Investigations On Turbine Endwall Detailed Flow Control Based On Spontaneous Injection Flow

The endwall losses as important part of the turbine internal loss of turbine can account for about 50% to 80% of the total losses on average.At present,the research methods of turbine endwall losses control technology can be divided into active and passive.With the further improvement of turbine performance requirements,the concept of endwall detailed flow control was proposed based on a large number of active and passive flow control research at home and abroad.Spontaneous injection control technology as a kind of passive control technology can further improve the performance of the turbine under the guidance of endwall detailed flow control concept.Spontaneous injection control technology through the use of differential pressure driving force as the driving force to form an injection to control the endwall secondary flow,tip clearance leakage flow etc.Therefore,it is very significance to study the control effect of spontaneous injection control on turbine endwall flow,which is of great significance to further improve the gas turbine efficiency.In this paper,a systematic study of spontaneous injection control technology on flow control in the turbine endwall was conducted by the experimental and numerical methods.The flow mechanism of spontaneous injection control the turbine tip clearance flow was first explained in detail,and the effect of injection parameters of spontaneous injection on the endwall flow control of the spontaneous injection was studied comprehensively and carefully.According to the research content of this paper,the conclusion is as follows: blade tip spontaneous injection flow can obstruct the tip leakage flow through the formation of an air wall in the blade tip and can effectively reduce the tip leakage,inhibit the tip leakage flow,improve the overall aerodynamic performance of the turbine.In addition,the change of control parameters of the spontaneous injection has a huge impact on the control effect of spontaneous injection.Among these parameters,the outlet position and the jet hole diameter have the greatest influence.The study shows that the spontaneous injection control can reduce the total pressure loss of 2.1% with the best effect when the injection hole near the blade pressure surface and the diameter of the spontaneous injection hole as 4.8%H relative blade height.Based on this,Then the study of endwall detailed flow spontaneous injection control at the position of the blade shrouded and the blade rim were carried.The shrouded spontaneous injection can further reduce the aerodynamic loss of the shrouded blade and optimizes the effectiveness of shrouded blade And the effect of shrouded spontaneous injection is directly affected by the arrangement in which the spontaneous injection was arranged in the shrouded.Research shows that the design of spontaneous injection from the leading edge to the top surface of shrouded cannot play an important role in optimizing the aerodynamic performance of the shrouded blade while the design of the injection located in shrouded above the blade pressure surface has a better flow control effect,it can reduce the total pressure loss of 2.4%.The results of the study about spontaneous injection on the turbine rim seal show that: The overall performance of the turbine rim will have a greater impact,the turbine efficiency will reduce about 1.26%,and the use of spontaneous injection flow on turbine rim can reduce the size and strength of the gas recirculation zone above rim seal while not adversely affecting the mainstream performance.In this paper,the research on the investigations on turbine endwall detailed flow control based on spontaneous injection flow,which can provide a new design idea for further improve the gas turbine efficiency.