Effect of Leading-Edge Optimization on the Loss Characteristics in a Low-Pressure Turbine Linear Cascade  

作　　者：CUI Tao WANG Songtao TANG Xiaolei WEN Fengbo WANG Zhongqi 

机构地区：[1]School of Energy Science and Engineering, Harbin Institute of Technology

出　　处：《Journal of Thermal Science》2019年第5期886-904,共19页热科学学报（英文版）

基　　金：sponsored by the Project NO.51576037 supported by National Natural Science Foundation of China (NSFC)

摘　　要：This paper presents a numerical study on the aerodynamics loss reduction characteristics after the leading-edge(LE) optimization in a low-pressure turbine linear cascade. The LE was optimized with a simple and practical method of "Class Function/Shape Function Transformation Technique"(CST). The simulation conditions, covering the whole working range, were independently determined by incidence, Reynolds number and Mach number. Quantitative loss analyses were carried out with a loss breakdown method based on volumetric integration of entropy production rates. To understand the reason of loss reduction, the local sources at different operating points were identified with entropy production rates. The results showed that LE optimization with the CST method played a positive role in decreasing the total losses, and the working range with lower loss was extended. The profile loss and the endwall loss were significantly reduced by the LE optimization, which were also verified to be the major causes of the total loss reduction by loss breakdown. The decrease of profile loss can be attributed to the boundary layer near the LE region and the boundary layer of downstream at off-design incidence. The reduction mostly came from the pressure side at negative incidence, while came from the suction side at the positive incidence. The endwall loss was decreased markedly about 2.5%–5% by the LE optimization at the incidence of-12°, which was 1% at the incidence of 12°. The mechanism for the endwall loss reduction at different incidences was different from each other. At negative incidence, the LE optimization diminished the corner separation vortex on the pressure side. While at positive incidence, the benefits came from three aspects, i.e., reduced suction LE separation bubbles close to the endwall, reduced passage vortex strength, and weakened shear process between passage vortex and trailing shed vortex. The loss of the downstream zone was relatively lower than that of the profile losses and the endwall losses. The effect This paper presents a numerical study on the aerodynamics loss reduction characteristics after the leading-edge(LE) optimization in a low-pressure turbine linear cascade. The LE was optimized with a simple and practical method of "Class Function/Shape Function Transformation Technique"(CST). The simulation conditions, covering the whole working range, were independently determined by incidence, Reynolds number and Mach number. Quantitative loss analyses were carried out with a loss breakdown method based on volumetric integration of entropy production rates. To understand the reason of loss reduction, the local sources at different operating points were identified with entropy production rates. The results showed that LE optimization with the CST method played a positive role in decreasing the total losses, and the working range with lower loss was extended. The profile loss and the endwall loss were significantly reduced by the LE optimization, which were also verified to be the major causes of the total loss reduction by loss breakdown. The decrease of profile loss can be attributed to the boundary layer near the LE region and the boundary layer of downstream at off-design incidence. The reduction mostly came from the pressure side at negative incidence, while came from the suction side at the positive incidence. The endwall loss was decreased markedly about 2.5%–5% by the LE optimization at the incidence of-12°, which was 1% at the incidence of 12°. The mechanism for the endwall loss reduction at different incidences was different from each other. At negative incidence, the LE optimization diminished the corner separation vortex on the pressure side. While at positive incidence, the benefits came from three aspects, i.e., reduced suction LE separation bubbles close to the endwall, reduced passage vortex strength, and weakened shear process between passage vortex and trailing shed vortex. The loss of the downstream zone was relatively lower than that of the profile losses and the endwall losses. The effect

关 键 词：low pressure TURBINE LEADING edge LOSS BREAKDOWN LOSS AUDIT boundary layer entropy production rates 

分 类 号：O4[理学—物理]