Abstract
The mid-passage gap is an inevitable structure in a vane passage due to turbine vanes being manufactured individually.The coolant from this gap is able to prevent hot mainstream ingression and provide cooling protection for the endwall.A novel idea of enlarging the endwall's coverage area and reducing the endwall's thermal load by applying the mid-passage gap with vari-able surface angles is carried out in this paper.The endwall's aerothermal and film cooling perfor-mances under four mid-passage gap modes at three typical mass flow ratio conditions are numerically investigated.Results indicate that under the traditional mid-passage mode,the coolant flows into the mainstream with a perpendicular incidence angle and can't stick to the endwall.Thus,cooling failure occurs,and the endwall's thermal load is badly increased.The film cooling level at the suction-side endwall is improved when applying the mid-passage gap of a 45° surface angle due to the secondary vortex being suppressed.In addition,when applying the mid-passage gap of a 135° surface angle,the horseshoe vortex is pushed away,and the coverage area at the pressure-side end-wall is enlarged significantly.The best film cooling performance is achieved when the upstream sur-face angle is 135° and the downstream surface angle is 45° due to the adiabatic film cooling effectiveness being increased at both the pressure-and suction-side endwall.When the mass flow ratio is 1.5％,the coverage area is enlarged by 43％,and the area-averaged adiabatic film cooling effectiveness is increased by 37％,when compared with those under the traditional mid-passage mode.
基金项目
National Science and Technology Major Project,China(J2019-Ⅱ-0011-0031)
National Natural Science Foundation of China(51936008)
NETL
NSTL
万方数据