射流孔分布对径流涡轮背盘冷效均匀性的改善

The uniformity improvement of back-disc impingement cooling performance of a radial turbine with different distribution strategies of jet-holes

由于可靠性和成本限制,微型燃气轮机涡轮冷却问题尚未形成成熟的解决方案。提出了一种简单、高可靠性的径流涡轮背盘冲击冷却技术,并针对由于涡壳几何周向不均匀导致的涡轮背盘冷效不均匀的问题,采用射流孔周向非均匀布置措施对其进行了改善。研究结果表明:在涡舌附近加密射流孔,使其附近对应的冷效极大和极小值均明显提升,冷效均匀性最高改善17.9%;不同非均布射流孔方案对涡轮背盘平均冷效及涡轮整机膨胀比的影响可忽略,对涡轮整机的效率影响不超过0.5%。

Due to reliability and cost constraints, the problem of micro gas turbine cooling has not yet got a mature solution. A simple and highly reliable back-disc impingement cooling technology is proposed.In order to solve the problem of cooling performance uniformity of turbine back-disc caused by the uneven circumferential geometry of turbine volute channel, the circumferential non-uniform arrangement of jet holes is adopted. Results showed that: the maximum and minimum values of the local cooling efficiency aresignificantly increased by concentrating jet holes near the volute tongue, and the cooling performance can be improved by 17.9% maximum. The influences of the strategy of concentrating jet holes near the volute tongue on the averaged cooling efficiency of the turbine back-disc and on the expansion ratio of the turbine stage can be ignored, of whichthe effect on the aerodynamic efficiency of the turbine is less than 0.5%.