Effect Of Serrated Trailing Edge On Aerodynamic Performance Of High-load Compressor Cascade

The compressor is an important component that produces internal thrust in an aerospace gas turbine engine while playing a decisive role in its performance.The manufacture of advanced gas turbines is inseparable from the compressors with excellent performance,and solving the contradiction between the high pressure ratio of the compressor and the high efficiency is the key to improving its performance.The high pressure ratio environment creates a complex flow structure in the cascade,which increases the flow loss and reduces the efficiency of the compressor.Therefore,controlling the complex flow structure inside the cascade in a high pressure ratio environment is the core of the development of the compressor.The excellent performance of the serrated trailing edge technology in controlling the aerodynamic noise demonstrates its potential in controlling the flow of airflow,which has received extensive attention from domestic researchers in recent years.In this paper,the high-load diffuser cascade NACA0065-K48 is taken as the research object,and the numerical method is used to study the flow loss,the pressure-expansion capacity,the limit flow line on the blade surface,the body flow line in the cascade,and the static pressure distribution on the blade surface.The mechanism of tooth width,tooth height and sawtooth arrangement on the performance of high load diffuser cascade and flow field structure,and then find the reason for its loss.In this paper,the sawtooth trailing edge structure scheme with better comprehensive performance is compared with the prototype scheme under different inflow conditions,and the action law under variable working conditions is obtained.Research shows:The sawtooth trailing edge technology can reduce the flow loss of the cascade without reducing the pressure-expansion capability of the cascade.It has a different effect on the reduction of flow loss in the wake area and in the corner area on the side of the suction side.That is to say,in the scope of this study,the flow Mach number is 0.5-0.7,and the flow angle is-13°-6°.This structure can reduce the wake loss,but in most cases,it will deteriorate the flow in the corner area,thus increasing the loss of the area.The method of cutting the trailing edge results in the formation of a zigzag trailing edge vortex pair which is formed under the action of a high and low pressure difference and has a entraining action.Because it redistributes the energy of the low-energy fluid,it improves the flow capacity of the flow channel and enhances its ability to resist separation.At the same time,the pressure difference at the trailing edge is reduced,which weakens the driving force of the channel vortex and the wall vortex,and further reduces the cascade flow loss.The sawtooth with better performance has geometrical features including reasonable width,small height and the arrangement of cutting the root width of the half-saw width.A reasonable width can control the increase in loss in the corner area.The smaller tooth height allows the sawtooth trailing edge cascade to achieve a function that reduces losses over a wide operating range.The arrangement of cutting the root of the tooth can extend the effect of reducing the loss to the corner area.The better overall performance of the sawtooth solution in this paper is 9mm tooth width,3mm tooth height,and the arrangement of cutting the root width of the half serrated width.The sawtooth trailing edge cascade can reduce the loss of flow in the normal working angle range under different inflow Mach numbers.The sawtooth trailing edge structure can reduce the loss rate by 2.0%,6.3%and 4.0%under the conditions of Mach number 0.5,0.6 and 0.7 respectively,which is the same as the attack angle condition with the minimum flow loss in the original cascade.When the Mach number of incoming flow is 0.5 and 0.6,the sawtooth trailing edge can still control some severely separated conditions.