Turbine with moving blades with pits at blade tops

Abstract

The invention aims at providing a turbine with moving blades with pits at blade tops. The turbine comprises a case and a hub. The moving blades are uniformly installed along the circumferential direction of the hub. The hub and the moving blades are installed in the case. The pits are arranged at the blade tops of the moving blades. By designing the turbine blades with the pits at the blade tops, on one hand, the clearance leakage amount is reduced, the turbine efficiency is improved and the attack angle change applicability is good; on the other hand, the heat load on the surfaces of the blade tops and the heat transfer coefficient of local areas of the blade tops are reduced, the non-uniform extent of heat transfer of the blade tops is reduced and the service life of the blades is improved; the weight of the ends of the blade tops can be reduced, the rigidity produced when the blades rub the case is reduced and the working reliability of the gas turbine is improved.

Description

Technical field [0001] The invention relates to a turbine, in particular to turbines of aero engines and gas turbines. Background technique [0002] Turbine tip clearance leakage flow is one of the most common flow phenomena in impeller machinery rotors. The transverse pressure difference on the tip surface causes leakage flow from the pressure surface to the suction surface. When the leakage flow flows out from the suction surface, it interacts with the main flow of the channel. Leakage vortex, leakage flow and leakage vortex have a very important impact on the aerodynamic loss, heat transfer and unsteadyness of the downstream flow field of the turbine: First, the leakage flow at the tip of the turbine blade produces a large aerodynamic loss. In a turbine without a crown, The top leakage loss can account for up to 45% of the rotor loss and 30% of the stage loss respectively; secondly, the leakage flow and leakage vortex have a greater impact on the unsteadyness of the downstream...

AI Technical Summary

Problems solved by technology

[0002] Turbine blade tip clearance leakage flow is one of the most common flow phenomena in turbomachinery rotors. The lateral pressure difference on the blade tip surface causes leakage flow from the pressure surface to the suction surface. When the leakage flow flows out from the suction surface, it interacts with the main flow of the channel to form Leakage vortex, leakage flow and leakage vortex have a very important influence on turbine aerodynamic loss, heat transfer and unsteady downstream flow field: First, the leakage flow at the tip of the turbine blade produces a large aerodynamic loss. In the unshrouded turbine, The tip leakage loss can account for up to 45% of the rotor blade loss and 30% of the stage loss; secondly, the leakage flow and leakage vortex have a greater impact on the unsteadiness of the downstream flow field, which can cause blade structure vibration and noise, reduce reliability, and reduce engine life; finally, leakage flow and leakage vortex increase the complexity of heat transfer near the tip of the turbine blade. The effect causes the heat transfer coefficient of the blade tip to be greatly improved, and the leakage flow undergoes complex flow processes such as separation and reattachment in the gap, which makes the heat transfer of the blade tip very complicated. Under the impact of the heat load in the gap, the turbine blade is prone to ablation and fracture

[0003] In order to reduce the negative impact of gas leakage from the blade tip clearance, most turbines currently use methods such as crowning the blade tip and modifying the blade tip to suppress the generation of gap leakage flow. Although these methods can reduce to a certain extent Gap leakage loss improves the internal flow of the turbine channel, but its effect varies with the turbine blades of specific applications, such as high and low pressure turbine blades, sub- and transonic gap flow, long and short blades, etc., and under variable operating conditions However, these methods are not effective in controlling gap leakage; in addition, although these methods can reduce the average heat transfer coefficient and heat load of the blade tip surface to a certain extent, they increase the heat transfer coefficient of the local area of ​​the blade tip, increasing the The degree of non-uniformity of heat transfer on the tip of the blade

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