Wind Tunnel Test Data Research Articles

Improving Quality of Wind Tunnel Test Data Through the MDOE

Researching on the improvement of the wind tunnel data quality through Modern Design Of Experiments (MDOE) was carried out. A body with fin model was tested in wind tunnel through the MDOE and traditional OFAT (One Factor at A Time) methods. The uncertainties of data from these two different methods were analyzed, and mechanism of defense against systematic error of Randomization and Repetition in the MDOE method was studied. The defense abilities against the time various systematic errors in wind tunnel tests of the MDOE and the OFAT method were compared, and the mean to improve test data quality using repetition principle in the MDOE was studied with the increasing of cost. Main conclusions: The MDOE method can test and eliminate the time various systematic errors during the wind tunnel tests, while the OFAT test data were polluted by the time various systematic errors; The independent variable changes sequently in the OFAT tests, so the test data are not statistically independent. It is the reason of the disability of the defense against the time various systematic errors in OFAT tests. Randomization can transform the systematic errors into random errors in MDOE tests, which can be eliminated. Repetition in MDOE tests can improve the quality of test data since the average variance in the predicted response can be reduced by adding sample points, and amount of the measured data are still less than the amount in OFAT tests.

풍력터빈의 구조특성 평가에 관한 연구-Part1

This paper presents the structural model development and verification processes of wind turbine blade. The National Renewable Energy Laboratory (NREL) Phase VI wind turbine which the wind tunnel and structural test data has publicly available is used for the study. The wind turbine assembled by blades, rotor, nacelle and tower. The wind blade connected to rotor. To make the whole turbine structural model, the mass and stiffness properties of all parts should be clear and given. However the wind blade, hub, nacelle, rotor and power generating machinery parts have difficulties to define the material properties because of the composite and assembling nature of that. Nowadays to increase the power generating coefficient and cost efficiency, the highly accurate aerodynamic loading evaluating technique should be developed. The Fluid-Structure Interaction (FSI) is the emerging new way to evaluate the aerodynamic force on the rotating wind blade. To perform the FSI analysis, the fluid and structural model which are sharing the associated interface topology have to be provided. In this paper, the structural model of blade development and verifying processes have been explained for Part1. In following Part2 paper, the processes of whole turbine system will be discussing.

Blockage effect correction for a scaled wind turbine rotor by using wind tunnel test data

This paper discusses the procedure of a blockage effect correction method involving small-scale wind turbine rotor experimental data. To simulate the aerodynamic performance of full-scale rotors in the field, however, measured data from scaled model experiments need to be analyzed appropriately. One of the most important elements of such an analysis is a procedure to remove the blockage effect of the wind tunnel wall from the measured power data. In this paper, a correction algorithm proposed as part of Glauert's blockage effect correction method is used to process the data from a wind turbine rotor tested with three different wind tunnel sizes. Also, this study considered the modified blockage effect correction method, which has been used to process the rotor thrust data in closed-circuit wind tunnels and open-circuit wind tunnels. A small-scale rotor was tested under the same operating conditions, i.e., the same advance ratio, rotating speed, rotor torque and speed of the wind tunnel. The small-scale wind turbine rotor has a diameter of 1.408 m and a rotating speed according to the tip speed ratio. In each case, the effect of the blockage ratio and aerodynamic characteristics are determined using wind tunnel test results and with a simple analytical correction method. The results of the modified correction method show that the aerodynamic performance levels during a wind tunnel test are cleared by the blockage effect.

Aerodynamic design of a descent vehicle in the Martian atmosphere under the exomars project

The paper considers mathematical support for calculation of the aerodynamics and flight trajectory of descent vehicles (DV) during entry into the Martian atmosphere. The study of aerodynamics of a segmental and conical DV is given under various reentry conditions. The paper presents comparison of computational results of the aerodynamic properties of the DV of the ExoMars project with wind tunnel test data of DV models.

Wind-excited stochastic vibration of long-span bridge considering wind field parameters during typhoon landfall

With the assistance of typhoon field data at aerial elevation level observed by meteorological satellites and wind velocity and direction records nearby the ground gathered in Guangzhou Weather Station between 1985 and 2001, some key wind field parameters under typhoon climate in Guangzhou region were calibrated based on Monte-Carlo stochastic algorithm and Meng\'s typhoon numerical model. By using Peak Over Threshold method (POT) and Generalized Pareto Distribution (GPD), Wind field characteristics during typhoons for various return periods in several typical engineering fields were predicted, showing that some distribution rules in relation to gradient height of atmosphere boundary layer, power-law component of wind profile, gust factor and extreme wind velocity at 1-3s time interval are obviously different from corresponding items in Chinese wind load Codes. In order to evaluate the influence of typhoon field parameters on long-span flexible bridges, 1:100 reduced-scale wind field of type B terrain was re-illustrated under typhoon and normal conditions utilizing passive turbulence generators in TJ-3 wind tunnel, and wind-induced performance tests of aero-elastic model of long-span Guangzhou Xinguang arch bridge were carried out as well. Furthermore, aerodynamic admittance function about lattice cross section in mid-span arch lib under the condition of higher turbulence intensity of typhoon field was identified via using high-frequency force-measured balance. Based on identified aerodynamic admittance expressions, Wind-induced stochastic vibration of Xinguang arch bridge under typhoon and normal climates was calculated and compared, considering structural geometrical non-linearity, stochastic wind attack angle effects, etc. Thus, the aerodynamic response characteristics under typhoon and normal conditions can be illustrated and checked, which are of satisfactory response results for different oncoming wind velocities with resemblance to those wind tunnel testing data under the two types of climate modes.

Simulation and Optimization for the Cooling System of Heavy Vehicle Engine

An engine cooling system of heavy vehicle was used as a research object in this thesis. Engine system model was designed with KULI software according to wind tunnel testing data of heat exchanger provided by supplier. Simulation calculation provides optimization program based on the results. The result is that it can simulate calculation with KULI software, in the early design on a cooling system of heavy vehicle engine. The study provides a theoretical basis for the design of a cooling system of heavy vehicle engine, improve the efficiency and save the cost.

Minimization of classification samples for supercritical and subcritical patterns of supersonic inlet

In order to investigate sample minimization for classification of supercritical and subcritical patterns in supersonic inlet, three optimization methods, namely, opposite one towards nearest method, closest one towards the hyper-plane method and random selection method, are proposed for investigation on minimization of classification samples for supercritical and subcritical patterns of supersonic inlet. The study has been carried out to analyze wind tunnel test data and to compare the classification accuracy based on those three methods with or without priori knowledge. Those three methods are different from each other by different selecting methods for samples. The results show that one of the optimization methods needs the minimization samples to get the highest classification accuracy without priori knowledge. Meanwhile, the number of minimization samples needed to get highest classification accuracy can be further reduced by introducing priori knowledge. Furthermore, it demonstrates that the best optimization method has been found by comparing all cases studied with or without introducing priori knowledge. This method can be applied to reduce the number of wind tunnel tests to obtain the inlet performance and to identify the supercritical/subcritical modes for supersonic inlet.

Prediction of Maximum Lift Capability of Helicopter Rotors

Maximum rotor lift capability is investigated using wind-tunnel test data of McHugh (modified 1/10-scale CH-47B rotor) and a full-scale UH-60A rotor. Rotor performance calculations with the comprehensive rotorcraft analysis CAMRAD II are compared with the wind-tunnel test data. The analysis of the McHugh rotor with the Reynolds-number-corrected airfoil table shows good correlation with the measurements for to 0.5 and is able to predict the maximum rotor lift reasonably well, especially at . The analysis is also able to predict the maximum lift of the full-scale UH-60A rotor within about 3.5% at and 0.3. Calculations with dynamic stall models, in general, show only a small influence on the rotor performance and are not necessary to predict maximum lift. Airfoils have an important role in defining the maximum lift capability of the rotor. The VR-12 airfoil, which has stall characteristics superior to the baseline V23010 airfoil, substantially improves the maximum lift capability of the McHugh rotor, showing the potential to improve the behavior of a rotor by improving the airfoil’s static stall characteristics.

통합된 상용 툴을 이용한 전투기급 항공기 개념설계

Automated design program using commercial process integration and optimization program was developed for conceptual design of fighter-class aircraft. Wind tunnel test data and performance analysis results were compared for the verification of analysis tool of this program, and the usefulness of the tool was found. After integration with radar cross section analysis tool, the correlation with configuration design variables of wing, tail and performance parameters was identified by design of experiment, and the optimized configuration for weight and RCS was derived from optimization of empty weight and average frontal RCS value. After parameter definition of fuselage, the program can be implemented for full aircraft configuration.

Supersonic Retropropulsion Computational-Fluid-Dynamics Validation with Ames Foot Test Data

A validation study of computational fluid dynamics for supersonic retropropulsion was conducted using three Navier–Stokes flow solvers. The study compared results from the computational-fluid-dynamics codes to each other and to wind-tunnel test data obtained in the NASA Ames Research Center Unitary Plan Wind Tunnel. Comparisons include surface pressure coefficient as well as unsteady plume effects and cover a range of Mach numbers, levels of thrust, and angles of orientation for zero-, one-, three-, and four-nozzle configurations. Flow-structure behavior changed with thrust and angle of orientation for all nozzle configurations. In general, the solvers compared best with the test data for the steadier cases of the one-nozzle and high-thrust three-nozzle configurations. Deviation in surface pressure was noted for the more unsteady cases and near transitions in behavioral modes. Strengths and weaknesses of the solvers are identified, and possible error sources are discussed.

Computational Fluid Dynamics as a Support to Counter-Rotating Open-Rotor Wind-Tunnel Test Analysis

The rising price of oil since the early 21st century produced a regain of interest in the counter-rotating open rotor, seen as an economic propulsive device for future transport aircraft. Although simple methods are used for design and optimization, the need for advanced methods to assess aerodynamic and acoustic performance of a counter-rotating open rotor within a complex configuration and to support wind-tunnel tests analysis is rising. In this paper, a methodology for complex counter-rotating open-rotor installations is set up to compute an actual test-rig geometry using high performance computing capabilities of ONERA computational-fluid-dynamics software elsA. Comparing the numerical results with the wind-tunnel test data enables to assess both the computational-fluid-dynamics code accuracy and the representativity of the wind-tunnel test, which relies on a somewhat intrusive test rig through a better understanding of the flowfield around the test rig.

Shielding Effects of Surrounding Buildings on Wind Loads on Low-Rise Building Roofs

Low-rise buildings are often built in groups, and their wind loads differ from those on isolated buildings. In this study, the wind pressures on flat roofs of low-rise buildings surrounded by similar buildings were measured with a series of wind tunnel tests. The general properties of the shielding effects of surrounding buildings were discussed. The effects of area density, relative height, and arrangement patterns of the surrounding buildings on the shielding factors of the smallest minimum negative extreme wind pressure coefficients and of the largest peak uplift force coefficients on the whole roof of the shielded building for all wind directions were analyzed. For practical purposes, both shielding factors were expressed as equations of the building area density and the relative height of the surrounding buildings based on the wind tunnel test data, which can cover most of the test results.

Trajectory Optimization of Reentry Capsule

Abstract Reentry vehicles are required to meet stringent boundary conditions and path constraints, while minimizing certain cost functional. Parameter optimal control is easier and faster to solve than indirect methods for complex problems, such as the problem of re-entry trajectory optimization subject to multiple path constraints. In this paper, a direct transcription method is applied for finding optimal trajectory of 2 problems. Firstly, Newtonian method is used for finding aerodynamic coefficients of blunt nose conical re-entry capsule in hypersonic regime. Using these coefficients, trajectory satisfying path constraints corresponding to heat influx, G-load and control angles is generated while minimizing the vehicle manoeuvres. In the second problem Apollo capsule's multiphase optimization problem is solved based on the aerodynamic coefficients obtained from wind tunnel test data.

Multibody analyses for performance and aeromechanics of a rotor in low-speed flight

Purpose – This paper aims to correlate the flexible multibody analysis for the performance, blade airloads, rotor pitch control angles, and blade structural loads of a full-scale utility helicopter rotor in low-speed forward flight with wind tunnel test and flight test data. Design/methodology/approach – A nonlinear flexible multibody dynamics analysis code, DYMORE, is used to analyze the performance and aeromechanics of a utility helicopter rotor in low-speed forward flight. The main rotor system is modeled using various multibody elements such as rigid bodies, nonlinear elastic beams, mechanical joints, and elastic springs/dampers. The freewake model is used to capture rotor wakes more elaborately in low-speed forward flight. Findings – Fair to good correlations of rotor performance such as figure of merit in hover, rotor power, propulsive force, and lift in low-speed forward flight are achieved with sweeps of the thrust, rotor shaft tilting angle, and advance ratio, against wind tunnel test data. The b...

Comparison of Wind Pressure Coefficients with Wind Load Provisions

This study has compared the equivalent external pressure coefficients, (GCpf)eq, with 6 wind load provisions and wind tunnel test data. The wind load provisions are the ASCE 7-10, NBCC 2010, AS/NZS 2011, EN 2005, AIJ 2004 and KBC 2009. Experiment data on low-rise building have been obtained at the University of Western Ontario (UWO) to contribute to the NIST aerodynamic database [. For the experiment, a model with 1:12 of roof slope and 4.9 and 12.2m of eave height was used under open terrain conditions (See also Ref. [). (GCpf)eq was re-normalized based on the external pressure coefficients, GCpf, of ASCE 7-10. When compared to (GCpf)eq of the experiment data with 4.9m of eave height, consequently, ASCE 7-10 (81%), NBCC 2010 (84%), AS/NZS 2011 (70%), AIJ 2004 (68%) and KBC 2009 (53%) were all underestimated. Among them, KBC 2009 reveals the lowest value. On the contrary, EN2005 was overestimated with 122%. When the eave height was 12.2m, in addition, the same pattern was observed in most codes. EN2005 was slightly overestimated with 115%.

양력선 방법을 이용한 다양한 형상의 날개 공력해석에 관한 연구

본 논문에서는 항공기 날개의 개념 설계에서 적용하기에 적합한 양력선 방법을 찾고 정확성과 적용범위를 분석한다. Prandtl의 양력선 이론에서 발전된 두 가지 양력선 방법으로서 얇은 익형의 가정을 갖고 3/4 시위의 제어점에서 속도경계조건을 부여하는 Weissinger방법과 3차원 와류 양력법칙을 적용한 Phillips의 방법을 택하였다. 계산 대상은 타원형 날개, 후퇴각이 있는 날개, 그리고 상반각과 비틀림이 있고 후퇴각 없는 테이퍼 날개이다. 계산을 통해 포텐셜 유동의 공력 데이터로 날개의 순환분포, 내리흐름 분포, 양력과 유도항력을 추출하여 이론식 결과 및 풍동시험 데이터와 비교하였다. Weissinger 방법은 날개의 형상에 상관없이 정확도와 신뢰성 있는 결과를 보여주지만 Phillips 방법은 후퇴각이 있는 날개에서는 부정확한 결과를 나타내었다. In this paper, we try to find the lifting-line method which is applicable to the conceptual design of aircraft wings, and analyze the accuracy and coverage of the method. Two methods that are extended from the lifting-line theory of Prandtl are selected. One of the methods is Weissinger's method which imposes the velocity boundary condition at the control points located at the quarter chord, and the other is Phillips's method which combines the three-dimensional vortex lifting law. Calculations are performed for an elliptic wing, a swept back wing, and a tapered unswept wing with dihedral angle and geometric twist. The aerodynamic data of the potential flow such as spanwise distributions of circulation and downwash, lift and induced drag are obtained through calculations, and these data are compared with theoretical results and wind tunnel test data. As a result, Weissinger's method showed good accuracy and reliability regardless of wing shapes, but Phillips's method revealed inaccurate results for a swept back wing.

A full-scale prediction method for wind turbine rotor noise by using wind tunnel test data

The development of a low-noise wind turbine rotor and propeller is often cost-effective and is in fact a race against time to those who wish to build and test a small-scale rotor instead of an expensive full-scale rotor. The issue of this approach has to do with the interpretation of wind tunnel model test data in terms of both the frequency band and sound pressure level information for the noise scaling effect.This paper discusses a prediction method for the estimation of the noise generated from a full-scale wind turbine rotor using wind tunnel test data measured with both a small-scale rotor and a 2D section of the blade. The 2D airfoil self-noise and the scaled rotor noise were investigated with a series of wind tunnel experiments. Wind tunnel data post-processing considered four aspects: removal of the test condition effect, scaling to full scale, consideration of the wind turbine rotor operating conditions, and the most important terms of full-scale rotor noise as adjustments to address the differences between the wind tunnel test conditions and the full-scale operating conditions.A full-scale rotor noise prediction results comparison was performed by initially dividing the test conditions into the condition of a 2D section noise test and the condition of a small-scale rotor noise test. Based on an airfoil section, the rotor was selected from a blade section at r/R = 0.75. The small-scale rotor was scaled down by a factor of 5.71 for the wind tunnel test.Finally, the full-scale rotor noise data was compared with the wind tunnel test data using a scaling estimation method.

Numerical simulation of wind loading on roadside noise mitigation structures

Numerical research on four typical configurations of noise mitigation structures and their characteristics of wind loads are reported in this paper. The turbulence model as well the model parameters, the modeling of the equilibrium atmospheric boundary layer, the mesh discretization etc., were carefully considered in the numerical model to improve the numerical accuracy. Also a numerical validation of one configuration with the wind tunnel test data was made. Through detailed analyses of the wind load characteristics with the inclined part and the wind incidence angle, it was found that the addition of an inclined part to a noise mitigation structure at-grade would affect the mean nett pressure coefficients on the vertical part, and that the extent of this effect depends on the length of the inclined part itself. The magnitudes of the mean nett pressure coefficients for both the vertical part and the inclined part of noise mitigation structure at-grade tended to increase with length of inclined part. Finally, a comparison with the wind load code British/European Standard BS EN 1991-1-4:2005 was made and the envelope of the mean nett pressure coefficients of the noise mitigation structures was given for design purposes. The current research should be helpful to improve current wind codes by providing more reasonable wind pressure coefficients for different configurations of noise mitigation structures.

Static Force Measurement Technology Wind Tunnel Test

Static force measurement aerodynamic wind tunnel test data provided by the aircraft normally used to predict the stall characteristics, predicted aircraft deviated,spin Sensitivities, numerical simulation of aircraft stall, spin dynamics and so on. Based on practical flight, the paper analyzed the harm of limit state flight-spin to the flight safe, emphasized the static force test techniques at high angles of attack, and obtained a series of aerodynamic test date, managed them to spin prediction analysis.

Research on Air Deflector Optimal Design and Matching for Heavy-Duty Vehicle Based on Design of Experiment Technology

The drag reduction characteristic of air deflector of a heavy-duty vehicle is examined through CFD simulations and wind tunnel test in this paper. The CFD model of the truck is built using the FLUENT software and the simulation results are compared with the wind tunnel test data to verify the accuracy of simulation model. An air deflector is designed for this truck, A design of experiments approach was chosen as an efficient technique to optimize the design parameter and match with the truck to obtain the optimal drag reduction performance.