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.

中文翻译：

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径流式汽轮机背盘冷却共轭传热研究

涡轮增压器和微型涡轮机中使用的径向涡轮机承受高入口温度。这会在涡轮机中产生高热应力，以及涡轮机导流叶片可能发生蠕变，并会降低涡轮机的可靠性。随着发动机排放法规的日益严格和对发动机功率密度的不断推动，近期涡轮进口温度显着升高，涡轮转子发生热机械故障的风险增加。为了解决这个问题，提出了一种创新的涡轮冷却方法，将少量压气机或中冷器排出的空气注入涡轮转子的上后盘区域，以冷却盘和诱导轮叶片。进行共轭传热模拟以研究这种冷却方法对涡轮增压器涡轮的影响。研究了流动条件和几何结构对方法冷却效率的影响。结果表明，使用中冷器后的压气机排气，仅涡轮质量流量的0.5-2.0%，涡轮后盘的平均冷却效率提高了23-43%；可能只需要四到六个喷嘴来冷却整个背盘；涡轮效率降低不到1个百分点。