Study On New Method Of Measuring Wind-driven Sand Load And Wind Flow Field Of Structures

The wind resistance and wind-driven sand resistance of building structures have always been the focus of attention,and to carry out these researches need methods and equipment first.Only when the effects of wind and wind-driven sand on building structures are more accurately obtained,can the research on wind and sand resistance of structures be further carried out.This research includes two aspects: the measurement method of the effect of wind and sand and the measurement meth od of the building wind field.1.Research on the measurement method of wind-sand effectThe essence of a sandstorm is a gas-solid two-phase flow that wind-driven sand,and its forces on structures include wind and sand impacts.However,due to the limitation of measurement methods,it is difficult to accurately obtain the im pact effect of sand,so the wind load is generally only considered on the structure design.In this research,the measurement method of the sand impact force on structure is studied,and the main work is as follows:(1)Due to the small particle size of sand and the short impact time on the object,it is difficult to obtain the sand impact force directly by general methods,so there are few related research results.The piezoelectric ceramic sensor is used as force sensor to measure the impact force of sand particles in the wind-driven sand flow field,and the systematic research is carried out.(2)The corresponding relationship between the imp act force of sand particles and the output voltage of the piezoelectric ceramic sensor was calibrated.It was proposed that the average impact force per unit time was used to measure the impact effect of sand on structure,and the unit was derived using the Dirac delta function.The time average impact force equation establishes the mathematical relationship between the sand impact force and the output voltage.(3)The wind-sand wind tunnel was used to simulate the wind-driven sand flow field,piezoelectric ceramic sensors were installed on the windward side of the low-rise building model,and the size and distribution of the impact force of sand particles on the windward side of the model were measured;under the same working conditions,use force-moment sensor measures the sand force on the windward side of a low-rise building model.(4)The sand impact force obtained by the piezoelectric ceramic and the forcemoment sensor test under the same test conditions is compared.The results show that the sand impact force of the two methods are in good a greement,which verifies the feasibility and accuracy of using piezoelectric ceramic sensor to measure the impact force of sand.(5)In the wind-sand tunnel test,the results of wind-driven sand flow field and impact force of four kinds of sand particle si zes,including coarse sand,medium sand,fine sand and mixed sand,were obtained,and the distribution characteristics and rules of impact force of different particle sizes on the windward side of the model were compared.2.Research on 3D digital wind field measurement method based on UAVThe current measurement methods for aerial wind fields have limitations.Using UAV equipped with related instruments to measure wind fields in the air is a valuable wind field measurement method.It has the characteris tics of low cost,flexible maneuverability,and full-area perception of the wind field.This research mainly completes the following research work:(1)A method of measuring the wind field using six-rotor UAV equipped with ultrasonic anemometer is proposed.Integrating with UAV,ultrasonic anemometers,and radio equipment for data receiving and sending,an UAV wind measurement system that can remotely transmit real-time wind field measured data has been established.(2)The wind tunnel test,the comparison test between the measured results of UAV and wind tower,and the comparison test between the measured results of two UAV are carried out to study the feasibility and accuracy of the UAV wind measurement.The test results show that the wind measurement resu lts of two UAVs are consistent.The measured results of UAV wind measurement system and wind tower are close to each other,and the parameters related to fluctuating wind characteristi cs are also close to each other.(3)The method of measuring the wind fi eld of a wind turbine by using two UAVs is proposed.Multiple wind speed profiles including the incoming flow and wake of the wind turbine,the plane wind field at the hub height of the wind turbine,and the downwind fluctuating wind speed power spectrum a re obtained,which provides a new idea and method for measuring the wind field of the wind turbine.(4)The wake flow field of a high-rise building is measured by using the wind measurement method of two UAVs,and the wind field data of incoming flow after the interference of high-rise buildings are obtained,which can provide reference for the subsequent research on the improvement of the wind environment around the building and the diffusion of pollution.(5)Based on the flow field results of the wake wind of high-rise buildings measured by UAV,a 3D digital wind field model based on Kriging method is proposed.Through the measured wind field results and the prediction of wind field results of unknown positions in the space,the method of establishing 3D digital wind field based on UAV wind measurement results is realized.