Advanced Measurement Techniques for High Reynolds Number Testing in Cryogenic Wind Tunnels

Abstract

The present paper addresses the development, qualification trials and application of some non-intrusive measurement techniques suitable for operation in industry-scale, pressurised cryogenic wind tunnels. The application of cryogenic Temperature-Sensitive Paint (cryoTSP) as a tool for transition detection is described as well as the implementation of the Image Pattern Correlation Technique (IPCT) and the Backward Oriented Schlieren method (BOS) in the European Transonic Windtunnel (ETW). Progress on the development of cryogenic Pressure-Sensitive Paint (cryoPSP) is shown, and considerations for the establishment of a Particle Image Velocimetry system suited for low temperatures (cryoPIV) are presented. Furthermore, the state of adaptation of the microphone array technique (MAT) to industry-scale, cryogenic wind tunnels is described.

Background-oriented schlieren (BOS) techniques

“…Loose et al (2000) and Alhaj and Seume (2010), for example, used a combined PIV and BOS investigation for the investigation of wake flows in linear turbine cascade facilities. Challenging wind tunnel applications under cryogenic conditions have been reported by Germain and Quest (2005), Loose et al (2006), andFey et al (2010). Combustion research can take advantage of the ability of BOS to visualize and measure heat plumes and flames (Iffa et al 2011), but also to determine concentration levels of different fuel sprays (Bang and Lee 2013; Lee et al 2011Lee et al , 2013Tillmann et al 2014) or gas jets as performed by Iffa et al (2010), Ducasse et al (2010) and Veser et al (2011).…”

FLEET Velocimetry Measurements on a Transonic Airfoil

“…4 However, since probebased measurements intrinsically disturb the flowfield of interest, there is a need for less intrusive diagnostics for the measurement of relevant flow quantities. 5 For example, a great deal of work has gone into the development of pressureand temperature-sensitive paints that operate in cryogenic, oxygen-free environments for measuring surface conditions and detecting turbulent boundary layer transition on test articles. 5,6,7,8 However, measurements of velocity have proven very challenging to researchers.…”

“…5 For example, a great deal of work has gone into the development of pressureand temperature-sensitive paints that operate in cryogenic, oxygen-free environments for measuring surface conditions and detecting turbulent boundary layer transition on test articles. 5,6,7,8 However, measurements of velocity have proven very challenging to researchers. Techniques such as particle image velocimetry 9 and Doppler global velocimetry 10 have been applied in ETW and its pilot facility; seeding was introduced by injecting steam-saturated nitrogen into the flow circuits and allowing the water vapor to condense at decreased temperatures.…”

Supersonic Testing of Natural Laminar Flow on Sharp Leading Edge Airfoils. Recent Experiments by Aerion Corporation

“…The TSP technique and postprocessing was made by DLR 13 . The leading edge was not painted, and extreme care had to be taken in avoiding a pronounced step at the edge of the paint part.…”