Rotating stall and surge control: a survey

Abstract

The AbstractThe paper presents an analysis of the current state of the art in the control of aero-or hydrodynamic instabilities in turbomachines. It describes the flow phenomena associated with rotating stall and surge, discusses methods devised to prevent these instabilities to occur, but concentrates mainly on the active control (stabilization) of the unstable flows. It appears that lately significant progress has been made in this area. It seems to foster to a more mature state, although several problems deserve further consideration. The consequences of this state of the art for several interested parties, researchers, developers, manufacturers, and users, are stipulated. The MotivationThere are two main types of continuous flow compressors: the axial compressor, where the flow leaves the compressor in the direction parallel to the rotational axis, and the centrifugal compressor, where the flow leaves the compressor in the direction perpendicular to the rotational axis. Rotating stall, surge, and other flow instabilities occur in turbomachinery, in particular in axial and radial compressors, and limit its efficiency and effectiveness, and by that its usefulness. Preventing these instabilities to occur would benefit the large community of users of turbomachines where these phenomena are important in employing this equipment. The PhenomenaRotating stall is an instability phenomenon, local to the compressor, in which a Circumferentially uniform flow pattem is disturbed. A local region or local regions appear where the flow is stagnant: the flow stalls. The regions propagate in the same direction as the blades (i.e., regions of stall rotate around the annular flow path), at a fraction of the rotor speed. This speed is often between one fifth and half of the wheel speed, at least for fully developed stall, initial rotating stall cells move faster [9]. The part of the area of the annular flow path the stalled regions occupy may also grow exponentially with time, until a certain size is reached. This depends on the slope of the pressure/flow characteristic for constant speed in the compressor performance map, in the sequel called compressor Characteristic or speed lines, and compressor map, respectively, see Fig. 1. 4The essential differences between rotating stall and surge are that the average flow in pure rotating stall is steady in time, but the flow has a circumferentially nonuniform mass deficit, while in pure surge the flow is unsteady but circumferentially uniform. Because it is steady, rotating stall may be local to the compressor or to parts of the compressor. Due to its unsteadiness, surge involves the entire compression system. So, the phenomena can be regarded as distinct. On the other hand, both phenomena are natural oscillatory modes of the compression system, with surge corresponding to the lowest (zero) order mode, and thus they are related [30,36].Discussions are still ongoing if rotating stall is important for centrifugal compressors, and perhaps also single stage axial compressors, or if only sur...

A high-speed valve for surge control in a centrifugal compression system

“…In general, the goal is to stabilize the system to the left of the surge line by modifying its dynamic through the use of appropriate feedback. Many promising results of this approach have been reported in literature, see for example the surveys in [2][3][4][5].…”

Current Management in a Hybrid Fuel Cell Power System: A Model-Predictive Control Approach

“…In summary, the compressor voltage v cm , controls the speed of the compressor through the first-order dynamics shown in (9) and (10). The speed of the compressor determines the compressor flow rate W cp , which then according to equation (4), affects the supply manifold pressure p sm . The latter, together with the cathode pressure, determines the supply manifold flow W sm , and the flow rate of the oxygen into the cathode W O 2 ,in which finally affects the excess ratio λ O 2 given in equation (1).…”

“…Centrifugal compressors of the type used with high-pressure fuel cells, are susceptible to surge and choke that limit the efficiency and performance of the compressor [4]. Choke occurs at high mass flows, during step-up in compressor motor command and surge occurs at low mass flows, normally during a sudden step-down in compressor motor command.…”

Co-Surge Detection and Control for Bi-Turbo Engines with Experimental Evaluation

“…There are several methods for avoiding or suppress surge in single compressors described in the literature (de Jager, 1995). In active surge control the operating region of the compressor is extended by stabilizing the compressor in the otherwise unstable region to the left of the surge line, see for example Willems and de Jager (1998);Gravdahl and Egeland (1999).…”