Performance Enhancement of Centrifugal Compressors Utilizing Impeller Tip Injection

Abstract

Effects of air injection on a centrifugal compressor performance are studied numerically and results are presented in this paper. Flow field is simulated based on solution of the Reynolds-Averaged Navier-Stokes equations utilizing the well-known k-ε turbulence modeling. To find optimum arrangement of the air injectors, including their numbers, positions and setting angles and also their mass flow rates, 10 different cases were proposed in this investigation. Results of velocity and pressure fields and streamlines patterns on various blade-to-blade and streamwise planes provided necessary data for analyses and discussions. These results revealed that a proper air tip injection can weaken the tip leakage flow strength and alleviate the blockages to the main stream near the casing. Hence, this technique can be used to extend the stable operating range of the compressor and delay the probable stall commencement. In addition, compressor can produce higher pressure ratios in cases of proper injections in comparison to no-injection case. Optimum injection configuration improved the stall margin of the proposed compressor by nearly 15.8%. Numerical results for no-injection case were compared with those of the authors own experimental works carried out on a proper test rig, which showed close agreement.

Entropy generation rate analysis of turbocharger radial flow compressor in range from surge to choke

“…Several advances have been made in the compressor design process to extend the operating range, while increasing isentropic efficiency. [1][2][3][4][5] There are two challenging restrictions in the operating range of compressors: surge margins and choke conditions, which limit stable compressor operation at low and high mass flow rates. Surge phenomena occur when the flow rate through the compressor suddenly decreases and severe fluctuations in the pressure ratio appear.…”

Investigation of Suction Flow Control on Centrifugal Compressor with Vaned Diffuser

“…With the addition of the second injection, the operating range has been increased. Taghavi-Zenouz et al [10] numerically tested different impeller tip injection parameters on a centrifugal compressor, resulting in an optimum configuration that increased the compressor stall margin by 15%. Halawa et al [11] numerically performed air injection studies at various injection flow rates and injection angles on the NASA CC3 compressor where actuators were placed on the shroud surface between the propeller and the diffuser.…”