Influence Of Bionic Non-smooth Structure On Drag Of Water Pump Blade

Water pumps are used in various fields of industrial and agricultural production.As indispensable energy supply equipment,the demand for different pump products in various industries is high.At the same time,the proportion of resources consumed in pump equipment has also increased year by year.Most of the energy consumed by the pump is consumed by the frictional resistance of the pump impeller.Therefore,how to reduce the friction resistance of the pump impeller,improve the pump energy utilization rate,reduce energy consumption and save resources are of great significance to China's energy saving and emission reductionNon-smooth surface drag reduction is a passively controlled drag reduction method,which is an efficient and energy-saving drag reduction method,without additional energy input during the operation of the equipment.Relying on its own non-smooth surface can achieve the purpose of drag reduction.In this paper,from the perspective of bionics,the method of computational fluid dynamics(CFD)is used to select the basic airfoil designed by pump machinery-NACA0012 airfoil to numerically study the drag reduction mechanism of non-smooth surfacesFirstly,the accuracy of CFD calculation is explored by a flat plate experiment,and the turbulence model is selected.Under various Reynolds numbers,the best drag reduction non-smooth structure is chosen from V-shaped,square-shaped and convex hull-shaped non-smooth structures.Simulations show that the V-shaped non-smooth structure has strong adaptability to the change of Reynolds number.It has an inhibitory effect on turbulence at the wall surface and shows excellent drag reduction ability.The V-shaped non-smooth structure is selected for the drag reduction of NACA0012 airfoil non-smooth surfaceAccording to the geometric characteristics of the NACA0012 airfoil,Non-smooth structure area is divided into front,middle and back parts.Set the height of the V-shaped structure as h,the size of the opening as s,and define the six types of roughness as s=h=1/100L,s=h=1/200L,s=h=1/500L,s=h=1/1000L,s=h=1/1500L,s=h=1/2000L.The calculation results show that the V-shaped structure with roughness of s=h=1/1500 L which was arranged in the rear section of the airfoil,when the Reynolds number is low,can increase the thickness of the viscous bottom layer,It can reduce the wall turbulent kinetic energy,and effectively suppress the turbulent burst.And its drag reduction effect is the best the maximum drag reduction is 7.4%The interval size d is introduced to construct a ridge structure similar to the geometry of the shark's epidermis.Define d=0,d=0.5s,d=s,d=1.5s,d=2s,d=2.5s,d=3s.Through numerical calculation,it is found that the ridge structures at different positions show different drag reduction effects under different Reynolds numbers,and the combination of roughness and interval size also shows a nonlinear relationship.The drag reduction mechanism is explained from the perspective of the secondary eddy current,and it is found that the ridge structure is more suitable for high Reynolds number environment.The phenomenon of increasing the optimal interval size at higher Reynolds number is more beneficial to the structure of the ridge structure.And it also can effectively reduce the processing cost of non-smooth water pump blades.