An Arched Groove Film Cooling Structure for Turbine Blades

Abstract

The invention discloses an arched groove gas film cooling structure for turbine blades. An arched groove front edge and a rounded groove back edge are arranged at an outlet of a gas film hole, and the structure is formed. The arched groove front edge is obtained through differencing of the bottom of a transverse groove and a quarter of a cylinder arc, and the radius of the cylinder arc is smaller than the groove depth. Smooth transition from the normal velocity of gas flow after the gas flow leaves the gas film hole to the flow-direction velocity is realized effectively by the aid of the arched front edge, and the cold gas loss caused by direct injection of a large quantity of cooling gas flow into a main flow is avoided; and the momentum loss of jet flow is reduced through smooth transition of the velocity of the cooling gas flow, so that the jet flow is better attached to the wall surface. Collisions between the jet flow and the back edge are reduced by the aid of the rounded groove back edge, so that the flow resistance of the cooling gas flow is reduced, the jet flow is divided to two sides more easily, the spanwise covering of the cold gas is increased, meanwhile, the cold gas climbing out of the groove can be closely attached to the position close to the wall surface, protection of the gas film on the downstream wall surface of the groove is formed, and the cooling effect is good.

Description

technical field [0001] The invention relates to the technical field of cooling the turbine blades of gas turbines, in particular to an arched groove air film cooling structure for the turbine blades. technical background [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 turbine blades to avoid high temperature corrosion and damage to the blades. Film cooling is one of the typical cooling methods used on blades. Air film cooling is to inject a low-temperature airflow along the tangent or 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] As the earliest hole type, air film cylindrical hole type has been widely used and studied. However, in subsequent studies, it ...

AI Technical Summary

Problems solved by technology

However, in subsequent studies, it was found that the gas film formed by the cylindrical hole could not provide cooling protection for the area between the holes, and the jet gas was raised so that the gas film covering the near wall could not be formed.

With the development of film cooling technology, it is found that opening a transverse groove with a certain depth and width at the exit of the film hole along the direction perpendicular to the flow of cold air can significantly improve the cooling effect of the cooling wall surface downstream of the groove, but in the case of the film hole The trailing edge of the groove at the exit has a strong blocking effect on the jet flow. It is difficult for the jet flow to spread to both sides, and a backflow vortex will be formed in the groove, which greatly increases the flow resistance. The jet flow between the holes is very limited and cannot form a uniform flow. The air film is covered by the air film, and after the jet leaves the air film hole, a large amount of jet flow is injected into the main flow due to the high normal velocity, the air film cannot be formed near the wall, and the cooling effect is not ideal. Edge trailing edge structure to improve film cooling effect

A structure similar to slot air film holes has also been proposed, but due to the slope-shaped front and rear edges of the groove, the jet flow cannot achieve a smooth transition, resulting in momentum loss, and the normal phase velocity of the jet flow has not been significantly improved.

Moreover, Jiang Yongjian and others found that changing the trailing edge of the groove to a slope shape can improve the span-wise coverage of the jet, but the improvement of cooling efficiency is not obvious

As a result, the reduction of the normal phase velocity and the improvement of the spanwise diffusion ability of the jet are limited.

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