Conjugate heat transfer study of backdisc cooling of a radial turbine

Abstract

Radial turbines used in turbochargers and micro-turbines are subjected to high inlet temperature. This creates high thermal stress in the turbines, and possible creep of turbine inducer blades, and can reduce turbines’ reliability. With the ever-stringent engine emission regulations and the continuous drive for engine power density, turbine inlet temperature is significantly increased recently and the risk of thermo-mechanical failure of turbine rotor is heightened. To solve this problem, an innovative turbine cooling method is proposed by injecting a small amount of compressor or intercooler discharge air onto the upper backdisc region of turbine rotor to cool the disc and the inducer blades. A conjugate heat transfer simulation was carried out to investigate the effects of this cooling method with a turbocharger turbine. Flow conditions and geometric configurations were investigated for their influences on the cooling effectiveness of the method. The results show that using the compressor discharger air after intercooler with only 0.5–2.0% of turbine mass flow, the averaged cooling efficiency of the turbine backdisc is promoted by 23–43%; only four to six jets may be needed to cool the entire backdisc; and turbine efficiency is reduced by less than 1% point.

Effect of jet flow on cooling performance and thermal stress of a radial turbine back disc

“…Aiming at the problems of radial turbine cooling technology, a back-disc impingement cooling technology with simple structure and high reliability was proposed. 10,11 In this paper, the influences of jet hole radial position and cooling flow consumption on the cooling characteristics of the back disc, the resultant stress and aerodynamic performance of turbine were studied.…”

Experimental and numerical investigation of the thermomechanical load on a turbine housing in a radial turbocharger

“…Turbine housing -a key part of the turbocharger -generates thermomechanical fatigue under the influence of high-temperature gas and engine vibrations. [1][2][3] Hence, the thermomechanical fatigue of turbochargers has become a concern in the design of turbochargers.…”