Three Dimensional Flow Field in a Highly Loaded Compressor Cascade

Abstract

Within the present paper a detailed experimental investigation is presented. The influence of blade loading on the development and interaction of secondary flow structures within an annular compressor stator cascade is examined. Experimental results at 3% chord hub clearance were obtained at four different blade loadings. Included are blade and endwall flow visualization, time resolved measurements of the static pressure on the endwall and radial-circumferential hot-wire traverse measurements within the passage as well as five-hole probe traverse measurements at the inlet and the outlet of the passage. The experimentally obtained results give detailed insight on the effect of the incidence on the development and interaction of the clearance vortex, horse-shoe vortex and the passage vortex. Furthermore it will be shown that a vortex breakdown of the clearance vortex occurs at higher loadings.

Physics of Prestall Propagating Disturbances in Axial Compressors and Their Potential as a Stall Warning Indicator

“…Regarding the fact that the disturbances are characterised by a sharp pressure drop, the third statistical momentum (skewness) seems to be suitable for analysing the inception process of prestall instabilities. If the majority of pressure fluctuations is higher than the average or the signal contains drops of very low pressure respectively, the skewness is negative [14]. Hence, evidence of prestall disturbances is indicated by negative values of the skewness.…”

Steady and Unsteady Numerical Characterization of the Secondary Flow Structures of a Highly Loaded Low-Pressure Compressor Stage

“…In this context, they classified the hub corner separation as a critical secondary structure that could possibly lead to aerodynamic stall, especially in highly loaded machines like the one presented in this paper. A similar analysis was proposed for the unsteady characterization of the tip clearance flow [4][5][6][7]. The flow redistribution observable at the casing prior to the stall and its impact on the development of spike-type stall inception mechanisms was proposed, together with suggestions for stability enhancement.…”

“…The von Karman Institute high-speed compressor test rig R4 (Figure 1a) was employed for the experimental characterization of the stage. It is composed by a tank used as settling chamber (1); the test section (2); a discharging collector at the compressor outlet (3); a return channel to guide the air back to the reservoir (4); and a throttling valve (5). The heat exchanger installed in the tank and the closed-loop configuration allow to set the temperature and pressure at the test section inlet independently, so that cruise and take-off conditions can be simulated.…”

Study on the Design Method of a New Type of Compressor Slotted Blade

“…At this time, the flow in the compressor presents a strong inverse pressure gradient, a large boundary layer separation zones will appear on the suction surface of the blade, and the compressor is easy to enter the stall surge state, and the working stability of the compressor decreases [7][8]. Therefore, in order to increase the single-stage aerodynamic load of the compressor blades, reduce the compressor stages, and expand the working range, it is necessary to use reasonable active or passive flow control technologies to inhibit boundary layer separation [9][10][11]. The active flow control technologies often require the input of external energy, and need to add complex additional devices, which increase the difficulty of engineering application, such as boundary layer suction technology, synthetic jet technology, plasma pneumatic excitation technology, etc.…”