利用诱导激波抑制跨音压气机转子叶尖间隙泄漏流的新方法

Title: A New Approach to Suppress Tip Leakage Flow Utilizing Induced Shock Wave in Tip Region of a Transonic Compressor Rotor

题目：利用诱导激波抑制跨音压气机转子叶尖间隙泄漏流的新方法

Authors: CUI Weiwei1, YAO Fei, LI Zongming, WANG Xiaonan, CHANG Guozhang,   WANG Cuiping

作者：崔伟伟，姚飞，李宗明，王晓楠，常国璋，王翠苹

单位：山东科技大学储能技术学院；山东科技大学土木工程与建筑学院；山东科技大学清洁能源实验室

Journal of Thermal Science, 2024, 33(6): 2059-2074.

Abstract: A tandem blade configuration is a significant flow control method that delays the onset of flow separation. This study numerically investigates the effects of diffusion factor and percentage pitch on the flow structure of tandem blades. Diffusion factors vary from 0.328 to 0.484. Percentage pitches change from 0.80 to 0.92. Results show that the loss coefficient increases with diffusion factor and decreases with percentage pitch. There is a hub-corner stall of the forward blade in all cases. Gap flow determines the rear blade corner separation. Varying the percentage pitch and diffusion factor changes the momentum distribution of the gap flow. Corner separation of the rear blade is inhibited as low-momentum gap fluids are involved in the passage vortex along with the hub-corner stall of the forward blade. Tip leakage flow affects the flow stability of high-loading compressors significantly. Therefore, a novel approach via induced shock wave near suction-side edge of blade tip was proposed to suppress the strength and influence range of leakage flow in a transonic rotor. Three new schemes with different circumferentially diverging degrees of clearance were designed to reveal the mechanism of the new approach. Through the action of the circumferentially diverging clearance (from the pressure side to the suction side over blade tip), a much more dramatic acceleration of the supersonic leakage jet flow appeared over blade tip of the new schemes. An induced shock wave was produced near the suction side edge of blade tip due to the pressure difference between the discharging leakage flow and the surrounding high-pressure mainflow in tip channel. As a result, both the mass flow rate and the outlet velocity of leakage flow were reduced significantly via the induced shock wave. Meanwhile, the suppressing effect of the new approach on the tip leakage jet flow was closely related to the strength and circumferential location of the induced shock wave. With the aids of the induced shock wave, the largest improvement of tip flow characteristics with an over 5% increase in stall margin was realized in new transonic rotor when the circumferential divergence angle equals 8°, accompanied with no more than a 0.4% decrease in isentropic efficiency.

摘要：间隙泄漏流对高负荷压气机的流动稳定性具有显著影响。因此，本文提出了一种新方法，利用转子叶顶吸力面侧诱导激波来抑制跨音转子间隙泄漏流强度及其影响范围。通过设计三种具有不同周向扩张度的渐扩型间隙结构方案，以揭示该新方法的作用机理。在叶顶周向渐扩型间隙结构（由转子叶顶压力面侧指向吸力面侧）的作用下，新方案使得跨音转子的叶顶间隙区的超音速泄漏流射流形成明显加速现象。在加速膨胀后的超音速泄漏流与叶尖区域高压主流流体之间压差的作用下，新转子方案的叶尖间隙区域就会产生诱导激波。借助于该诱导激波，可以大幅减小泄漏流由转子叶顶吸力面侧流出时的速度和流量。此外，诱导激波对转子叶顶超音速泄漏流射流的抑制效果与其强度和周向位置密切相关。相比于具有均匀设计间隙的原型方案，当转子叶顶间隙的周向扩张角等于8°时，诱导激波对间隙泄漏流的抑制效果相对最优，能够实现跨音转子失速裕度增加5%以上，且引起的等熵效率下降不超过0.4%。

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