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采用数值模拟方法对某1.5级轴流带冠涡轮的流场进行了研究,分析了全冠、部分冠以及改进的部分冠密封的流场及总体参数。研究结果表明,相对于全冠密封,未改进的部分冠密封降低了涡轮的效率,而改进的部分冠使效率提高到与全冠基本相等。由于叶冠容腔泄漏流周向速度与主流速度不同,导致90%以上叶展出口气流角小于主流的出口气流角,与未改部分冠相比,改进的部分冠减小了这种气流角差别和掺混损失。未改部分冠前部存在压力面向吸力面的横向流动,这种流动造成很大的损失,而改进的部分冠密封减弱了这种横向流动。
The numerical simulation method was used to study the flow field of a 1.5-stage axial-flow capped turbine. The flow field and overall parameters of the full crown, partial crown and the improved partial crown seal were analyzed. The results show that the uncorrected partial crown seal reduces the efficiency of the turbine relative to the full crown seal, while the improved partial crown results in an efficiency equivalent to that of the full crown. Due to the difference between the circumferential velocity and the main velocity of the leakage flow in the crown chamber, the airflow angles at the exit of 90% of the blades are smaller than those at the mainstream. Compared with the uncorrected ones, the improved partial crown reduces the difference between the airflow angles and Blending loss. The uncorrected part of the front of the crown has a lateral flow of pressure towards the suction side, which causes great losses, while the improved partial crown seal weakens this lateral flow.