Jürgen Quest

Going for Experimental and Numerical Unsteady Wake Analyses Combined with Wall Interference Assessment by Using the NASA CRM Model in ETW

Detailed experimental and accompanying numerical studies on the development of unsteady wakes past an aircraft under stall conditions are currently prepared by a consortium of research institutions and universities. The experiments will be performed in the ETW cryogenic wind tunnel on the NASA Common Research Model. Besides wake surveys using time-resolved cryo PIV measuring technique, wall interference measurements are planned. The tests scheduled for July 2013 are funded by the European Commission in the 7th framework program. In this paper results of preparatory CFD studies and wake analyses of the CRM model, the TR-PIV measuring technique and the ETW facility are presented along with the wind tunnel model and the planned test program.

Slotted Wall Interference Investigation in ETW using the NASA CRM model

The experiments described in this paper were performed in the ETW cryogenic wind tunnel in February 2014 using the NASA Common Research Model to investigate slotted wall interference effects and form a test case for the verification and validation of relevant CFD tools. These tests were performed in the frame of the ESWI project funded by the European Commission in the 7 framework program. The EWT-TsAGI software with a cryogenic solver is described. Analyses of distributions of the wall pressure coefficient are presented along with comparisons with CFD results.

Hotwires in pressurized, cryogenic environment - It works!

The European Transonic Windtunnel is an unique aerodynamictesting facility also for laminar flow investigations at flight Reynolds numbers. To analyze the lami nar flow results additional information about the actual flow quality are essential. Therefore ETW is inves tigating the possibility of using the hotwire measurement technique for an application under its cryogen ic and pressurized conditions. Although the hotwire technique is widely used and very common to assess flo w qualities in wind tunnels the operation under the harsh conditions of a cryogenic wind tunnel facility is rare and very poorly documented. Therefore ETW has performed a test campaign in its pilot faci lity (PETW) to investigate and understand the basic behavior of hotwires over the complete operating e nvelope of ETW /PETW. The present paper summarizes the results of this test campaign and documents w hy the hotwire measurement technique is applicable under pressurized and cryogenic conditions.

Hot-Wire Measurements in Cryogenic Environment

The hotwire anemometry is a well known measurement technique used in several applications to determine flow velocity and to investigate flow quality. Using this measurement technique in a cryogenic environment is not very common and therefore the knowledge about it is very limited. The European Transonic Windtunnel, as cryogenic high Reynolds number test facility, is establishing the hotwire measurement technique to support flow quality measurements required by future laminar flow test campaigns. The present paper describes the challenges of such a system setup in ETW, its application and presents first results gathered in the pilot facility of the European Transonic Windtunnel. Thereby the main objective of this paper is to give a general overview about the first achieved results and to discuss the different influencing parameters on the hotwire output signal over the complete operational envelope of ETW/PETW.

Comparison of the NASA Common Research Model European Transonic Wind Tunnel Test Data to NASA Test Data

Experimental aerodynamic investigations of the NASA Common Research Model have been conducted in the NASA Langley National Transonic Facility, the NASA Ames 11-ft wind tunnel, and the European Transonic Wind Tunnel. In the NASA Ames 11-ft wind tunnel, data have been obtained at only a chord Reynolds number of 5 million for a wing/body/tail = 0 degree incidence configuration. Data have been obtained at chord Reynolds numbers of 5, 19.8 and 30 million for the same configuration in the National Transonic Facility and in the European Transonic Facility. Force and moment, surface pressure, wing bending and twist, and surface flow visualization data were obtained in all three facilities but only the force and moment, surface pressure and wing bending and twist data are presented herein.

Low Speed High Lift Validation Tests within the European Project EUROLIFT II

The present paper describes the wind tunnel tests performed within the framework of the European High-Lift Project EUROLIFT II and focuses on the discussion of their results. The goal of the project is to optimize and validate numerical and theoretical methods for exact prediction of the aerodynamics of an aircraft in high-lift configuration at flight Reynolds numbers. To increase the basic understanding of complex high-lift aerodynamics and to produce comparative data for numerical design methods, wind tunnel test were executed inthe Airbus Low Speed Windtunnel (LSWT) and the European Transonic Windtunnel (ETW). During these tests, which covered low and high Reynolds number conditions, the model complexity was increased stepwise up to a fully high-lift aircraft configuration. Various measurement techniques were applied to gain the maximum of aerodynamic information. Because the presentation of a complete results analysis is far beyond the scope of this paper it gives an overview over the test facilities, the used test techniques and highlights selected results.

Assessing Model Dynamics within the Critical Alpha Range

The European Transonic Windtunnel (ETW) is Europe’s unique testing facility for high Reynolds number testing, enabling the aircraft manufactures to test their designs under real flight Reynolds and Mach numbers at defined aeroelastic conditions. Driven by the increasing demand for flight Reynolds number wind tunnel testing up to the boundaries of the flight envelope and beyond, the European Transonic Windtunnel has enhanced its productivity for this type of testing by improving its capabilities to assess the model dynamics. This is on one side essential to provide more valuable data for the clients and on the other hand to secure ETW’s high safety standards for tunnel and model. Serving clients needs to test up to and even beyond the buffet onset while ensuring the mechanical model integrity is challenging. Test conditions at high Reynolds numbers and critical alpha values around the lift breakdown combine high steady loads with the risk of occurring model dynamics such that appropriate risk mitigation measures are vital. The present paper discusses a setup for tests including the critical alpha range, describing the availability of specific instrumentation for such test campaigns, the data acquisition and processing possibilities as well as the applied safety measures. Results of a recent test campaign are used to illustrate the described capabilities.