Optimization of the Porosity Distribution in Transonic Wind Tunnel

2012 ◽  
Author(s):  
Antonello Marino ◽  
Aldo Bonfiglioli
Keyword(s):  
Wind Tunnel ◽  
Response Surface ◽  
Design Of Experiment ◽  
Wind Tunnels ◽  
Experimental Setup ◽  
Porosity Distribution ◽  
Variable Porosity ◽  
Wind Tunnel Data ◽  
Transonic Wind Tunnel

During past years, to improve the quality of wind tunnel data in transonic configurations, researchers first designed new wind tunnel geometries (as porous and/or slotted wind tunnels), then developed more accurate correction laws giving acceptable results in certain conditions but absolutely not sufficient to satisfy the increasing aeronautical requirements. Recent studies showed that the quality of wind tunnel data can be improved by using test sections provided with variable streamwise porosity distributions instead of the typical uniform ones. Some authors identified this new concept of variable porosity distribution as the third generation of porous wind tunnels. In order to improve knowledge about effects of the porosity distribution on the wall interference in subsonic/transonic conditions, an experimental investigation was carried out in the PT-1 CIRA transonic wind tunnel in the Mach range between 0.3 and 0.9 (over 400 test points were measured on different models and wall porosity configurations). At this aim, a dedicated experimental setup consisting in five plates positioned on the top and bottom walls of the PT-1 porous test section, has been designed and realized. Setting independently each plate, it is possible to obtain practically unlimited combinations of porosity distributions along the streamwise direction. The final purpose of the present activity was to evaluate the optimal porosity distribution able to minimize wind tunnel wall interferences in the considered Mach range. The huge number of factors (Mach number and the positions of the five plates setting the porosity distribution) made practically impossible to study the porosity distribution effects by using a traditional One Factor At a Time (OFAT) approach. Therefore, the optimum porosity distribution has been achieved through an experiment designed with a Modern Design of Experiment (MDOE) approach. Within the MDOE approach, the RSM (Response Surface Modeling) has been selected. The objective of the experiment, designed with the RSM approach, is to acquire a sufficient number of data to create one or more response surface models to be used to predict the response variable of interest (within a specified uncertainty) as function of the factors which can affect the selected response variables. The best porosity distribution able to improve the quality of wind tunnel data has been found for the PT-1 Wind Tunnel (but results and/or the procedure are applicable to all similar Wind Tunnels). In the present paper, to contextualize the activity, after a short summary of the historical wind tunnel development, the stat of art of the variable streamwise porosity distribution is discussed. Then, the experimental setup to simulate in wind tunnel several streamwise variable porosity distribution and the design of Experiment are described. Finally, the main experimental results are reported and critically analyzed.

A Novel Single-Passage Transonic Wind Tunnel for Turbine-Vane Film Cooling

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Mohamed Qenawy ◽  
Lin Yuan ◽  
Yingzheng Liu ◽  
Di Peng ◽  
Xin Wen ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Film Cooling ◽  
Three Dimensional ◽  
Fast Response ◽  
Low Flow ◽  
Wind Tunnels ◽  
Single Passage ◽  
Turbine Vane ◽  
Response Pressure ◽  
Transonic Wind Tunnel

Abstract Wind-tunnel testing of turbines cascade is an important technique for quantifying the realistic conditions of turbine-vane film cooling. However, the complex and expensive facilities needed for the multipassage design of such wind tunnels have prompted the introduction of the single-passage design strategy. In this contribution, detailed procedures for building a novel single-passage transonic wind-tunnel using additive manufacturing are presented. In addition, the detailed flow structure caused by the passage was investigated. The proposed design was evaluated step-by-step using an integrated model that successively comprised two-dimensional (2D) periodic passage simulation, 2D single-passage simulation, three-dimensional (3D) single-passage simulation, construction, and testing. The proposed design was found to achieve flow periodicity at transonic flow conditions with relatively low-flow consumption. The results were validated by comparison to the available literature data. In addition, an endwall-cooling configuration was successfully deployed using fast-response pressure-sensitive paint (fast-PSP). This study, combined with the help of commercial software and 3D printing, shed light upon strategies for time- and cost-reduction in linear cascade design, which could benefit the turbomachinery community.

scholarly journals Estimation of Aerodynamic Coefficients in a Small Subsonic Wind Tunnel

2018 ◽  
Vol 30 (4) ◽  
pp. 457-463
Author(s):  
Karolina Krajček Nikolić ◽  
Anita Domitrović ◽  
Slobodan Janković
Keyword(s):  
Reynolds Number ◽  
Wind Tunnel ◽  
Internal Force ◽  
Force Balance ◽  
Wind Tunnels ◽  
Subsonic Wind Tunnel ◽  
Lower Reynolds Number ◽  
Scaling Methods ◽  
Reynolds Number Effects ◽  
Wind Tunnel Data

To apply the experimental data measured in a wind tunnel for a scaled aircraft to a free-flying model, conditions of dynamical similarity must be met or scaling procedures introduced. The scaling methods should correct the wind tunnel data regarding model support, wall interference, and lower Reynolds number. To include the necessary corrections, the current scaling techniques use computational fluid dynamics (CFD) in combination with measurements in cryogenic wind tunnels. There are a few methods that enable preliminary calculations of typical corrections considering specific measurement conditions and volume limitation of test section. The purpose of this paper is to present one possible approach to estimating corrections due to sting interference and difference in Reynolds number between the real airplane in cruise regime and its 1:100 model in the small wind tunnel AT-1. The analysis gives results for correction of axial and normal force coefficients. The results of this analysis indicate that the Reynolds number effects and the problem of installation of internal force balance are quite large. Therefore, the wind tunnel AT-1 has limited  usage for aerodynamic coefficient determination of transport airplanes, like Dash 8 Q400 analyzed in this paper.

A Kriging Approach for CFD/Wind-Tunnel Data Comparison

2005 ◽  
Vol 128 (4) ◽  
pp. 847-855 ◽  
Author(s):  
J.-C. Jouhaud ◽  
P. Sagaut ◽  
B. Labeyrie
Keyword(s):  
Wind Tunnel ◽  
Response Surface ◽  
Uncertain Parameters ◽  
Free Flight ◽  
Wind Tunnel Experiments ◽  
Data Comparison ◽  
Wind Tunnel Data ◽  
Compressible Turbulent Flow ◽  
Kriging Approach ◽  
Insight Into

A Kriging-based method for the parametrization of the response surface spanned by uncertain parameters in computational fluid dynamics is proposed. A multiresolution approach in the sampling space is used to improve the accuracy of the method. It is illustrated considering the problem of the computation of the corrections needed to recover equivalent free-flight conditions from wind-tunnel experiments. Using the surface response approach, optimal corrected values of the freestream Mach number and the angle of attack for the compressible turbulent flow around the RAE 2822 wing are computed. The use of the response surface to gain an insight into the sensitivity of the results with respect to other parameter is also assessed.

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