Study On The Unsteady Flow Calculation & Transient Mathematical Model Of Vectoring Nozzle

Thrust Vectoring is the key technique for the modem fighter with agility and post-stall maneuver ability and good flight quality. And now it is the necessary technique for the fourth generation fighter and hot technique for the performance improvement for the third generation fighter. Therefore, more and more attention is paid to this technique recently. Vectoring nozzle is the main component for generating vectoring thrust. And establishing the model of the thrust vectoring nozzle is the base for researching thrust vectoring technique and engine performance with vectoring nozzle, especially the integration of flight and propulsion system control (IFPSC). So thrust vector modeling is very important and meaningful.This paper is focused on how to establish mathematical model of vectoring nozzle on the basis of flow field calculation. In order to obtain transient mathematical model as vectoring deflection which is very important in engineering and valuable in theory, three-dimensional and unsteady flow fields must be researched. In our study computational fluid dynamic(CFD) is used to calculate the performance parameters such as the coefficients of mass rate and thrust and efficient deflected angle of the thrust vectoring nozzle. CFD is also used to get the data of performance parameters of the nozzle at different nozzle pressure ratio, different nozzle area ratio and different geometric defected angle. The theory of function approximation is used to establish the transient model of thrust vectoring with the data calculated. The main works and contribution of this paper are as follows:1.Central type finite volume method proposed by Jameson A. is investigated and the boundary condition of the method is improved. Compared with the testing data it is proved that the program for 3D viscosity steady flow in thrust vectoring nozzle developed is correct and reasonable.2. More than 200 different condition 3D viscosity steady flow fields in the thrust vectoring nozzle at different nozzle pressure ratio and different nozzle arearatio and different geometric defected angle is calculated by the program developed. And the related performance parameters are acquired by numerical simulation.3. The affecting factors of the performance parameters of the thrust vectoring nozzle are investigated. And the affect of nozzle pressure ratio, nozzle area ratio and geometric defected angle on the performance parameters is also investigated.4. The affect of flow separation on the nozzle is investigated and the macroscopical factor that leads to flow separation is also analyzed.5. The unsteady flow as thrust vectoring nozzle deflecting dynamically is investigated. The method of calculating the unsteady flow in the nozzle is given and the flow of the nozzle in the maximum power setting and maximum A/B power setting of the engine is calculated.6. The calculating results of steady flow and unsteady flow in the nozzle are compared. And it proves that both the results of the steady flow and the results of the unsteady .flow are uniform basically. This is very valuable because it is convenient to study the flow in the vectoring nozzle by steady hypothesis or steady test.7. The upwind finite volume method based on flux vector splitting is investigated, especially the splitting scheme of Steger-Warming, Van Leer, Roe and AUSM+.8.The method of the parameter fitting based B-spline is investigated. And the method of the parameter fitting which has three free variables is proposed. Based on this method the transient mathematical model of the thrust vectoring nozzle which has three free variables is established.