Improved Design And Performance Analysis Of An Ultra-highly Loaded Booster

For aero engines,high thrust-weight ratio is the throughout invariable pursue goal.Under the condition of achieving the same total pressure ratio,increasing the load of single booster stage and reduce the series of booster are helpful to increase thrust-weight ratio of the engine.Therefore,based on the performance parameters of a conventional three-stage booster,this thesis tries to design a new unltra-highly loaded booster with only one stage to replace the original one by applying a new concept of diffusion blade profile with large camber and low flow losses.Utilizing mature blade design and optimization platform,a two-dimensional(2D)design method of S1(blade to blade)/S2(hub to tip)stream surfaces is applied to design the blades of rotor and stator in the booster,and combined with the automatic optimization method to further inprove the performance of the booster.This thesis can be divided into three parts.In the first part,an untra-highly loaded booster stage based on a three-stage booster's parameters and the original three-stage booster are compared and analyzed under the environment of internal and external connotation calculation,including economic cruise speed,take-off speed and the maximum climb speed.It shows that the efficiency of the two boosters is basically the same at the three speeds,while the total pressure ratio and stability margin of the single stage booster are lower than those of the original three stages,especially the pressure ratio at the root of the single stage blade is quite lower than that of the three-stage booster.In the second part,based on the performance parameters of an advanced three-stage booster,this thesis tries to design a new unltra-highly loaded booster with only one stage to replace the original one by applying a new concept of diffusion blade profile with large camber and low flow losses.With the index of performance parameters at design point,an optimization method based on genetic algorithm is used to optimize the rotor blade and stator blade,and the surge margin is further improved by change the blade stacking line of the rotor blade.It shows that 3-D optimization method can improve the performance parameters at the design point highly.For ultra-highly loaded rotor,forward-swept of the rotor blade can make the load of the blade move downstream,decrease the load of the leading edge,increase the tolerance range of the attack angle,and lift the surge margin of the booster stage.At the design point,the newly designed booster has nearly the same total pressure ratio and mass flow rate as the original booster and exhibits higher efficiency than the original booster.It indicates that the newly designed booster can match the transition channel well.In order to reduce the high loss on the root of the rotor blade,the last part uses the throughflow program to study the effect on the performance parameters by changing inlet flow angle on the root of rotor blade,and selects the appropriate inlet angle to redesign the inlet guide vane,rotor and stator blade.The simulation result shows that increasing the inlet absolute flow angle will decrease the outlet relative flowangle and absolute Mach number of the airfoil,which can effiectively improve the flow condition in the rotor and stator channel.Whereas,it will also increase the fluid turning angle in the inlet guide vane,which will increase design difficulty of the inlet guide vane.The booster stage that designed by increasing the inlet flowangle of the rotor can achieve the same pressure ratio,higher efficiency than the original one(86.83% to 87.84% at the design point),and increase the total pressure recovery coefficient of the transition channel(97.77% to 98%).It shows that appropriately increasing the inlet flow angle of the rotor is beneficial to improve the flow condition in the ultra-highly loaded booster stage.