High Reynolds number transition experiments in the ETW test facility with the pathfinder model

Abstract

The Pathfinder model was designed in the course of the TELFONA European Research Project as a calibration tool to evaluate the transonic, cryogenic ETW facility for laminar flow testing, and assess the possibility for studies of NLF or HLF wings in ETW. The Pathfinder wing is a simplified, low taper, swept wing with an optimized profile allowing almost linear evolution of the N-factors in a wide range of flow conditions, especially designed for a precise estimation of transition N-factors. Temperature sensitive paint is used to allow optical detection of the transition location, and a series of pressure taps is used for measuring the pressure distribution. This general paper will cover model design, pre-test numerical evaluation, instrumentation and measurement methods, and will present a first set of cases selected for stability analysis and transition evaluation. Various tools for stability analysis and transition predictions will be tested, from local stability theory with the envelope methods to nonlocal theories taking into account curvature and non-local effects, based on the parabolized stability equations or on a multiple scale approach for compressible flows.