Research On Wind Pressure Control Method For The Surface Of A Low-rise Building Based On Plasma Actuation

Strong wind or typhoon are one of the major natural disasters faced by human beings.They have brought enormous property losses and casualties to mankind.Most of the buildings in China are low-rise buildings.Such buildings are often damaged or destroyed under the influence of strong wind or typhoon.Statistical investigation of wind disaster shows that the destruction of such buildings usually results from damage to the roof,such as roof windward edges,roof corners and roof ridges.The roof in strong wind is subject to huge wind pressure.When it exceeds the carrying capacity of the building roof,the roof can be overturned to induce the damage of the gable and even the collapse of the whole house.Therefore,it is necessary to adopt effective flow-control methods to reduce the wind pressure on building roofs.In order to improve the wind-resistance performance of the building roofs,the plasma flow-control method derived from aerospace and mechanical engineering is introduced by the present paper into structural wind engineering.The flow control methods adopted by structural wind engineering in the past all have some problems,such as complex control system,limited control effects and structural shape changes and so on.The plasma flow-control method does not have these disadvantages,and it has been widely concerned in other fields due to the advantages of no moving parts,small size,light weight and fast response time.At present,the application research of this method in the field of the building wind resistance is still in a blank.The plasma flow-control method herein is based on the multiple Surface Dielectric Barrier Discharge(SDBD)plasma actuators.The method is to install the electrodes of the plasma actuators on the upper and lower surfaces of the building roof.Under the action of the body force caused by the plasma actuation,the near-roof flow generates directional movement to induce wall jet.The wall jet can control flow field and wind pressure on the roof.Through wind tunnel pressure tests and numerical simulations,this paper systematically studies the control effect of the plasma actuators with different arrangement types on wind pressure on the roof of the low-rise building.The following research results are obtained:(1)The wind tunnel pressure measurement method for the low-rise building of plasma flow control is established by exploring the realization method of the plasma actuator and mastering the optimal material and manufacturing process of the plasmaactuator.The wind tunnel pressure test shows that,the multiple SDBD plasma actuators with different arrangement types can significantly reduce the absolute value of the mean,peak positive and peak negative wind pressure coefficients in different regions of the roof centerline.In all arrangement types,the arrangement type with the wall-jet direction blowing from the trailing edge to the leading edge has the best control effect on these wind pressure coefficients.(2)The large eddy simulation method for the flow field around the low-rise building under the action of plasma flow control is proposed by the present paper.The change rates of mean and peak negative wind pressure coefficients along the roof centerline are obtained after the plasma actuators are ignited,and these change rates are compared with experiment results to verify the rationality of the present simulation method.By studying the change regulation of the flow field around the roof without and with the plasma actuation,the influence characteristics and regulations of the plasma actuators on the flow field structure and flow state on the roof are revealed.(3)The influence regulation of the plasma actuators on the wind pressure and flow field on the building roof is studied.Then,the variation of many physical quantities is specifically analyzed before and after the plasma actuators are ignited.These physical quantities include the vertical mean and fluctuating wind pressure distributions of the low-rise building,the fluctuating power spectrum of the wind pressure,and the velocity and vorticity fields of the wind around the low-rise building.Finally,the control mechanism of plasma actuation on wind pressure on the roof is revealed.(4)Based on the large eddy simulation method for the flow field around the low-rise building under the action of plasma flow control,the change regulations and characteristics of the mean and fluctuating wind pressure coefficients on the whole roof are analyzed with the main influence factors(i.e.the actuation frequency,actuation voltage and arrangement type of the plasma actuators,and the wind direction of the incoming flow).The empirical formulas for the changes of the mean and fluctuating wind pressure coefficients with each main influence factor are fitted.These results can provide the basis for the application of the plasma flow-control method to the low-rise building.