Wind Tunnels for Aircraft Testing
Development of a Complex Technique for Testing Highly-Economical, Ecologically-Promising Civil Aircraft in Transonic Wind Tunnels
Tech Area / Field
- SAT-AER/Aeronautics/Space, Aircraft and Surface Transportation
8 Project completed
Senior Project Manager
Malakhov Yu I
Central Aerodynamic Institute, Russia, Moscow reg., Zhukovsky
- Aicraft Research Association Ltd., UK, Bedfort\nEuropean Transonic Windtunnel, Germany, Köln
Project summaryThe present study is aimed at conversion of the technology developed for the military airplanes and rockets testing in transonic wind tunnels. Now the group of TsAGI specialists has got the universal technology which had been used for wind tunnel tests of different kind military airplanes more than 15 years. The special feature of this technology is very exact prediction of transonic wind tunnel (TWT) walls' porosity distribution necessary for the minimization of walls interference to the model. Implementation of this technology gives essential diminishing of time necessary for tests (40%). The purpose of the Project is modification and implementation of this technology for civil airplanes investigations.
The practical purpose of the present study is participation in the development of economical civil aircraft with a reduced fuel consumption designed for extremely long-range flights. High velocities of such aircraft will enable the time to be saved considerably provided respective ground services are modified. Besides, improved characteristics of aircraft will allow the fuel to be saved.
The present study to be carried out in TsAGI involves several basic items:
- analytical, numerical and experimental investigations of the wall interference and possibilities of its minimization in wind tunnels;
- improvement of methods to investigate flows over models by applying pressure sensitive paints.
The main feature of aerodynamic ground-based tests of civil aircraft models is more stringent requirements for the vehicle drag measurement accuracy.
In order to exclude systematic errors due to test section wall interference on flows over large-scale models, different strategies are presently used at TsAGI, for example:
- method of corrections;
- method of pre-test optimization;
- so-called "adaptive wall technique" (optimization during the test).
Within the framework of the present project it is suggested that the calculation process be accelerated as much as possible by extending admissible simplifications inherent in this class of problems to maximum reasonable test condition ranges. It is expected to design an automatic system for conducting wind tunnel experiments in the so-called adaptive wall technique mode when optimal test conditions are attained by iterations just during the run.
Only a comprehensive investigation of flow over aircraft models may serve as the somewhat guarantee of the aircraft safety in service. In view of this, of particular interest are methods of physical investigations which are a certain synthesis of measurements and visualization. For example, the method of pressure sensitive paints (PSP), apart from observability and large-scale view inherent in all most widespread flow visualization methods, is characterized, at the present time, by a quantitative nature which makes it possible to acquire an abundant amount of information about a flow over a test model for one wind tunnel run.
The recognized advantages of the PSP method are as follows:
- small time period for model preparation in comparison with the case of standard pressure measurements implying the application of a great number of pressure taps;
- possibility of investigating pressure fields and distributed loads over models at earlier aircraft design stages characterized by frequent aircraft configuration changes.
In the course of the work, it is expected to increase the accuracy of PSP method up to the level corresponding to pressure tap measurements by means of modifying the measurement technology.
Thus, the main purpose of the present project is to introduce advanced technologies into wind tunnel tests which will allow a thorough utilization of this unique facility for execution of Russian, foreign and international projects on development of advanced civil aircraft, as well as the application of the proved techniques and approaches when developing a new facility of this type.
Potential role of foreign collaborators
Potential for continuation of collaborative activities due to the project concerns both advanced civil aircraft development programs and new-generation wind tunnel design programs (or existing facility modifications).
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