Propagation of Multiple Short-Length-Scale Stall Cells in an Axial Compressor Rotor

Abstract

Evolution and structure of multiple stall cells with short-length-scale in an axial compressor rotor have been investigated experimentally. In a low-speed research compressor rotor tested, a short-length-scale stall cell appeared at first, but did not grow rapidly in size, unlike a so-called “spike-type stall inception” observed in many multistage compressors. Alternatively, the number of cells increased to a certain stable state (a mild stall state) under a fixed throttle condition. In the mild stall state the multiple stall cells, the size of which was on the same order of the inception cell (a few blade spacings), were rotating at 72 percent of rotor speed and at intervals of 4.8 blade spacings. With further throttling, a long-length-scale wave appeared overlapping the multiple short-length-scale waves, then developed to a deep stall state with a large cell. In order to capture the short-length-scale cells in the mild stall state, a so-called “double phase-locked averaging technique” has been developed, by which the flow field can be measured phase locked to both the rotor and the stall cell rotation. Then, time-dependent ensemble averages of the three-dimensional velocity components upstream and downstream of the rotor have been obtained with a slanted hot-wire, and the pressure distributions on the casing wall with high-response pressure transducers. By a physically plausible explanation for the experimental results, a model for the flow mechanism of the short-length-scale stall cell has been presented. The distinctive feature of the stall cell structure is on the separation vortex bubble with a leg traveling ahead of the rotor, with changing the blade in turn on which the vortex leg stands. [S0889-504X(00)00701-7]

A Behavior of the Diffuser Rotating Stall in a Low Specific Speed Mixed-Flow Pump

“…The vortex rapidly develops toward the inlet of the diffuser vane, and a three-dimensional stall cell structure is generated [11]. Then, it disturbs the outward flow entering into the inlet of the diffuser vane and static pressure reaches its minimum due to the vortex core, which condition is found at (b) in Fig.8, and vector maps are displayed as Passage Y of Figs.…”

Detailed measurements of the static pressure characteristics around the centrifugal compressor casing wall

“…Studies of the stall inception were always to find the initial moment and inception location as early as possible. The early structure of the stall inception was explained through measuring the static pressure at the initial moment of the stall (Inoue et al, 2000;Chen et al, 2007). The asymmetry of the structure caused the stall inception at the particular blade passage of an axial compressor (Weichert and Day, 2012).…”

Experimental Study on Surge Inception in a Centrifugal Compressor

“…Numerous works have been done on rotating stall and surge for compressors, axial compressors particularly. For example, the process leading to the formation of finite amplitude rotating stall cells has been extensively studied experimentally and numerically [1][2][3]. It is said that two types of rotating stall inception occur in axial compressors.…”