顶部间隙对超声速膨胀器流动特性的影响
收稿日期: 2014-11-27
修回日期: 2015-10-12
网络出版日期: 2015-10-21
基金资助
高等学校博士学科点专项科研基金(20132125120006);中央高校基本科研业务费专项资金(3132014319);辽宁省高校创新团队支持计划(LT2015004)
Influence of tip clearance on flow characteristics of a supersonic expander
Received date: 2014-11-27
Revised date: 2015-10-12
Online published: 2015-10-21
Supported by
Specialized Research Fund for the Doctoral Program of Higher Education of China(20132125120006);The Fundamental Research Funds for the Central Universities(3132014319);Supported by Program for Liaoning Innovative Research Team in University(LT2015004)
隔板与机匣之间留有间隙,间隙的存在势必会对超声速膨胀器的内部流场和总体性能产生影响,为了获得超声速膨胀器内部间隙流动的流动细节,采用三维雷诺平均Navier-Stokes方程和标准k-ε湍流模型,就顶部间隙对超声速膨胀器流动特性的影响进行了数值研究。结果表明:膨胀流道出口斜激波导致吸力面压力高于压力面,隔板尾缘附近部分泄漏流体经间隙流回压力面侧;间隙的存在导致吸力面进口及中、后部近下端壁压力上升,而压力面前缘附近压力下降,对比同一隔板位置,间隙高度每增加1%喉部高度,超声速膨胀器隔板载荷系数最高下降2.6%;端壁损失和斜激波损失降低,但产生了泄漏损失,三维流道内总的流动损失增加,膨胀器效率降低,本文研究范围内效率最多下降8.8%;马蹄涡、泄漏涡及二者之间的相互作用是顶部区域的主要涡系结构;前缘附近气流经间隙流到吸力面侧和尾缘附近泄漏流体越过间隙重新流回压力面侧是间隙内气流的主要运动形式。
黄振宇 , 钟兢军 , 杨凌 , 韩吉昂 . 顶部间隙对超声速膨胀器流动特性的影响[J]. 航空学报, 2016 , 37(2) : 555 -567 . DOI: 10.7527/S1000-6893.2015.0269
A clearance exists between strake wall and casing, which will certainly influence internal flow field and overall performance of a supersonic expander. To obtain the flow details of tip clearance flow in a supersonic expander, the three-dimensional Reynolds-averaged Navier-Stokes equations and the k-ε turbulent model are adopted in this paper to simulate numerically the tip clearance flow of a supersonic expander. It has been found that oblique shock wave at the outlet of the expansion passage leads to the fact that static pressure of the suction surface is higher than the pressure surface, parts of the leakage fluid near the trailing edge passes the clearance and reflows to the pressure surface. Because of the tip clearance, static pressures of the suction surface at the location of inlet and near the lower end wall increase, while the pressure at the pressure surface near the leading edge decreases. Compared with the same location of the strake wall, increasing the tip clearance height by 1% throat height, load coefficient of the strake wall of supersonic expander drops by as much as 2.6%. The loss of end wall and oblique shock wave reduces, but the tip leakage loss is produced, increasing the overall flow loss of the three-dimensional flow passage, and the efficiency of the supersonic expander drops, which decreases by up to 8.8% in this paper. The horseshoe vortex, the leakage vortex, and the interaction between them constitute the main vortex system of the tip area. The airflow near the leading edge through the clearance flow to the suction surface and the leakage fluid around the trailing edge across the gap back to the pressure surface is the main form of movement within the clearance.
Key words： supersonic expander; strake wall; tip clearance; expansion waves; leakage vortex
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