Performance Effect of Trench Casing on a Transonic Compressor at Different Rotating Speeds

doi:10.1007/s12204-022-2541-3

Abstract

Abstract: The trench casing often occurs in axial compressors due to the casing rubbing or casing treatment. However, the effect of the trench casing on the aerodynamic performance of axial compressors has not been fully understood, especially at different rotating speeds. Therefore, we numerically investigate the effect of the trench casing on a transonic compressor at two rotating speeds. A detailed comparison of overall performance and flow characteristics has been performed. The results show that the trench configurations slightly increase the total pressure ratio and mass flow rate near the choking condition but reduce the total pressure ratio and adiabatic efficiency at small mass flow rates. The largest efficiency reduction of the parallel trench (PT) and within trench (IT) cases is more than 1%, which is located at the mid blade passage near 90% span. The effect of the trench configurations on the stall margin is different for the two rotating speeds. At 100% rotating speed, the outside trench (OT) and IT cases improve the stall margin by 2.8% and 1.1%, respectively, but the PT case decreases the stall margin by 1.3% due to the increased blockage in the core region of the tip leakage vortex. At 80% rotating speed, the stall margin of the trench configurations becomes worse. Because of the increased blockage of the mid blade passage, the PT and IT cases decrease the stall margin by 2.9% and 2.1%, respectively. Though there are some differences in the flow characteristics of the trench configurations at the two rotating speeds, the change of the stall margin always depends on the blockage near the tip region. This work can contribute to further understanding the impact of the trench casing on axial compressors.

Key words: axial compressor, trench casing, tip leakage flow, numerical simulation

摘要： 在轴向压气机中，由于机匣摩擦或机匣处理，经常会出现沟槽型机匣。然而，沟槽型机匣对轴流压气机气动性能的影响尚未完全了解，特别是在不同转速下。因此，数值研究了在两种转速下，沟槽型机匣对跨声速压气机的影响。对其整体性能和流动特性进行了详细的比较。结果表明，在堵塞工况附近，沟槽构型略微提高了总压比和质量流量，但在小质量流量工况下降低了总压比和绝热效率。平行沟槽和沟槽内情况的最大效率降低超过1%，位于90%跨度附近的叶片中间通道。在两种转速下，沟槽构型对失速裕度的影响是不同的。在100%转速下，沟槽外和沟槽内情况分别使失速裕度提高2.8%和1.1%，而平行沟槽由于叶尖泄漏涡核心区域堵塞增加，使失速裕度降低1.3%。在80%转速下，沟槽构型的失速裕度变差。由于叶片中间通道的堵塞增加，平行沟槽和沟槽内情况分别降低了2.9%和2.1%的失速裕度。虽然两种转速下的沟槽结构的流动特性存在一定的差异，但失速裕度的变化始终取决于叶尖附近的阻塞。这项工作有助于进一步了解沟槽型机匣对轴向压气机的影响。

关键词: 轴向压气机，沟槽型机匣，叶尖泄漏流，数值模拟

CLC Number:

V231.3

DENG Hefang (邓贺方), XIA Kailong (夏凯龙), TENG Jinfang (滕金芳), QIANG Xiaoqing (羌晓青), ZHU Mingmin^∗ (朱铭敏), LU Shaopeng (卢少鹏). Performance Effect of Trench Casing on a Transonic Compressor at Different Rotating Speeds[J]. J Shanghai Jiaotong Univ Sci, 2024, 29(6): 1151-1160.

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