Theoretical And Experimental Study On The Leading-edge Tubercle Of Three-dimensional Airfoil

The stalling issue of the airfoil at the big angle of attack is the hot one that people hasstudied now. At present using additional equipment can control the airfoil separated flow andvortexes. But the additional equipments make the whole airfoil device be complex, and makethe manipulability reduce. The ordinary and uncontrollable additional device increases theresistance of the airfoil.The leading-edge tubercle of airfoil can control stalling and reduce theresistance by changing the geometry of the leading-edge of airfoil, and do not need additionaldevice. The characteristics of the structure are simple and easy to realize. The thesis mainlystudies to delay the stalling of airfoil and improve the performance of airfoil by the methodsof model test and numerical simulation.First, the method of the model test verifies that the leading-edge tubercles can improvethe performance of the airfoil and delay the effectiveness of the stalling. Choosing the sectionprofile of NACA0020makes the normal three-dimensional flat airfoil, based on this, todesign and make the leading-edge tubercle of three-dimensional airfoil. In the circulationchannel for open water test, according to the test datum, other conditions remain constant, theanalysis results verify the leading-edge tubercle can delay the stalling of the airfoil andimprove the lift and lift-drag ratio of airfoil. Especially at the big angle of attack, the effects ofthe drag reduction and energy saving are more obviously. It has laid the foundation on thefollow-up study.Second, to set up CFD numerical simulation prediction method, this can analyze theperformance of the leading-edge tubercle of airfoil. According to the characteristics of theleading-edge of airfoil, Detached Eddy Simulation is chosen as the turbulent model.Numerical simulation models are built by the size of the model test. The grid division meetsthe quality requirements of the Detached Eddy Simulation method. The normal andleading-edge tubercle of airfoil are simulated by using the software Fluent. By comparison theexperimental values with the numerical simulation results, the numerical simulation of thisthesis is correct.Finally, this thesis studies the variable parameters of the leading-edge tubercle, andanalyzes the effects of geometric parameters of leading-edge tubercle on the performances. According to the humpback whale fin, the normal and leading-edge tubercle of airfoils arebuilt. To change the parameters of the leading-edge tubercle, such as the wave heights、wavelength and distribution density. The effects of the geometric parameters on the performance ofthree-dimensional airfoils are analyzed, and the numerical results can get the correspondingcurve.The experimental values of the model test、CFD numerical simulation method andnumerical results in this thesis can lay the foundation on the stalling issue of airfoil at the bigangle of attack.