flow model

International Nuclear Information System (INIS)

Madsen, H Aa; Paulsen, U S; Vitae, L

2014-01-01

The actuator cylinder (AC) flow model is defined as the ideal VAWT rotor. Radial directed volume forces are applied on the circular path of the VAWT rotor airfoil and constitute an energy conversion in the flow. The power coefficient for the ideal as well as the real energy conversion is defined. The describing equations for the two-dimensional AC model are presented and a solution method splitting the final solution in a linear and non-linear part is briefly described. A family of loadforms approaching the uniform loading is used to study the ideal energy conversion indicating that the maximum power coefficient for the ideal energy conversion of a VAWT could exceed the Betz limit. The real energy conversion of the 5MW DeepWind rotor is simulated with the AC flow model in combination with the blade element analysis. Aerodynamic design aspects are discussed on this basis revealing that the maximum obtainable power coefficient for a fixed pitch VAWT is constrained by the fundamental cyclic variation of inflow angle and relative velocity leading to a loading that deviates considerably from the uniform loading

Aerodynamic performance investigation on waverider with variable blunt radius in hypersonic flows

Science.gov (United States)

Li, Shibin; Wang, Zhenguo; Huang, Wei; Xu, Shenren; Yan, Li

2017-08-01

Waverider is an important candidate for the design of hypersonic vehicles. However, the ideal waverider cannot be manufactured because of its sharp leading edge, so the leading edge should be blunted. In the paper, the HMB solver and laminar flow model have been utilized to obtain the flow field properties around the blunt waverider with the freestream Mach number being 8.0, and several novel strategies have been suggested to improve the aerodynamic performance of blunt waverider. The numerical method has been validated against experimental data, and the Stanton number(St) of the predicted result has been analyzed. The obtained results show good agreement with the experimental data. Stmax decreases by 58% and L/D decreases by 8.2% when the blunt radius increases from 0.0002 m to 0.001 m. ;Variable blunt waverider; is a good compromise for aerodynamic performance and thermal insulation. The aero-heating characteristics are very sensitive to Rmax. The position of the smallest blunt radius has a great effect on the aerodynamic performance. In addition, the type of blunt leading edge has a great effect on the aero-heating characteristics when Rmax is fixed. Therefore, out of several designs, Type 4is the best way to achieve the good overall performance. The ;Variable blunt waverider; not only improves the aerodynamic performance, but also makes the aero-heating become evenly-distributed, leading to better aero-heating characteristics.

Aerodynamic Analysis and Three-Dimensional Redesign of a Multi-Stage Axial Flow Compressor

Directory of Open Access Journals (Sweden)

Tao Ning

2016-04-01

Full Text Available This paper describes the introduction of three-dimension (3-D blade designs into a 5-stage axial compressor with multi-stage computational fluid dynamic (CFD methods. Prior to a redesign, a validation study is conducted for the overall performance and flow details based on full-scale test data, proving that the multi-stage CFD applied is a relatively reliable tool for the analysis of the follow-up redesign. Furthermore, at the near stall point, the aerodynamic analysis demonstrates that significant separation exists in the last stator, leading to the aerodynamic redesign, which is the focus of the last stator. Multi-stage CFD methods are applied throughout the three-dimensional redesign process for the last stator to explore their aerodynamic improvement potential. An unconventional asymmetric bow configuration incorporated with leading edge re-camber and re-solidity is employed to reduce the high loss region dominated by the mainstream. The final redesigned version produces a 13% increase in the stall margin while maintaining the efficiency at the design point.

License Application Design Selection Feature Report: Waste Package Self Shielding Design Feature 13

International Nuclear Information System (INIS)

Tang, J.S.

2000-01-01

In the Viability Assessment (VA) reference design, handling of waste packages (WPs) in the emplacement drifts is performed remotely, and human access to the drifts is precluded when WPs are present. This report will investigate the feasibility of using a self-shielded WP design to reduce the radiation levels in the emplacement drifts to a point that, when coupled with ventilation, will create an acceptable environment for human access. This provides the benefit of allowing human entry to emplacement drifts to perform maintenance on ground support and instrumentation, and carry out performance confirmation activities. More direct human control of WP handling and emplacement operations would also be possible. However, these potential benefits must be weighed against the cost of implementation, and potential impacts on pre- and post-closure performance of the repository and WPs. The first section of this report will provide background information on previous investigations of the self-shielded WP design feature, summarize the objective and scope of this document, and provide quality assurance and software information. A shielding performance and cost study that includes several candidate shield materials will then be performed in the subsequent section to allow selection of two self-shielded WP design options for further evaluation. Finally, the remaining sections will evaluate the impacts of the two WP self-shielding options on the repository design, operations, safety, cost, and long-term performance of the WPs with respect to the VA reference design

Experimental aerodynamic and acoustic model testing of the Variable Cycle Engine (VCE) testbed coannular exhaust nozzle system: Comprehensive data report

Science.gov (United States)

Nelson, D. P.; Morris, P. M.

1980-01-01

The component detail design drawings of the one sixth scale model of the variable cycle engine testbed demonstrator exhaust syatem tested are presented. Also provided are the basic acoustic and aerodynamic data acquired during the experimental model tests. The model drawings, an index to the acoustic data, an index to the aerodynamic data, tabulated and graphical acoustic data, and the tabulated aerodynamic data and graphs are discussed.

Design and Analysis of Winglets for Military Aircraft

Science.gov (United States)

1976-02-03

Company to determine the aerodynamic characteristics and performance benefits from winglets on the KC-135 aircraft. Unclassified SECURITY CLASSIFICATION...1 II ANALYSIS OF WINGLETS ...... ............................................ 3 A Aerodynamic ...were estimated and compared to the conventional design. The aerodynamic shape of the winglet was designed for the KC-135 and this design was then used

Studies on aerodynamic interferences between the components of transport airplane using unstructured Navier-Stokes simulations

International Nuclear Information System (INIS)

Wang, G.; Ye, Z.

2005-01-01

It is well known that the aerodynamic interference flows widely exist between the components of conventional transport airplane, for example, the wing-fuselage juncture flow, wing-pylon-nacelle flow and tail-fuselage juncture flow. The main characteristic of these aerodynamic interferences is flow separation, which will increase the drag, reduce the lift and cause adverse influence on the stability and controllability of the airplane. Therefore, the modern civil transport designers should do their best to eliminate negative effects of aerodynamic interferences, which demands that the aerodynamic interferences between the aircraft components should be predicted and analyzed accurately. Today's CFD techniques provide us powerful and efficient analysis tools to achieve this objective. In this paper, computational investigations of the interferences between transport aircraft components have been carried out by using a viscous flow solver based on mixed element type unstructured meshes. (author)

Aerodynamic efficiency of a bioinspired flapping wing rotor at low Reynolds number.

Science.gov (United States)

Li, H; Guo, S

2018-03-01

This study investigates the aerodynamic efficiency of a bioinspired flapping wing rotor kinematics which combines an active vertical flapping motion and a passive horizontal rotation induced by aerodynamic thrust. The aerodynamic efficiencies for producing both vertical lift and horizontal thrust of the wing are obtained using a quasi-steady aerodynamic model and two-dimensional (2D) CFD analysis at Reynolds number of 2500. The calculated efficiency data show that both efficiencies (propulsive efficiency- η p , and efficiency for producing lift- P f ) of the wing are optimized at Strouhal number ( St ) between 0.1 and 0.5 for a range of wing pitch angles (upstroke angle of attack α u less than 45°); the St for high P f ( St  = 0.1 ∼ 0.3) is generally lower than for high η p ( St  = 0.2 ∼ 0.5), while the St for equilibrium rotation states lies between the two. Further systematic calculations show that the natural equilibrium of the passive rotating wing automatically converges to high-efficiency states: above 85% of maximum P f can be obtained for a wide range of prescribed wing kinematics. This study provides insight into the aerodynamic efficiency of biological flyers in cruising flight, as well as practical applications for micro air vehicle design.

Aerodynamic structures and processes in rotationally augmented flow fields

DEFF Research Database (Denmark)

Schreck, S.J.; Sørensen, Niels N.; Robinson, M.C.

2007-01-01

. Experimental measurements consisted of surface pressure data statistics used to infer sectional boundary layer state and to quantify normal force levels. Computed predictions included high-resolution boundary layer topologies and detailed above-surface flow field structures. This synergy was exploited...... to reliably identify and track pertinent features in the rotating blade boundary layer topology as they evolved in response to varying wind speed. Subsequently, boundary layer state was linked to above-surface flow field structure and used to deduce mechanisms; underlying augmented aerodynamic force...

Centrifugal compressor design options for small turbochargers

Energy Technology Data Exchange (ETDEWEB)

Rodgers, C. [ITC, San Diego (United States)

1998-07-01

Evolutionary development of the small turbocharger centrifugal compressor over the past four decades has resulted in a finely honed turbomachinery component satisfying both thermodynamic and economic constraints. At this penultimate stage of development an appraisal was considered timely of the remaining design options that exist to enhance the performance characteristics and cost reduction features. This paper presents the results of an analytical study of various small centrifugal compressor design options, assessed in merit of both aerodynamic and manufacturing cost attributes, together with recommendations for future research avenues. (author)

Optimal Aerodynamic Design of Conventional and Coaxial Helicopter Rotors in Hover and Forward Flight

Science.gov (United States)

Giovanetti, Eli B.

This dissertation investigates the optimal aerodynamic performance and design of conventional and coaxial helicopters in hover and forward flight using conventional and higher harmonic blade pitch control. First, we describe a method for determining the blade geometry, azimuthal blade pitch inputs, optimal shaft angle (rotor angle of attack), and division of propulsive and lifting forces among the components that minimize the total power for a given forward flight condition. The optimal design problem is cast as a variational statement that is discretized using a vortex lattice wake to model inviscid forces, combined with two-dimensional drag polars to model profile losses. The resulting nonlinear constrained optimization problem is solved via Newton iteration. We investigate the optimal design of a compound vehicle in forward flight comprised of a coaxial rotor system, a propeller, and optionally, a fixed wing. We show that higher harmonic control substantially reduces required power, and that both rotor and propeller efficiencies play an important role in determining the optimal shaft angle, which in turn affects the optimal design of each component. Second, we present a variational approach for determining the optimal (minimum power) torque-balanced coaxial hovering rotor using Blade Element Momentum Theory including swirl. We show that the optimal hovering coaxial rotor generates only a small percentage of its total thrust on the portion of the lower rotor operating in the upper rotor's contracted wake, resulting in an optimal design with very different upper and lower rotor twist and chord distributions. We also show that the swirl component of induced velocity has a relatively small effect on rotor performance at the disk loadings typical of helicopter rotors. Third, we describe a more refined model of the wake of a hovering conventional or coaxial rotor. We approximate the rotor or coaxial rotors as actuator disks (though not necessarily uniformly loaded

The aerodynamic cost of flight in bats--comparing theory with measurement

Science.gov (United States)

von Busse, Rhea; Waldman, Rye M.; Swartz, Sharon M.; Breuer, Kenneth S.

2012-11-01

Aerodynamic theory has long been used to predict the aerodynamic power required for animal flight. However, even though the actuator disk model does not account for the flapping motion of a wing, it is used for lack of any better model. The question remains: how close are these predictions to reality? We designed a study to compare predicted aerodynamic power to measured power from the kinetic energy contained in the wake shed behind a bat flying in a wind tunnel. A high-accuracy displaced light-sheet stereo PIV system was used in the Trefftz plane to capture the wake behind four bats flown over a range of flight speeds (1-6m/s). The total power in the wake was computed from the wake vorticity and these estimates were compared with the power predicted using Pennycuick's model for bird flight as well as estimates derived from measurements of the metabolic cost of flight, previously acquired from the same individuals.

Indigenous development and performance evaluation of BARC aerodynamic size separator (BASS)

CERN Document Server

Singh, S; Khan, A; Mayya, Y S; Narayanan, K P; Purwar, R C; Sapra, B K; Sunny, F

2002-01-01

Commercially available cascade impactors, commonly used for aerodynamic size separation of aerosol particles, are based on the principle of inertial impaction. As of now, these instruments are imported at a cost of several lakhs of rupees; hence an effort has been made to develop an aerodynamic particle sizer indigenously in BARC. This unit, referred to as BARC Aerodynamic Size Separator (BASS), separates aerosols into seven size classes ranging from 0.53 mu m to 10 mu m and operates at a flow rate of 45 Ipm. Intercomparison studies between the standard Andersen Mark-II (Grasbey Andersen Inc.) impactor and BASS using nebulizer generated aerosols have consistently shown excellent performance by BASS in all respects. In particular, BASS yielded the parameters of polydisperse aerosols quite accurately. Experiments to evaluate the individual stage cut-off diameters show that these are within 8% of their designed value for all stages except the higher two stages which indicate about 30% lower values than the desig...

New Mercedes-Benz Roadster - car body: Body concept, aerodynamics and vibration behaviour

Energy Technology Data Exchange (ETDEWEB)

Huber, G.; Goetz, H.; Schwede, W.

1989-04-01

The new convertible series from Mercedes-Benz has been developed among other things, with the objective of setting new standards for open cars, especially in the area of bodywork design. To achieve this objective with this highly complex car, the design of the bodywork has been extremely systematically defined through the stages, from the general specification framework via the development sector's internal specification outline to the project description. The project was optimised in its sequence with regard to technics, costs, deadlines and availability of capacity. Because of the high performance of the new convertible, for which unrestricted everyday usefulness has been a top-priority demand, its aerodynamic design is first and foremost geared to ensure a high degree of road-holding and crosswind stability, the basic model's drag coefficient being c/sub w/=0,32. To effectively complement the comfort-enhancing appointments and controls, which have been designed with reference to S-class standards, in the development of the body-in-white, very exacting demands were made on torsional rigidity and natural frequency under torsional excitation with a view to provide excellent vibration behaviour. The body-in-white, complemented by special features such as struts underneath the front and the rear axle point forward in this respect.

EPR design features to mitigate severe accident challenges

International Nuclear Information System (INIS)

Mazurkiewicz, S.M.; Fischer, M.; Bittermann, D.

2005-01-01

The EPR, an evolutionary pressurized water reactor (PWR), is a 4300-4500 MWth that incorporates proven technology within an optimized configuration to enhance safety. EPR was originally developed through a joint effort between Framatome ANP and Siemens by incorporating the best technological features from the French and German nuclear reactor fleets into a cost-competitive product. Commercial EPR units are currently being built in Finland at the Olkiluoto site, and planned for France at the Flamanville site. In recent months, Framatome ANP announced their intention to market the EPR units to China in response to a request for vendor bids as well as their intent to pursue design certification in the United States under 10CFR52. The EPR safety philosophy is based on a deterministic consideration of defense-in-depth complemented by probabilistic analyses. Not only is the EPR designed to prevent and mitigate design basis accidents (DBAs), it employs an extra level of safety associated with severe accident response. Therefore, as a design objective, features are included to ensure that radiological consequences are limited such that the need for stringent counter measures, such as evacuation and relocation of the nearby population, can be reasonably excluded. This paper discusses some of the innovative features of the EPR to address severe accident challenges. (author)

Aerodynamic shape optimization of Airfoils in 2-D incompressible flow

Science.gov (United States)

Rangasamy, Srinivethan; Upadhyay, Harshal; Somasekaran, Sandeep; Raghunath, Sreekanth

2010-11-01

An optimization framework was developed for maximizing the region of 2-D airfoil immersed in laminar flow with enhanced aerodynamic performance. It uses genetic algorithm over a population of 125, across 1000 generations, to optimize the airfoil. On a stand-alone computer, a run takes about an hour to obtain a converged solution. The airfoil geometry was generated using two Bezier curves; one to represent the thickness and the other the camber of the airfoil. The airfoil profile was generated by adding and subtracting the thickness curve from the camber curve. The coefficient of lift and drag was computed using potential velocity distribution obtained from panel code, and boundary layer transition prediction code was used to predict the location of onset of transition. The objective function of a particular design is evaluated as the weighted-average of aerodynamic characteristics at various angles of attacks. Optimization was carried out for several objective functions and the airfoil designs obtained were analyzed.

Surrogate Based Optimization of Aerodynamic Noise for Streamlined Shape of High Speed Trains

Directory of Open Access Journals (Sweden)

Zhenxu Sun

2017-02-01

Full Text Available Aerodynamic noise increases with the sixth power of the running speed. As the speed increases, aerodynamic noise becomes predominant and begins to be the main noise source at a certain high speed. As a result, aerodynamic noise has to be focused on when designing new high-speed trains. In order to perform the aerodynamic noise optimization, the equivalent continuous sound pressure level (SPL has been used in the present paper, which could take all of the far field observation probes into consideration. The Non-Linear Acoustics Solver (NLAS approach has been utilized for acoustic calculation. With the use of Kriging surrogate model, a multi-objective optimization of the streamlined shape of high-speed trains has been performed, which takes the noise level in the far field and the drag of the whole train as the objectives. To efficiently construct the Kriging model, the cross validation approach has been adopted. Optimization results reveal that both the equivalent continuous sound pressure level and the drag of the whole train are reduced in a certain extent.

Influence of inflow angle on flexible flap aerodynamic performance

International Nuclear Information System (INIS)

Zhao, H Y; Ye, Z; Li, Z M; Li, C

2013-01-01

Large scale wind turbines have larger blade lengths and weights, which creates new challenges for blade design. This paper selects NREL S809 airfoil, and uses the parameterized technology to realize the flexible trailing edge deformation, researches the dynamic aerodynamic characteristics in the process of continuous flexible deformation, analyses the influence of inflow angle on flexible flap aerodynamic performance, in order to further realize the flexible wind turbine blade design and provides some references for the active control scheme. The results show that compared with the original airfoil, proper trailing edge deformation can improve the lift coefficient, reduce the drag coefficient, and thereby more efficiently realize flow field active control. With inflow angle increases, dynamic lift-drag coefficient hysteresis loop shape deviation occurs, even turns into different shapes. Appropriate swing angle can improve the flap lift coefficient, but may cause early separation of flow. To improve the overall performance of wind turbine blades, different angular control should be used at different cross sections, in order to achieve the best performance

Aerodynamic characteristics of the modified 40- by 80-foot wind tunnel as measured in a 1/50th-scale model

Science.gov (United States)

Smith, Brian E.; Naumowicz, Tim

1987-01-01

The aerodynamic characteristics of the 40- by 80-Foot Wind Tunnel at Ames Research Center were measured by using a 1/50th-scale facility. The model was configured to closely simulate the features of the full-scale facility when it became operational in 1986. The items measured include the aerodynamic effects due to changes in the total-pressure-loss characteristics of the intake and exhaust openings of the air-exchange system, total-pressure distributions in the flow field at locations around the wind tunnel circuit, the locations of the maximum total-pressure contours, and the aerodynamic changes caused by the installation of the acoustic barrier in the southwest corner of the wind tunnel. The model tests reveal the changes in the aerodynamic performance of the 1986 version of the 40- by 80-Foot Wind Tunnel compared with the performance of the 1982 configuration.

Influence of Reynolds Number on Multi-Objective Aerodynamic Design of a Wind Turbine Blade.

Science.gov (United States)

Ge, Mingwei; Fang, Le; Tian, De

2015-01-01

At present, the radius of wind turbine rotors ranges from several meters to one hundred meters, or even more, which extends Reynolds number of the airfoil profile from the order of 105 to 107. Taking the blade for 3MW wind turbines as an example, the influence of Reynolds number on the aerodynamic design of a wind turbine blade is studied. To make the study more general, two kinds of multi-objective optimization are involved: one is based on the maximum power coefficient (CPopt) and the ultimate load, and the other is based on the ultimate load and the annual energy production (AEP). It is found that under the same configuration, the optimal design has a larger CPopt or AEP (CPopt//AEP) for the same ultimate load, or a smaller load for the same CPopt//AEP at higher Reynolds number. At a certain tip-speed ratio or ultimate load, the blade operating at higher Reynolds number should have a larger chord length and twist angle for the maximum Cpopt//AEP. If a wind turbine blade is designed by using an airfoil database with a mismatched Reynolds number from the actual one, both the load and Cpopt//AEP will be incorrectly estimated to some extent. In some cases, the assessment error attributed to Reynolds number is quite significant, which may bring unexpected risks to the earnings and safety of a wind power project.

Influence of Reynolds Number on Multi-Objective Aerodynamic Design of a Wind Turbine Blade

Science.gov (United States)

Ge, Mingwei; Fang, Le; Tian, De

2015-01-01

At present, the radius of wind turbine rotors ranges from several meters to one hundred meters, or even more, which extends Reynolds number of the airfoil profile from the order of 105 to 107. Taking the blade for 3MW wind turbines as an example, the influence of Reynolds number on the aerodynamic design of a wind turbine blade is studied. To make the study more general, two kinds of multi-objective optimization are involved: one is based on the maximum power coefficient (C Popt) and the ultimate load, and the other is based on the ultimate load and the annual energy production (AEP). It is found that under the same configuration, the optimal design has a larger C Popt or AEP (C Popt//AEP) for the same ultimate load, or a smaller load for the same C Popt//AEP at higher Reynolds number. At a certain tip-speed ratio or ultimate load, the blade operating at higher Reynolds number should have a larger chord length and twist angle for the maximum C popt//AEP. If a wind turbine blade is designed by using an airfoil database with a mismatched Reynolds number from the actual one, both the load and C popt//AEP will be incorrectly estimated to some extent. In some cases, the assessment error attributed to Reynolds number is quite significant, which may bring unexpected risks to the earnings and safety of a wind power project. PMID:26528815

The use of interpractive graphic displays for interpretation of surface design parameters

Science.gov (United States)

Talcott, N. A., Jr.

1981-01-01

An interactive computer graphics technique known as the Graphic Display Data method has been developed to provide a convenient means for rapidly interpreting large amounts of surface design data. The display technique should prove valuable in such disciplines as aerodynamic analysis, structural analysis, and experimental data analysis. To demonstrate the system's features, an example is presented of the Graphic Data Display method used as an interpretive tool for radiation equilibrium temperature distributions over the surface of an aerodynamic vehicle. Color graphic displays were also examined as a logical extension of the technique to improve its clarity and to allow the presentation of greater detail in a single display.

Aerodynamic and related hydrodynamic studies using water facilities

Energy Technology Data Exchange (ETDEWEB)

1987-06-01

Related problems, experiences and advancements in aeronautical and maritime fluid dynamics through the use of water facilities are reviewed. In recent years there has been an increasing use of water facilities for aerodynamic investigations. These include water tunnels, towing channels, and stationary tanks. Examples include basic research problems as well as flow fields around fighter aircraft, inlet flows, recirculation flow patterns associated with VTOL, ramjet simulation, etc., and, in general, 3-D flows with vortices or separated regimes as prominent features. The Symposium was organized to provide an appropriate forum for the exchange of information within the aeronautical and maritime fluid dynamics community.

Aerodynamics of wind turbines emerging topics

CERN Document Server

Amano, R S

2014-01-01

Focusing on Aerodynamics of Wind Turbines with topics ranging from Fundamental to Application of horizontal axis wind turbines, this book presents advanced topics including: Basic Theory for Wind turbine Blade Aerodynamics, Computational Methods, and Special Structural Reinforcement Technique for Wind Turbine Blades.

The ACR: Advanced design features for a short construction schedule

International Nuclear Information System (INIS)

Elgohary, M.; Fairclough, N.

2003-01-01

Building on the successful CANDU construction at Qinshan, the ACR-700 is designed with constructability considerations as a major requirement during all project phases from the concept design stage to the detail design stage. A project schedule of 48 months has been developed for the nth ACR unit with a 36 months construction period from First Concrete to Fuel Load. This paper describes some of the advanced design features implemented in the reactor building design in order to achieve this short construction period. These features include large volume concrete pours, prefabricated rebar, composite structures, prefabricated permanent formwork and significant modularization and prefabrication

Flow and Convective Heat Transfer of Cylinder Misaligned from Aerodynamic Axis of Cyclone Flow

Directory of Open Access Journals (Sweden)

I. L. Leukhin

2008-01-01

Full Text Available The paper provides and analyzes results of experimental investigations on physical specific features of hydrodynamics and convective heat transfer of a cyclone flow with a group of round cylinders located symmetrically relative to its aerodynamic axis, calculative equations for average and local heat transfer factors at characteristic sections of cylinder surface.

Parametric study on off-design aerodynamic performance of a horizontal axis wind turbine blade and proposed pitch control

International Nuclear Information System (INIS)

Najafian Ashrafi, Z.; Ghaderi, M.; Sedaghat, A.

2015-01-01

Highlights: • A pitch controlled 200 kW HAWT blade is designed with BEM for off-design conditions. • Parametric study conducted on power coefficient, axial and angular induction factors. • The optimal pitch angles were determined at off-design operating conditions. - Abstract: In this paper, a 200 kW horizontal axis wind turbine (HAWT) blade is designed using an efficient iterative algorithm based on the blade element momentum theory (BEM) on aerodynamic of wind turbines. The effects of off-design variations of wind speed are investigated on the blade performance parameters according to constant rotational speed of the rotor. The performance parameters considered are power coefficient, axial and angular induction factors, lift and drag coefficients on the blade, angle of attack and angle of relative wind. At higher or lower wind speeds than the designed rated speed, the power coefficient is reduced due to considerable changes in the angle of attacks. Therefore, proper pitch control angles were calculated to extract maximum possible power at various off-design speeds. The results showed a considerable improvement in power coefficient for the pitch controlled blade as compared with the baseline design in whole operating range. The present approach can be equally employed for determining pitch angles to design pitch control system of medium and large-scale wind turbines

Review paper on wind turbine aerodynamics

DEFF Research Database (Denmark)

Hansen, Martin Otto Laver; Aagaard Madsen, Helge

2011-01-01

The paper describes the development and description of the aerodynamic models used to estimate the aerodynamic loads on wind turbine constructions. This includes a status of the capabilities of computation fluid dynamics and the need for reliable airfoil data for the simpler engineering models...

3-D Navier-Stokes Analysis of Blade Root Aerodynamics for a Tiltrotor Aircraft In Cruise

Science.gov (United States)

Romander, Ethan

2006-01-01

The blade root area of a tiltrotor aircraft's rotor is constrained by a great many factors, not the least of which is aerodynamic performance in cruise. For this study, Navier-Stokes CFD techniques are used to study the aerodynamic performance in cruise of a rotor design as a function of airfoil thickness along the blade and spinner shape. Reducing airfoil thickness along the entire blade will be shown to have the greatest effect followed by smaller but still significant improvements achieved by reducing the thickness of root airfoils only. Furthermore, altering the shape of the spinner will be illustrated as a tool to tune the aerodynamic performance very near the blade root.

Aerodynamic and acoustic test of a United Technologies model scale rotor at DNW

Science.gov (United States)

Yu, Yung H.; Liu, Sandy R.; Jordan, Dave E.; Landgrebe, Anton J.; Lorber, Peter F.; Pollack, Michael J.; Martin, Ruth M.

1990-01-01

The UTC model scale rotors, the DNW wind tunnel, the AFDD rotary wing test stand, the UTRC and AFDD aerodynamic and acoustic data acquisition systems, and the scope of test matrices are discussed and an introduction to the test results is provided. It is pointed out that a comprehensive aero/acoustic database of several configurations of the UTC scaled model rotor has been created. The data is expected to improve understanding of rotor aerodynamics, acoustics, and dynamics, and lead to enhanced analytical methodology and design capabilities for the next generation of rotorcraft.

Ice Accretions and Full-Scale Iced Aerodynamic Performance Data for a Two-Dimensional NACA 23012 Airfoil

Science.gov (United States)

Addy, Harold E., Jr.; Broeren, Andy P.; Potapczuk, Mark G.; Lee, Sam; Guffond, Didier; Montreuil, Emmanuel; Moens, Frederic

2016-01-01

in the IRT. From these molds, castings were made that closely replicated the features of the accreted ice. The castings were then mounted on the full-scale model in the F1 tunnel, and aerodynamic performance measurements were made using model surface pressure taps, the facility force balance system, and a large wake rake designed specifically for these tests. Tests were run over a range of Reynolds and Mach numbers. For each run, the model was rotated over a range of angles-of-attack that included airfoil stall. The benchmark data collected during these campaigns were, and continue to be, used for various purposes. The full-scale data form a unique, ice-accretion and associated aerodynamic performance dataset that can be used as a reference when addressing concerns regarding the use of subscale ice-accretion data to assess full-scale icing effects. Further, the data may be used in the development or enhancement of both ice-accretion prediction codes and computational fluid dynamic codes when applied to study the effects of icing. Finally, as was done in the wider study, the data may be used to help determine the level of geometric fidelity needed for artificial ice used to assess aerodynamic degradation due to aircraft icing. The structured, multifaceted approach used in this research effort provides a unique perspective on the aerodynamic effects of aircraft icing. The data presented in this report are available in electronic form upon formal approval by proper NASA and ONERA authorities.

Aerodynamic Drag Scoping Work.

Energy Technology Data Exchange (ETDEWEB)

Voskuilen, Tyler [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Erickson, Lindsay Crowl [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knaus, Robert C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2018-02-01

This memo summarizes the aerodynamic drag scoping work done for Goodyear in early FY18. The work is to evaluate the feasibility of using Sierra/Low-Mach (Fuego) for drag predictions of rolling tires, particularly focused on the effects of tire features such as lettering, sidewall geometry, rim geometry, and interaction with the vehicle body. The work is broken into two parts. Part 1 consisted of investigation of a canonical validation problem (turbulent flow over a cylinder) using existing tools with different meshes and turbulence models. Part 2 involved calculating drag differences over plate geometries with simple features (ridges and grooves) defined by Goodyear of approximately the size of interest for a tire. The results of part 1 show the level of noise to be expected in a drag calculation and highlight the sensitivity of absolute predictions to model parameters such as mesh size and turbulence model. There is 20-30% noise in the experimental measurements on the canonical cylinder problem, and a similar level of variation between different meshes and turbulence models. Part 2 shows that there is a notable difference in the predicted drag on the sample plate geometries, however, the computational cost of extending the LES model to a full tire would be significant. This cost could be reduced by implementation of more sophisticated wall and turbulence models (e.g. detached eddy simulations - DES) and by focusing the mesh refinement on feature subsets with the goal of comparing configurations rather than absolute predictivity for the whole tire.

Aerodynamic drag of modern soccer balls.

Science.gov (United States)

Asai, Takeshi; Seo, Kazuya

2013-12-01

Soccer balls such as the Adidas Roteiro that have been used in soccer tournaments thus far had 32 pentagonal and hexagonal panels. Recently, the Adidas Teamgeist II and Adidas Jabulani, respectively having 14 and 8 panels, have been used at tournaments; the aerodynamic characteristics of these balls have not yet been verified. Now, the Adidas Tango 12, having 32 panels, has been developed for use at tournaments; therefore, it is necessary to understand its aerodynamic characteristics. Through a wind tunnel test and ball trajectory simulations, this study shows that the aerodynamic resistance of the new 32-panel soccer ball is larger in the high-speed region and lower in the middle-speed region than that of the previous 14- and 8-panel balls. The critical Reynolds number of the Roteiro, Teamgeist II, Jabulani, and Tango 12 was ~2.2 × 10(5) (drag coefficient, C d  ≈ 0.12), ~2.8 × 10(5) (C d  ≈ 0.13), ~3.3 × 10(5) (C d  ≈ 0.13), and ~2.4 × 10(5) (C d  ≈ 0.15), respectively. The flight trajectory simulation suggested that the Tango 12, one of the newest soccer balls, has less air resistance in the medium-speed region than the Jabulani and can thus easily acquire large initial velocity in this region. It is considered that the critical Reynolds number of a soccer ball, as considered within the scope of this experiment, depends on the extended total distance of the panel bonds rather than the small designs on the panel surfaces.

Fundamentals of modern unsteady aerodynamics

CERN Document Server

Gülçat, Ülgen

2016-01-01

In this book, the author introduces the concept of unsteady aerodynamics and its underlying principles. He provides the readers with a comprehensive review of the fundamental physics of free and forced unsteadiness, the terminology and basic equations of aerodynamics ranging from incompressible flow to hypersonics. The book also covers modern topics related to the developments made in recent years, especially in relation to wing flapping for propulsion. The book is written for graduate and senior year undergraduate students in aerodynamics and also serves as a reference for experienced researchers. Each chapter includes ample examples, questions, problems and relevant references.   The treatment of these modern topics has been completely revised end expanded for the new edition. It now includes new numerical examples, a section on the ground effect, and state-space representation.

Design of Mechanically Actuated Aerodynamic Braking System on a Formula Student Race Car

Science.gov (United States)

Muralidharan, Vivek; Balakrishnan, Abhijith; Vardhan, Vinit Ketan; Meena, Nikita; Kumar, Y. Suresh

2018-04-01

Every second in a racing competition counts the performance of a team against the other. Many innovative and sophisticated techniques are being employed to overcome loses in time and add to the performance of the vehicle. Especially in a car racing challenge there is more freedom to install these innovative systems to empower the car to maximum efficiency due to availability of more space. At the global spectrum there are few events which encourage such innovations. Formula Student Racing competitions are one of the global events organized by the Society of Automotive Engineers of different countries which gives opportunity to university students to build and race formula style cars. Like any other racing competitions in this high octane event having an inch over their opponents is always an advantage. Not just better acceleration and high velocities but also good deceleration is required to excel in the competition. Aerodynamic braking system is utilizing the aerodynamic drag force to create high deceleration. This mechanism can be installed on any car with spoilers with minimum modification. Being a student event great amount of care needs to be given to the safety concerns of the driver.

CFD analysis on effect of front windshield angle on aerodynamic drag

Science.gov (United States)

Abdellah, Essaghouri; Wang, Bo

2017-09-01

The external aerodynamics plays an important role in the design process of any automotive. The whole performance of the vehicle can be improved with the help of external aerodynamics. The aerodynamic analysis nowadays is implemented in the recent research in the automotive industry to achieve better cars in terms of design and efficiency. The major objective of the present work is to find out the effect of changing the angle between the engine hood and the front windshield on reducing the car air resistance. A full scale three dimensional (BMW 3 series) sedan car model was carried out using the ALIAS AUTOSTUDIO 2016 a NURBS modeling tool with high quality surfaces, only the external shape of the car was modeled while the interior was not modeled. The ANSYS 17.0 WORKBENCH software package was used to analyse the airflow around the external shape of the car - the solutions of Reynolds Average Navier Stokes (RANS) equations has been carried out using realizable k-epsilon turbulence model (which is perfectly suitable for the automated calculation process) for the given car domain. In this work, the boundary layer, mesh quality, and turbulent value simulation has been compared and discussed in the result section. Finally the optimal model was selected and the redesigned car was analysed to verify the results.

Multi-Objective Aerodynamic and Structural Optimization of Horizontal-Axis Wind Turbine Blades

Directory of Open Access Journals (Sweden)

Jie Zhu

2017-01-01

Full Text Available A procedure based on MATLAB combined with ANSYS is presented and utilized for the multi-objective aerodynamic and structural optimization of horizontal-axis wind turbine (HAWT blades. In order to minimize the cost of energy (COE and improve the overall performance of the blades, materials of carbon fiber reinforced plastic (CFRP combined with glass fiber reinforced plastic (GFRP are applied. The maximum annual energy production (AEP, the minimum blade mass and the minimum blade cost are taken as three objectives. Main aerodynamic and structural characteristics of the blades are employed as design variables. Various design requirements including strain, deflection, vibration and buckling limits are taken into account as constraints. To evaluate the aerodynamic performances and the structural behaviors, the blade element momentum (BEM theory and the finite element method (FEM are applied in the procedure. Moreover, the non-dominated sorting genetic algorithm (NSGA II, which constitutes the core of the procedure, is adapted for the multi-objective optimization of the blades. To prove the efficiency and reliability of the procedure, a commercial 1.5 MW HAWT blade is used as a case study, and a set of trade-off solutions is obtained. Compared with the original scheme, the optimization results show great improvements for the overall performance of the blade.

Design Features of Modern Mechanical Ventilators.

Science.gov (United States)

MacIntyre, Neil

2016-12-01

A positive-pressure breath ideally should provide a V T that is adequate for gas exchange and appropriate muscle unloading while minimizing any risk for injury or discomfort. The latest generation of ventilators uses sophisticated feedback systems to sculpt positive-pressure breaths according to patient effort and respiratory system mechanics. Currently, however, these new control strategies are not totally closed-loop systems. This is because the automatic input variables remain limited, some clinician settings are still required, and the specific features of the perfect breath design still are not entirely clear. Despite these limitations, there are some rationale for many of these newer feedback features. Copyright © 2016 Elsevier Inc. All rights reserved.

Aerodynamic analysis of formula student car

Science.gov (United States)

Dharmawan, Mohammad Arief; Ubaidillah, Nugraha, Arga Ahmadi; Wijayanta, Agung Tri; Naufal, Brian Aqif

2018-02-01

Formula Society of Automotive Engineering (FSAE) is a contest between ungraduated students to create a high-performance formula student car that completes the regulation. Body and the other aerodynamic devices are significant because it affects the drag coefficient and the down force of the car. The drag coefficient is a measurement of the resistance of an object in a fluid environment, a lower the drag coefficient means it will have a less drag force. Down force is a force that pushes an object to the ground, in the car more down force means more grip. The objective of the research was to study the aerodynamic comparison between the race vehicle when attached to the wings and without it. These studies were done in three dimensional (3D) computational fluid dynamic (CFD) simulation method using the Autodesk Flow Design software. These simulations were done by conducted in 5 different velocities. The results of those simulations are by attaching wings on race vehicle has drag coefficient 0.728 and without wings has drag coefficient 0.56. Wings attachment will decrease the drag coefficient about 23 % and also the contour pressure and velocity were known at these simulations.

Aerodynamic performance analysis of an airborne wind turbine system with NREL Phase IV rotor

International Nuclear Information System (INIS)

Saeed, Muhammad; Kim, Man-Hoe

2017-01-01

Highlights: • Aerodynamic predictions for a buoyant airborne system at an altitude of 400 m. • Aerodynamic characteristics of NREL Phase IV rotor operating in a shell casing. • Buoyant shell aerodynamics under varying wind conditions. - Abstract: Wind energy becomes more powerful and consistent with an increase in altitude, therefore, harvesting the wind energy at high altitude results in a naturally restocked source of energy which is cheaper and far more efficient than the conventional wind power system. Airborne wind turbine (AWT), one of the many techniques being employed for this purpose, stands out due to its uninterrupted scheme of energy production. This paper presents the aerodynamic performance of AWT system with NREL Phase IV rotor at an altitude of 400 m. Unsteady simulation of the airborne system has been carried out and variations in the rotor’s torque for a complete revolution are reported and discussed. In order to compare the performance of the shell mounted configuration of Phase IV rotor with its standard test configuration, steady state simulations of the rotor are also conducted under various wind conditions for both configurations. Finally, for stable design of the buoyant airborne system, aerodynamic forces on the shell body are computed and reported.

Dynamic soaring: aerodynamics for albatrosses

International Nuclear Information System (INIS)

Denny, Mark

2009-01-01

Albatrosses have evolved to soar and glide efficiently. By maximizing their lift-to-drag ratio L/D, albatrosses can gain energy from the wind and can travel long distances with little effort. We simplify the difficult aerodynamic equations of motion by assuming that albatrosses maintain a constant L/D. Analytic solutions to the simplified equations provide an instructive and appealing example of fixed-wing aerodynamics suitable for undergraduate demonstration

Aerodynamic efficiency of flapping flight: analysis of a two-stroke model.

Science.gov (United States)

Wang, Z Jane

2008-01-01

To seek the simplest efficient flapping wing motions and understand their relation to steady flight, a two-stroke model in the quasi-steady limit was analyzed. It was found that a family of two-stroke flapping motions have aerodynamic efficiency close to, but slightly lower than, the optimal steady flight. These two-stroke motions share two common features: the downstroke is a gliding motion and the upstroke has an angle of attack close to the optimal of the steady flight of the same wing. With the reduced number of parameters, the aerodynamic cost function in the parameter space can be visualized. This was examined for wings of different lift and drag characteristics at Reynolds numbers between 10(2) and 10(6). The iso-surfaces of the cost function have a tube-like structure, implying that the solution is insensitive to a specific direction in the parameter space. Related questions in insect flight that motivated this work are discussed.

Measured wavenumber: frequency spectrum associated with acoustic and aerodynamic wall pressure fluctuations.

Science.gov (United States)

Arguillat, Blandine; Ricot, Denis; Bailly, Christophe; Robert, Gilles

2010-10-01

Direct measurements of the wavenumber-frequency spectrum of wall pressure fluctuations beneath a turbulent plane channel flow have been performed in an anechoic wind tunnel. A rotative array has been designed that allows the measurement of a complete map, 63×63 measuring points, of cross-power spectral densities over a large area. An original post-processing has been developed to separate the acoustic and the aerodynamic exciting loadings by transforming space-frequency data into wavenumber-frequency spectra. The acoustic part has also been estimated from a simple Corcos-like model including the contribution of a diffuse sound field. The measured acoustic contribution to the surface pressure fluctuations is 5% of the measured aerodynamic surface pressure fluctuations for a velocity and boundary layer thickness relevant for automotive interior noise applications. This shows that for aerodynamically induced car interior noise, both contributions to the surface pressure fluctuations on car windows have to be taken into account.

Cable Aerodynamic Control

DEFF Research Database (Denmark)

Kleissl, Kenneth

to a categorization of the different control technics together with an identification of two key mechanisms for reduction of the design drag force. During this project extensive experimental work examining the aerodynamics of the currently used cable surface modifications together with new innovative proposals have...... been conducted. The two current prevailing systems consisting of helically filleted cables and cables with a pattern-indented surface were directly compared under the same conditions and both applications were found with attractive properties. The pattern-indented surface maintained a low supercritical...... of reducing the intensity of the axial flow and disrupting the near wake flow structures. Similar studies during wet conditions with artificial simulation of light rain in the wind tunnel showed that the plain cable suffered from severe rain-wind induced vibrations. But despite the presence of both upper...

Safety analysis for key design features of KALIMER-600 design concept

International Nuclear Information System (INIS)

Lee, Yong-Bum; Kwon, Y. M.; Kim, E. K.; Suk, S. D.; Chang, W. P.; Joeng, H. Y.; Ha, K. S.; Heo, S.

2005-03-01

KAERI is developing the conceptual design of a Liquid Metal Reactor, KALIMER-600 (Korea Advanced LIquid MEtal Reactor) under the Long-term Nuclear R and D Program. KALIMER-600 addresses key issues regarding future nuclear power plants such as plant safety, economics, proliferation, and waste. In this report, key safety design features are described and safety analyses results for typical ATWS accidents, containment design basis accidents, and flow blockages in the KALIMER design are presented. First, the basic approach to achieve the safety goal and main design features of KALIMER-600 are introduced in Chapter 1, and the event categorization and acceptance criteria for the KALIMER-600 safety analysis are described in Chapter 2, In Chapter 3, results of inherent safety evaluations for the KALIMER-600 conceptual design are presented. The KALIMER-600 core and plant system are designed to assure benign performance during a selected set of events without either reactor control or protection system intervention. Safety analyses for the postulated anticipated transient without scram (ATWS) have been performed using the SSC-K code to investigate the KALIMER-600 system response to the events. The objectives of Chapter 4, are to assess the response of KALIMER-600 containment to the design basis accidents and to evaluate whether the consequences are acceptable or not in the aspect of structural integrity and the exposure dose rate. In Chapter 5, the analysis of flow blockage for KALIMER-600 with the MATRA-LMR-FB code, which has been developed for the internal flow blockage in a LMR subassembly, are described. The cases with a blockage of 6-subchannel, 24-subchannel, and 54-subchannel are analyzed

Test-retest reliability for aerodynamic measures of voice.

Science.gov (United States)

Awan, Shaheen N; Novaleski, Carolyn K; Yingling, Julie R

2013-11-01

The purpose of this study was to investigate the intrasubject reliability of aerodynamic characteristics of the voice within typical/normal speakers across testing sessions using the Phonatory Aerodynamic System (PAS 6600; KayPENTAX, Montvale, NJ). Participants were 60 healthy young adults (30 males and 30 females) between the ages 18 and 31 years with perceptually typical voice. Participants were tested using the PAS 6600 (Phonatory Aerodynamic System) on two separate days with approximately 1 week between each session at approximately the same time of day. Four PAS protocols were conducted (vital capacity, maximum sustained phonation, comfortable sustained phonation, and voicing efficiency) and measures of expiratory volume, maximum phonation time, mean expiratory airflow (during vowel production) and target airflow (obtained via syllable repetition), peak air pressure, aerodynamic power, aerodynamic resistance, and aerodynamic efficiency were obtained during each testing session. Associated acoustic measures of vocal intensity and frequency were also collected. All phonations were elicited at comfortable pitch and loudness. All aerodynamic and associated variables evaluated in this study showed useable test-retest reliability (ie, intraclass correlation coefficients [ICCs] ≥ 0.60). A high degree of mean test-retest reliability was found across all subjects for aerodynamic and associated acoustic measurements of vital capacity, maximum sustained phonation, glottal resistance, and vocal intensity (all with ICCs > 0.75). Although strong ICCs were observed for measures of glottal power and mean expiratory airflow in males, weaker overall results for these measures (ICC range: 0.60-0.67) were observed in females subjects and sizable coefficients of variation were observed for measures of power, resistance, and efficiency in both men and women. Differences in degree of reliability from measure to measure were revealed in greater detail using methods such as ICCs and

Take-off aerodynamics in ski jumping.

Science.gov (United States)

Virmavirta, M; Kivekäs, J; Komi, P V

2001-04-01

The effect of aerodynamic forces on the force-time characteristics of the simulated ski jumping take-off was examined in a wind tunnel. Vertical and horizontal ground reaction forces were recorded with a force plate installed under the wind tunnel floor. The jumpers performed take-offs in non-wind conditions and in various wind conditions (21-33 m s(-1)). EMGs of the important take-off muscles were recorded from one jumper. The dramatic decrease in take-off time found in all jumpers can be considered as the result of the influence of aerodynamic lift. The loss in impulse due to the shorter force production time with the same take-off force is compensated with the increase in lift force, resulting in a higher vertical velocity (V(v)) than is expected from the conventional calculation of V(v) from the force impulse. The wind conditions emphasized the explosiveness of the ski jumping take-off. The aerodynamic lift and drag forces which characterize the aerodynamic quality of the initial take-off position (static in-run position) varied widely even between the examined elite ski jumpers. According to the computer simulation these differences can decisively affect jumping distance. The proper utilization of the prevailing aerodynamic forces before and during take-off is a very important prerequisite for achieving a good flight position.

Aerodynamic performance and particle image velocimetery of piezo actuated biomimetic manduca sexta engineered wings towards the design and application of a flapping wing flight vehicle

Science.gov (United States)

DeLuca, Anthony M.

Considerable research and investigation has been conducted on the aerodynamic performance, and the predominate flow physics of the Manduca Sexta size of biomimetically designed and fabricated wings as part of the AFIT FWMAV design project. Despite a burgeoning interest and research into the diverse field of flapping wing flight and biomimicry, the aerodynamics of flapping wing flight remains a nebulous field of science with considerable variance into the theoretical abstractions surrounding aerodynamic mechanisms responsible for aerial performance. Traditional FWMAV flight models assume a form of a quasi-steady approximation of wing aerodynamics based on an infinite wing blade element model (BEM). An accurate estimation of the lift, drag, and side force coefficients is a critical component of autonomous stability and control models. This research focused on two separate experimental avenues into the aerodynamics of AFIT's engineered hawkmoth wings|forces and flow visualization. 1. Six degree of freedom force balance testing, and high speed video analysis was conducted on 30°, 45°, and 60° angle stop wings. A novel, non-intrusive optical tracking algorithm was developed utilizing a combination of a Gaussian Mixture Model (GMM) and ComputerVision (OpenCV) tools to track the wing in motion from multiple cameras. A complete mapping of the wing's kinematic angles as a function of driving amplitude was performed. The stroke angle, elevation angle, and angle of attack were tabulated for all three wings at driving amplitudes ranging from A=0.3 to A=0.6. The wing kinematics together with the force balance data was used to develop several aerodynamic force coefficient models. A combined translational and rotational aerodynamic model predicted lift forces within 10%, and vertical forces within 6%. The total power consumption was calculated for each of the three wings, and a Figure of Merit was calculated for each wing as a general expression of the overall efficiency of

Major NSSS design features of the Korean next generation reactor

International Nuclear Information System (INIS)

Kim, Insk; Kim, Dong-Su

1999-01-01

In order to meet national needs for increasing electric power generation in the Republic of Korea in the 2000s, the Korean nuclear development group (KNDG) is developing a standardized evolutionary advanced light water reactor (ALWR), the Korean Next Generation Reactor (KNGR). It is an advanced version of the successful Korean Standard Nuclear Power Plant (KSNP) design, which meets utility needs for safety enhancement, performance improvement and ease of operation and maintenance. The KNGR design starts fro the proven design concept of the currently operating KSNPs with uprated power and advanced design features required by the utility. The KNGR design is currently in the final stage of the basic design, and the paper describes the major nuclear steam supply system (NSSS) design features of the KNGR together with introduction of the KNGR development program. (author)

Calculation and Identification of the Aerodynamic Parameters for Small-Scaled Fixed-Wing UAVs

Directory of Open Access Journals (Sweden)

Jieliang Shen

2018-01-01

Full Text Available The establishment of the Aircraft Dynamic Model (ADM constitutes the prerequisite for the design of the navigation and control system, but the aerodynamic parameters in the model could not be readily obtained especially for small-scaled fixed-wing UAVs. In this paper, the procedure of computing the aerodynamic parameters is developed. All the longitudinal and lateral aerodynamic derivatives are firstly calculated through semi-empirical method based on the aerodynamics, rather than the wind tunnel tests or fluid dynamics software analysis. Secondly, the residuals of each derivative are proposed to be identified or estimated further via Extended Kalman Filter(EKF, with the observations of the attitude and velocity from the airborne integrated navigation system. Meanwhile, the observability of the targeted parameters is analyzed and strengthened through multiple maneuvers. Based on a small-scaled fixed-wing aircraft driven by propeller, the airborne sensors are chosen and the model of the actuators are constructed. Then, real flight tests are implemented to verify the calculation and identification process. Test results tell the rationality of the semi-empirical method and show the improvement of accuracy of ADM after the compensation of the parameters.

Calculation and Identification of the Aerodynamic Parameters for Small-Scaled Fixed-Wing UAVs.

Science.gov (United States)

Shen, Jieliang; Su, Yan; Liang, Qing; Zhu, Xinhua

2018-01-13

The establishment of the Aircraft Dynamic Model(ADM) constitutes the prerequisite for the design of the navigation and control system, but the aerodynamic parameters in the model could not be readily obtained especially for small-scaled fixed-wing UAVs. In this paper, the procedure of computing the aerodynamic parameters is developed. All the longitudinal and lateral aerodynamic derivatives are firstly calculated through semi-empirical method based on the aerodynamics, rather than the wind tunnel tests or fluid dynamics software analysis. Secondly, the residuals of each derivative are proposed to be identified or estimated further via Extended Kalman Filter(EKF), with the observations of the attitude and velocity from the airborne integrated navigation system. Meanwhile, the observability of the targeted parameters is analyzed and strengthened through multiple maneuvers. Based on a small-scaled fixed-wing aircraft driven by propeller, the airborne sensors are chosen and the model of the actuators are constructed. Then, real flight tests are implemented to verify the calculation and identification process. Test results tell the rationality of the semi-empirical method and show the improvement of accuracy of ADM after the compensation of the parameters.

Turbofan Engine Core Compartment Vent Aerodynamic Configuration Development Methodology

Science.gov (United States)

Hebert, Leonard J.

2006-01-01

This paper presents an overview of the design methodology used in the development of the aerodynamic configuration of the nacelle core compartment vent for a typical Boeing commercial airplane together with design challenges for future design efforts. Core compartment vents exhaust engine subsystem flows from the space contained between the engine case and the nacelle of an airplane propulsion system. These subsystem flows typically consist of precooler, oil cooler, turbine case cooling, compartment cooling and nacelle leakage air. The design of core compartment vents is challenging due to stringent design requirements, mass flow sensitivity of the system to small changes in vent exit pressure ratio, and the need to maximize overall exhaust system performance at cruise conditions.

Evaluating public awareness of new currency design features

Science.gov (United States)

DiNunzio, Lisa; Church, Sara E.

2002-04-01

One of the goals of the 1996 series design was to integrate highly recognizable features that enable the general public to more easily distinguish counterfeit from genuine notes, thereby reducing the chance of counterfeit notes being passed. The purpose of this study is to evaluate how knowledgeable the public is concerning the new currency, to identify the channels through which the public learns about new currency design, and to assess the usefulness of the new currency's authentication features. Also, the study will serve as a baseline measurement for future design studies and in comparative analysis with other countries. The results of the qualitative research will be described in the following sections of this paper. The quantitative research is scheduled to begin in February 2002, at the same time as the Netherlands' opinion poll of the Euro and NLG-notes in an effort to compare results.

Effects of axial gap and nozzle distribution on aerodynamic forces of a supersonic partial-admission turbine

Directory of Open Access Journals (Sweden)

Jinpeng JIANG

2017-12-01

Full Text Available The turbine in an LH2/LOX rocket engine is designed as a two-stage supersonic partial-admission turbine. Three-dimensional steady and unsteady simulations were conducted to analyze turbine performance and aerodynamic forces on rotor blades. Different configurations were employed to investigate the effects of the axial gap and nozzle distribution on the predicted performance and aerodynamic forces. Rotor blades experience unsteady aerodynamic forces because of the partial admission. Aerodynamic forces show periodicity in the admission region, and are close to zero after leaving the admission region. The unsteady forces in frequency domain indicate that components exist in a wide frequency region, and the admission passing frequency is dominant. Those multiples of the rotational frequency which are multiples of the nozzle number in a full-admission turbine are notable components. Results show that the turbine efficiency decreases as the axial gap between nozzles and the 1st stage rotor (rotor 1 increases. Fluctuation of the circumferential aerodynamic force on rotor 1 blades decreases with the axial gap increasing. The turbine efficiency decreases as the circumferential spacing between nozzles increases. Fluctuations of the circumferential and axial aerodynamic forces increase as the circumferential spacing increases. As for the non-equidistant nozzle distribution, it produces similar turbine performance and amplitude-frequency characteristics of forces to those of the normal configuration, when the mean spacing is equal to that of the normal case. Keywords: Aerodynamic force, Axial gap, Computational fluid dynamics (CFD, Nozzle distribution, Partial admission, Turbine

AEROSTATIC AND AERODYNAMIC MODULES OF A HYBRID BUOYANT AIRCRAFT: AN ANALYTICAL APPROACH

Directory of Open Access Journals (Sweden)

Anwar Ul Haque

2015-05-01

Full Text Available An analytical approach is essential for the estimation of the requirements of aerodynamic and aerostatic lift for a hybrid buoyant aircraft. Such aircrafts have two different modules to balance the weight of aircraft; aerostatic module and aerodynamic module. Both these modules are to be treated separately for estimation of the mass budget of propulsion systems and required power. In the present work, existing relationships of aircraft and airship are reviewed for its further application for these modules. Limitations of such relationships are also disussed and it is precieved that it will provide a strating point for better understanding of design anatomy of such aircraft.

Study on the aerodynamic behavior of a UAV with an applied seeder for agricultural practices

Science.gov (United States)

Felismina, Raimundo; Silva, Miguel; Mateus, Artur; Malça, Cândida

2017-06-01

It is irrefutable that the use of Unmanned Airborne Vehicle Systems (UAVs) in agricultural tasks and on the analysis of health and vegetative conditions represents a powerful tool in modern agriculture. To contribute to the growth of the agriculture economic sector a seeder to be coupled to any type of UAV was previously developed and designed by the authors. This seeder allows for the deposition of seeds with positional accuracy, i.e., seeds are accurately deposited at pre-established distances between plants [1]. This work aims at analyzing the aerodynamic behavior of UAV/Seeder assembly to determine the suitable inclination - among 0°, 15° and 30° - for its takeoff and for its motion during the seeding operation and, in turn, to define the suitable flight plan that increases the batteries autonomy. For this the ANSYS® FLUENT computational tool was used to simulate a wind tunnel which has as principle the Navier-Stokes differential equations, that designates the fluid flow around the UAV/Seeder assembly. The aerodynamic results demonstrated that for take-off the UAV inclination of 30° is the aerodynamically most favorable position due to the lower aerodynamic drag during the climb. Concerning flying motion during the seeding procedure the UAV inclination of 0° is that which leads to lower UAV/Seeder frontal area and drag coefficient.

[Aerodynamic focusing of particles and heavy molecules

International Nuclear Information System (INIS)

de la Mora, J.F.

1990-01-01

By accelerating a gas containing suspended particles or large molecules through a converging nozzle, the suspended species may be focused and therefore used to write fine lines on a surface. Our objective was to study the limits on how narrow this focal region could be as a function of particle size. We find that, for monodisperse particles with masses m p some 3.6 x 10 5 times larger than the molecular mass m of the carrier gas (diameters above some 100 angstrom), there is no fundamental obstacle to directly write submicron features. However, this conclusion has been verified experimentally only with particles larger than 0.1 μm. Experimental, theoretical and numerical studies on the defocusing role of Brownian motion for very small particles or heavy molecules have shown that high resolution (purely aerodynamic) focusing is impossible with volatile molecules whose masses are typically smaller than 1000 Dalton. For these, the minimal focal diameter after optimization appears to be 5√(m/m p ) times the nozzle diameter d n . But combinations of focused lasers and aerodynamic focusing appear as promising for direct writing with molecular precursors. Theoretical and numerical schemes capable of predicting the evolution of the focusing beam, including Brownian motion effects, have been developed, although further numerical work would be desirable. 11 refs

Selected advanced aerodynamics and active controls technology concepts development on a derivative B-747 aircraft

Science.gov (United States)

1983-01-01

Analytical design and wind tunnel test evaluations covering the feasibility of applying wing tip extensions, winglets, and active control wing had alleviation to the model B747 are described. Aerodynamic improvement offered by wing tip extension and winglet individually, and the combined aerodynamic and weight improvements when wing load alleviation is combined with the tip extension or the winglet are evaluated. Results are presented in the form of incremental effects on weight mission range, fuel usage, cost, and airline operating economics.

Computer subroutine for estimating aerodynamic blade loads on Darrieus vertical axis wind turbines. [FORCE code

Energy Technology Data Exchange (ETDEWEB)

Sullivan, W. N.; Leonard, T. M.

1980-11-01

An important aspect of structural design of the Darrieus rotor is the determination of aerodynamic blade loads. This report describes a load generator which has been used at Sandia for quasi-static and dynamic rotor analyses. The generator is based on the single streamtube aerodynamic flow model and is constructed as a FORTRAN IV subroutine to facilitate its use in finite element structural models. Input and output characteristics of the subroutine are described and a complete listing is attached as an appendix.

Future Computer Requirements for Computational Aerodynamics

Science.gov (United States)

1978-01-01

Recent advances in computational aerodynamics are discussed as well as motivations for and potential benefits of a National Aerodynamic Simulation Facility having the capability to solve fluid dynamic equations at speeds two to three orders of magnitude faster than presently possible with general computers. Two contracted efforts to define processor architectures for such a facility are summarized.

The aerodynamic cost of flight in the short-tailed fruit bat (Carollia perspicillata): comparing theory with measurement.

Science.gov (United States)

von Busse, Rhea; Waldman, Rye M; Swartz, Sharon M; Voigt, Christian C; Breuer, Kenneth S

2014-06-06

Aerodynamic theory has long been used to predict the power required for animal flight, but widely used models contain many simplifications. It has been difficult to ascertain how closely biological reality matches model predictions, largely because of the technical challenges of accurately measuring the power expended when an animal flies. We designed a study to measure flight speed-dependent aerodynamic power directly from the kinetic energy contained in the wake of bats flying in a wind tunnel. We compared these measurements with two theoretical predictions that have been used for several decades in diverse fields of vertebrate biology and to metabolic measurements from a previous study using the same individuals. A high-accuracy displaced laser sheet stereo particle image velocimetry experimental design measured the wake velocities in the Trefftz plane behind four bats flying over a range of speeds (3-7 m s(-1)). We computed the aerodynamic power contained in the wake using a novel interpolation method and compared these results with the power predicted by Pennycuick's and Rayner's models. The measured aerodynamic power falls between the two theoretical predictions, demonstrating that the models effectively predict the appropriate range of flight power, but the models do not accurately predict minimum power or maximum range speeds. Mechanical efficiency--the ratio of aerodynamic power output to metabolic power input--varied from 5.9% to 9.8% for the same individuals, changing with flight speed.

Numerical investigation of geometric parameter effects on the aerodynamic performance of a Bladeless fan

OpenAIRE

Mohammad Jafari; Hossein Afshin; Bijan Farhanieh; Atta Sojoudi

2016-01-01

Aerodynamic performance of a Bladeless fan is numerically investigated considering the effect of five geometric parameters. Airflow through this fan was analyzed by simulating a Bladeless fan within a 2 m × 2 m × 4 m room. Analysis of the flow field inside the fan and the evaluation of its performance were obtained by solving conservations of mass and momentum equations for the aerodynamic investigations. In order to design the Bladeless fan an Eppler 473 airfoil profile was used as the cross...

HANARO cooling features: design and experience

International Nuclear Information System (INIS)

Park, Cheol; Chae, Hee-Taek; Han, Gee-Yang; Jun, Byung-Jin; Ahn, Guk-Hoon

1999-01-01

In order to achieve the safe core cooling during normal operation and upset conditions, HANARO adopted an upward forced convection cooling system with dual containment arrangements instead of the forced downward flow system popularly used in the majority of forced convection cooling research reactors. This kind of upward flow system was selected by comparing the relative merits of upward and downward flow systems from various points of view such as safety, performance, maintenance. However, several operational matters which were not regarded as serious at design come out during operation. In this paper are presented the design and operational experiences on the unique cooling features of HANARO. (author)

Aerodynamical calculation of turbomachinery bladings

International Nuclear Information System (INIS)

Fruehauf, H.H.

1978-01-01

Various flow models are presented in comparison to one another, these flow models being obtained from the basic equations of turbomachinery aerodynamics by means of a series of simplifying assumptions on the spatial distribution of the flow quantities. The simplifying assumptions are analysed precisely. With their knowledge it is possible to construct more accurate simplified flow models, which are necessary for the efficient aerodynamical development of highperformance turbomachinery bladings by means of numerical methods. (orig.) 891 HP [de

Indigenous development and performance evaluation of BARC aerodynamic size separator (BASS)

International Nuclear Information System (INIS)

Singh, Sanjay; Purwar, R.C.; Das, Tanmoy; Narayanan, K.P.; Sapra, B.K.; Sunny, Faby; Khan, Arshad; Mayya, Y.S.

2002-06-01

Commercially available cascade impactors, commonly used for aerodynamic size separation of aerosol particles, are based on the principle of inertial impaction. As of now, these instruments are imported at a cost of several lakhs of rupees; hence an effort has been made to develop an aerodynamic particle sizer indigenously in BARC. This unit, referred to as BARC Aerodynamic Size Separator (BASS), separates aerosols into seven size classes ranging from 0.53 μm to 10 μm and operates at a flow rate of 45 Ipm. Intercomparison studies between the standard Andersen Mark-II (Grasbey Andersen Inc.) impactor and BASS using nebulizer generated aerosols have consistently shown excellent performance by BASS in all respects. In particular, BASS yielded the parameters of polydisperse aerosols quite accurately. Experiments to evaluate the individual stage cut-off diameters show that these are within 8% of their designed value for all stages except the higher two stages which indicate about 30% lower values than the designed ones. The replotting of all the mass distribution data using the experimental cut-off diameters showed perfect lognormal fits, thereby indicating that these diameters are closer to the true stage cut-off diameters for BASS. The studies show that BASS will be suitable for determining the particle size distributions in the context of the radiological safety programmes of DAE. Being indigenous in design, it may be fabricated on a commercial scale at a cost far less than that of the imported units. Such a venture will greatly help several national programmes on atmospheric pollution being carried out by many laboratories and institutions across the country. (author)

High-Fidelity Aerodynamic Shape Optimization for Natural Laminar Flow

Science.gov (United States)

Rashad, Ramy

To ensure the long-term sustainability of aviation, serious effort is underway to mitigate the escalating economic, environmental, and social concerns of the industry. Significant improvement to the energy efficiency of air transportation is required through the research and development of advanced and unconventional airframe and engine technologies. In the quest to reduce airframe drag, this thesis is concerned with the development and demonstration of an effective design tool for improving the aerodynamic efficiency of subsonic and transonic airfoils. The objective is to advance the state-of-the-art in high-fidelity aerodynamic shape optimization by incorporating and exploiting the phenomenon of laminar-turbulent transition in an efficient manner. A framework for the design and optimization of Natural Laminar Flow (NLF) airfoils is developed and demonstrated with transition prediction capable of accounting for the effects of Reynolds number, freestream turbulence intensity, Mach number, and pressure gradients. First, a two-dimensional Reynolds-averaged Navier-Stokes (RANS) flow solver has been extended to incorporate an iterative laminar-turbulent transition prediction methodology. The natural transition locations due to Tollmien-Schlichting instabilities are predicted using the simplified eN envelope method of Drela and Giles or, alternatively, the compressible form of the Arnal-Habiballah-Delcourt criterion. The boundary-layer properties are obtained directly from the Navier-Stokes flow solution, and the transition to turbulent flow is modeled using an intermittency function in conjunction with the Spalart-Allmaras turbulence model. The RANS solver is subsequently employed in a gradient-based sequential quadratic programming shape optimization framework. The laminar-turbulent transition criteria are tightly coupled into the objective and gradient evaluations. The gradients are obtained using a new augmented discrete-adjoint formulation for non-local transition

Multi-objective Optimization Strategies Using Adjoint Method and Game Theory in Aerodynamics

Science.gov (United States)

Tang, Zhili

2006-08-01

There are currently three different game strategies originated in economics: (1) Cooperative games (Pareto front), (2) Competitive games (Nash game) and (3) Hierarchical games (Stackelberg game). Each game achieves different equilibria with different performance, and their players play different roles in the games. Here, we introduced game concept into aerodynamic design, and combined it with adjoint method to solve multi-criteria aerodynamic optimization problems. The performance distinction of the equilibria of these three game strategies was investigated by numerical experiments. We computed Pareto front, Nash and Stackelberg equilibria of the same optimization problem with two conflicting and hierarchical targets under different parameterizations by using the deterministic optimization method. The numerical results show clearly that all the equilibria solutions are inferior to the Pareto front. Non-dominated Pareto front solutions are obtained, however the CPU cost to capture a set of solutions makes the Pareto front an expensive tool to the designer.

Multi-objective optimization strategies using adjoint method and game theory in aerodynamics

Institute of Scientific and Technical Information of China (English)

Zhili Tang

2006-01-01

There are currently three different game strategies originated in economics:(1) Cooperative games (Pareto front),(2)Competitive games (Nash game) and (3)Hierarchical games (Stackelberg game).Each game achieves different equilibria with different performance,and their players play different roles in the games.Here,we introduced game concept into aerodynamic design, and combined it with adjoint method to solve multicriteria aerodynamic optimization problems.The performance distinction of the equilibria of these three game strategies was investigated by numerical experiments.We computed Pareto front, Nash and Stackelberg equilibria of the same optimization problem with two conflicting and hierarchical targets under different parameterizations by using the deterministic optimization method.The numerical results show clearly that all the equilibria solutions are inferior to the Pareto front.Non-dominated Pareto front solutions are obtained,however the CPU cost to capture a set of solutions makes the Pareto front an expensive tool to the designer.

The aerodynamic cost of head morphology in bats: maybe not as bad as it seems.

Science.gov (United States)

Vanderelst, Dieter; Peremans, Herbert; Razak, Norizham Abdul; Verstraelen, Edouard; Dimitriadis, Grigorios; Dimitriadis, Greg

2015-01-01

At first sight, echolocating bats face a difficult trade-off. As flying animals, they would benefit from a streamlined geometric shape to reduce aerodynamic drag and increase flight efficiency. However, as echolocating animals, their pinnae generate the acoustic cues necessary for navigation and foraging. Moreover, species emitting sound through their nostrils often feature elaborate noseleaves that help in focussing the emitted echolocation pulses. Both pinnae and noseleaves reduce the streamlined character of a bat's morphology. It is generally assumed that by compromising the streamlined charactered of the geometry, the head morphology generates substantial drag, thereby reducing flight efficiency. In contrast, it has also been suggested that the pinnae of bats generate lift forces counteracting the detrimental effect of the increased drag. However, very little data exist on the aerodynamic properties of bat pinnae and noseleaves. In this work, the aerodynamic forces generated by the heads of seven species of bats, including noseleaved bats, are measured by testing detailed 3D models in a wind tunnel. Models of Myotis daubentonii, Macrophyllum macrophyllum, Micronycteris microtis, Eptesicus fuscus, Rhinolophus formosae, Rhinolophus rouxi and Phyllostomus discolor are tested. The results confirm that non-streamlined facial morphologies yield considerable drag forces but also generate substantial lift. The net effect is a slight increase in the lift-to-drag ratio. Therefore, there is no evidence of high aerodynamic costs associated with the morphology of bat heads.

Computational electromagnetic-aerodynamics

CERN Document Server

Shang, Joseph J S

2016-01-01

Presents numerical algorithms, procedures, and techniques required to solve engineering problems relating to the interactions between electromagnetic fields, fluid flow, and interdisciplinary technology for aerodynamics, electromagnetics, chemical-physics kinetics, and plasmadynamics This book addresses modeling and simulation science and technology for studying ionized gas phenomena in engineering applications. Computational Electromagnetic-Aerodynamics is organized into ten chapters. Chapter one to three introduce the fundamental concepts of plasmadynamics, chemical-physics of ionization, classical magnetohydrodynamics, and their extensions to plasma-based flow control actuators, high-speed flows of interplanetary re-entry, and ion thrusters in space exploration. Chapter four to six explain numerical algorithms and procedures for solving Maxwell’s equation in the time domain for computational electromagnetics, plasma wave propagation, and the time-dependent c mpressible Navier-Stokes equation for aerodyn...

Aerodynamic shape optimization directed toward a supersonic transport using sensitivity analysis

Science.gov (United States)

Baysal, Oktay

1995-01-01

This investigation was conducted from March 1994 to August 1995, primarily, to extend and implement the previously developed aerodynamic design optimization methodologies for the problems related to a supersonic transport design. These methods had demonstrated promise to improve the designs (more specifically, the shape) of aerodynamic surfaces, by coupling optimization algorithms (OA) with Computational Fluid Dynamics (CFD) algorithms via sensitivity analyses (SA) with surface definition methods from Computer Aided Design (CAD). The present extensions of this method and their supersonic implementations have produced wing section designs, delta wing designs, cranked-delta wing designs, and nacelle designs, all of which have been reported in the open literature. Despite the fact that these configurations were highly simplified to be of any practical or commercial use, they served the algorithmic and proof-of-concept objectives of the study very well. The primary cause for the configurational simplifications, other than the usual simplify-to-study the fundamentals reason, were the premature closing of the project. Only after the first of the originally intended three-year term, both the funds and the computer resources supporting the project were abruptly cut due to their severe shortages at the funding agency. Nonetheless, it was shown that the extended methodologies could be viable options in optimizing the design of not only an isolated single-component configuration, but also a multiple-component configuration in supersonic and viscous flow. This allowed designing with the mutual interference of the components being one of the constraints all along the evolution of the shapes.

Design features of SMART for barge mounted application

International Nuclear Information System (INIS)

Doo-Jeong Lee; Ju-Hyeon Yoon; Ju-Pyung Kim; Jong-In Kim; Moon-Hee Chang

2000-01-01

SMART is an integral reactor of 330 MWt capacity with passive safety features being developed for a wide range of applications including the barge mounted co-generation plant. Its design strives to combine the firmly-established commercial reactor design with new advanced technologies. Thus the use of the industry proven KOFA (Korea Optimized Fuel Assembly) based nuclear fuels is pursued while such radically new technologies as self-pressurizing pressurizer, helical once-through steam generators, and advanced control concepts are being developed. The safety of SMART centers around enhancing the inherent safety characteristics of the reactor and salient features include low core power density, integral arrangement to eliminate large break loss of coolant accident, etc. The progression of emergency situations into accidents is prevented with a number of advanced engineered safety features such as Passive Residual Heat Removal System, Passive Emergency Core Cooling System, Safeguard Vessel, Passive Containment Over-pressure Protection. This paper presents the status of current SMART development, characteristics of SMART safety systems and the possibility of SMART application to barge mounted environment. (author)

Aerodynamics power consumption for mechanical flapping wings undergoing flapping and pitching motion

Science.gov (United States)

Razak, N. A.; Dimitriadis, G.; Razaami, A. F.

2017-07-01

Lately, due to the growing interest in Micro Aerial Vehicles (MAV), interest in flapping flight has been rekindled. The reason lies in the improved performance of flapping wing flight at low Reynolds number regime. Many studies involving flapping wing flight focused on the generation of unsteady aerodynamic forces such as lift and thrust. There is one aspect of flapping wing flight that received less attention. The aspect is aerodynamic power consumption. Since most mechanical flapping wing aircraft ever designed are battery powered, power consumption is fundamental in improving flight endurance. This paper reports the results of experiments carried out on mechanical wings under going active root flapping and pitching in the wind tunnel. The objective of the work is to investigate the effect of the pitch angle oscillations and wing profile on the power consumption of flapping wings via generation of unsteady aerodynamic forces. The experiments were repeated for different airspeeds, flapping and pitching kinematics, geometric angle of attack and wing sections with symmetric and cambered airfoils. A specially designed mechanical flapper modelled on large migrating birds was used. It will be shown that, under pitch leading conditions, less power is required to overcome the unsteady aerodnamics forces. The study finds less power requirement for downstroke compared to upstroke motion. Overall results demonstrate power consumption depends directly on the unsteady lift force.

Generation of Fullspan Leading-Edge 3D Ice Shapes for Swept-Wing Aerodynamic Testing

Science.gov (United States)

Camello, Stephanie C.; Lee, Sam; Lum, Christopher; Bragg, Michael B.

2016-01-01

The deleterious effect of ice accretion on aircraft is often assessed through dry-air flight and wind tunnel testing with artificial ice shapes. This paper describes a method to create fullspan swept-wing artificial ice shapes from partial span ice segments acquired in the NASA Glenn Icing Reserch Tunnel for aerodynamic wind-tunnel testing. Full-scale ice accretion segments were laser scanned from the Inboard, Midspan, and Outboard wing station models of the 65% scale Common Research Model (CRM65) aircraft configuration. These were interpolated and extrapolated using a weighted averaging method to generate fullspan ice shapes from the root to the tip of the CRM65 wing. The results showed that this interpolation method was able to preserve many of the highly three dimensional features typically found on swept-wing ice accretions. The interpolated fullspan ice shapes were then scaled to fit the leading edge of a 8.9% scale version of the CRM65 wing for aerodynamic wind-tunnel testing. Reduced fidelity versions of the fullspan ice shapes were also created where most of the local three-dimensional features were removed. The fullspan artificial ice shapes and the reduced fidelity versions were manufactured using stereolithography.

Urban Aerodynamic Roughness Length Mapping Using Multitemporal SAR Data

Directory of Open Access Journals (Sweden)

Fengli Zhang

2017-01-01

Full Text Available Aerodynamic roughness is very important to urban meteorological and climate studies. Radar remote sensing is considered to be an effective means for aerodynamic roughness retrieval because radar backscattering is sensitive to the surface roughness and geometric structure of a given target. In this paper, a methodology for aerodynamic roughness length estimation using SAR data in urban areas is introduced. The scale and orientation characteristics of backscattering of various targets in urban areas were firstly extracted and analyzed, which showed great potential of SAR data for urban roughness elements characterization. Then the ground truth aerodynamic roughness was calculated from wind gradient data acquired by the meteorological tower using fitting and iterative method. And then the optimal dimension of the upwind sector for the aerodynamic roughness calculation was determined through a correlation analysis between backscattering extracted from SAR data at various upwind sector areas and the aerodynamic roughness calculated from the meteorological tower data. Finally a quantitative relationship was set up to retrieve the aerodynamic roughness length from SAR data. Experiments based on ALOS PALSAR and COSMO-SkyMed data from 2006 to 2011 prove that the proposed methodology can provide accurate roughness length estimations for the spatial and temporal analysis of urban surface.

Interactive Graphics Analysis for Aircraft Design

Science.gov (United States)

Townsend, J. C.

1983-01-01

Program uses higher-order far field drag minimization. Computer program WDES WDEM preliminary aerodynamic design tool for one or two interacting, subsonic lifting surfaces. Subcritical wing design code employs higher-order far-field drag minimization technique. Linearized aerodynamic theory used. Program written in FORTRAN IV.

Development of Design Methodology for a Small Solar-Powered Unmanned Aerial Vehicle

Directory of Open Access Journals (Sweden)

Parvathy Rajendran

2018-01-01

Full Text Available Existing mathematical design models for small solar-powered electric unmanned aerial vehicles (UAVs only focus on mass, performance, and aerodynamic analyses. Presently, UAV designs have low endurance. The current study aims to improve the shortcomings of existing UAV design models. Three new design aspects (i.e., electric propulsion, sensitivity, and trend analysis, three improved design properties (i.e., mass, aerodynamics, and mission profile, and a design feature (i.e., solar irradiance are incorporated to enhance the existing small solar UAV design model. A design validation experiment established that the use of the proposed mathematical design model may at least improve power consumption-to-take-off mass ratio by 25% than that of previously designed UAVs. UAVs powered by solar (solar and battery and nonsolar (battery-only energy were also compared, showing that nonsolar UAVs can generally carry more payloads at a particular time and place than solar UAVs with sufficient endurance requirement. The investigation also identified that the payload results in the highest effect on the maximum take-off weight, followed by the battery, structure, and propulsion weight with the three new design aspects (i.e., electric propulsion, sensitivity, and trend analysis for sizing consideration to optimize UAV designs.

Aerodynamic flow deflector to increase large scale wind turbine power generation by 10%.

Science.gov (United States)

2015-11-01

The innovation proposed in this paper has the potential to address both the efficiency demands of wind farm owners as well as to provide a disruptive design innovation to turbine manufacturers. The aerodynamic deflector technology was created to impr...

Application Program Interface for the Orion Aerodynamics Database

Science.gov (United States)

Robinson, Philip E.; Thompson, James

2013-01-01

The Application Programming Interface (API) for the Crew Exploration Vehicle (CEV) Aerodynamic Database has been developed to provide the developers of software an easily implemented, fully self-contained method of accessing the CEV Aerodynamic Database for use in their analysis and simulation tools. The API is programmed in C and provides a series of functions to interact with the database, such as initialization, selecting various options, and calculating the aerodynamic data. No special functions (file read/write, table lookup) are required on the host system other than those included with a standard ANSI C installation. It reads one or more files of aero data tables. Previous releases of aerodynamic databases for space vehicles have only included data tables and a document of the algorithm and equations to combine them for the total aerodynamic forces and moments. This process required each software tool to have a unique implementation of the database code. Errors or omissions in the documentation, or errors in the implementation, led to a lengthy and burdensome process of having to debug each instance of the code. Additionally, input file formats differ for each space vehicle simulation tool, requiring the aero database tables to be reformatted to meet the tool s input file structure requirements. Finally, the capabilities for built-in table lookup routines vary for each simulation tool. Implementation of a new database may require an update to and verification of the table lookup routines. This may be required if the number of dimensions of a data table exceeds the capability of the simulation tools built-in lookup routines. A single software solution was created to provide an aerodynamics software model that could be integrated into other simulation and analysis tools. The highly complex Orion aerodynamics model can then be quickly included in a wide variety of tools. The API code is written in ANSI C for ease of portability to a wide variety of systems. The

Aerodynamic Flight-Test Results for the Adaptive Compliant Trailing Edge

Science.gov (United States)

Cumming, Stephen B.; Smith, Mark S.; Ali, Aliyah N.; Bui, Trong T.; Ellsworth, Joel C.; Garcia, Christian A.

2016-01-01

The aerodynamic effects of compliant flaps installed onto a modified Gulfstream III airplane were investigated. Analyses were performed prior to flight to predict the aerodynamic effects of the flap installation. Flight tests were conducted to gather both structural and aerodynamic data. The airplane was instrumented to collect vehicle aerodynamic data and wing pressure data. A leading-edge stagnation detection system was also installed. The data from these flights were analyzed and compared with predictions. The predictive tools compared well with flight data for small flap deflections, but differences between predictions and flight estimates were greater at larger deflections. This paper describes the methods used to examine the aerodynamics data from the flight tests and provides a discussion of the flight-test results in the areas of vehicle aerodynamics, wing sectional pressure coefficient profiles, and air data.

Handling and safety enhancement of race cars using active aerodynamic systems

Science.gov (United States)

Diba, Fereydoon; Barari, Ahmad; Esmailzadeh, Ebrahim

2014-09-01

A methodology is presented in this work that employs the active inverted wings to enhance the road holding by increasing the downward force on the tyres. In the proposed active system, the angles of attack of the vehicle's wings are adjusted by using a real-time controller to increase the road holding and hence improve the vehicle handling. The handling of the race car and safety of the driver are two important concerns in the design of race cars. The handling of a vehicle depends on the dynamic capabilities of the vehicle and also the pneumatic tyres' limitations. The vehicle side-slip angle, as a measure of the vehicle dynamic safety, should be narrowed into an acceptable range. This paper demonstrates that active inverted wings can provide noteworthy dynamic capabilities and enhance the safety features of race cars. Detailed analytical study and formulations of the race car nonlinear model with the airfoils are presented. Computer simulations are carried out to evaluate the performance of the proposed active aerodynamic system.

Continuous-time state-space unsteady aerodynamic modelling for efficient aeroelastic load analysis

NARCIS (Netherlands)

Werter, N.P.M.; De Breuker, R.; Abdalla, M.M.

2015-01-01

Over the years, wings have become lighter and more flexible, making them more prone to aeroelastic effects. Thus, aeroelasticity in design becomes more important. In order to determine the response of an aircraft to, for example, a gust, an unsteady aerodynamic model is required to determine the

Evaluation of aerodynamic derivatives from a magnetic balance system

Science.gov (United States)

Raghunath, B. S.; Parker, H. M.

1972-01-01

The dynamic testing of a model in the University of Virginia cold magnetic balance wind-tunnel facility is expected to consist of measurements of the balance forces and moments, and the observation of the essentially six degree of freedom motion of the model. The aerodynamic derivatives of the model are to be evaluated from these observations. The basic feasibility of extracting aerodynamic information from the observation of a model which is executing transient, complex, multi-degree of freedom motion is demonstrated. It is considered significant that, though the problem treated here involves only linear aerodynamics, the methods used are capable of handling a very large class of aerodynamic nonlinearities. The basic considerations include the effect of noise in the data on the accuracy of the extracted information. Relationships between noise level and the accuracy of the evaluated aerodynamic derivatives are presented.

The design and safety features of the IRIS reactor

International Nuclear Information System (INIS)

Carelli, Mario D.; Conway, L.E.; Oriani, L.; Petrovic, B.; Lombardi, C.V.; Ricotti, M.E.; Barroso, A.C.O.; Collado, J.M.; Cinotti, L.; Todreas, N.E.; Grgic, D.; Moraes, M.M.; Boroughs, R.D.; Ninokata, H.; Ingersoll, D.T.; Oriolo, F.

2004-01-01

Salient features of the International Reactor Innovative and Secure (IRIS) are presented here. IRIS, an integral, modular, medium size (335 MWe) PWR, has been under development since the turn of the century by an international consortium led by Westinghouse and including over 20 organizations from nine countries. Described here are the features of the integral design which includes steam generators, pumps and pressurizer inside the vessel, together with the core, control rods, and neutron reflector/shield. A brief summary is provided of the IRIS approach to extended maintenance over a 48-month schedule. The unique IRIS safety-by-design approach is discussed, which, by eliminating accidents, at the design stage, or decreasing their consequences/probabilities when outright elimination is not possible, provides a very powerful first level of defense in depth. The safety-by-design allows a significant reduction and simplification of the passive safety systems, which are presented here, together with an assessment of the IRIS response to transients and postulated accidents

Examining the design features of a communication-rich, problem-centred mathematics professional development

Science.gov (United States)

de Araujo, Zandra; Orrill, Chandra Hawley; Jacobson, Erik

2018-04-01

While there is considerable scholarship describing principles for effective professional development, there have been few attempts to examine these principles in practice. In this paper, we identify and examine the particular design features of a mathematics professional development experience provided for middle grades teachers over 14 weeks. The professional development was grounded in a set of mathematical tasks that each had one right answer, but multiple solution paths. The facilitator engaged participants in problem solving and encouraged participants to work collaboratively to explore different solution paths. Through analysis of this collaborative learning environment, we identified five design features for supporting teacher learning of important mathematics and pedagogy in a problem-solving setting. We discuss these design features in depth and illustrate them by presenting an elaborated example from the professional development. This study extends the existing guidance for the design of professional development by examining and operationalizing the relationships among research-based features of effective professional development and the enacted features of a particular design.

Aerodynamic Performance of a Compact, High Work-Factor Centrifugal Compressor at the Stage and Subcomponent Level

Science.gov (United States)

Braunscheidel, Edward P.; Welch, Gerard E.; Skoch, Gary J.; Medic, Gorazd; Sharma, Om P.

2015-01-01

The measured aerodynamic performance of a compact, high work-factor, single-stage centrifugal compressor, comprising an impeller, diffuser, 90deg-bend, and exit guide vane is reported. Performance levels are based on steady-state total-pressure and total-temperature rake and angularity-probe data acquired at key machine rating planes during recent testing at NASA Glenn Research Center. Aerodynamic performance at the stage level is reported for operation between 70 to 105 percent of design corrected speed, with subcomponent (impeller, diffuser, and exit-guide-vane) flow field measurements presented and discussed at the 100 percent design-speed condition. Individual component losses from measurements are compared with pre-test CFD predictions on a limited basis.

New features in the design code TLIE

International Nuclear Information System (INIS)

van Zeijts, J.

1993-01-01

We present features recently installed in the arbitrary-order accelerator design code TLIE. The code uses the MAD input language, and implements programmable extensions modeled after the C language that make it a powerful tool in a wide range of applications: from basic beamline design to high precision-high order design and even control room applications. The basic quantities important in accelerator design are easily accessible from inside the control language. Entities like parameters in elements (strength, current), transfer maps (either in Taylor series or in Lie algebraic form), lines, and beams (either as sets of particles or as distributions) are among the type of variables available. These variables can be set, used as arguments in subroutines, or just typed out. The code is easily extensible with new datatypes

EC6 design features and pre-project licensing review

Energy Technology Data Exchange (ETDEWEB)

Yu, S.; Lee, A.G.; Dinh, N.B.; Soulard, M. [CANDU Energy Inc., Mississauga, Ontario, (Canada)

2013-07-01

The Enhanced CANDU 6 (EC6) is the new Generation III CANDU reactor design that meets the most up to date Canadian regulatory requirements and customer expectations. Candu Energy Inc. is finalizing development of the EC6 which incorporates the CANDU 6's well-proven features, and adds enhancements that strengthened reactor safety margin and improved operability. The EC6 builds on the proven high performance design and the defence-in-depth features of CANDU 6 units, and has incorporated extensive operational feedback including lessons learned from Fukushima. This paper will provide status of the engineering program including progress on the pre-licensing review of the EC6 design by the Canadian Regulator, CNSC, and will also highlight the design and safety enhancements incorporated in the EC6 product. Safety enhancements to meet safety goals and to improve robustness of systems to respond to design basis accidents and beyond design basis accidents include: new severe accident recovery and heat removal system; improved emergency heat removal system; faster shutoff rods with improved safety margins; mechanical guaranteed shutdown rods; daily load cycling capability; robust containment with containment filter venting system; and improved backed-up electrical supply and cooling services. (author)

Research status and trend of wind turbine aerodynamic noise?

Institute of Scientific and Technical Information of China (English)

Xiaodong LI; Baohong BAI; Yingbo XU; Min JIANG

2016-01-01

The main components of the wind turbine aerodynamic noise are introduced. A detailed review is given on the theoretical prediction, experimental measurement, and numerical simulation methods of wind turbine noise, with speci?c attention to appli-cations. Furthermore, suppression techniques of wind turbine aerodynamic noise are discussed. The perspective of future research on the wind turbine aerodynamic noise is presented.

New Look at Nonlinear Aerodynamics in Analysis of Hypersonic Panel Flutter

Directory of Open Access Journals (Sweden)

Dan Xie

2017-01-01

Full Text Available A simply supported plate fluttering in hypersonic flow is investigated considering both the airflow and structural nonlinearities. Third-order piston theory is used for nonlinear aerodynamic loading, and von Karman plate theory is used for modeling the nonlinear strain-displacement relation. The Galerkin method is applied to project the partial differential governing equations (PDEs into a set of ordinary differential equations (ODEs in time, which is then solved by numerical integration method. In observation of limit cycle oscillations (LCO and evolution of dynamic behaviors, nonlinear aerodynamic loading produces a smaller positive deflection peak and more complex bifurcation diagrams compared with linear aerodynamics. Moreover, a LCO obtained with the linear aerodynamics is mostly a nonsimple harmonic motion but when the aerodynamic nonlinearity is considered more complex motions are obtained, which is important in the evaluation of fatigue life. The parameters of Mach number, dynamic pressure, and in-plane thermal stresses all affect the aerodynamic nonlinearity. For a specific Mach number, there is a critical dynamic pressure beyond which the aerodynamic nonlinearity has to be considered. For a higher temperature, a lower critical dynamic pressure is required. Each nonlinear aerodynamic term in the full third-order piston theory is evaluated, based on which the nonlinear aerodynamic formulation has been simplified.

Joint Feature Extraction and Classifier Design for ECG-Based Biometric Recognition.

Science.gov (United States)

Gutta, Sandeep; Cheng, Qi

2016-03-01

Traditional biometric recognition systems often utilize physiological traits such as fingerprint, face, iris, etc. Recent years have seen a growing interest in electrocardiogram (ECG)-based biometric recognition techniques, especially in the field of clinical medicine. In existing ECG-based biometric recognition methods, feature extraction and classifier design are usually performed separately. In this paper, a multitask learning approach is proposed, in which feature extraction and classifier design are carried out simultaneously. Weights are assigned to the features within the kernel of each task. We decompose the matrix consisting of all the feature weights into sparse and low-rank components. The sparse component determines the features that are relevant to identify each individual, and the low-rank component determines the common feature subspace that is relevant to identify all the subjects. A fast optimization algorithm is developed, which requires only the first-order information. The performance of the proposed approach is demonstrated through experiments using the MIT-BIH Normal Sinus Rhythm database.

The Impact Of Website Design Features On Behavioral Intentions

Directory of Open Access Journals (Sweden)

Chun-Chin Chiu

2015-08-01

Full Text Available The design of a website interface plays an important role in online purchasing and customers are more likely to visit and buy from better-designed websites. However previous studies have not provided consistent information about the features a website should provide. Based on Hausman and Siekpes 2009 comprehensive model this study aims to empirically verify whether the model can be applied in e-service markets to predict and explain website users behavioral intentions trade intentions and revisit intentions. Based on the data from a survey of 303 Internet users the results indicate that computer factors and human factors the key website design features are significantly related to website users experiences perceived usefulness perceived entertainment value and perceived informativeness in turn significantly affect the intermediary outcomes of attitude toward the site and ultimately influence users behavioral intentions.

Optimization of aerodynamic efficiency for twist morphing MAV wing

Directory of Open Access Journals (Sweden)

N.I. Ismail

2014-06-01

Full Text Available Twist morphing (TM is a practical control technique in micro air vehicle (MAV flight. However, TM wing has a lower aerodynamic efficiency (CL/CD compared to membrane and rigid wing. This is due to massive drag penalty created on TM wing, which had overwhelmed the successive increase in its lift generation. Therefore, further CL/CDmax optimization on TM wing is needed to obtain the optimal condition for the morphing wing configuration. In this paper, two-way fluid–structure interaction (FSI simulation and wind tunnel testing method are used to solve and study the basic wing aerodynamic performance over (non-optimal TM, membrane and rigid wings. Then, a multifidelity data metamodel based design optimization (MBDO process is adopted based on the Ansys-DesignXplorer frameworks. In the adaptive MBDO process, Kriging metamodel is used to construct the final multifidelity CL/CD responses by utilizing 23 multi-fidelity sample points from the FSI simulation and experimental data. The optimization results show that the optimal TM wing configuration is able to produce better CL/CDmax magnitude by at least 2% than the non-optimal TM wings. The flow structure formation reveals that low TV strength on the optimal TM wing induces low CD generation which in turn improves its overall CL/CDmax performance.

Some lessons from NACA/NASA aerodynamic studies following World War II

Science.gov (United States)

Spearman, M. L.

1983-01-01

An historical account is presented of the new departures in aerodynamic research conducted by NACA, and subsequently NASA, as a result of novel aircraft technologies and operational regimes encountered in the course of the Second World War. The invention and initial development of the turbojet engine furnished the basis for a new speed/altitude regime in which numerous aerodynamic design problems arose. These included compressibility effects near the speed of sound, with attendant lift/drag efficiency reductions and longitudinal stability enhancements that were accompanied by a directional stability reduction. Major research initiatives were mounted in the investigation of swept, delta, trapezoidal and variable sweep wing configurations, sometimes conducted through flight testing of the 'X-series' aircraft. Attention is also given to the development of the first generation of supersonic fighter aircraft.

On Improving Efficiency of Differential Evolution for Aerodynamic Shape Optimization Applications

Science.gov (United States)

Madavan, Nateri K.

2004-01-01

Differential Evolution (DE) is a simple and robust evolutionary strategy that has been proven effective in determining the global optimum for several difficult optimization problems. Although DE offers several advantages over traditional optimization approaches, its use in applications such as aerodynamic shape optimization where the objective function evaluations are computationally expensive is limited by the large number of function evaluations often required. In this paper various approaches for improving the efficiency of DE are reviewed and discussed. These approaches are implemented in a DE-based aerodynamic shape optimization method that uses a Navier-Stokes solver for the objective function evaluations. Parallelization techniques on distributed computers are used to reduce turnaround times. Results are presented for the inverse design of a turbine airfoil. The efficiency improvements achieved by the different approaches are evaluated and compared.

An Aerodynamic Investigation of a Forward Swept Wing

Science.gov (United States)

1977-12-01

attached flow at higher angles of attack. 59 -. - . -- ~II The use of winglets should-also be considered to determine their effect on the aerodynamic ...INVSTGAIO OF A" ’/7AI/A/A7D1 ¾~nnt ¾ý’i ~~~)a al -A ApprovedYA~I forSIATO OFli Aees;dsrbuinulmtd AFIT/GAE/AA/77D -4 .1 AN AERODYNAMIC INVESTIGATION OF A...this study was to experimentally and analytically determine certain aerodynamic characteristics of a recently proposed high subsonic, forward swept wing

Aerodynamics, sensing and control of insect-scale flapping-wing flight

Science.gov (United States)

Shyy, Wei; Kang, Chang-kwon; Chirarattananon, Pakpong; Ravi, Sridhar; Liu, Hao

2016-01-01

There are nearly a million known species of flying insects and 13 000 species of flying warm-blooded vertebrates, including mammals, birds and bats. While in flight, their wings not only move forward relative to the air, they also flap up and down, plunge and sweep, so that both lift and thrust can be generated and balanced, accommodate uncertain surrounding environment, with superior flight stability and dynamics with highly varied speeds and missions. As the size of a flyer is reduced, the wing-to-body mass ratio tends to decrease as well. Furthermore, these flyers use integrated system consisting of wings to generate aerodynamic forces, muscles to move the wings, and sensing and control systems to guide and manoeuvre. In this article, recent advances in insect-scale flapping-wing aerodynamics, flexible wing structures, unsteady flight environment, sensing, stability and control are reviewed with perspective offered. In particular, the special features of the low Reynolds number flyers associated with small sizes, thin and light structures, slow flight with comparable wind gust speeds, bioinspired fabrication of wing structures, neuron-based sensing and adaptive control are highlighted. PMID:27118897

Rotor-generated unsteady aerodynamic interactions in a 1½ stage compressor

Science.gov (United States)

Papalia, John J.

Because High Cycle Fatigue (HCF) remains the predominant surprise failure mode in gas turbine engines, HCF avoidance design systems are utilized to identify possible failures early in the engine development process. A key requirement of these analyses is accurate determination of the aerodynamic forcing function and corresponding airfoil unsteady response. The current study expands the limited experimental database of blade row interactions necessary for calibration of predictive HCF analyses, with transonic axial-flow compressors of particular interest due to the presence of rotor leading edge shocks. The majority of HCF failures in aircraft engines occur at off-design operating conditions. Therefore, experiments focused on rotor-IGV interactions at off-design are conducted in the Purdue Transonic Research Compressor. The rotor-generated IGV unsteady aerodynamics are quantified when the IGV reset angle causes the vane trailing edge to be nearly aligned with the rotor leading edge shocks. A significant vane response to the impulsive static pressure perturbation associated with a shock is evident in the point measurements at 90% span, with details of this complex interaction revealed in the corresponding time-variant vane-to-vane flow field data. Industry wide implementation of Controlled Diffusion Airfoils (CDA) in modern compressors motivated an investigation of upstream propagating CDA rotor-generated forcing functions. Whole field velocity measurements in the reconfigured Purdue Transonic Research Compressor along the design speedline reveal steady loading had a considerable effect on the rotor shock structure. A detached rotor leading edge shock exists at low loading, with an attached leading edge and mid-chord suction surface normal shock present at nominal loading. These CDA forcing functions are 3--4 times smaller than those generated by the baseline NACA 65 rotor at their respective operating points. However, the IGV unsteady aerodynamic response to the CDA

Design features of the radioactive Liquid-Fed Ceramic Melter system

International Nuclear Information System (INIS)

Holton, L.K. Jr.

1985-06-01

During 1983, the Pacific Northwest Laboratory (PNL), at the request of the Department of Energy (DOE), undertook a program with the principal objective of testing the Liquid-Fed Ceramic Melter (LFCM) process in actual radioactive operations. This activity, termed the Radioactive LFCM (RLFCM) Operations is being conducted in existing shielded hot-cell facilities in B-Cell of the 324 Building, 300 Area, located at Hanford, Washington. This report summarizes the design features of the RLFCM system. These features include: a waste preparation and feed system which uses pulse-agitated waste preparation tanks for waste slurry agitation and an air displacement slurry pump for transferring waste slurries to the LFCM; a waste vitrification system (LFCM) - the design features, design approach, and reasoning for the design of the LFCM are described; a canister-handling turntable for positioning canisters underneath the RLFCM discharge port; a gamma source positioning and detection system for monitoring the glass fill level of the product canisters; and a primary off-gas treatment system for removing the majority of the radionuclide contamination from the RLFCM off gas. 8 refs., 48 figs., 6 tabs

Strain measurement of objects subjected to aerodynamic heating using digital image correlation: experimental design and preliminary results.

Science.gov (United States)

Pan, Bing; Jiang, Tianyun; Wu, Dafang

2014-11-01

In thermomechanical testing of hypersonic materials and structures, direct observation and quantitative strain measurement of the front surface of a test specimen directly exposed to severe aerodynamic heating has been considered as a very challenging task. In this work, a novel quartz infrared heating device with an observation window is designed to reproduce the transient thermal environment experienced by hypersonic vehicles. The specially designed experimental system allows the capture of test article's surface images at various temperatures using an optical system outfitted with a bandpass filter. The captured images are post-processed by digital image correlation to extract full-field thermal deformation. To verify the viability and accuracy of the established system, thermal strains of a chromiumnickel austenite stainless steel sample heated from room temperature up to 600 °C were determined. The preliminary results indicate that the air disturbance between the camera and the specimen due to heat haze induces apparent distortions in the recorded images and large errors in the measured strains, but the average values of the measured strains are accurate enough. Limitations and further improvements of the proposed technique are discussed.

[Role of aerodynamic parameters in voice function assessment].

Science.gov (United States)

Guo, Yong-qing; Lin, Sheng-zhi; Xu, Xin-lin; Zhou, Li; Zhuang, Pei-yun; Jiang, Jack J

2012-10-01

To investigate the application and significance of aerodynamic parameters in voice function assessment. The phonatory aerodynamic system (PAS) was used to collect aerodynamic parameters from subjects with normal voice, vocal fold polyp, vocal fold cyst, and vocal fold immobility. Multivariate statistical analysis was used to compare measurements across groups. Phonation threshold flow (PTF), mean flow rate (MFR), maximum phonation time (MPT), and glottal resistance (GR) in one hundred normal subjects were significantly affected by sex (P efficiency (VE) were not (P > 0.05). PTP, PTF, MFR, SGP, and MPT were significantly different between normal voice and voice disorders (P 0.05). Receiver operating characteristic (ROC) analysis found that PTP, PTF, SGP, MFR, MPT, and VE in one hundred thirteen voice dis orders had similar diagnostic utility (P aerodynamic parameters of the three degrees of voice dysfunction due to vocal cord polyps were compared and found to have no significant differences (P > 0.05). PTP, PTF, MFR, SGP and MPT in forty one patients with vocal polyps were significantly different after surgical resection of vocal cord polyps (P aerodynamic parameters can objectively and effectively evaluate the variations of vocal function, and have good auxiliary diagnostic value.

Relevance of aerodynamic modelling for load reduction control strategies of two-bladed wind turbines

Science.gov (United States)

Luhmann, B.; Cheng, P. W.

2014-06-01

A new load reduction concept is being developed for the two-bladed prototype of the Skywind 3.5MW wind turbine. Due to transport and installation advantages both offshore and in complex terrain two-bladed turbine designs are potentially more cost-effective than comparable three-bladed configurations. A disadvantage of two-bladed wind turbines is the increased fatigue loading, which is a result of asymmetrically distributed rotor forces. The innovative load reduction concept of the Skywind prototype consists of a combination of cyclic pitch control and tumbling rotor kinematics to mitigate periodic structural loading. Aerodynamic design tools must be able to model correctly the advanced dynamics of the rotor. In this paper the impact of the aerodynamic modelling approach is investigated for critical operational modes of a two-bladed wind turbine. Using a lifting line free wake vortex code (FVM) the physical limitations of the classical blade element momentum theory (BEM) can be evaluated. During regular operation vertical shear and yawed inflow are the main contributors to periodic blade load asymmetry. It is shown that the near wake interaction of the blades under such conditions is not fully captured by the correction models of BEM approach. The differing prediction of local induction causes a high fatigue load uncertainty especially for two-bladed turbines. The implementation of both cyclic pitch control and a tumbling rotor can mitigate the fatigue loading by increasing the aerodynamic and structural damping. The influence of the time and space variant vorticity distribution in the near wake is evaluated in detail for different cyclic pitch control functions and tumble dynamics respectively. It is demonstrated that dynamic inflow as well as wake blade interaction have a significant impact on the calculated blade forces and need to be accounted for by the aerodynamic modelling approach. Aeroelastic simulations are carried out using the high fidelity multi body

Optimization of wind turbine rotors - using advanced aerodynamic and aeroelastic models and numerical optimization

DEFF Research Database (Denmark)

Døssing, Mads

of very large machines introduces new problems in the practical design, and optimization tools are necessary. These must combine the dynamic eects of both aerodynamics and structure in an integrated optimization environment. This is referred to as aeroelastic optimization. The Ris DTU optimization...... software HAWTOPT has been used in this project. The quasi-steady aerodynamic module have been improved with a corrected blade element momentum method. A structure module has also been developed which lays out the blade structural properties. This is done in a simplied way allowing fast conceptual design...... studies and with focus on the overall properties relevant for the aeroelastic properties. Aeroelastic simulations in the time domain were carried out using the aeroelastic code HAWC2. With these modules coupled to HAWTOPT, optimizations have been made. In parallel with the developments of the mentioned...

Airfoil design and optimization

Energy Technology Data Exchange (ETDEWEB)

Lutz, T. [Stuttgart Univ. (Germany). Inst. fuer Aerodynamik und Gasdynamik

2001-07-01

The aerodynamic efficiency of mildly swept wings is mainly influenced by the characteristics of the airfoil sections. The specific design of airfoils is therefore one of the classical tasks of aerodynamics. Since the airfoil characteristics are directly dependent on the inviscid pressure distribution the application of inverse calculation methods is obvious. The direct numerical airfoil optimization offers an alternative to the manual design and attracts increasing interest. (orig.)

Technology development for metallic hot structures in aerodynamic control surfaces of reusable launchers

NARCIS (Netherlands)

Sudmeijer, K.J.; Wentzel, C.; Lefeber, B.M.; Kloosterman, A.

2002-01-01

In this paper a summary is presented of the technology development in the Netherlands focussed on the design and development of a metallic aerodynamic control surface for the future European reusable launcher. The applied materials are mainly Oxide Dispersion Strengthened (ODS) alloys produced by

Application of porous material to reduce aerodynamic sound from bluff bodies

International Nuclear Information System (INIS)

Sueki, Takeshi; Takaishi, Takehisa; Ikeda, Mitsuru; Arai, Norio

2010-01-01

Aerodynamic sound derived from bluff bodies can be considerably reduced by flow control. In this paper, the authors propose a new method in which porous material covers a body surface as one of the flow control methods. From wind tunnel tests on flows around a bare cylinder and a cylinder with porous material, it has been clarified that the application of porous materials is effective in reducing aerodynamic sound. Correlation between aerodynamic sound and aerodynamic force fluctuation, and a surface pressure distribution of cylinders are measured to investigate a mechanism of aerodynamic sound reduction. As a result, the correlation between aerodynamic sound and aerodynamic force fluctuation exists in the flow around the bare cylinder and disappears in the flow around the cylinder with porous material. Moreover, the aerodynamic force fluctuation of the cylinder with porous material is less than that of the bare cylinder. The surface pressure distribution of the cylinder with porous material is quite different from that of the bare cylinder. These facts indicate that aerodynamic sound is reduced by suppressing the motion of vortices because aerodynamic sound is induced by the unstable motion of vortices. In addition, an instantaneous flow field in the wake of the cylinder is measured by application of the PIV technique. Vortices that are shed alternately from the bare cylinder disappear by application of porous material, and the region of zero velocity spreads widely behind the cylinder with porous material. Shear layers between the stationary region and the uniform flow become thin and stable. These results suggest that porous material mainly affects the flow field adjacent to bluff bodies and reduces aerodynamic sound by depriving momentum of the wake and suppressing the unsteady motion of vortices. (invited paper)

Prediction of Aerodynamic Coefficient using Genetic Algorithm Optimized Neural Network for Sparse Data

Science.gov (United States)

Rajkumar, T.; Bardina, Jorge; Clancy, Daniel (Technical Monitor)

2002-01-01

Wind tunnels use scale models to characterize aerodynamic coefficients, Wind tunnel testing can be slow and costly due to high personnel overhead and intensive power utilization. Although manual curve fitting can be done, it is highly efficient to use a neural network to define the complex relationship between variables. Numerical simulation of complex vehicles on the wide range of conditions required for flight simulation requires static and dynamic data. Static data at low Mach numbers and angles of attack may be obtained with simpler Euler codes. Static data of stalled vehicles where zones of flow separation are usually present at higher angles of attack require Navier-Stokes simulations which are costly due to the large processing time required to attain convergence. Preliminary dynamic data may be obtained with simpler methods based on correlations and vortex methods; however, accurate prediction of the dynamic coefficients requires complex and costly numerical simulations. A reliable and fast method of predicting complex aerodynamic coefficients for flight simulation I'S presented using a neural network. The training data for the neural network are derived from numerical simulations and wind-tunnel experiments. The aerodynamic coefficients are modeled as functions of the flow characteristics and the control surfaces of the vehicle. The basic coefficients of lift, drag and pitching moment are expressed as functions of angles of attack and Mach number. The modeled and training aerodynamic coefficients show good agreement. This method shows excellent potential for rapid development of aerodynamic models for flight simulation. Genetic Algorithms (GA) are used to optimize a previously built Artificial Neural Network (ANN) that reliably predicts aerodynamic coefficients. Results indicate that the GA provided an efficient method of optimizing the ANN model to predict aerodynamic coefficients. The reliability of the ANN using the GA includes prediction of aerodynamic

Implicit geometric representations for optimal design of gas turbine blades

International Nuclear Information System (INIS)

Mansour, T.; Ghaly, W.

2004-01-01

Shape optimization requires a proper geometric representation of the blade profile; the parameters of such a representation are usually taken as design variables in the optimization process. This implies that the model must possess three specific features: flexibility, efficiency, and accuracy. For the specific task of aerodynamic optimization for turbine blades, it is critical to have flexibility in both the global and local design spaces in order to obtain a successful optimization. This work is concerned with the development of two geometric representations of turbine blade profiles that are appropriate for aerodynamic optimization: the Modified Rapid Axial Turbine Design (MRATD) model where the blade is represented by five low-order curves that satisfy eleven designer parameters; this model is suitable for a global search of the design space. The second model is NURBS parameterization of the blade profile that can be used for a local refinement. The two models are presented and are assessed for flexibility and accuracy when representing several typical turbine blade profiles. The models will be further discussed in terms of curve smoothness and blade shape representation with a multi-NURBS curve versus one curve and its effect on the flow field, in particular the pressure distribution along the blade surfaces, will be elaborated. (author)

Unsteady aerodynamics simulation of a full-scale horizontal axis wind turbine using CFD methodology

International Nuclear Information System (INIS)

Cai, Xin; Gu, Rongrong; Pan, Pan; Zhu, Jie

2016-01-01

Highlights: • A full-scale HAWT is simulated under operational conditions of wind shear and yaw. • The CFD method and sliding mesh are adopted to complete the calculation. • Thrust and torque of blades reach the peak and valley at the same time in wind shear. • The wind turbine produces yaw moment during the whole revolution in yaw case. • The torques and thrusts of the three blades present cyclical changes. - Abstract: The aerodynamic performance of wind turbines is significantly influenced by the unsteady flow around the rotor blades. The research on unsteady aerodynamics for Horizontal Axis Wind Turbines (HAWTs) is still poorly understood because of the complex flow physics. In this study, the unsteady aerodynamic configuration of a full-scale HAWT is simulated with consideration of wind shear, tower shadow and yaw motion. The calculated wind turbine which contains tapered tower, rotor overhang and tilted rotor shaft is constructed by making reference of successfully commercial operated wind turbine designed by NEG Micon and Vestas. A validated CFD method is utilized to analyze unsteady aerodynamic characteristics which affect the performance on such a full-scale HAWT. The approach of sliding mesh is used to carefully deal with the interface between static and moving parts in the flow field. The annual average wind velocity and wind profile in the atmospheric border are applied as boundary conditions. Considering the effects of wind shear and tower shadow, the simulation results show that the each blade reaches its maximum and minimum aerodynamic loads almost at the same time during the rotation circle. The blade–tower interaction imposes great impact on the power output performance. The wind turbine produces yaw moment during the whole revolution and the maximum aerodynamic loads appear at the upwind azimuth in the yaw computation case.

The aerodynamics of wind turbines

DEFF Research Database (Denmark)

Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming; Troldborg, Niels

2013-01-01

In the paper we present state-of-the-art of research in wind turbine aerodynamics. We start be giving a brief historical review and a survey over aerodynamic research in wind energy. Next, we focus on some recent research results obtained by our wind energy group at Department of Mechanical...... Engineering at DTU. In particular, we show some new results on the classical problem of the ideal rotor and present a series of new results from an on-going research project dealing with the modelling and simulation of turbulent flow structures in the wake behind wind turbines....

AN INVESTIGATION ON THE AERODYNAMIC CHARACTERISTICS OF 2-D AIRFIOL IN GROUND COLLISION

Directory of Open Access Journals (Sweden)

AK KARTIGESH A/L KALAI CHELVEN

2011-06-01

Full Text Available Near ground operation of airplanes represents a critical and an important aerodynamic practical problem due to the wing-ground collision. The aerodynamic characteristics of the wing are subjected to dramatic changes due to the flow field interference with the ground. In the present paper, the wing-ground collision was investigated experimentally and numerically. The investigation involved a series of wind tunnel measurements of a 2-D wing model having NACA4412 airfoil section. An experimental set up has been designed and constructed to simulate the collision phenomena in a low speed wind tunnel. The investigations were carried out at different Reynolds numbers ranging from 105 to 4×105, various model heights to chord ratios, H/C ranging from 0.1 to 1, and different angles of attack ranging from -4o to 20o. Numerical simulation of the wing-ground collision has been carried out using FLUENT software. The results of the numerical simulation have been validated by comparison with previous and recent experimental data and it was within acceptable agreement. The results have shown that the aerodynamic characteristics are considerably influenced when the wing is close to the ground, mainly at angles of attacks 4o to 8o. The take off and landing speeds are found to be very influencing parameters on the aerodynamic characteristics of the wing in collision status, mainly the lift.

A Reduced-Complexity Investigation of Blunt Leading-Edge Separation Motivated by UCAV Aerodynamics

Science.gov (United States)

Luckring, James M.; Boelens, Okko J.

2015-01-01

A reduced complexity investigation for blunt-leading-edge vortical separation has been undertaken. The overall approach is to design the fundamental work in such a way so that it relates to the aerodynamics of a more complex Uninhabited Combat Air Vehicle (UCAV) concept known as SACCON. Some of the challenges associated with both the vehicle-class aerodynamics and the fundamental vortical flows are reviewed, and principles from a hierarchical complexity approach are used to relate flow fundamentals to system-level interests. The work is part of roughly 6-year research program on blunt-leading-edge separation pertinent to UCAVs, and was conducted under the NATO Science and Technology Organization, Applied Vehicle Technology panel.

Effects of Leading Edge Defect on the Aerodynamic and Flow Characteristics of an S809 Airfoil.

Science.gov (United States)

Wang, Yan; Zheng, Xiaojing; Hu, Ruifeng; Wang, Ping

dynamic stall, leading edge defect imposes a greater influence on the aerodynamic characteristics of airfoil than steady conditions. By increasing in defect length, it is found that the separated area becomes more intense and moves forward along the suction surface. Leading edge defect has significant influence on the aerodynamic and flow characteristics of the airfoil, which will reach a stable status with enough large defect size. The leading edge separation bubble, circulation in the defect cavity and intense tailing edge vortex are the main features of flow around defective airfoils.

The Aerodynamic Performance of the 24 Inch Houck Configuration

Science.gov (United States)

2007-03-01

Winglets “ Winglets are aerodynamic components, placed at the tip of a wing to improve its efficiency during cruise” (6). The purpose of the winglet ... winglets have, by and large, been accepted as effective fuel-saving aerodynamic devices by both small and large aircraft manufacturers. 12 2.6... Winglet Airfoil for Low-Speed Aircraft.” AIAA 19th Applied Aerodynamics Conference, 11-14 June, 2001. AIAA Paper 2001-2406. 22. Mock, R. M. “The

The Aerodynamic Performance of the Houck Configuration Flow Guides

Science.gov (United States)

2007-06-01

efficiency factor (e = 1 for elliptical wing). 2.5 Winglets A winglet is best described by Jean Chattot’s quote: “ Winglets are aerodynamic components...spite of all the disadvantages, many aviation manufacturers have accepted winglets as a proven fuel- saving aerodynamic device (4). A study...conducted by Smith and Campbell in 1996 showed the effect of winglets on aerodynamic efficiency of a low-aspect-ratio model with respect to lift-to-drag

Future requirements and roles of computers in aerodynamics

Science.gov (United States)

Gregory, T. J.

1978-01-01

While faster computers will be needed to make solution of the Navier-Stokes equations practical and useful, most all of the other aerodynamic solution techniques can benefit from faster computers. There is a wide variety of computational and measurement techniques, the prospect of more powerful computers permits extension and an enhancement across all aerodynamic methods, including wind-tunnel measurement. It is expected that, as in the past, a blend of methods will be used to predict aircraft aerodynamics in the future. These will include methods based on solution of the Navier-Stokes equations and the potential flow equations as well as those based on empirical and measured results. The primary flows of interest in aircraft aerodynamics are identified, the predictive methods currently in use and/or under development are reviewed and two of these methods are analyzed in terms of the computational resources needed to improve their usefulness and practicality.

Design features of an automated entry control system

International Nuclear Information System (INIS)

Reynolds, D.A.

1978-01-01

Features of an entry control system designed to automatically control access to nuclear facilities is described. Control independent of variable human factors is stressed, but security force action is required for assessment and response as a result of an alarm. A design based on a distributed processing capability is utilized. Flexibility and generality are emphasized in an effort to maximize applicability to the entry-control problem faced by nuclear facilities upgrading security as a result of the Safeguards Program

Appraisal of ALM predictions of turbulent wake features

Science.gov (United States)

Rocchio, Benedetto; Cilurzo, Lorenzo; Ciri, Umberto; Salvetti, Maria Vittoria; Leonardi, Stefano

2017-11-01

Wind turbine blades create a turbulent wake that may persist far downstream, with significant implications on wind farm design and on its power production. The numerical representation of the real blade geometry would lead to simulations beyond the present computational resources. We focus our attention on the Actuator Line Model (ALM), in which the blade is replaced by a rotating line divided into finite segments with representative aerodynamic coefficients. The total aerodynamic force is projected along the computational axis and, to avoid numerical instabilities, it is distributed among the nearest grid points by using a Gaussian regularization kernel. The standard deviation of this kernel is a fundamental parameter that strongly affects the characteristics of the wake. We compare here the wake features obtained in direct numerical simulations of the flow around 2D bodies (a flat plate and an airfoil) modeled using the Immersed Boundary Method with the results of simulations in which the body is modeled by ALM. In particular, we investigate whether the ALM is able to reproduce the mean velocity field and the turbulent kinetic energy in the wake for the considered bodies at low and high angles of attack and how this depends on the choice of the ALM kernel. S. Leonardi was supported by the National Science Foundation, Grant No. 1243482 (the WINDINSPIRE project).

Aerodynamic Reconstruction Applied to Parachute Test Vehicle Flight Data Analysis

Science.gov (United States)

Cassady, Leonard D.; Ray, Eric S.; Truong, Tuan H.

2013-01-01

The aerodynamics, both static and dynamic, of a test vehicle are critical to determining the performance of the parachute cluster in a drop test and for conducting a successful test. The Capsule Parachute Assembly System (CPAS) project is conducting tests of NASA's Orion Multi-Purpose Crew Vehicle (MPCV) parachutes at the Army Yuma Proving Ground utilizing the Parachute Test Vehicle (PTV). The PTV shape is based on the MPCV, but the height has been reduced in order to fit within the C-17 aircraft for extraction. Therefore, the aerodynamics of the PTV are similar, but not the same as, the MPCV. A small series of wind tunnel tests and computational fluid dynamics cases were run to modify the MPCV aerodynamic database for the PTV, but aerodynamic reconstruction of the flights has proven an effective source for further improvements to the database. The acceleration and rotational rates measured during free flight, before parachute inflation but during deployment, were used to con rm vehicle static aerodynamics. A multibody simulation is utilized to reconstruct the parachute portions of the flight. Aerodynamic or parachute parameters are adjusted in the simulation until the prediction reasonably matches the flight trajectory. Knowledge of the static aerodynamics is critical in the CPAS project because the parachute riser load measurements are scaled based on forebody drag. PTV dynamic damping is critical because the vehicle has no reaction control system to maintain attitude - the vehicle dynamics must be understood and modeled correctly before flight. It will be shown here that aerodynamic reconstruction has successfully contributed to the CPAS project.

Photogrammetry of a Hypersonic Inflatable Aerodynamic Decelerator

Science.gov (United States)

Kushner, Laura Kathryn; Littell, Justin D.; Cassell, Alan M.

2013-01-01

In 2012, two large-scale models of a Hypersonic Inflatable Aerodynamic decelerator were tested in the National Full-Scale Aerodynamic Complex at NASA Ames Research Center. One of the objectives of this test was to measure model deflections under aerodynamic loading that approximated expected flight conditions. The measurements were acquired using stereo photogrammetry. Four pairs of stereo cameras were mounted inside the NFAC test section, each imaging a particular section of the HIAD. The views were then stitched together post-test to create a surface deformation profile. The data from the photogram- metry system will largely be used for comparisons to and refinement of Fluid Structure Interaction models. This paper describes how a commercial photogrammetry system was adapted to make the measurements and presents some preliminary results.

Physics of badminton shuttlecocks. Part 1 : aerodynamics

Science.gov (United States)

Cohen, Caroline; Darbois Texier, Baptiste; Quéré, David; Clanet, Christophe

2011-11-01

We study experimentally shuttlecocks dynamics. In this part we show that shuttlecock trajectory is highly different from classical parabola. When one takes into account the aerodynamic drag, the flight of the shuttlecock quickly curves downwards and almost reaches a vertical asymptote. We solve the equation of motion with gravity and drag at high Reynolds number and find an analytical expression of the reach. At high velocity, this reach does not depend on velocity anymore. Even if you develop your muscles you will not manage to launch the shuttlecock very far because of the ``aerodynamic wall.'' As a consequence you can predict the length of the field. We then discuss the extend of the aerodynamic wall to other projectiles like sports balls and its importance.

BOUNDARY LAYER AND AMPLIFIED GRID EFFECTS ON AERODYNAMIC PERFORMANCES OF S809 AIRFOIL FOR HORIZONTAL AXIS WIND TURBINE (HAWT

Directory of Open Access Journals (Sweden)

YOUNES EL KHCHINE

2017-11-01

Full Text Available The design of rotor blades has a great effect on the aerodynamics performances of horizontal axis wind turbine and its efficiency. This work presents the effects of mesh refinement and boundary layer on aerodynamic performances of wind turbine S809 rotor. Furthermore, the simulation of fluid flow is taken for S809 airfoil wind turbine blade using ANSYS/FLUENT software. The problem is solved by the conservation of mass and momentum equations for unsteady and incompressible flow using advanced SST k-ω turbulence model, in order to predict the effects of mesh refinement and boundary layer on aerodynamics performances. Lift and drag coefficients are the most important parameters in studying the wind turbine performance, these coefficients are calculated for four meshes refinement and different angles of attacks with Reynolds number is 106. The study is applied to S809 airfoil which has 21% thickness, specially designed by NREL for horizontal axis wind turbines.

Influence of Different Diffuser Angle on Sedan's Aerodynamic Characteristics

Science.gov (United States)

Hu, Xingjun; Zhang, Rui; Ye, Jian; Yan, Xu; Zhao, Zhiming

The aerodynamic characteristics have a great influence on the fuel economics and the steering stability of a high speed vehicle. The underbody rear diffuser is one of important aerodynamic add-on devices. The parameters of the diffuser, including the diffuser angle, the number and the shape of separators, the shape of the end plate and etc, will affect the underbody flow and the wake. Here, just the influence of the diffuser angle was investigated without separator and the end plate. The method of Computational Fluid Dynamics was adopted to study the aerodynamic characteristics of a simplified sedan with a different diffuser angle respectively. The diffuser angle was set to 0°, 3°, 6°, 9.8° and 12° respectively. The diffuser angle of the original model is 9.8°. The conclusions were drawn that when the diffuser angle increases, the underbody flow and especially the wake change greatly and the pressure change correspondingly; as a result, the total aerodynamic drag coefficients of car first decrease and then increases, while the total aerodynamic lift coefficients decrease.

License Application Design Selection Feature Report: Aging and Blending

International Nuclear Information System (INIS)

Coltoni, B.; Anderson, M.J.

1999-01-01

The purpose of this document is to evaluate the concepts of Aging and Blending for waste sent to the Monitored Geologic Repository (MGR). These design features are based on pre-emplacement treatment of the waste stream. The envelope of the analysis has been performed under the direction of the License Application Design Selection Team (LADST), which advocated utilizing the Viability Assessment (VA) repository design (DOE 1998c) as the basis. Therefore, this evaluation attempts to modify the VA design only to the extent that Aging and Blending can be accomplished. This modified VA design will be contrasted to the VA Design and the difference in design, costs, and performance will be presented

Aerodynamic analysis of an isolated vehicle wheel

Science.gov (United States)

Leśniewicz, P.; Kulak, M.; Karczewski, M.

2014-08-01

Increasing fuel prices force the manufacturers to look into all aspects of car aerodynamics including wheels, tyres and rims in order to minimize their drag. By diminishing the aerodynamic drag of vehicle the fuel consumption will decrease, while driving safety and comfort will improve. In order to properly illustrate the impact of a rotating wheel aerodynamics on the car body, precise analysis of an isolated wheel should be performed beforehand. In order to represent wheel rotation in contact with the ground, presented CFD simulations included Moving Wall boundary as well as Multiple Reference Frame should be performed. Sliding mesh approach is favoured but too costly at the moment. Global and local flow quantities obtained during simulations were compared to an experiment in order to assess the validity of the numerical model. Results of investigation illustrates dependency between type of simulation and coefficients (drag and lift). MRF approach proved to be a better solution giving result closer to experiment. Investigation of the model with contact area between the wheel and the ground helps to illustrate the impact of rotating wheel aerodynamics on the car body.

Aerodynamic analysis of an isolated vehicle wheel

International Nuclear Information System (INIS)

Leśniewicz, P; Kulak, M; Karczewski, M

2014-01-01

Increasing fuel prices force the manufacturers to look into all aspects of car aerodynamics including wheels, tyres and rims in order to minimize their drag. By diminishing the aerodynamic drag of vehicle the fuel consumption will decrease, while driving safety and comfort will improve. In order to properly illustrate the impact of a rotating wheel aerodynamics on the car body, precise analysis of an isolated wheel should be performed beforehand. In order to represent wheel rotation in contact with the ground, presented CFD simulations included Moving Wall boundary as well as Multiple Reference Frame should be performed. Sliding mesh approach is favoured but too costly at the moment. Global and local flow quantities obtained during simulations were compared to an experiment in order to assess the validity of the numerical model. Results of investigation illustrates dependency between type of simulation and coefficients (drag and lift). MRF approach proved to be a better solution giving result closer to experiment. Investigation of the model with contact area between the wheel and the ground helps to illustrate the impact of rotating wheel aerodynamics on the car body.

Research on the Aerodynamic Resistance of Trickle Biofilter

Directory of Open Access Journals (Sweden)

Alvydas Zagorskis

2011-12-01

Full Text Available A four – section trickle biofilter was constructed for experimental research. The filter was filled with the packing material of artificial origin. The material consists of plastic balls having a large surface area. The dependence of biofilter aerodynamic resistance on supply air flow rate and the number of filter sections was determined. The aerodynamic resistance of the biofilter was measured in two cases. In the first case, the packing material of the filter was dry, whereas in the second case it was wet. The experimental research determined that an increase in the air flow rate from 0.043 m/s to 0.076 m/s causes an increase in biofilter aerodynamic resistance from 30.5 to 62.5 Pa after measuring four layers of dry packing material. In case of wet packing material, biofilter aerodynamic resistance after measuring four layers of plastic balls increases from 42.1 to 90.4 Pa.Article in Lithuanian

Quasi-steady state aerodynamics of the cheetah tail

Directory of Open Access Journals (Sweden)

Amir Patel

2016-08-01

Full Text Available During high-speed pursuit of prey, the cheetah (Acinonyx jubatus has been observed to swing its tail while manoeuvring (e.g. turning or braking but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry tail to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the tail are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the tail without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw tail motion primitives. The inertial and quasi-steady state aerodynamic effects of tail actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the tail's angular impulse, especially at the highest forward velocities.

Projected role of advanced computational aerodynamic methods at the Lockheed-Georgia company

Science.gov (United States)

Lores, M. E.

1978-01-01

Experience with advanced computational methods being used at the Lockheed-Georgia Company to aid in the evaluation and design of new and modified aircraft indicates that large and specialized computers will be needed to make advanced three-dimensional viscous aerodynamic computations practical. The Numerical Aerodynamic Simulation Facility should be used to provide a tool for designing better aerospace vehicles while at the same time reducing development costs by performing computations using Navier-Stokes equations solution algorithms and permitting less sophisticated but nevertheless complex calculations to be made efficiently. Configuration definition procedures and data output formats can probably best be defined in cooperation with industry, therefore, the computer should handle many remote terminals efficiently. The capability of transferring data to and from other computers needs to be provided. Because of the significant amount of input and output associated with 3-D viscous flow calculations and because of the exceedingly fast computation speed envisioned for the computer, special attention should be paid to providing rapid, diversified, and efficient input and output.

A study on the pressure distribution in the centrifugal compressor channel diffuser at design and off-design conditions

International Nuclear Information System (INIS)

Kang, Jeong Seek; Kang, Shin Hyoung

2000-01-01

The aim of this paper is to understand the time averaged pressure distributions in a high-speed centrifugal compressor channel diffuser at design and off-design flow rates. Pressure distributions from the impeller exit to the channel diffuser exit are measured and discussed for various flow rates from choke to near surge condition, and the effect of operating condition is discussed. The strong non-uniformity in the pressure distribution is obtained over the vaneless space and semi-vaneless space caused by the impeller-diffuser interaction. As the flow rate increases, flow separation near the throat, due to large incidence angle at the vane leading edge, increases aerodynamic blockage and reduces the aerodynamic flow area downstream. Thus the minimum pressure location occurs downstream of the geometric throat, and it is named as the aerodynamic throat. And at choke condition, normal shock occurs downstream of this aerodynamic throat. The variation in the location of the aerodynamic throat is discussed

Introduction to transonic aerodynamics

CERN Document Server

Vos, Roelof

2015-01-01

Written to teach students the nature of transonic flow and its mathematical foundation, this book offers a much-needed introduction to transonic aerodynamics. The authors present a quantitative and qualitative assessment of subsonic, supersonic, and transonic flow around bodies in two and three dimensions. The book reviews the governing equations and explores their applications and limitations as employed in modeling and computational fluid dynamics.  Some concepts, such as shock and expansion theory, are examined from a numerical perspective. Others, including shock-boundary-layer interaction, are discussed from a qualitative point of view. The book includes 60 examples and more than 200 practice problems. The authors also offer analytical methods such as Method of Characteristics (MOC) that allow readers to practice with the subject matter.  The result is a wealth of insight into transonic flow phenomena and their impact on aircraft design, including compressibility effects, shock and expansion waves, sho...

Do Particular Design Features Assist People with Aphasia to Comprehend Text? An Exploratory Study

Science.gov (United States)

Wilson, Lucy; Read, Jennifer

2016-01-01

Background: Much of the evidence underlying guidelines for producing accessible information for people with aphasia focuses on client preference for particular design features. There is limited evidence regarding the effects of these features on comprehension. Aims: To examine the effects of specific design features on text comprehension. It was…

Innovative features and fuel design approach in the iris reactor

International Nuclear Information System (INIS)

Petrovic, B.; Carelli, M.; Greenspan, E.; Matsumoto, H.; Padovani, E.; Ganda, F.

2002-01-01

The International Reactor Innovative and Secure (IRIS) is being developed by an international consortium of industry, laboratory, university and utility establishments, led by Westinghouse. The IRIS design addresses key requirements associated with advanced reactors, including improved safety, enhanced proliferation resistance, competitive electricity production cost, and improved waste management. IRIS is a modular, small/medium size (335 MWe) PWR with an integral vessel configuration. The objective has been to base its design on proven LWR technology, so that no new technology development is needed and near-term deployment is possible, yet at the same time to introduce innovative features making it attractive when compared to present PWRs. These opposing requirements resulted in an evolutionary approach to fuel and core design, balancing new features against the need to avoid extensive testing and demonstration programmes. (author)

CALCULATION OF ROCKET NOSE FAIRING SHELLS AERODYNAMIC CHARACTERISTICS

Directory of Open Access Journals (Sweden)

Vladimir T. Kalugin

2018-01-01

Full Text Available The aerodynamic characteristics of the detachable elements of transport systems are introduced, they allow to calculate the trajectories of these elements after their separation and determine the size of elements impact areas. Special consideration is given to head fairing shells, containing cylindrical, conical and spherical sections. Head fairing shells have high lift-to-drag ratio and the widest impact areas. Aerodynamics of bodies of such configurations has been insufficiently studied. The paper presents the numerical results of modeling the flow around a typical head fairing shell in free flight. Open source OpenFOAM package is used for numerical simulation. The aerodynamic characteristics at trans- and supersonic velocities are obtained, flow pattern transformation with the change of the angle of attack and Mach number is analyzed. The possibility of OpenFOAM package for aerodynamic calculations of thin shells is shown. The analysis of the obtained results demonstrate that there are many complex shock waves interacting with each other at flow supersonic speeds, at subsonic speeds vast regions of flow separations are observed. The authors identify intervals of angles of attack, where different types of flow structures are realized, both for trans- and supersonic flow speeds. The flow pattern change affects the aerodynamic characteristics, the aerodynamic coefficients significantly change with increase of the angle of attack. There are two trim angles of attack at all examined flow velocities. The results obtained can be used to develop a passive stabilization system for fairing shell that will balance the body at the angle of attack with minimum lift-to-drag ratio and will reduce random deviations.

Design Feature 7: Continuous Preclosure Ventilation

International Nuclear Information System (INIS)

A.T. Watkins

1999-01-01

This design feature (DF) is intended to evaluate the effects of continuous ventilation in the emplacement drifts during preclosure and how the effects, if any, compare to the Viability Assessment (VA) reference design for postclosure long term performance. This DF will be evaluated against a set of criteria provided by the License Application Design Selection (LADS) group. The VA reference design included a continuous ventilation airflow quantity of 0.1 m 3 /s in the emplacement drifts in the design of the repository subsurface facilities. The effects of this continuous ventilation during the preclosure was considered to have a negligible effect on postclosure performance and therefore is not included during postclosure in the assessment of the long term performance. This DF discusses the effects of continuous ventilation on the emplacement drift environment and surrounding rock conditions during preclosure for three increased airflow quantities. The three cases of continuous ventilation systems are: System A, 1.0 m 3 /s (Section 8), System B, 5.0 m 3 /s (Section 9), and System C, 10.0 m 3 /s (Section 10) in each emplacement drift split. An emplacement drift split is half total length of emplacement drift going from the east or west main to the exhaust main. The difference in each system is the quantity of airflow in the emplacement drifts

The key design features of the Indian advanced heavy water reactor

International Nuclear Information System (INIS)

Sinha, R.K.; Kakodkar, A.; Anand, A.K.; Venkat Raj, V.; Balakrishnan, K.

1999-01-01

The 235 MWe Indian Advanced Heavy Water Reactor (AHWR) is a vertical, pressure tube type, boiling light water cooled reactor. The three key specific features of design of the AHWR, having a large impact on its viability, safety and economics, relate to its reactor physics, coolant channel, and passive safety features. The reactor physics design is tuned for maximising use of thorium based fuel, and achieving a slightly negative void coefficient of reactivity. The fulfilment of these requirements has been possible through use of PuO 2 -ThO 2 MOX, and ThO 2 -U 233 O 2 MOX in different pins of the same fuel cluster, and use of a heterogeneous moderator consisting of pyrolytic carbon and heavy water in 80%-20% volume ratio. The coolant channels of AHWR are designed for easy replaceability of pressure tubes, during normal maintenance shutdowns. The removal of pressure tube along with bottom end-fitting, using rolled joint detachment technology, can be done in AHWR coolant channels without disturbing the top end-fitting, tail pipe and feeder connections, and all other appendages of the coolant channel. The AHWR incorporates several passive safety features. These include core heat removal through natural circulation, direct injection of Emergency Core Coolant System (ECCS) water in fuel, passive systems for containment cooling and isolation, and availability of a large inventory of borated water in overhead Gravity Driven Water Pool (GDWP) to facilitate sustenance of core decay heat removal, ECCS injection, and containment cooling for three days without invoking any active systems or operator action. Incorporation of these features has been done together with considerable design simplifications, and elimination of several reactor grade equipment. A rigorous evaluation of feasibility of AHWR design concept has been completed. The economy enhancing aspects of its key design features are expected to compensate for relative complexity of the thorium fuel cycle activities

Quasi steady-state aerodynamic model development for race vehicle simulations

Science.gov (United States)

Mohrfeld-Halterman, J. A.; Uddin, M.

2016-01-01

Presented in this paper is a procedure to develop a high fidelity quasi steady-state aerodynamic model for use in race car vehicle dynamic simulations. Developed to fit quasi steady-state wind tunnel data, the aerodynamic model is regressed against three independent variables: front ground clearance, rear ride height, and yaw angle. An initial dual range model is presented and then further refined to reduce the model complexity while maintaining a high level of predictive accuracy. The model complexity reduction decreases the required amount of wind tunnel data thereby reducing wind tunnel testing time and cost. The quasi steady-state aerodynamic model for the pitch moment degree of freedom is systematically developed in this paper. This same procedure can be extended to the other five aerodynamic degrees of freedom to develop a complete six degree of freedom quasi steady-state aerodynamic model for any vehicle.

Study of Swept Angle Effects on Grid Fins Aerodynamics Performance

Science.gov (United States)

Faza, G. A.; Fadillah, H.; Silitonga, F. Y.; Agoes Moelyadi, Mochamad

2018-04-01

Grid fin is an aerodynamic control surface that usually used on missiles and rockets. In the recent several years many researches have conducted to develop a more efficient grid fins. There are many possibilities of geometric combination could be done to improve aerodynamics characteristic of a grid fin. This paper will only discuss about the aerodynamics characteristics of grid fins compared by another grid fins with different swept angle. The methodology that used to compare the aerodynamics is Computational Fluid Dynamics (CFD). The result of this paper might be used for future studies to answer our former question or as a reference for related studies.

Influence of Unsteady Aerodynamics on Driving Dynamics of Passenger Cars

OpenAIRE

Huemer, J.; Stickel, T.; Sagan, E.; Schwarz, M.; Wall, W.A.

2015-01-01

Recent approaches towards numerical investigations with CFD-Methods on unsteady aerodynamic loads of passenger cars identified major differences compared to steady state aerodynamic excitations. Furthermore innovative vehicle concepts like electric-vehicles or hybrid drives further challenge the basic layout of passenger cars. Therefore the relevance of unsteady aerodynamic loads on cross-wind stability of changing basic vehicle architectures should be analysed. In order to assure and improve...

Aerodynamics Education: Where We’ve Been and Where We’re Going

Science.gov (United States)

2013-06-24

2661. June 1992. 3 Kroo. I.. "Aerodynamic Analyses for Design and Education ... AIAA Paper 92-2664 . . lune 1992. 12 American Institute of Aeronautics...Paper 98-2792 . . lune 1998. 13 Anderson. J.D .. A l-/ist01y <~/Aero<~wwmics. Cambridge Univers ity Press. Cambridge. 1998. 14http

Aerodynamic performance of a hovering hawkmoth with flexible wings: a computational approach.

Science.gov (United States)

Nakata, Toshiyuki; Liu, Hao

2012-02-22

Insect wings are deformable structures that change shape passively and dynamically owing to inertial and aerodynamic forces during flight. It is still unclear how the three-dimensional and passive change of wing kinematics owing to inherent wing flexibility contributes to unsteady aerodynamics and energetics in insect flapping flight. Here, we perform a systematic fluid-structure interaction based analysis on the aerodynamic performance of a hovering hawkmoth, Manduca, with an integrated computational model of a hovering insect with rigid and flexible wings. Aerodynamic performance of flapping wings with passive deformation or prescribed deformation is evaluated in terms of aerodynamic force, power and efficiency. Our results reveal that wing flexibility can increase downwash in wake and hence aerodynamic force: first, a dynamic wing bending is observed, which delays the breakdown of leading edge vortex near the wing tip, responsible for augmenting the aerodynamic force-production; second, a combination of the dynamic change of wing bending and twist favourably modifies the wing kinematics in the distal area, which leads to the aerodynamic force enhancement immediately before stroke reversal. Moreover, an increase in hovering efficiency of the flexible wing is achieved as a result of the wing twist. An extensive study of wing stiffness effect on aerodynamic performance is further conducted through a tuning of Young's modulus and thickness, indicating that insect wing structures may be optimized not only in terms of aerodynamic performance but also dependent on many factors, such as the wing strength, the circulation capability of wing veins and the control of wing movements.

Unsteady Aerodynamics of Flapping Wing of a Bird

Directory of Open Access Journals (Sweden)

M. Agoes Moelyadi

2013-04-01

Full Text Available The unsteady flow behavior and time-dependent aerodynamic characteristics of the flapping motion of a bird’s wing were investigated using a computational method. During flapping, aerodynamic interactions between bird wing surfaces and surrounding flow may occur, generating local time-dependent flow changes in the flow field and aerodynamic load of birds. To study the effect of flapping speed on unsteady aerodynamic load, two kinds of computational simulations were carried out, namely a quasi-steady and an unsteady simulation. To mimic the movement of the down-stroke and the upstroke of a bird, the flapping path accorded to a sinus function, with the wing attitude changing in dihedral angle and time. The computations of time-dependent viscous flow were based on the solution of the Reynolds Averaged Navier-Stokes equations by applying the k-e turbulence model. In addition, the discretization for the computational domain around the model used multi-block structured grid to provide more accuracy in capturing viscous flow, especially in the vicinity of the wing and body surfaces, to obtain a proper wing-body geometry model. For this research, the seagull bird was chosen, which has high aspect ratio wings with pointed wing-tips and a high camber wing section. The results include mesh movement, velocity contours as well as aerodynamic coefficients of the flapping motion of the bird at various flapping frequencies.

Aerodynamic performance of a vibrating piezoelectric fan under varied operational conditions

International Nuclear Information System (INIS)

Stafford, J; Jeffers, N

2014-01-01

This paper experimentally examines the bulk aerodynamic performance of a vibrating fan operating in the first mode of vibration. The influence of operating condition on the local velocity field has also been investigated to understand the flow distribution at the exit region and determine the stalling condition for vibrating fans. Fan motion has been generated and controlled using a piezoelectric ceramic attached to a stainless steel cantilever. The frequency and amplitude at resonance were 109.4 Hz and 12.5 mm, respectively. A test facility has been developed to measure the pressure-flow characteristics of the vibrating fan and simultaneously conduct local velocity field measurements using particle image velocimetry. The results demonstrate the impact of system characteristics on the local velocity field. High momentum regions generated due to the oscillating motion exist with a component direction that is tangent to the blade at maximum displacement. These high velocity zones are significantly affected by increasing impedance while flow reversal is a dominant feature at maximum pressure rise. The findings outlined provide useful information for design of thermal management solutions that may incorporate this air cooling approach.

Aerodynamic investigation of winglets on wind turbine blades using CFD

OpenAIRE

Johansen, Jeppe; Sørensen, Niels N.

2006-01-01

The present report describes the numerical investigation of the aerodynamics around a wind turbine blade with a winglet using Computational Fluid Dynamics, CFD. Five winglets were investigated with different twist distribution and camber. Four of themwere pointing towards the pressure side (upstream) and one was pointing towards the suction side (downstream). Additionally, a rectangular modification of the original blade tip was designed with the same planform area as the blades with winglets...

Investigation of Aerodynamic Interference between Twin Deck Bridges

Energy Technology Data Exchange (ETDEWEB)

Sitek, M. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division. Transportation Research and Analysis Computing Center (TRACC); Bojanowski, C. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division. Transportation Research and Analysis Computing Center (TRACC); Lottes, S. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division. Transportation Research and Analysis Computing Center (TRACC)

2016-05-01

Construction of a twin bridge can be a cost effective and minimally disruptive way to increase capacity when an existing bridge is not near the end of its service life. With ever growing vehicular traffic, when demand approaches the capacity of many existing roads and bridges. Remodeling a structure with an insufficient number of lanes can be a good solution in case of smaller and less busy bridges. Closing down or reducing traffic on crossings of greater importance for the construction period, however, can result in major delays and revenue loss for commerce and transportation as well as increasing the traffic load on alternate route bridges. Multiple-deck bridges may be the answer to this issue. A parallel deck can be built next to the existing one, without reducing the flow. Additionally, a new bridge can be designed as a twin or multi-deck structure. Several such structures have been built throughout the United States, among them: - The New NY Bridge Project - the Tappan Zee Hudson River Crossing, - SR-182 Columbia River Bridge, - The Thaddeus Kosciusko Bridge (I-87), - The Allegheny River Bridge, Pennsylvania, which carries I76, - Fred Hartman Bridge, TX, see Figure 1.2. With a growing number of double deck bridges, additional, more detailed, studies on the interaction of such bridge pairs in windy conditions appears appropriate. Aerodynamic interference effects should be examined to assure the aerodynamic stability of both bridges. There are many studies on aerodynamic response of single deck bridges, but the literature on double-deck structures is not extensive. The experimental results from wind tunnels are still limited in number, as a parametric study is required, they can be very time consuming. Literature review shows that some investigation of the effects of gap-width and angle of wind incidence has been done. Most of the CFD computational studies that have been done were limited to 2D simulations. Therefore, it is desirable to investigate twin decks

Error Estimate of the Ares I Vehicle Longitudinal Aerodynamic Characteristics Based on Turbulent Navier-Stokes Analysis

Science.gov (United States)

Abdol-Hamid, Khaled S.; Ghaffari, Farhad

2011-01-01

Numerical predictions of the longitudinal aerodynamic characteristics for the Ares I class of vehicles, along with the associated error estimate derived from an iterative convergence grid refinement, are presented. Computational results are based on the unstructured grid, Reynolds-averaged Navier-Stokes flow solver USM3D, with an assumption that the flow is fully turbulent over the entire vehicle. This effort was designed to complement the prior computational activities conducted over the past five years in support of the Ares I Project with the emphasis on the vehicle s last design cycle designated as the A106 configuration. Due to a lack of flight data for this particular design s outer mold line, the initial vehicle s aerodynamic predictions and the associated error estimates were first assessed and validated against the available experimental data at representative wind tunnel flow conditions pertinent to the ascent phase of the trajectory without including any propulsion effects. Subsequently, the established procedures were then applied to obtain the longitudinal aerodynamic predictions at the selected flight flow conditions. Sample computed results and the correlations with the experimental measurements are presented. In addition, the present analysis includes the relevant data to highlight the balance between the prediction accuracy against the grid size and, thus, the corresponding computer resource requirements for the computations at both wind tunnel and flight flow conditions. NOTE: Some details have been removed from selected plots and figures in compliance with the sensitive but unclassified (SBU) restrictions. However, the content still conveys the merits of the technical approach and the relevant results.

Investigation of the Aerodynamic Performance of a DG808s UAS in Propeller Slipstream Using Computational Fluid Dynamics

Science.gov (United States)

Chandra, Yatish

Unmanned Aerial Systems (UASs) are relatively affordable and immediately available compared to commercial aircraft. Hence, their aerodynamics and design accuracies are often based on extrapolating from design standards and procedures widely used in the aerospace industry for commercial aircraft with most often, acceptable results. Engineering level software such as Advanced Aircraft Analysis (AAA) use general aviation aircraft data and later extrapolate them onto UASs for aerodynamic and flight dynamics modeling but are limited by their platform repository and relatively high Reynolds number evaluations. UASs however, are aircraft which fly at comparatively low speeds and low Reynolds number with close proximities between the components wherein such standards may not hold good. This thesis focuses on evaluating the accuracy and impact of such industry standards on the aerodynamics and flight dynamics of UASs. A DG808s UAS is chosen for the study which was previously modeled using the AAA software at The University of Kansas by the Flight Systems Team. Using the STAR-CCM+ code, performance data were compared and assessed with AAA. Aerodynamic simulations were carried out for two different configurations viz., aircraft with and without propeller slipstream effects. Data obtained for the non-powered simulations were found to be in good agreement with the AAA model. For the powered flight however, discrepancies between the AAA model and CFD data were observed with large values for the vertical tail side-force coefficient. A comparison with the system identification data from the flight tests was made to confirm and validate this vertical tail behavior with the help of rudder deflection inputs. A relationship between the propeller RPM and the aerodynamic model was established by simulating two different propeller speeds. Based on the STAR-CCM+ data and the resulting comparisons with AAA, updates necessary to the UAS aerodynamic and flight dynamics models currently used

Overall Design Features and Key Technology Development for KJRR

Energy Technology Data Exchange (ETDEWEB)

Park, C.; Lee, B. C.; Ryu, J. S.; Kim, Y. K. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

The KJRR (Ki-Jang Research Reactor) project was launched on Apr., 2012; 1) to make up the advanced technology related to RRs, 2) to provide the self-sufficiency in terms of medical and industrial radioisotope (RI) supply, and 3) to enlarge the NTD silicon doping services for growing the power device industry. The major facilities to be built through the KJRR project are, • 15 MW Research Reactor and Reactor building • Radioisotopes Production Facility (RIPF) and related R and D Facility • Fission Mo Production Facility (FMPF) with LEU Target • Radio-waste Treatment Facility (RTF) • Neutron Irradiation Facility such as PTS and HTS. This paper describes the overall design features of the KJRR and the key technology development for RRs during the project. The overall design features of the KJRR and RR technology under development have been overviewd. The design of the KJRR will comply with the Korean Nuclear Law, regulatory requirements and guidelines as well as international standards and guidelines. The KJRR is expected to be put into operation in the middle of 2019.

Research on aerodynamic means of isotope enrichment

International Nuclear Information System (INIS)

Cattolica, R.J.; Gallagher, R.J.; Talbot, L.; Willis, D.R.; Hurlbut, F.C.; Fiszdon, W.; Anderson, J.B.

1978-03-01

The results of a research program directed toward the understanding of the fundamental gas dynamics involved in aerodynamic isotope enrichment are summarized. The specific aerodynamic isotope enrichment method which was examined in this research is based on a velocity slip phenomenon which occurs in the rarefied hypersonic expansion of a heavy molecular weight gas and a light carrier gas in a nozzle or free jet. This particular aerodynamic method was chosen for study because it contains the fundamental molecular physics of other more complex techniques within the context of a one-dimensional flow without boundary effects. From both an experimental and theoretical modeling perspective this provides an excellent basis for testing the experimental and numerical tools with which to investigate more complex aerodynamic isotope enrichment processes. This report consists of three separate parts. Part I contains a theoretical analysis of the velocity slip effect in free jet expansions of binary and ternary gas mixtures. The analysis, based on a source flow model and using moment equations is derived from the Boltzmann equation using the hypersonic approximation. Part II contains the experimental measurements of velocity slip. The numerical simulation of the slip process was carried out by using a Monte-Carlo numerical technique. In addition, comparisons between the theoretical analysis of Part I and the experiments are presented. Part III describes impact pressure measurements of free jet expansions from slot shaped two dimensional nozzles. At least two methods of aerodynamic isotope enrichment (opposed jet and velocity slip) would depend on the use of this type of two dimensional expansion. Flow surveys of single free jet and the interferene of crossed free jets are presented

Bifurcation Analysis with Aerodynamic-Structure Uncertainties by the Nonintrusive PCE Method

Directory of Open Access Journals (Sweden)

Linpeng Wang

2017-01-01

Full Text Available An aeroelastic model for airfoil with a third-order stiffness in both pitch and plunge degree of freedom (DOF and the modified Leishman–Beddoes (LB model were built and validated. The nonintrusive polynomial chaos expansion (PCE based on tensor product is applied to quantify the uncertainty of aerodynamic and structure parameters on the aerodynamic force and aeroelastic behavior. The uncertain limit cycle oscillation (LCO and bifurcation are simulated in the time domain with the stochastic PCE method. Bifurcation diagrams with uncertainties were quantified. The Monte Carlo simulation (MCS is also applied for comparison. From the current work, it can be concluded that the nonintrusive polynomial chaos expansion can give an acceptable accuracy and have a much higher calculation efficiency than MCS. For aerodynamic model, uncertainties of aerodynamic parameters affect the aerodynamic force significantly at the stage from separation to stall at upstroke and at the stage from stall to reattach at return. For aeroelastic model, both uncertainties of aerodynamic parameters and structure parameters impact bifurcation position. Structure uncertainty of parameters is more sensitive for bifurcation. When the nonlinear stall flutter and bifurcation are concerned, more attention should be paid to the separation process of aerodynamics and parameters about pitch DOF in structure.

Summary analysis of the Gemini entry aerodynamics

Science.gov (United States)

Whitnah, A. M.; Howes, D. B.

1972-01-01

The aerodynamic data that were derived in 1967 from the analysis of flight-generated data for the Gemini entry module are presented. These data represent the aerodynamic characteristics exhibited by the vehicle during the entry portion of Gemini 2, 3, 5, 8, 10, 11, and 12 missions. For the Gemini, 5, 8, 10, 11, and 12 missions, the flight-generated lift-to-drag ratios and corresponding angles of attack are compared with the wind tunnel data. These comparisons show that the flight generated lift-to-drag ratios are consistently lower than were anticipated from the tunnel data. Numerous data uncertainties are cited that provide an insight into the problems that are related to an analysis of flight data developed from instrumentation systems, the primary functions of which are other than the evaluation of flight aerodynamic performance.

Quasi-steady state aerodynamics of the cheetah tail.

Science.gov (United States)

Patel, Amir; Boje, Edward; Fisher, Callen; Louis, Leeann; Lane, Emily

2016-08-15

During high-speed pursuit of prey, the cheetah (Acinonyx jubatus) has been observed to swing its tail while manoeuvring (e.g. turning or braking) but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry tail to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the tail are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the tail without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw tail motion primitives. The inertial and quasi-steady state aerodynamic effects of tail actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the tail's angular impulse, especially at the highest forward velocities. © 2016. Published by The Company of Biologists Ltd.

Preliminary Design of a LSA Aircraft Using Wind Tunnel Tests

Directory of Open Access Journals (Sweden)

Norbert ANGI

2015-12-01

Full Text Available This paper presents preliminary results concerning the design and aerodynamic calculations of a light sport aircraft (LSA. These were performed for a new lightweight, low cost, low fuel consumption and long-range aircraft. The design process was based on specific software tools as Advanced Aircraft Analysis (AAA, XFlr 5 aerodynamic and dynamic stability analysis, and Catia design, according to CS-LSA requirements. The calculations were accomplished by a series of tests performed in the wind tunnel in order to assess experimentally the aerodynamic characteristics of the airplane.

Aeroelastic Limit-Cycle Oscillations resulting from Aerodynamic Non-Linearities

NARCIS (Netherlands)

van Rooij, A.C.L.M.

2017-01-01

Aerodynamic non-linearities, such as shock waves, boundary layer separation or boundary layer transition, may cause an amplitude limitation of the oscillations induced by the fluid flow around a structure. These aeroelastic limit-cycle oscillations (LCOs) resulting from aerodynamic non-linearities

Effects of Leading Edge Defect on the Aerodynamic and Flow Characteristics of an S809 Airfoil.

Directory of Open Access Journals (Sweden)

Yan Wang

unchanged. In dynamic stall, leading edge defect imposes a greater influence on the aerodynamic characteristics of airfoil than steady conditions. By increasing in defect length, it is found that the separated area becomes more intense and moves forward along the suction surface.Leading edge defect has significant influence on the aerodynamic and flow characteristics of the airfoil, which will reach a stable status with enough large defect size. The leading edge separation bubble, circulation in the defect cavity and intense tailing edge vortex are the main features of flow around defective airfoils.

Mechanical Design, Analysis, and Testing of a Two-Bladed Wind Turbine Hub

Energy Technology Data Exchange (ETDEWEB)

Cotrell, J.

2002-06-01

Researchers at the National Wind Technology Center (NWTC) in Golden, Colorado, began performing the Unsteady Aerodynamics Experiment in 1993 to better understand the unsteady aerodynamics and structural responses of horizontal-axis wind turbines. The experiment consists of an extensively instrumented, downwind, three-bladed, 20-kilowatt wind turbine. In May 1995, I received a request from the NWTC to design a two-bladed hub for the experiment. For my thesis, I present the results of the mechanical design, analysis, and testing of the hub. The hub I designed is unique because it runs in rigid, teetering, or independent blade-flapping modes. In addition, the design is unusual because it uses two servomotors to pitch the blades independently. These features are used to investigate new load reduction, noise reduction, blade pitch optimization, and yaw control techniques for two-bladed turbines. I used a methodology by G. Phal and W. Bietz to design the hub. The hub meets all the performance specifications except that it achieves only 90% of the specified teeter range. In my thesis, I focus on the analysis and testing of the hub body. I performed solid-mechanics calculations, ran a finite-element analysis simulation, and experimentally investigated the structural integrity of the hub body.

Biomimetic Approach for Accurate, Real-Time Aerodynamic Coefficients, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Aerodynamic and structural reliability and efficiency depends critically on the ability to accurately assess the aerodynamic loads and moments for each lifting...

Experimental Investigation on the Characteristics of Sliding Discharge Plasma Aerodynamic Actuation

International Nuclear Information System (INIS)

Song Huimin; Zhang Qiaogen; Li Yinghong; Jia Min; Wu Yun

2011-01-01

A new electrical discharge called sliding discharge was developed to generate plasma aerodynamic actuation for flow control. A microsecond-pulse high voltage with a DC component was used to energize a three-electrode actuator to generate sliding discharge. The characteristics of plasma aerodynamic actuation by sliding discharge were experimentally investigated. Discharge morphology shows that sliding discharge is formed when energized by properly adjusting microsecond-pulse and DC voltage. Compared to dielectric barrier discharge (DBD), the plasma extension of sliding discharge is quasi-diffusive and stable but longer and more intensive. Results from particle image velocimetry (PIV) test indicate that plasma aerodynamic actuation by sliding discharge can induce a ‘starting vortex’ and a quasi-steady ‘near-wall jet’. Body force induced by plasma aerodynamic actuation is about the order of mN, which is stronger than that induced by single DBD. It is inferred that microsecond-pulse sliding discharge may be more effective to generate large-scale plasma aerodynamic actuation, which is very promising for improving aircraft aerodynamic characteristics and propulsion efficiency.

Experimental Investigation on the Characteristics of Sliding Discharge Plasma Aerodynamic Actuation

Science.gov (United States)

Song, Huimin; Li, Yinghong; Zhang, Qiaogen; Jia, Min; Wu, Yun

2011-10-01

A new electrical discharge called sliding discharge was developed to generate plasma aerodynamic actuation for flow control. A microsecond-pulse high voltage with a DC component was used to energize a three-electrode actuator to generate sliding discharge. The characteristics of plasma aerodynamic actuation by sliding discharge were experimentally investigated. Discharge morphology shows that sliding discharge is formed when energized by properly adjusting microsecond-pulse and DC voltage. Compared to dielectric barrier discharge (DBD), the plasma extension of sliding discharge is quasi-diffusive and stable but longer and more intensive. Results from particle image velocimetry (PIV) test indicate that plasma aerodynamic actuation by sliding discharge can induce a ‘starting vortex’ and a quasi-steady ‘near-wall jet’. Body force induced by plasma aerodynamic actuation is about the order of mN, which is stronger than that induced by single DBD. It is inferred that microsecond-pulse sliding discharge may be more effective to generate large-scale plasma aerodynamic actuation, which is very promising for improving aircraft aerodynamic characteristics and propulsion efficiency.

Advances in wind turbine blade design and materials

DEFF Research Database (Denmark)

Wind energy is gaining critical ground in the area of renewable energy, with wind energy being predicted to provide up to 8% of the world’s consumption of electricity by 2021. Advances in wind turbine blade design and materials reviews the design and functionality of wind turbine rotor blades...... as well as the requirements and challenges for composite materials used in both current and future designs of wind turbine blades. Part one outlines the challenges and developments in wind turbine blade design, including aerodynamic and aeroelastic design features, fatigue loads on wind turbine blades......, and characteristics of wind turbine blade airfoils. Part two discusses the fatigue behavior of composite wind turbine blades, including the micromechanical modelling and fatigue life prediction of wind turbine blade composite materials, and the effects of resin and reinforcement variations on the fatigue resistance...

Content and Design Features of Academic Health Sciences Libraries' Home Pages.

Science.gov (United States)

McConnaughy, Rozalynd P; Wilson, Steven P

2018-01-01

The goal of this content analysis was to identify commonly used content and design features of academic health sciences library home pages. After developing a checklist, data were collected from 135 academic health sciences library home pages. The core components of these library home pages included a contact phone number, a contact email address, an Ask-a-Librarian feature, the physical address listed, a feedback/suggestions link, subject guides, a discovery tool or database-specific search box, multimedia, social media, a site search option, a responsive web design, and a copyright year or update date.

Recent Darrieus vertical axis wind turbine aerodynamical experiments at Sandia National Laboratories

Science.gov (United States)

Klimas, P. C.

1981-01-01

Experiments contributing to the understanding of the aerodynamics of airfoils operating in the vertical axis wind turbine (VAWT) environment are described. These experiments are ultimately intended to reduce VAWT cost of energy and increase system reliability. They include chordwise pressure surveys, circumferential blade acceleration surveys, effects of blade camber, pitch and offset, blade blowing, and use of sections designed specifically for VAWT application.

Hypersonic Inflatable Aerodynamic Decelerator (HIAD)

Data.gov (United States)

National Aeronautics and Space Administration — Develop an entry and descent technology to enhance and enable robotic and scientific missions to destinations with atmospheres.The Hypersonic Inflatable Aerodynamic...

Computational aerodynamics requirements: The future role of the computer and the needs of the aerospace industry

Science.gov (United States)

Rubbert, P. E.

1978-01-01

The commercial airplane builder's viewpoint on the important issues involved in the development of improved computational aerodynamics tools such as powerful computers optimized for fluid flow problems is presented. The primary user of computational aerodynamics in a commercial aircraft company is the design engineer who is concerned with solving practical engineering problems. From his viewpoint, the development of program interfaces and pre-and post-processing capability for new computational methods is just as important as the algorithms and machine architecture. As more and more details of the entire flow field are computed, the visibility of the output data becomes a major problem which is then doubled when a design capability is added. The user must be able to see, understand, and interpret the results calculated. Enormous costs are expanded because of the need to work with programs having only primitive user interfaces.

Design data and safety features of commerical nuclear power plant

International Nuclear Information System (INIS)

Heddleson, F.A.

1976-06-01

Design data, safety features, and site characteristics are summarized for 34 nuclear power units in 17 power stations in the United States. Six pages of data are presented for each plant, consisting of thermal-hydraulic and nuclear factors, containment features, emergency-core-cooling systems, site features, circulating water system data, and miscellaneous factors. An aerial perspective is also presented for each plant. This volume covers Light Water Reactors (LWRs) with dockets 50-508 through 50-549, four HTGRs--50-171, 50-267, 50-450/451, 50-463/464, the Atlantic Floating Station 50-477/478, and the Clinch River Breeder 50-537

Global optimization methods for the aerodynamic shape design of transonic cascades

International Nuclear Information System (INIS)

Mengistu, T.; Ghaly, W.

2003-01-01

Two global optimization algorithms, namely Genetic Algorithm (GA) and Simulated Annealing (SA), have been applied to the aerodynamic shape optimization of transonic cascades; the objective being the redesign of an existing turbomachine airfoil to improve its performance by minimizing the total pressure loss while satisfying a number of constraints. This is accomplished by modifying the blade camber line; keeping the same blade thickness distribution, mass flow rate and the same flow turning. The objective is calculated based on an Euler solver and the blade camber line is represented with non-uniform rational B-splines (NURBS). The SA and GA methods were first assessed for known test functions and their performance in optimizing the blade shape for minimum loss is then demonstrated on a transonic turbine cascade where it is shown to produce a significant reduction in total pressure loss by eliminating the passage shock. (author)

Fourier analysis of the aerodynamic behavior of cup anemometers

International Nuclear Information System (INIS)

Pindado, Santiago; Pérez, Imanol; Aguado, Maite

2013-01-01

The calibration results (the transfer function) of an anemometer equipped with several cup rotors were analyzed and correlated with the aerodynamic forces measured on the isolated cups in a wind tunnel. The correlation was based on a Fourier analysis of the normal-to-the-cup aerodynamic force. Three different cup shapes were studied: typical conical cups, elliptical cups and porous cups (conical-truncated shape). Results indicated a good correlation between the anemometer factor, K, and the ratio between the first two coefficients in the Fourier series decomposition of the normal-to-the-cup aerodynamic force. (paper)

Multidisciplinary design and optimization (MDO) methodology for the aircraft conceptual design

Science.gov (United States)

Iqbal, Liaquat Ullah

An integrated design and optimization methodology has been developed for the conceptual design of an aircraft. The methodology brings higher fidelity Computer Aided Design, Engineering and Manufacturing (CAD, CAE and CAM) Tools such as CATIA, FLUENT, ANSYS and SURFCAM into the conceptual design by utilizing Excel as the integrator and controller. The approach is demonstrated to integrate with many of the existing low to medium fidelity codes such as the aerodynamic panel code called CMARC and sizing and constraint analysis codes, thus providing the multi-fidelity capabilities to the aircraft designer. The higher fidelity design information from the CAD and CAE tools for the geometry, aerodynamics, structural and environmental performance is provided for the application of the structured design methods such as the Quality Function Deployment (QFD) and the Pugh's Method. The higher fidelity tools bring the quantitative aspects of a design such as precise measurements of weight, volume, surface areas, center of gravity (CG) location, lift over drag ratio, and structural weight, as well as the qualitative aspects such as external geometry definition, internal layout, and coloring scheme early in the design process. The performance and safety risks involved with the new technologies can be reduced by modeling and assessing their impact more accurately on the performance of the aircraft. The methodology also enables the design and evaluation of the novel concepts such as the blended (BWB) and the hybrid wing body (HWB) concepts. Higher fidelity computational fluid dynamics (CFD) and finite element analysis (FEA) allow verification of the claims for the performance gains in aerodynamics and ascertain risks of structural failure due to different pressure distribution in the fuselage as compared with the tube and wing design. The higher fidelity aerodynamics and structural models can lead to better cost estimates that help reduce the financial risks as well. This helps in

Aerodynamic profiles of women with muscle tension dysphonia/aphonia.

Science.gov (United States)

Gillespie, Amanda I; Gartner-Schmidt, Jackie; Rubinstein, Elaine N; Abbott, Katherine Verdolini

2013-04-01

In this study, the authors aimed to (a) determine whether phonatory airflows and estimated subglottal pressures (est-Psub) for women with primary muscle tension dysphonia/aphonia (MTD/A) differ from those for healthy speakers; (b) identify different aerodynamic profile patterns within the MTD/A subject group; and (c) determine whether results suggest new understanding of pathogenesis in MTD/A. Retrospective review of aerodynamic data collected from 90 women at the time of primary MTD/A diagnosis. Aerodynamic profiles were significantly different for women with MTD/A as compared with healthy speakers. Five distinct profiles were identified: (a) normal flow, normal est-Psub; (b) high flow, high est-Psub; (c) low flow, normal est-Psub; (d) normal flow, high est-Psub; and (e) high flow, normal est-Psub. This study is the first to identify distinct subgroups of aerodynamic profiles in women with MTD/A and to quantitatively identify a clinical phenomenon sometimes described in association with it-"breath holding"-that is shown by low airflow with normal est-Psub. Results were consistent with clinical claims that diverse respiratory and laryngeal functions may underlie phonatory patterns associated with MTD/A. One potential mechanism, based in psychobiological theory, is introduced to explain some of the variability in aerodynamic profiles of women with MTD/A.

Design Features in Games for Health: Disciplinary and Interdisciplinary Expert Perspectives.

Science.gov (United States)

Kelley, Christina; Wilcox, Lauren; Ng, Wendy; Schiffer, Jade; Hammer, Jessica

2017-06-01

Games for health (G4H) aim to improve health outcomes and encourage behavior change. While existing theoretical frameworks describe features of both games and health interventions, there has been limited systematic investigation into how disciplinary and interdisciplinary stakeholders understand design features in G4H. We recruited 18 experts from the fields of game design, behavioral health, and games for health, and prompted them with 16 sample games. Applying methods including open card sorting and triading, we elicited themes and features (e.g., real-world interaction, game mechanics) around G4H. We found evidence of conceptual differences suggesting that a G4H perspective is not simply the sum of game and health perspectives. At the same time, we found evidence of convergence in stakeholder views, including areas where game experts provided insights about health and vice versa. We discuss how this work can be applied to provide conceptual tools, improve the G4H design process, and guide approaches to encoding G4H-related data for large-scale empirical analysis.

Multi-objective optimization of generalized reliability design problems using feature models-A concept for early design stages

International Nuclear Information System (INIS)

Limbourg, Philipp; Kochs, Hans-Dieter

2008-01-01

Reliability optimization problems such as the redundancy allocation problem (RAP) have been of considerable interest in the past. However, due to the restrictions of the design space formulation, they may not be applicable in all practical design problems. A method with high modelling freedom for rapid design screening is desirable, especially in early design stages. This work presents a novel approach to reliability optimization. Feature modelling, a specification method originating from software engineering, is applied for the fast specification and enumeration of complex design spaces. It is shown how feature models can not only describe arbitrary RAPs but also much more complex design problems. The design screening is accomplished by a multi-objective evolutionary algorithm for probabilistic objectives. Comparing averages or medians may hide the true characteristics of this distributions. Therefore the algorithm uses solely the probability of a system dominating another to achieve the Pareto optimal set. We illustrate the approach by specifying a RAP and a more complex design space and screening them with the evolutionary algorithm

Mechanical design features and challenges for the ITER ICRH antenna

Energy Technology Data Exchange (ETDEWEB)

Borthwick, A. [UKAEA/Euratom Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)], E-mail: andy.borthwick@yahoo.co.uk; Agarici, G. [Fusion for Energy, Barcelona (Spain); Davis, A. [UKAEA/Euratom Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Dumortier, P.; Durodie, F. [LPP-ERM-KMS, Association EURATOM-Belgian State, Brussels (Belgium); Fanthome, J.; Hamlyn-Harris, C.; Hancock, A.D.; Lockley, D. [UKAEA/Euratom Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Mitteau, R. [Euratom-CEA Association, DSM/IRFM, CEA-Cadarache, 13108 St Paul lez Durance (France); Nightingale, M. [UKAEA/Euratom Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Sartori, R. [Fusion for Energy, Barcelona (Spain); Vulliez, K. [Euratom-CEA Association, DSM/IRFM, CEA-Cadarache, 13108 St Paul lez Durance (France)

2009-06-15

The ITER Ion Cyclotron Resonant Heating (ICRH) antenna provides plasma heating at a power of 20 MW. Operation in the ITER environment imposes significant thermal power handling capability, structural integrity, shielding and operations requirements. The design will require a step change over any predecessor in terms of power, scale and complexity. This paper reports the main mechanical design features that address the challenges and often conflicting requirements during the conceptual design phase.

Naval Aerodynamics Test Facility (NATF)

Data.gov (United States)

Federal Laboratory Consortium — The NATF specializes in Aerodynamics testing of scaled and fullsized Naval models, research into flow physics found on US Navy planes and ships, aerosol testing and...

Numerical Investigations on the Aerodynamic Performance of Wind Turbine：Downwind Versus Upwind Configuration

Institute of Scientific and Technical Information of China (English)

Hu Zhou; Decheng Wan

2015-01-01

Although the upwind configuration is more popular in the field of wind energy, the downwind one is a promising type for the offshore wind energy due to its special advantages. Different configurations have different aerodynamic performance and it is important to predict the performance of both downwind and upwind configurations accurately for designing and developing more reliable wind turbines. In this paper, a numerical investigation on the aerodynamic performance of National Renewable Energy Laboratory (NREL) phase VI wind turbine in downwind and upwind configurations is presented. The open source toolbox OpenFOAM coupled with arbitrary mesh interface (AMI) method is applied to tackle rotating problems of wind turbines. Two 3D numerical models of NREL phase VI wind turbine with downwind and upwind configurations under four typical working conditions of incoming wind velocities are set up for the study of different unsteady characteristics of the downwind and upwind configurations, respectively. Numerical results of wake vortex structure, time histories of thrust, pressure distribution on the blade and limiting streamlines which can be used to identify points of separation in a 3D flow are presented. It can be concluded that thrust reduction due to blade-tower interaction is small for upwind wind turbines but relatively large for downwind wind turbines and attention should be paid to the vibration at a certain frequency induced by the cyclic reduction for both configurations. The results and conclusions are helpful to analyze the different aerodynamic performance of wind turbines between downwind and upwind configurations, providing useful references for practical design of wind turbine.

Aerodynamic problems of cable-stayed bridges spanning over one thousand meters

Institute of Scientific and Technical Information of China (English)

Chen Airong; Ma Rujin; Wang Dalei

2009-01-01

Tbe elongating of cable-stayed bridge brings a series of aerodynamic problems. First of all, geometric nonlin-ear effect of extreme long cable is much more significant for cable-stayed bridge spanning over one thousand meters. Lat-eral static wind load will generate additional displacement of long cables, which causes the decrease of supporting rigidi-ty of the whole bridge and the change of dynamic properties. Wind load, being the controlling load in the design of ca-hie-stayed bridge, is a critical problem and needs to be solved. Meanwhile, research on suitable system between pylon and deck indicates fixed-fixed connection system is an effective way for improvement performance of cable-stayed bridges under longitudinal wind load. In order to obtain aerodynamic parameters of cable-stayed bridge spanning over one thou-sand meters, identification method for flutter derivatives of full bridge aero-elastic model is developed in this paper. Furthermore, vortex induced vibration and Reynolds number effect are detailed discussed.

Scientific visualization in computational aerodynamics at NASA Ames Research Center

Science.gov (United States)

Bancroft, Gordon V.; Plessel, Todd; Merritt, Fergus; Walatka, Pamela P.; Watson, Val

1989-01-01

The visualization methods used in computational fluid dynamics research at the NASA-Ames Numerical Aerodynamic Simulation facility are examined, including postprocessing, tracking, and steering methods. The visualization requirements of the facility's three-dimensional graphical workstation are outlined and the types hardware and software used to meet these requirements are discussed. The main features of the facility's current and next-generation workstations are listed. Emphasis is given to postprocessing techniques, such as dynamic interactive viewing on the workstation and recording and playback on videodisk, tape, and 16-mm film. Postprocessing software packages are described, including a three-dimensional plotter, a surface modeler, a graphical animation system, a flow analysis software toolkit, and a real-time interactive particle-tracer.

Improving the efficiency of aerodynamic shape optimization procedures

Science.gov (United States)

Burgreen, Greg W.; Baysal, Oktay; Eleshaky, Mohamed E.

1992-01-01

The computational efficiency of an aerodynamic shape optimization procedure which is based on discrete sensitivity analysis is increased through the implementation of two improvements. The first improvement involves replacing a grid point-based approach for surface representation with a Bezier-Bernstein polynomial parameterization of the surface. Explicit analytical expressions for the grid sensitivity terms are developed for both approaches. The second improvement proposes the use of Newton's method in lieu of an alternating direction implicit (ADI) methodology to calculate the highly converged flow solutions which are required to compute the sensitivity coefficients. The modified design procedure is demonstrated by optimizing the shape of an internal-external nozzle configuration. A substantial factor of 8 decrease in computational time for the optimization process was achieved by implementing both of the design improvements.

PyFly: A fast, portable aerodynamics simulator

KAUST Repository

Garcia, D.; Ghommem, M.; Collier, N.; Varga, B.O.N.; Calo, V.M.

2018-01-01

We present a fast, user-friendly implementation of a potential flow solver based on the unsteady vortex lattice method (UVLM), namely PyFly. UVLM computes the aerodynamic loads applied on lifting surfaces while capturing the unsteady effects such as the added mass forces, the growth of bound circulation, and the wake while assuming that the flow separation location is known a priori. This method is based on discretizing the body surface into a lattice of vortex rings and relies on the Biot–Savart law to construct the velocity field at every point in the simulated domain. We introduce the pointwise approximation approach to simulate the interactions of the far-field vortices to overcome the computational burden associated with the classical implementation of UVLM. The computational framework uses the Python programming language to provide an easy to handle user interface while the computational kernels are written in Fortran. The mixed language approach enables high performance regarding solution time and great flexibility concerning easiness of code adaptation to different system configurations and applications. The computational tool predicts the unsteady aerodynamic behavior of multiple moving bodies (e.g., flapping wings, rotating blades, suspension bridges) subject to incoming air. The aerodynamic simulator can also deal with enclosure effects, multi-body interactions, and B-spline representation of body shapes. We simulate different aerodynamic problems to illustrate the usefulness and effectiveness of PyFly.

PyFly: A fast, portable aerodynamics simulator

KAUST Repository

Garcia, D.

2018-03-18

We present a fast, user-friendly implementation of a potential flow solver based on the unsteady vortex lattice method (UVLM), namely PyFly. UVLM computes the aerodynamic loads applied on lifting surfaces while capturing the unsteady effects such as the added mass forces, the growth of bound circulation, and the wake while assuming that the flow separation location is known a priori. This method is based on discretizing the body surface into a lattice of vortex rings and relies on the Biot–Savart law to construct the velocity field at every point in the simulated domain. We introduce the pointwise approximation approach to simulate the interactions of the far-field vortices to overcome the computational burden associated with the classical implementation of UVLM. The computational framework uses the Python programming language to provide an easy to handle user interface while the computational kernels are written in Fortran. The mixed language approach enables high performance regarding solution time and great flexibility concerning easiness of code adaptation to different system configurations and applications. The computational tool predicts the unsteady aerodynamic behavior of multiple moving bodies (e.g., flapping wings, rotating blades, suspension bridges) subject to incoming air. The aerodynamic simulator can also deal with enclosure effects, multi-body interactions, and B-spline representation of body shapes. We simulate different aerodynamic problems to illustrate the usefulness and effectiveness of PyFly.

IEA joint action. Aerodynamics of wind turbines

Energy Technology Data Exchange (ETDEWEB)

Maribo Pedersen, B. [ed.

1997-12-31

In the period 1992-1997 the IEA Annex XIV `Field Rotor Aerodynamics` was carried out. Within its framework 5 institutes from 4 different countries participated in performing detailed aerodynamic measurements on full-scale wind turbines. The Annex was successfully completed and resulted in a unique database of aerodynamic measurements. The database is stored on an ECN disc (available through ftp) and on a CD-ROM. It is expected that this base will be used extensively in the development and validation of new aerodynamic models. Nevertheless at the end of IEA Annex XIV, it was recommended to perform a new IEA Annex due to the following reasons: In Annex XIV several data exchange rounds appeared to be necessary before a satisfactory result was achieved. This is due to the huge amount of data which had to be supplied, by which a thorough inspection of all data is very difficult and very time consuming; Most experimental facilities are still operational and new, very useful, measurements are expected in the near future; The definition of angle of attack and dynamic pressure in the rotating environment is less straightforward than in the wind tunnel. The conclusion from Annex XIV was that the uncertainty which results from these different definitions is still too large and more investigation in this field is required. (EG)

A study on HCI design strategy using emergent features and response time

International Nuclear Information System (INIS)

Lee, Sung Jin; Chang, Soon Heung; Park, Jin Gyun

2001-01-01

Existing design process of user interface has some weak point that there is no feedback information and no quantitative information between each sub process. If they're such information in design process, the design time cycle will be decreased and the contentment of HCI in the aspect of user will be more easily archived. In this study, new design process with feedback information and quantitative information was proposed using emergent features and user response time. The proposed methodology was put together with three main parts. First part is to calculate distinctiveness of a user interface or expanded user interface with consideration of emergent features. Second part is to expand a prototype user interface with design option for purpose of design requirement using directed structure graph (or nodal graph) theory. Last part is to convert non-realized value, distinctiveness, into realized value, response time, by response time database or response time correlation in the form of Hick-Hyman law equation. From the present validations, the usefulness of the proposed methodology was obtained by simple validation testing. It was found that emergent features should be improved for high reflection of real user interface. For the reliability of response time database, lots of end-user experiment is necessary. Expansion algorithm and representation technique of qualitative information should be somewhat improved for more efficient design process

Aerodynamic study of state transport bus using computational fluid dynamics

Science.gov (United States)

Kanekar, Siddhesh; Thakre, Prashant; Rajkumar, E.

2017-11-01

The main purpose of this study was to develop the aerodynamic study of a Maharashtra state road transport bus. The rising fuel price and strict government regulations makes the road transport uneconomical now days. With the objective of increasing fuel efficiency and reducing the emission of harmful exhaust gases. It has been proven experimentally that vehicle consumes almost 40% of the available useful engine power to overcome the drag resistance. This provides us a huge scope to study the influence of aerodynamic drag. The initial of the project was to identify the drag coefficient of the existing ordinary type model called “Parivartan” from ANSYS fluent. After preliminary analysis of the existing model corresponding changes are made in such a way that their implementation should be possible at workshop level. The simulation of the air flow over the bus was performed in two steps: design on SolidWorks CAD and ANSYS (FLUENT) is used as a virtual analysis tool to estimate the drag coefficient of the bus. We have used the turbulence models k-ε Realizable having a better approximation of the actual result. Around 28% improvement in the drag coefficient is achieved by CFD driven changes in the bus design. Coefficient of drag is improved by 28% and fuel efficiency increased by 20% by CFD driven changes.

AERODYNAMIC STUDIES IN THE STATIC COMPONENTS OF A CENTRIFUGAL COMPRESSOR STAGE

Directory of Open Access Journals (Sweden)

K. Srinivasa Reddy

2011-12-01

Full Text Available Aerodynamic studies in the static components of a centrifugal compressor stage were conducted using the computational fluid dynamics solver FLUENT. For the simulation study, a typical centrifugal compressor stage geometry with a flow coefficient of 0.053 was chosen, The study is confined to the static components of the centrifugal compressor stage, i.e., the crossover bend (180° U-bend, a radial cascade of return channel vanes, and the exit ducting (90° L-turn. The aerodynamic performance is reported in terms of total pressure loss coefficient, static pressure recovery coefficient, return channel vane surface static pressure distribution, and stage exit swirl angle distribution. The simulated flow through the static components covered five different operating conditions of the actual centrifugal compressor stage: the design point with 100% flow rate, and the off-design operating conditions with 70%, 80%, 110%, and 120% flow rates. The standard k-ε model was used with standard wall functions to predict the turbulence. A minimum total pressure loss coefficient was observed near 80% flow rate when the average flow angle at the U-bend inlet was 24°. Better static pressure recovery was observed with 70%, 80%, and 100% flow rates. The swirl angle distribution at the stage exit was recognized as satisfactory.

Design features of Beijing Shijingshan 3 x 200 MW cogeneration plant

International Nuclear Information System (INIS)

Li, T.X.; Ou, Y.Z.

1991-01-01

This paper describes the design feature of Beijing Shijingshan 3 x 200 MW Cogeneration Plant. The design optimized the scheme and system of 200 MW units for heating. The cogeneration plant has achieved comprehensive economic benefit in energy saving and environmental pollution reduction

Building Integrated Active Flow Control: Improving the Aerodynamic Performance of Tall Buildings Using Fluid-Based Aerodynamic Modification

Science.gov (United States)

Menicovich, David

material and energy consumption profiles of tall building. To date, the increasing use of light-weight and high-strength materials in tall buildings, with greater flexibility and reduced damping, has increased susceptibility to dynamic wind load effects that limit the gains afforded by incorporating these new materials. Wind, particularly fluctuating wind and its interaction with buildings induces two main responses; alongwind - in the direction of the flow and crosswind - perpendicular to the flow. The main risk associated with this vulnerability is resonant oscillations induced by von-Karman-like vortex shedding at or near the natural frequency of the structure caused by flow separation. Dynamic wind loading effects often increase with a power of wind speed greater than 3, thus increasingly, tall buildings pay a significant price in material to increase the natural frequency and/or the damping to overcome this response. In particular, crosswind response often governs serviceability (human habitability) design criteria of slender buildings. Currently, reducing crosswind response relies on a Solid-based Aerodynamic Modification (SAM), either by changing structural or geometric characteristics such as the tower shape or through the addition of damping systems. While this approach has merit it has two major drawbacks: firstly, the loss of valuable rentable areas and high construction costs due to increased structural requirements for mass and stiffness, further contributing towards the high consumption of non-renewable resources by the commercial building sector. For example, in order to insure human comfort within an acceptable range of crosswind response induced accelerations at the top of a building, an aerodynamically efficient plan shape comes at the expense of floor area. To compensate for the loss of valuable area compensatory stories are required, resulting in an increase in wind loads and construction costs. Secondly, a limited, if at all, ability to adaptively

Improving the efficiency of aerodynamic shape optimization

Science.gov (United States)

Burgreen, Greg W.; Baysal, Oktay; Eleshaky, Mohamed E.

1994-01-01

The computational efficiency of an aerodynamic shape optimization procedure that is based on discrete sensitivity analysis is increased through the implementation of two improvements. The first improvement involves replacing a grid-point-based approach for surface representation with a Bezier-Bernstein polynomial parameterization of the surface. Explicit analytical expressions for the grid sensitivity terms are developed for both approaches. The second improvement proposes the use of Newton's method in lieu of an alternating direction implicit methodology to calculate the highly converged flow solutions that are required to compute the sensitivity coefficients. The modified design procedure is demonstrated by optimizing the shape of an internal-external nozzle configuration. Practically identical optimization results are obtained that are independent of the method used to represent the surface. A substantial factor of 8 decrease in computational time for the optimization process is achieved by implementing both of the design procedure improvements.

Design features to achieve defence-in-depth in small and medium sized reactors

International Nuclear Information System (INIS)

Kuznetsov, Vladimir

2009-01-01

Broader incorporation of inherent and passive safety design features has become a 'trademark' of many advanced reactor concepts, including several evolutionary designs and nearly all innovative small and medium sized design concepts. Ensuring adequate defence-in-depth is important for reactors of smaller output because many of them are being designed to allow more proximity to the user, specifically, when non-electrical energy products are targeted. Based on the activities recently performed by the International Atomic Energy Agency, the paper provides a summary description of the design features used to achieve defence in depth in the eleven representative concepts of small and medium sized reactors. (author)

Aerodynamically shaped vortex generators

DEFF Research Database (Denmark)

Hansen, Martin Otto Laver; Velte, Clara Marika; Øye, Stig

2016-01-01

An aerodynamically shaped vortex generator has been proposed, manufactured and tested in a wind tunnel. The effect on the overall performance when applied on a thick airfoil is an increased lift to drag ratio compared with standard vortex generators. Copyright © 2015 John Wiley & Sons, Ltd....

Method determination of aerodynamic performances of profile in the plane airfoil cascade

Directory of Open Access Journals (Sweden)

Л. Г. Волянська

2003-03-01

Full Text Available Method determination of aerodynamic forces by direct measurement using three-component aerodynamic balance are given in the article. There are the schematic model of the facility for determination airfoil cascade aerodynamic performances in the article. Drawing and description of slewing pack of blades are shown in the article

Aerodynamic characteristics of flying fish in gliding flight.

Science.gov (United States)

Park, Hyungmin; Choi, Haecheon

2010-10-01

The flying fish (family Exocoetidae) is an exceptional marine flying vertebrate, utilizing the advantages of moving in two different media, i.e. swimming in water and flying in air. Despite some physical limitations by moving in both water and air, the flying fish has evolved to have good aerodynamic designs (such as the hypertrophied fins and cylindrical body with a ventrally flattened surface) for proficient gliding flight. Hence, the morphological and behavioral adaptations of flying fish to aerial locomotion have attracted great interest from various fields including biology and aerodynamics. Several aspects of the flight of flying fish have been determined or conjectured from previous field observations and measurements of morphometric parameters. However, the detailed measurement of wing performance associated with its morphometry for identifying the characteristics of flight in flying fish has not been performed yet. Therefore, in the present study, we directly measure the aerodynamic forces and moment on darkedged-wing flying fish (Cypselurus hiraii) models and correlated them with morphological characteristics of wing (fin). The model configurations considered are: (1) both the pectoral and pelvic fins spread out, (2) only the pectoral fins spread with the pelvic fins folded, and (3) both fins folded. The role of the pelvic fins was found to increase the lift force and lift-to-drag ratio, which is confirmed by the jet-like flow structure existing between the pectoral and pelvic fins. With both the pectoral and pelvic fins spread, the longitudinal static stability is also more enhanced than that with the pelvic fins folded. For cases 1 and 2, the lift-to-drag ratio was maximum at attack angles of around 0 deg, where the attack angle is the angle between the longitudinal body axis and the flying direction. The lift coefficient is largest at attack angles around 30∼35 deg, at which the flying fish is observed to emerge from the sea surface. From glide polar

A Unified Methodology for Aerospace Systems Integration Based on Entropy and the Second Law of Thermodynamics: Aerodynamics Assessment

National Research Council Canada - National Science Library

Camberos, Jose A; Nomura, Shohei; Stewart, Jason; Figliola, Richard

2004-01-01

.... The objective of this project is to relate work-potential losses (exergy destruction) to the aerodynamics forces in an attempt to validate a new design methodology based on the second law of thermodynamic...

Flow field analysis of a pentagonal-shaped bridge deck by unsteady RANS

Directory of Open Access Journals (Sweden)

Md. Naimul Haque

2016-01-01

Full Text Available Long-span cable-stayed bridges are susceptible to dynamic wind effects due to their inherent flexibility. The fluid flow around the bridge deck should be well understood for the efficient design of an aerodynamically stable long-span bridge system. In this work, the aerodynamic features of a pentagonal-shaped bridge deck are explored numerically. The analytical results are compared with past experimental work to assess the capability of two-dimensional unsteady RANS simulation for predicting the aerodynamic features of this type of deck. The influence of the bottom plate slope on aerodynamic response and flow features was investigated. By varying the Reynolds number (2 × 104 to 20 × 104 the aerodynamic behavior at high wind speeds is clarified.

Variation in aerodynamic coefficients with altitude

Science.gov (United States)

Shahid, Faiza; Hussain, Mukkarum; Baig, Mirza Mehmood; Haq, Ihtram ul

Precise aerodynamics performance prediction plays key role for a flying vehicle to get its mission completed within desired accuracy. Aerodynamic coefficients for same Mach number can be different at different altitude due to difference in Reynolds number. Prediction of these aerodynamics coefficients can be made through experiments, analytical solution or Computational Fluid Dynamics (CFD). Advancements in computational power have generated the concept of using CFD as a virtual Wind Tunnel (WT), hence aerodynamic performance prediction in present study is based upon CFD (numerical test rig). Simulations at different altitudes for a range of Mach numbers with zero angle of attack are performed to predict axial force coefficient behavior with altitude (Reynolds number). Similar simulations for a fixed Mach number '3' and a range of angle of attacks are also carried out to envisage the variation in normal force and pitching moment coefficients with altitude (Reynolds number). Results clearly depict that the axial force coefficient is a function of altitude (Reynolds number) and increase as altitude increases, especially for subsonic region. Variation in axial force coefficient with altitude (Reynolds number) slightly increases for larger values of angle of attacks. Normal force and pitching moment coefficients do not depend on altitude (Reynolds number) at smaller values of angle of attacks but show slight decrease as altitude increases. Present study suggests that variation of normal force and pitching moment coefficients with altitude can be neglected but the variation of axial force coefficient with altitude should be considered for vehicle fly in dense atmosphere. It is recommended to continue this study to more complex configurations for various Mach numbers with side slip and real gas effects.

THERMAL AND AERODYNAMIC PERFORMANCES OF THE SUPERSONIC MOTION

Directory of Open Access Journals (Sweden)

Dejan P Ninković

2010-01-01

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

Aeroacoustic and aerodynamic applications of the theory of nonequilibrium thermodynamics

Science.gov (United States)

Horne, W. Clifton; Smith, Charles A.; Karamcheti, Krishnamurty

1991-01-01

Recent developments in the field of nonequilibrium thermodynamics associated with viscous flows are examined and related to developments to the understanding of specific phenomena in aerodynamics and aeroacoustics. A key element of the nonequilibrium theory is the principle of minimum entropy production rate for steady dissipative processes near equilibrium, and variational calculus is used to apply this principle to several examples of viscous flow. A review of nonequilibrium thermodynamics and its role in fluid motion are presented. Several formulations are presented of the local entropy production rate and the local energy dissipation rate, two quantities that are of central importance to the theory. These expressions and the principle of minimum entropy production rate for steady viscous flows are used to identify parallel-wall channel flow and irrotational flow as having minimally dissipative velocity distributions. Features of irrotational, steady, viscous flow near an airfoil, such as the effect of trailing-edge radius on circulation, are also found to be compatible with the minimum principle. Finally, the minimum principle is used to interpret the stability of infinitesimal and finite amplitude disturbances in an initially laminar, parallel shear flow, with results that are consistent with experiment and linearized hydrodynamic stability theory. These results suggest that a thermodynamic approach may be useful in unifying the understanding of many diverse phenomena in aerodynamics and aeroacoustics.

Design of Large Wind Turbines using Fluid-Structure Coupling Technique

DEFF Research Database (Denmark)

Sessarego, Matias

Aerodynamic and structural dynamic performance analysis of modern wind turbines are routinely carried out in the wind energy field using computational tools known as aero-elastic codes. Most aero-elastic codes use the blade element momentum (BEM) technique to model the rotor aerodynamics......-dimensional viscous-inviscid interactive method, MIRAS, with the dynamics model used in the aero-elastic code FLEX5. Following the development of MIRAS-FLEX, a surrogate optimization methodology using MIRAS alone has been developed for the aerodynamic design of wind-turbine rotors. Designing a rotor using...... a computationally expensive MIRAS instead of an inexpensive BEM code represents a challenge, which is resolved by using the proposed surrogate-based approach. The approach is unique because most aerodynamic wind-turbine rotor design codes use the more common and inexpensive BEM technique. As a verification case...

Particle Methods in Bluff Body Aerodynamics

DEFF Research Database (Denmark)

Rasmussen, Johannes Tophøj

. The implementation is two-dimensional and sequential. The implementation is validated against the analytic solution to the Perlman test case and by free-space simulations of the onset flow around fixed and rotating circular cylinders and bluff body flows around bridge sections. Finally a three-dimensional vortex...... is important. This dissertation focuses on the use of vortex particle methods and computational efficiency. The work is divided into three parts. A novel method for the simulation of the aerodynamic admittance in bluff body aerodynamics is presented. The method involves a model for describing oncoming...... section during the construction phase and the swimming motion of the medusa Aurelia aurita....

Controller Design Automation for Aeroservoelastic Design Optimization of Wind Turbines

NARCIS (Netherlands)

Ashuri, T.; Van Bussel, G.J.W.; Zaayer, M.B.; Van Kuik, G.A.M.

2010-01-01

The purpose of this paper is to integrate the controller design of wind turbines with structure and aerodynamic analysis and use the final product in the design optimization process (DOP) of wind turbines. To do that, the controller design is automated and integrated with an aeroelastic simulation

Reliability and Applicability of Aerodynamic Measures in Dysphonia Assessment

Science.gov (United States)

Yiu, Edwin M.-L.; Yuen, Yuet-Ming; Whitehill, Tara; Winkworth, Alison

2004-01-01

Aerodynamic measures are frequently used to analyse and document pathological voices. Some normative data are available for speakers from the English-speaking population. However, no data are available yet for Chinese speakers despite the fact that they are one of the largest populations in the world. The high variability of aerodynamic measures…

Development of quantitative goals for inherent safety feature design and licensing

International Nuclear Information System (INIS)

Kastenberg, W.E.; Apostolakis, G.; Dhir, V.K.; Okrent, D.

1987-01-01

There is now considerable interest in the development of advanced fast reactors whose major focus is inherent safety. The achievement of inherent safety can be viewed from several aspects. In the Integral Fast Reactor Concept the approach is to utilize the intrinsic characteristics of pool-type liquid metal fast breeder reactors (LMFBRs) and the properties of metal fuels to integrate a high degree of inherent safety into the design. The PRISM and SAFR concepts focus on other inherent safety features. The reactors discussed above represent a radical departure from existing LWR designs as well as previous LMFBR designs (e.g., CRBRP) which are based, for the most part, on the General Design Criteria found in 10CFR50 Appendix. In view of these parallel developments (advanced reactors exploiting inherent safety and the use of quantitative goals to augment licensing), there appears to be a need to perform research on the development of methods for designing, assessing, and licensing inherent safety features in advanced reactors. The objectives of such research are outlined

Aerodynamic efficiency of a bio-inspired flapping wing rotor at low Reynolds number

OpenAIRE

Li, Hao; Guo, Shijun

2018-01-01

This study investigates the aerodynamic efficiency of a bioinspired flapping wing rotor kinematics which combines an active vertical flapping motion and a passive horizontal rotation induced by aerodynamic thrust. The aerodynamic efficiencies for producing both vertical lift and horizontal thrust of the wing are obtained using a quasi-steady aerodynamic model and two-dimensional (2D) CFD analysis at Reynolds number of 2500. The calculated efficiency data show that both efficiencies (propulsiv...

Experimental Investigation of Aerodynamic Instability of Iced Bridge Cable Sections

DEFF Research Database (Denmark)

Koss, Holger; Lund, Mia Schou Møller

2013-01-01

The accretion of ice on structural bridge cables changes the aerodynamic conditions of the surface and influences hence the acting wind load process. Full-scale monitoring indicates that light precipitation at moderate low temperatures between zero and -5°C may lead to large amplitude vibrations...... of bridge cables under wind action. This paper describes the experimental simulation of ice accretion on a real bridge cable sheet HDPE tube segment (diameter 160mm) and its effect on the aerodynamic load. Furthermore, aerodynamic instability will be estimated with quasi-steady theory using the determined...

Bayesian inference of nonlinear unsteady aerodynamics from aeroelastic limit cycle oscillations

Energy Technology Data Exchange (ETDEWEB)

Sandhu, Rimple [Department of Civil and Environmental Engineering, Carleton University, Ottawa, Ontario (Canada); Poirel, Dominique [Department of Mechanical and Aerospace Engineering, Royal Military College of Canada, Kingston, Ontario (Canada); Pettit, Chris [Department of Aerospace Engineering, United States Naval Academy, Annapolis, MD (United States); Khalil, Mohammad [Department of Civil and Environmental Engineering, Carleton University, Ottawa, Ontario (Canada); Sarkar, Abhijit, E-mail: abhijit.sarkar@carleton.ca [Department of Civil and Environmental Engineering, Carleton University, Ottawa, Ontario (Canada)

2016-07-01

A Bayesian model selection and parameter estimation algorithm is applied to investigate the influence of nonlinear and unsteady aerodynamic loads on the limit cycle oscillation (LCO) of a pitching airfoil in the transitional Reynolds number regime. At small angles of attack, laminar boundary layer trailing edge separation causes negative aerodynamic damping leading to the LCO. The fluid–structure interaction of the rigid, but elastically mounted, airfoil and nonlinear unsteady aerodynamics is represented by two coupled nonlinear stochastic ordinary differential equations containing uncertain parameters and model approximation errors. Several plausible aerodynamic models with increasing complexity are proposed to describe the aeroelastic system leading to LCO. The likelihood in the posterior parameter probability density function (pdf) is available semi-analytically using the extended Kalman filter for the state estimation of the coupled nonlinear structural and unsteady aerodynamic model. The posterior parameter pdf is sampled using a parallel and adaptive Markov Chain Monte Carlo (MCMC) algorithm. The posterior probability of each model is estimated using the Chib–Jeliazkov method that directly uses the posterior MCMC samples for evidence (marginal likelihood) computation. The Bayesian algorithm is validated through a numerical study and then applied to model the nonlinear unsteady aerodynamic loads using wind-tunnel test data at various Reynolds numbers.

Numerical Investigation on Vortex-Structure Interaction Generating Aerodynamic Noises for Rod-Airfoil Models

Directory of Open Access Journals (Sweden)

FeiFei Liu

2017-01-01

Full Text Available In past several decades, vortex-structure interaction generated aerodynamic noise became one of the main concerns in aircraft design. In order to understand the mechanism, the acoustic analogy method combined with the RANS-based nonlinear acoustics solver (NLAS is investigated. The numerical method is firstly evaluated by the experiment data of the classic rod-airfoil model. Compared with the traditional analogy methods, the RANS/NLAS can capture the nonlinear aerodynamic noise more accurately with lower gird requirements. Then different rod-airfoil configurations were simulated to investigate the aeroacoustic interaction effects. The numerical results are in good agreement with those of the earlier experimental research. It is found that the vortex-shedding crash to the airfoil is the main reason for the noise generation which is dependent on the configurations, distance, and flow conditions.

Comparison of advanced aerodynamic models

Energy Technology Data Exchange (ETDEWEB)

McWilliam, M.; Cline, S.; Lawton, S.; Crawford, C. [Victoria Univ., BC (Canada). Inst. for Integrated Energy Systems; Victoria Univ., BC (Canada). Sustainable Systems Design Laboratory

2010-07-01

This PowerPoint presentation discussed the development of aerodynamic tools for designing sweep and out-of-plane curvatures for wind turbine blades. Potential flow and vortex methods are used to simulate individual vortex elements at the blade and in the wake, and are appropriate modelling tools are both out-of-plane and sweep curvatures. Centrifugal pumping, hub loss, and turbulent wake models are used to correct the blade element momentum (BEM) theory, where a blade's wake is modelled as a momentum balance between the far upstream and downstream. Wake shape can be numerically solved using the vortex theory. Wake vorticity is then integrated to characterize rotor conditions. Potential flow and vortex methods are used to account for the influence of the rotor and to model the wake structure. Details of experimental studies and validation test cases using the modelling methods were provided. tabs., figs.

Advanced multistage turbine blade aerodynamics, performance, cooling, and heat transfer

Energy Technology Data Exchange (ETDEWEB)

Fleeter, S.; Lawless, P.B. [Purdue Univ., West Lafayette, IN (United States)

1995-10-01

The gas turbine has the potential for power production at the highest possible efficiency. The challenge is to ensure that gas turbines operate at the optimum efficiency so as to use the least fuel and produce minimum emissions. A key component to meeting this challenge is the turbine. Turbine performance, both aerodynamics and heat transfer, is one of the barrier advanced gas turbine development technologies. This is a result of the complex, highly three-dimensional and unsteady flow phenomena in the turbine. Improved turbine aerodynamic performance has been achieved with three-dimensional highly-loaded airfoil designs, accomplished utilizing Euler or Navier-Stokes Computational Fluid Dynamics (CFD) codes. These design codes consider steady flow through isolated blade rows. Thus they do not account for unsteady flow effects. However, unsteady flow effects have a significant impact on performance. Also, CFD codes predict the complete flow field. The experimental verification of these codes has traditionally been accomplished with point data - not corresponding plane field measurements. Thus, although advanced CFD predictions of the highly complex and three-dimensional turbine flow fields are available, corresponding data are not. To improve the design capability for high temperature turbines, a detailed understanding of the highly unsteady and three-dimensional flow through multi-stage turbines is necessary. Thus, unique data are required which quantify the unsteady three-dimensional flow through multi-stage turbine blade rows, including the effect of the film coolant flow. This requires experiments in appropriate research facilities in which complete flow field data, not only point measurements, are obtained and analyzed. Also, as design CFD codes do not account for unsteady flow effects, the next logical challenge and the current thrust in CFD code development is multiple-stage analyses that account for the interactions between neighboring blade rows.

Numerical simulation of aerodynamic sound radiated from a two-dimensional airfoil

OpenAIRE

飯田, 明由; 大田黒, 俊夫; 加藤, 千幸; Akiyoshi, Iida; Toshio, Otaguro; Chisachi, Kato; 日立機研; 日立機研; 東大生研; Mechanical Engineering Research Laboratory, Hitachi Ltd.; Mechanical Engineering Research Laboratory, Hitachi Ltd.; University of Tokyo

2000-01-01

An aerodynamic sound radiated from a two-dimensional airfoil has been computed with the Lighthill-Curle's theory. The predicted sound pressure level is agreement with the measured one. Distribution of vortex sound sources is also estimated based on the correlation between the unsteady vorticity fluctuations and the aerodynamic sound. The distribution of vortex sound source reveals that separated shear layers generate aerodynamic sound. This result is help to understand noise reduction method....