Study on status of force acting on VNT guide vanes under different engine working conditions

Commercial CFD software package is used to simulate the flow field in a variable nozzle turbine. Experimental study was performed on a turbine characteristic test bench. The working conditions obtained in experiments were taken as the boundary conditions for CFD simulations. CFD results are also validated through experiments. The model was used to simulate the working conditions of turbine-engine matching. The pressure distribution on the vanes under different representative engine working conditions was calculated, and it is used subsequently to derive the torque of pneumatic force acting on the vanes. CFD results showed that the direction of pneumatic torque would change as working conditions of internal combustion engine were changed, leading to the discontinuity of turbine characteristic, and this should be avoided in maintaining stable engine operation. An effective method was carried out to optimize the position of the vanes' pin and improve the force status of the nozzle guide vane.