Investigations of Shock/Boundary-Layer Interaction in a Highly Loaded Compressor Cascade

Abstract

Experimental investigations of the shock/boundary-layer interaction were carried out in a highly loaded compressor cascade under realistic turbomachinery conditions in order to improve the accuracy of semi-empirical flow and loss prediction methods. Different shock positions and strengths were obtained by variations of inlet flow angle and inlet Mach number. The free stream turbulence intensity, depending on the inlet Mach number, changed between 4% and 8%. The influence of the inlet Reynolds number based on blade chord is also examined for two different values (Re1=450000, 900000). Schlieren pictures of the transonic cascade flow reveal an unsteady flow behavior with different shock configurations, depending on the pre-shock Mach number. Wake distributions and boundary-layer measurements with the Laser two-focus velocimetry show that the increase of total pressure loss with increasing inlet Mach number is mainly due to the shock/boundary-layer interaction. The shock interaction with a laminar/transitional boundary-layer causes a wide streamwise pressure diffusion, clearly shown by profile pressure distributions. This has a strong influence on the flow outside of the boundary-layer presented by a quantitative Schlieren image. The transition process, investigated with the analysis of thin-film signals, is induced by the shock-wave and occurs above a separated-flow region. At the higher Reynolds number a shock-induced transition takes place without separation.

Use of computational fluid dynamics to implement an aerodynamic inverse design method based on exact Riemann solution and moving wall boundary

“…The compressor cascade V103-220 shown in Figure 4 is chosen as the verification model. It was designed for the hub section of a stator blade in a highly loaded axial compressor (Bell & Fottner, 1995;Hilgenfeld, Cardamone, & Fottner, 2003). This compressor cascade is constructed by conventional NACA-65 blades with a circular camber line.…”

“…In view of these facts, the V103-220 compressor cascade is considered to be an appropriate model for investigating inverse design under high subsonic and transonic flow regimes. More detailed information about the test facility and measuring techniques of this compressor cascade can be found in Bell are Fottner (1995) and Hilgenfeld et al (2003).…”

Boundary layer investigations on a highly loaded transonic compressor cascade with shock/laminar boundary layer interactions

“…The blade aspect ratio is therefore h/lˆ1.36. The ow can be considered two-dimensional in the mid-span section for the investigated Mach and Reynolds number range, as con rmed by the oil ow visualizations performed on the blade surface [10].…”

“…Some of the rst detailed experimental studies of shock/boundary layer interactions in compressor cascades include the work of Schreiber and Starken [8] and Schreiber [9] for strong shock/turbulent boundary layer interference. Bell [10] showed that the interaction of the shock with a laminar or transitional boundary layer produces signi cantly different effects on the ow behaviour in compressor cascades in comparison with shock/turbulent boundary layer interaction. Only a few experiments have been carried out for Mach and Reynolds numbers representative of real turbomachinery conditions with moderate preshock Mach numbers and laminar/transitional boundary layer interaction, such as the investigations by Fuchs et al [11] and Bell [10].…”

“…Bell [10] showed that the interaction of the shock with a laminar or transitional boundary layer produces signi cantly different effects on the ow behaviour in compressor cascades in comparison with shock/turbulent boundary layer interaction. Only a few experiments have been carried out for Mach and Reynolds numbers representative of real turbomachinery conditions with moderate preshock Mach numbers and laminar/transitional boundary layer interaction, such as the investigations by Fuchs et al [11] and Bell [10]. Recent investigations in a transonic cascade with a low supersonic inlet Mach number and laminar shock interaction are reported by Weber et al [12].…”