发散冷却与槽缝射流对涡轮静叶端壁气热性能影响的研究

Effects of Effusion Cooling and Slot Jet Flow on Aerothermal Performance of Turbine Vane Endwall

关键词:  涡轮静叶  端壁  发散冷却  槽缝射流  气热性能

Key words:  Turbine vane  Endwall  Effusion cooling  Slot jet  Aerothermal performance

摘要:

燃烧室壁面发散冷却气流影响下游涡轮静叶端壁的气热性能。采用数值求解三维RANS （Reynolds-Averaged Navier-Stokes）方程和SST湍流模型的方法研究了燃烧室壁面发散冷却和前缘槽缝射流作用下的涡轮静叶端壁流动结构和传热冷却特性。分析了3种发散冷却流量质量比和3种前缘槽缝射流质量流量比下的涡轮静叶端壁绝热冷却有效度、静叶叶片泛冷却特性和叶栅流动结构。研究表明：在3种发散冷却气质量比工况下，槽缝射流质量流量比由1.0%增加至1.5%时，整体绝热冷却有效度可至少提升60%，且叶片前缘与压力面角区也得到充分冷却；发散冷却质量流量比增加会改善叶栅出口下游部分端壁冷却效果。上游发散孔流量大于下游孔且槽缝吸力面侧局部吹风比高于滞止点附近位置，发散冷却与槽缝射流流量增加能够减小冷却气流量局部差异。发散冷却与槽缝射流流量增加会削弱马蹄涡，增强空腔涡，并对二次涡产生影响，从而改变冷却气流覆盖特性；提高冷却气流量会使总压损失增加。静叶端壁气热性能的研究需要考虑上游燃烧室壁面发散冷却的影响。

Abstract:

Effusion cooling of combustor wall impacts on the aerothermal performance of the downstream turbine vane endwall. The flow structures and heat transfer cooling characteristics of turbine vane endwall under the influence of combustor wall effusion cooling and leading edge slot jet were numerically investigated using three-dimensional Reynolds-Averaged Navier-Stokes （RANS） and SST turbulence model. The adiabatic cooling effectiveness of endwall， vane phantom cooling performance and flow structures of turbine vane cascade are compared and analyzed at three kinds of effusion cooling mass flow rate （MFR_E） and three kinds of slot jet mass flow rate （MFR_S）. The obtained results show that the overall adiabatic cooling effectiveness of turbine vane endwall increases up to more than 60% when the MFR_S increases from 1.0% to 1.5% at three kinds of MFR_E. In addition， the regions near vane leading-edge and corner zone of the pressure surface can be covered by coolant. The increase of MFR_E can improve the cooling performance of the endwall downstream of the turbine vane outlet. The coolant flow rate of the upstream effusion holes usually is larger than that of the downstream holes. The local blowing ratio of the slot jet near the suction side is larger than that of stagnation region near the leading edge. These local mass flow rate difference decreases with the MFR_E and MFR_S increase. The increase of the MFR_E and MFR_S can weaken the horse-shoe vortex strength and enhance the cavity vortex strength， as well as influence the secondary vortex. The total pressure loss increases with the coolant mass flow increases. These flow structures would have impacts on the coolant coverage characteristics. Investigation on the aerothermal performance of turbine vane endwall should consider the influence of the upstream effusion cooling of combustor.