燃烧室-涡轮耦合流动传热超大涡模拟研究

Very-Large Eddy Simulation of Turbulent Flow and Heat Transfer for Coupled Combustor-Turbine Components

关键词:  大涡模拟  涡轮传热  预混燃烧  湍流燃烧  耦合

Key words:  Large eddy simulation  Turbine heat transfer  Premixed flame combustion  Turbulent combustion  Coupling

摘要:

为了准确预测发动机燃烧室和涡轮耦合复杂气热环境下涡轮部件的流动和换热特性，应用基于BSL k-ω湍流模型的高精度超大涡模拟方法（VLES），以及SST k-ω雷诺平均湍流模型对雷诺数为Re=3.8×10⁵的高压涡轮导叶在均匀进口条件以及燃烧室-涡轮耦合情况进口条件下的涡轮流动和传热进行了数值研究。耦合火焰面生成流型（FGM）燃烧模型和VLES湍流模型，对GE LM6000燃机燃烧室进行了数值计算，验证了非稳态燃烧计算的精度和可靠性。研究表明，均匀涡轮进口条件下，VLES方法能够更准确地捕捉到高压涡轮叶栅内的非定常流动结构和传热特征，包括吸力面尾缘处出现的弱激波以及在叶片前缘上下端壁形成且向下游发展的马蹄涡，而SST k-ω湍流模型捕捉涡系能力较弱，导致叶片表面压力和换热分布的差异。在燃烧室-涡轮耦合计算中，基于VLES-FGM方法的数值计算预测到燃烧室出口/涡轮进口位置存在明显残余旋流。燃烧室出口速度和温度畸变对下游涡轮叶栅内流动和换热影响显著，加剧了涡轮通道内流动和传热的非稳态特征。表明燃烧室和涡轮耦合对于准确预测和研究涡轮相关的流动和传热特性具有显著影响。

Abstract:

In order to accurately predict the complex turbulent flow and heat transfer characteristics in the turbine component under the condition of coupled combustor-turbine components， numerical investigations of the flow and heat transfer around the high-pressure turbine guide vane with Reynolds number of Re=3.8×10⁵ using SST k-ω RANS turbulence model and high-fidelity very-large eddy simulation （VLES） method which based on the BSL k-ω turbulence model are conducted. Both the uniform inlet condition and the inlet condition of coupled combustor-turbine components are considered. Coupled with the flamelet generated manifold （FGM） combustion model and the VLES turbulence model， numerical assessment is conducted for the combustion in the gas turbine combustor of GE LM6000. The prediction accuracy and the reliability of the present numerical method for the turbulent combustion are then assured. It is found that， for the uniform inlet case， the VLES method can capture the flow and heat transfer characteristics more accurately of the high-pressure turbine cascade， including the weak shock wave appearing at the trailing edge of the suction surface and the horseshoe vortex formed and developed downstream the upper and lower endwalls of the leading edge of the blade. However， the SST k-ω RANS turbulence model predicts weak flow unsteadiness and it results in differences of pressure and heat transfer coefficient distributions on blade surface. Furthermore， in the coupled combustor-turbine calculation， the VLES-FGM simulation reveals that there is a significant residual swirling effect at the combustor outlet， i.e. turbine inlet. The distortion of velocity and temperature at combustor outlet has significant effects on the flow and heat transfer and enhances the unsteady characteristics of the flow and heat transfer in the downstream turbine cascade. It demonstrates that the coupling effects of combustor and turbine have significant effects on the flow and heat transfer characteristics in the turbine design.