Determination of residual wall interferences for measurements on the TWIG model-comparison of different methods and analysis

Abstract

Measurements have been carried out in the dimensional adaptive test sections of the Transonic Windtunnel Gottingen TWG of DLR and the T2 wind tunnel of ONERA Toulouse. The TWIG model (Transonic Wall Interference Generator) was available in two different scales, so that for the test sections of different sizes, the relative model size was the same. The wall adaptation was performed using the fast Wedemeyer/Lamarche method for determining the wall shapes in both cases. As a first step, different methods for the determination of residual wall interferences have been applied to data from the adaptive test section of the University of Southampton, U.o.S. These were regarded as very reliable and accurate, and wall contour data and very dense pressure distributions were available. Residual wall interferences computed by the U.o.S., DLR, ONERA and NLR show very good agreement. The measurements on the two different TWIG models in the adaptive test sections of T2 and TWG show good agreement for the wall shapes and the measured pressure distribution. Data from TWG were taken for the determination of residual wall interferences by the different methods. The residual wall interferences do not agree so perfectly as they had with the U.o.S. Data. The reasons for this are/could possibly be: wall pressure data not so dense as before; influence of the finite length of the test section; model representation not "good" enough; model not centrally placed; support influences; exit section not taken into account.