Drag Reduction Of A Turbulent Boundary Layer Based On Plasma-induced Blowing And Suction

Frictional drag is always related to our daily lives.For example,aircraft,railway trains,ships and other vehicles that we often see in our lives,a considerable part of the energy consumed in their operation is used to overcome the frictional drag,how to implement drag reduction control in the turbulent boundary layer to reduce energy loss is becoming a frontier issue in the field of fluid mechanics.In this paper,by using the physical properties of dielectric barrier discharge(DBD)plasma actuator,the control schemes of different gap layouts under the two configurations of blowing-suction and suction-blowing are studied to find the drag the best parameters and explore the relevant mechanisms.This experiment was carried out in a wind tunnel with Re_?=1450.The force balance measurement and the constant temperature anemometer(CTA)are used to measure the length of the control area and the amount of drag reduction of the control scheme under different layouts.This paper proposes an improved scheme for the discharge damage that may occur in the process of measuring the plasma flow by the hot wire,which is used to measure the structure generated by the plasma jet and the average flow velocity curve of the relevant region.Finally,using the smoke line and particle flow display technology,the in-plane control mechanism of x-y is explored.The experimental results show that the suction-blowing scheme has the best control effect when the distance between the two slits is d=75 mm,and the corresponding blowing intensity coefficient is 0.0379(E=12 kVp-p,f=2 kHz).When the blowing and suction ratio is 2.48,the best local drag reduction at the measurement point at x~+=67 is 66%,the corresponding average drag reduction is 25%,and the drag is recovered at x~+=1400;The blowing-suction scheme has the best control effect when the distance between the two slots is d=22.5mm,Under the same control parameters,the best local drag reduction at the measurement point at x~+=67 is 57%,the corresponding average drag reduction is 23%,and the drag is recovered at x~+=1200.In addition,the error of the improved CTA for measuring the velocity in the linear region near the wall is less than 5%.The smoke-wire visualization shows that the blowing-suction scheme creates a "bridge" structure between the two slots that helps retard the vortex structure landing on the wall;finally,suction-blowing stabilizes the flow field structure behind and reduces the instability,thereby enhancing the drag reduction effect of the blowing effect.Therefore,the scheme can obtain a larger partial drag reduction and a longer resistance recovery zone than blowing-suction.