Adaptation of PIV for Application in Cryogenic Pressurized Wind Tunnel Facilities at High Reynolds Numbers

Abstract

A measurement system is developed for an application of Stereo-PIV in the cryogenic transonic wind tunnel of ETW to enable detailed flow field analyses on scaled models of transport aircraft at flight Mach and Reynolds numbers. The specific conditions in such wind tunnels - cryogenic gas temperatures down to 110 K and moderate gas pressures of up to 450 kPa as well as a large plenum encapsulating the test section - made specific developments necessary. This comprises the generation of suitable flow tracers for cryogenic flows considering the specific requirements for an application in the ETW as well as the provision of laser light of high pulse energy and the placement of optical components within a cryogenic environment. Optical effects due to gas density changes within the wind tunnel plenum and light beam deflections or shifts are considered in the optical design of the Cryo-PIV system. The applicability of the developed Cryo-PIV system has been recently demonstrated in the ETW during two test campaigns on a full scale and a halfwing model of a transport aircraft. The employed Stereo-PIV system and first results will be discussed.