Aerodynamic Drag Reduction Of Zero Degree Ahmed Car Model Based On AI Control

With the development of economy,the number of vehicles in China has increased rapidly in recent years,which is the first in the world.With the rapid development of the automotive industry,the problems of energy loss and pollution caused by vehicles are becoming more and more serious.Reducing drag of vehicles is an effective solution.A lot of researches are based on the Ahmed model now.One method for drag reduction of Ahmed model is to use flow control technology to change the wake structure of the model.The control methods include passive control and active control.The purpose of this paper is to reduce the drag of the zero-degree Ahmed model.Four actuators are designed on the back edge of the car model.We use an active control technology based on artificial intelligence to carry out experimental research in the low-speed wind tunnel environment.For the experimental content and research purposes,the Ahmed model open-loop control experiment is designed.The experiment includes pulse blowing control and steady blowing control.When the Reynolds number is 1.67×105,we use different blowing angles,frequency and the shape of outlet to find the optimal control combination.A similar experiment is conducted under steady blow control.It was finally determined that the optimum blowing angle was 45 degrees inward,and the optimum blowing outlet shape was a circular hole array.The max drag reduction in open-loop experiment is 3.6%.Based on the results of the single actuator open-loop control experiment,the artificial intelligence control experiment of the Ahmed model multi-actuator is designed.The blowing method includes pulse blowing and steady blowing.The experiment uses linear genetic programming as the basis of the algorithm,and performs several generations data measurement and calculation.Finally,the optimal control combination is found in both the pulse jet and the steady jet.Under the pulse jet control,the pressure of model is increased by 10.5% and the drag reduction rate is 8.8%.Under the steady jet control,the pressure of model is increased by 11.5% and the drag reduction rate is 9.5%.An AI control experiment of the Ahmed model multi-actuator with the combined algorithm is designed.Based on the combined algorithm of Latin hypercube sampling and simplex method,the blowing control experiment combining pulse blowing and steady blowing gas is carried out.The drag reduction effect is further improved,with a back pressure increase of 16.0% and a drag reduction rate of 12.9%.