blowing

In this study, the effect of blowing angle on coefficients of aerodynamic of NACA0012 airfoil at Re=4×106 has been investigated. In the present research, the effect of three-dimensional blowing jet on the aerodynamic performance of the wing has been considered. The changes of lift and drag coefficients were studied by using the blowing near the leading edge of the airfoil for angles of attack of 12, 14, 16, 18 and 20 degrees. Due to the application of blowing through circular holes, a three-dimensional solution was used for the purpose of analysis and study, which will be computationally expensive. The analysis carried out in this case was performed with the assumption of incompressible and steady flow around a three-dimensional wing section in Fluent software. The results showed that the blowing has a negligible effect on the lift and drag coefficients at angles of attack less than 14 degrees. It is for this reason that only the effects of the blowing at high angles of attack are considered. The greatest increase in the lift coefficient and the greatest decrease in the drag coefficient occurs at the angle of attack of 16 degrees, which is the stall angle. The results showed that as the jet angle increases, the aerodynamic performance decreases.

In this article, a numerical investigation of the effect of simultaneous suction and blowing on an airfoil is studied to reduce the separation bubble. This investigation was done at Re=8.5×106 and the simulations are done by commercial Fluent software. First, the suction and blowing systems are used at different blowing and suction angles (30, 45 and 90 degrees) along with their location (distance ratio 0, 0.1, 0.2, 0.3, 0.6, 0.7 and 0.8) were investigated. In this study, the ratio of lift to drag, pressure coefficient, velocity and pressure contours were compared in different cases compared to the one with no slot, and finally the best state was determined. The results of this study showed that the suction on the leading edge and blowing on the tailing edge can improve the aerodynamic performance of the airfoil at an angle of attack of 17 degree. The best performance was the blowing at a distance ratio of 0.6C and suction at 0.1C, which increased the lift-to-drag ratio by 55%. Compared to the one without any slot.

In the present study, active flow control was performed by blowing jet at the leading edge of NACA 0015 airfoil to delay the separation of the boundary layer from the airfoil suction side. By employing 48 numerical simulations and the Response Surface Method, the relationship between the blowing jet parameters and the aerodynamic coefficients is presented as a specific regression function. The blowing width has been studied in three levels, the blowing angle and speed each in four levels. Transition SST turbulence model is used for numerical simulation and flow Reynolds number is 232940. According to the results, tangential blowing shows the most aerodynamic performance increase. This value increases from 2.56 to 42.83 inside the range under investigation for tangential blowing whereas 45° blowing jet loses its efficiency completely. Furthermore, when the blowing jet velocity rises, aerodynamic performance continuously increases. The response surface model indicates that blowing variables interactively influence the aerodynamic performance.

In this paper, the numerical simulation of suction and blowing on airfoil NACA0012 are performed. In the past, the effect of suction and blowing jets on the airfoil has been explored separately. The result of this study showed that the occurrence of suction at a distance of 10% in length of the chord from the entrance edge would be increased the lift factor. The result of this study showed that occurrence of suction at a distance 10% of its length and length in the distance 10% of the chord from entrance edge causes to maximum increasing to lift coefficient. In this study the suction and blowing zone lengths were same and 2.5% longer in length as well as the suction and blowing range of 0.3 , 0.2 , 0.1 , 0.5 and were examined. The flow of an incompressible airfoil, the Reynolds number of 500000 and also desired fluid is air. SST turbulence model has been used for this numerical study and for flow near wall a scalable wall function has been used. Due to the suction and blowing simulation results in the areas mentioned it increases lift factor by 1.2 in the suction range 0.5. Also the angle of attack on which stall occurs is significantly increased and reaches a range of 0.5 to 26 degrees.

This paper deals with water flow in a backward-facing step with blowing of different nanofluids. The objective is to evaluate the effect of nanofluid blowing on the heat transfer rate. For this purpose, the Eulerian-Eulerian two-phase model is employed. The accuracy of the current simulations is demonstrated by comparing the obtained results with those of open literature. The results show that increasing the nanofluid blowing as well as nanoparticles fraction therein improve heat exchange from different surfaces of the channel. Comparing the results of different nanofluids leads one to conclude that the bottom wall heat transfer attains its maximum value when the blowed nanofluid contains nanoparticles with the highest thermal conductivity. However, it is found that maximum heat transfer in the top wall is achieved during blowing of a nanofluid with the highest nanoparticle penetration into the channel flow. Moreover, it is observed that discrepancies appearing between the results of different nanofluids become more remarkable as one increases the nanofluid blowing or nanoparticles fraction therein. Finally, the Eulerian-Eulerian model demonstrates that among the interphase forces, the effects of virtual mass and particle-particle interaction forces are negligible in such a way that they can be ignored.

Numerical analysis and simulation of cavitating flows due to appearance and its application in the maritime industry، water turbomachinery، hydrofoils، underwater vehicles، etc. have specific importance. For this reason in this research، the effect of blowing on hydrodynamic behavior of cavitating flows over hydrofoils has been investigated. Jameson''s finite volume method and power-law preconditioning method with single-phase cavitation model (Barotropic model) have been used to the analyzing of cavitating flow. The stabilization of solution has been achieved with help of the second and fourth-order dissipation term. Explicit four step Runge-Kutta method has been used to achieve the steady state condition. As regards the cavitation often occurs at high Reynolds number، to facilitate the simulation the inviscid flow equations are considered. For apply the blowing from hydrofoil surface، a jet has been placed on hydrofoil’s upper surface. The parameters of jet location، blowing velocity ratio، blowing angle and width of jet are investigated and simulation has been performed for two different cavitation numbers. The numerical results show that the power-law precondition increases the convergence speed significantly. Blowing reduces the cavity length، lift and pressure drag coefficients compared to no blowing case. Also the increase of blowing velocity ratio، blowing angle and width of jet، decrease the cavity length، lift and pressure drag coefficients.

Effect of boundary layer and its local separation on lift and drag coefficients، especially in the analysis of hydrodynamic behavior of hydrofoils is considered as an interesting subject for fluid mechanics researchers. Boundary layer control methods to increase the lift coefficient and reduce the drag coefficient، are very common. Aerodynamic study of flows at low Reynolds to special applications such as micro unmanned underwater vehicles، underwater robots and explorers are interested. For this reason in this study، the effect of fluid blowing and suction through upper surface of hydrofoils on flow control، lift and drag coefficients for flow under Re =500 and Re=2000 are investigated. Jameson’s finite volume method and power-law preconditioning method for analyzing viscous incompressible flows are presented. To control the boundary layer a jet with a width of 2. 5% of chord length is placed on hydrofoil’s upper surface and results for different blowing (suction) parameters are introduced. Results show that، blowing far from leading edge at low blowing angel and perpendicular suction far from leading edge increase the lift coefficient. Also blowing with law velocity ratio and suction with large velocity ratio، has the better impact on increasing lift coefficient.

In this paper, optimal control of vortex shedding behind square cylinder in laminar flow regime (Re=200) has been investigated. When Navier-Stokes equations are used as state equations, the discretization of the optimality system leads to large scale discretized optimization problems that represent a tremendous computational task. In order to reduce the number of state variables during the optimization process, a Reduced-Order Model (ROM) based on POD modes is derived to be used as state equations. Then, these equations are modified by introducing a Control Function to ROM in order to gain equations which are suitable for optimal control. Optimal trajectory for control input has been found by employment of Quasi-linearization which is one of the numerical methods for solving optimal control equations. The flow is actuated via suction and blowing slots. The results have been investigated in Results Section.Keywords: Optimal Control- Vortex Shedding- Suction and blowing- Reduced Order Model- POD modes- Quasi-linearization method.