Experimental investigation of the transonic flow around the leading edge of an eroded fan airfoil

• Published in: Experiments in fluids Vol. 55; no. 9
• Main Authors: Klinner, Joachim, Hergt, Alexander, Willert, Christian
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.09.2014; Springer
• Subjects: Applied fluid mechanics; Engineering; Engineering Fluid Dynamics; Engineering Thermodynamics; Exact sciences and technology; Fluid dynamics; Fluid- and Aerodynamics; Fundamental areas of phenomenology (including applications); Heat and Mass Transfer; Hydraulic and pneumatic machinery; Instrumentation for fluid dynamics; Physics; Research Article; Particle Image Velocimetry Measurement; Normal Shock; Transonic Flow; Suction Side; Particle Image Velocimetry; Transonic flow; Stall; Wind tunnel test; Airfoils; Schlieren method; Experimental study; Blowers; Shadowscopy; Shock waves; Leading edge; Aerofoil cascade; Flow visualization; Particle image velocimetry
• ISSN: 0723-4864; 1432-1114
• DOI: 10.1007/s00348-014-1800-y

The influence of leading edge modification on the time-averaged and instantaneous flow around a fan airfoil is investigated by particle image velocimetry (PIV), schlieren imaging and high-speed shock shadowgraphs in a transonic cascade windtunnel. In addition to a global characterization of the time-averaged flow using PIV, the instantaneous passage shock position was extracted from single-shot PIV measurements by matching the tracer velocity across the normal shock with an exponential fit. The instantaneous shock positions are assigned to a probability density distribution in order to obtain the average position and the range of fluctuations of the eroded and reference leading edge. The profiles are used to estimate the response time of the particles to the normal shock which was found to be in the sub-microsecond range. Averaged PIV measurements and the probability density of shock position from both geometries are obtained at near stall and choked conditions. In order to extract the frequency range of the shock motion, the shadow of the shock wave was tracked using high-speed shadowgraphy. The paper also provides details on the experimental implementation such as a specifically designed light-sheet probe.