Abstract

Some rows of steam and gas turbines, with the exception of the first vanes, operate at the inlet flow conditions created by the upstream turbine stages. In particular, the conditions of the flow at the inlet of a low-pressure turbine vanes (LPT vanes) depend on the upstream high-pressure turbine (HPT). The first stages of the gas turbines are, as a rule, cooled and transonic stages with high power losses; therefore, the nonuniformity of the radial distribution of the angles of flow, the total pressure, and the total temperature may be extremely substantial at the LPT inlet. This leads to increased levels of profile and, especially, secondary losses in the LPT rows. Normally, the LPT vanes have a meridional opening along the inner and outer outlines of the flow path that causes the intensification of the secondary flows and, accordingly, an increase in the secondary losses. To minimize adverse effects on the operation of LPT vanes, such as a nonuniform distribution of the flow parameters at the vane inlet, the meridional opening, and the unfavorable aspect ratio, the width of the blade was increased to decrease the meridional angle of the opening and the three-dimensional design of the vanes was applied to reduce the secondary losses. In particular, variants of the LPT vanes of different spatial configurations were investigated, viz., “reversed bow” vanes, bowed vanes, and leaned vanes in a circumferential direction. The radical change in the vane shape was restricted by the design of the cooling system of the blades that comprises a deflector in the inner hollow of the blade designed to enhance the efficiency of the cooling. As a result, a compromise between the aerodynamic characteristics and the restrictions imposed by the cooling system was found.

中文翻译：

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在非均匀入口边界条件下提高涡轮机排的性能

摘要

除第一批叶片外，某些排汽轮机和燃气轮机在上游涡轮机级产生的入口流量条件下运行。特别地，低压涡轮叶片（LPT叶片）的入口处的流动条件取决于上游高压涡轮（HPT）。燃气轮机的第一级通常是功率损失高的冷却和跨音速级。因此，LPT入口处的流角，总压力和总温度的径向分布的不均匀性可能非常严重。这导致配置文件级别增加，尤其是LPT行中的次要损耗。通常，LPT叶片沿流道的内部和外部轮廓具有子午线开口，这会引起二次流的增强，因此，二次损失增加。为了最大程度地减少对LPT叶片运行的不利影响，例如叶片入口处的流量参数分布不均匀，子午线开口和不利的长宽比，请增加叶片的宽度以减小开口的子午角并采用叶片的三维设计来减少二次损失。特别地，研究了具有不同空间构造的LPT叶片的变体，即沿圆周方向的“倒弓”叶片，弓形叶片和倾斜叶片。叶片形状的根本变化受到叶片冷却系统设计的限制，该系统在叶片内部空腔中包括一个导流板，该导流板设计用于增强冷却效率。因此，