Investigation On Influence Of Adiustable Inlet Guide Vane On Performance Of Two-stage Centrifugal Compressor

In energy storage process, exhaust pressure of compressor increases continually as compression subsystem aerates to tank, which leads to continuous changing of operating point. Adjustable inlet guide vane (IGV) is usually used to extend operating range and improve efficiency of centrifugal compressor. The two-stage centrifugal compressor with adjustable guide vane of every stage and interstage cooler is taken as research object, and the regulating law and internal flow are analyzed by performance prediction and numerical simulation. The main research contents and conclusions are as follows:1. Off-design performance of centrifugal compressor with IGV is simulated by performance prediction. Based on 11 kinds of loss model, a performance prediction model of centrifugal compressor is developed by Matlab. The result of prediction model agrees well with numerical simulation result at design point, and the error gets bigger when the degree of deviation from the design condition increases. Through analyzing the loss characteristics, four main loss models are modified by flow coefficient. The errors of pressure ratio and efficiency can be controlled within 5% and the prediction of the highest efficiency point matches well.2. Off-design performance of two-stage centrifugal compressor with IGV joint adjusting is calculated by prediction model. The error of pressure ratio increases when operating condition is close to choke. The maximum error is about 6%. The error of efficiency increases when operating condition is close to stall and choke, especially choke. The maximum error is about 8.3% and the highest efficiency point matches well.3. Off-design performance of the first and second stage with IGV separately is simulated by numerical simulation and the generating mechanism of regulating law is analyzed. It is shown that IGV extends the range of stable operating condition. That’s because attack angle of impeller inlet is bigger at low mass flow rate, and bigger positive opening can improve the flow at suction surface of blade tip end and reduce the possibility of stall at low mass flow rate. The efficiency decreases when the opening of IGV is changed. That is because the Mach number distribution gets more non-uniform and the velocity gradient gets bigger when the opening of IGV gets larger which leads to bigger loss.4. Using porous medium model to simulate interstage cooler, the off-design performance of two-stage centrifugal compressor with IGV joint adjusting is simulated by numerical simulation. The pressure ratio increases only when opening of two stages’ guide vane are all negative, and the pressure ratio decreases at the other conditions. Compared with no IGV and single stage IGV adjusting, joint adjusting extends the operating range. The efficiency of most of operating condition is above 80% by joint adjusting.5. At impeller inlet, the area of high velocity at suction surface around shroud increases when the opening of IGV is negative. The area disappears gradually at suction surface around shroud and appears at pressure surface around shroud as positive opening increases. At impeller outlet, the area full of low velocity and low energy flow at suction surface around hub reduces as positive opening gets bigger.