Slot jet flow gas film cooling structure for end wall of turbine

Abstract

The invention discloses a slot jet flow gas film cooling structure for the end wall of a turbine, and belongs to the field of cooling of turbine guide vane end walls of gas turbines. The cooling structure is formed by arranging jet flow gas film holes in the step surface of a backward step on the upstream of the end wall. The jet flow angle is parallel to the surface of the end wall and abuts against the surface of the end wall. In order to ensure the structural strength, the inlet diameter Df of the gas film holes is required to be smaller than two thirds of the height of the step. The slot jet flow holes parallel to the surface of the end wall only have a tangential jet flow speed, so that cold gas losses caused by direct injection of a large amount of cooling gas flow into main flow areavoided; and in addition, horseshoe vortexes at the front edges of blades are greatly weakened by the high-momentum slot jet flow cold gas, so that the jet flow is better attached to the wall surface. Meanwhile, the slot cold gas jet flow further breaks through a gas backflow dead zone formed on the downstream of the step, the downstream of the step is prevented from being located in a high-temperature area, and a gas film is formed to protect the surface of the end wall of the turbine.

Description

technical field [0001] The invention belongs to the cooling field of the turbine vane end wall of a gas turbine, and in particular relates to a slot jet air film cooling structure for the turbine end wall. Background technique [0002] With the improvement of gas turbine performance, the turbine inlet temperature continues to increase. Nowadays, the inlet temperature of some advanced engines has reached more than 2000K. Therefore, effective cooling measures must be used to protect the end wall of the turbine guide vane to avoid the end wall from being exposed to high temperature. corrosion and damage. Film cooling is one of the typical cooling methods used on end walls. Air film cooling is to inject a low-temperature airflow at a certain angle near the wall to isolate the high-temperature combustion body from the wall to achieve cooling protection for the heated wall. [0003] Arranging cylindrical air film holes on the surface of the end wall is a common cooling method, w...

AI Technical Summary

Problems solved by technology

Leakage cooling structures with different leak groove widths, jet angles, and distances from the leak groove to the leading edge of the blade have been proposed successively, but the jet tangential velocity has not been significantly improved due to the momentum loss caused by the lift of the jet gas.

The slot jet is tangent to the surface of the end wall, which solves the problem of jet gas elevation, but the relatively large slot gap reduces the jet flow of the cold air, and the improvement of the cooling efficiency of the turbine end wall is not obvious

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