Aerodynamic And Infrared Stealth Comprehensive Design Of 2D Convergent Nozzle Of Mixed Flow

The objective of this thesis is to develop the design method of two-dimensional convergent nozzle of mixed flow turbofan engine to meet aerodynamic and infrared stealth requirements. Configuration design method for two-dimensional convergent nozzle is studied. The effect of geometric parameters on internal performance and infrared (IR) signatures of two-dimensional convergent nozzle is calculated and compared. Matching method for core and bypass mass flux is researched. Integration design method for internal performance and infrared stealth of mixed flow two-dimensional convergent nozzle is explored and verified by numerical simulation and experiments.The main results are as follows:(1) Configuration design method for two-dimensional convergent nozzle based on super-ellipse cross-section or a rectangle cross-section with filleted corner is developed. Controling parameters for these two kinds of cross-section are analysed. Variation functions of the cross-section controling parameters are constructed based on polynomial functions. Restricting relationship between cross- section controling parameters and the variation functions is analysed and pointed out. The cross section controling parameters and the variation functions choosing criterion for high performance two-dimensional convergent nozzle are concluded.(2) The effect of geometric parameters on internal performance and IR signatures of two-dimensional convergent nozzle is obtained. The configuration of nozzle has some effect on internal performance, but little on the IR signatures. Aspect ratio of nozzle exit, nozzle length, and throate area have masurable effect on internal performance. Nozzle inlet section position has little effect on internal performance. The effect of aspect ration on IR signatures is of the most significance, but nozzle length, throate area, and nozzle inlet section position have less effect on the IR.(3) Matching method for core and bypass mass flux base on 3-D viscous numerical simulation is proposed. Non-linear dimensionless mass flux matching equations for core and bypass channel with 2D nozzle are formulated. Solving procedure of the nolinear equations is presented. Numerical simulation and matching results for some nozzle cases indicate that the method for solving the non-linear mass flux equations is effective.(4) Integration design procedures for internal performance and IR stealth of two-dimensional mixed flow convergent nozzle are proposed. Based on the requirements for the nozzle, a nozzle sketch is selected and is matched with the core and bypass mass flux throuth the methods mentioned above. Then the design result of the nozzle is evaluated for its internal performance and IR streath and a decision is made if further refinement is necessary. The feasibility of the design procedures is evaluated and verified by numerical simulation and experiment of nozzle internal performance and IR radiation. The results indicate that determinating throate area properly play a key role for the required nozzle gross thrust. The two-dimensional convergent nozzle designed and matched at engine design point, makes engine operational state different from axisymmetric nozzle at off design point. Choosing a reasonable nozzle exit aspect ratio is important for meeting the IR stealth requirement.