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高性能燃气轮机的发展迫切要求对涡轮内部损失来源及其物理机制有更清楚的认识。采用带冠设计的涡轮中,气动损失的很大一部分来自叶冠的泄漏流动。为了深入分析叶冠泄漏损失对涡轮性能的影响,选取高负荷涡轮,采用带有掺混面模型的三维定常计算方法和熵增的分析方法来研究叶冠泄漏的损失来源和损失机理。计算中考虑了详细的叶冠几何结构,打破了经验公式在模拟叶冠泄漏流时的局限性。结果表明,带冠涡轮比不带冠涡轮的气动效率高出约0.9%。叶冠泄漏所带来的损失主要分为腔体损失、泄漏损失、掺混损失和攻角损失四个部分,这四种损失来源在不同间隙下所占比例并不相同。因此,考虑完整的叶冠几何结构对涡轮性能的预测和气动设计至关重要。
The development of high-performance gas turbines urgently requires a clearer understanding of the sources of internal turbomachinery and their physical mechanisms. In turbines with a crown design, a significant portion of the aerodynamic loss comes from the leakage of the crown. In order to deeply analyze the influence of the leakage loss on turbine performance, high-load turbine is selected. The three-dimensional steady-state calculation method and the method of entropy increase are used to study the source of the leakage and the loss mechanism. The detailed geometry of the crown was considered in the calculation, which broke the limitation of the empirical formula when simulating the leakage of the tip crown. The results show that the aerodynamic efficiency of the capped turbine is about 0.9% higher than that of the uncapped turbine. The losses caused by the leakage of the crown are mainly divided into four parts: cavity loss, leakage loss, blending loss and angle of attack loss, and the proportions of the four loss sources under different gaps are not the same. Therefore, it is of crucial importance to consider the complete geometry of the crown to predict turbine performance and design of the turbine.