Research On The Application Of Co-Flow Jet In Numerical Simulation Of Low Speed Separation Problems

The phenomenon of flow separation is very common in engineering,and flow separation often leads to a series of adverse consequences at the same time.Therefore,inhibiting flow separation has always been a hot topic in fluid mechanics.This article takes thin airfoils and high-rise buildings as the research objects,applies aerodynamic control schemes,and analyzes the control effect based on the numerical simulation method of RANS to solve the steady wind field.The adopted aerodynamic control measures are mainly the collaborative jet scheme,and different aerodynamic control schemes are supplemented according to different research objects.The main work and conclusions are as follows:(1)Apply the collaborative jet scheme to the problem of low-speed flow separation,and discuss it with other flow control schemes.For thin airfoils,the scheme of "Co-flow Jet+leading edge droop" is proposed.The aerodynamic characteristics and stall causes of leading edge droop airfoils,Co-flow Jet airfoils,and "leading edge droop+Co-flow Jet" airfoils are analyzed respectively.The results show that the leading edge droop effectively increases the leading edge radius of the airfoil.The Co-flow Jet is to improve the surface circulation of the airfoil by continuously injecting energy into the boundary layer to improve the maximum lift coefficient and curve slope,The "leading edge droop+collaborative jet" scheme can effectively combine the advantages of the two technologies,greatly improving the flow field characteristics of thin airfoils;For the high-rise architectural model,the scheme of "Co-flow Jet+section optimization" is proposed.The results show that the flow separation at the side and back of the square section can be effectively suppressed after arc angle treatment,and the addition of Co-flow Jet can further advance the reattachment position of incoming flow.(2)To verify the feasibility of the calculations in this article,it is necessary to compare the numerical simulation results with wind tunnel tests.For thin airfoils,the lift coefficient curves of reference airfoils and cooperative jet airfoils obtained through numerical simulation are compared with wind tunnel tests.For high-rise architectural model,the wind pressure coefficient curves of three-dimensional reference model and three-dimensional suction model obtained through numerical simulation are compared with wind tunnel tests.The results show that the grid is reasonably divided and appropriate turbulence model is selected,Numerical simulation test data close to wind tunnel tests can be obtained.Among them,grid generation needs to densify the first layer grid of thin airfoil and high-rise architectural model,and SST k is selected for turbulence model-ω Model.(3)Discuss the key parameters of collaborative jet,including jet opening angle,opening position,opening size,jet mass flow rate,and propose recommendations for selecting the most suitable key parameters for improving the separation of low-speed flow fields in collaborative jet models.The thin airfoil and high-rise architectural model discussed in this paper are both in the low speed flow field condition.Aiming at the low speed flow separation generated by different research objects,the aerodynamic control scheme of "Co-flow Jet+" is proposed.The numerical simulation results obtained can confirm that significant control effect can be achieved only by using relatively low jet momentum coefficient,so it has certain engineering application prospects.