Experimental Study Of LDA On The Wind Velocity Distribution In Rectangular Cross Section

Wind speed distribution is the basis that calculate the combination of underground roadway gas,fire in the gas,dust transport rules,temperature and moisture distribution,heat and mass transfer process,of rectangular tunnel sectional velocity distribution for the study of ladder,semicircle arch tunnel complex airflow state has guiding significance,also has the very important significance to wind speed sensor arrangement.Using the fluid non contact type measuring technique of laser Doppler anemometry(LDA)of rectangular roadway section airflow state distribution of wind speed rules and turbulence characteristics experiments were conducted to study,analysis of rectangular roadway section of single point velocity,the perpendicular bisector of the wind speed and the sectional velocity distribution in this paper.The results of experiments show that,measuring points' instantaneous velocity under the condition of stable flow in rectangular tunnel have irregular nature.However,it has statistical average results for rules,obey normal distribution.Roadway along the perpendicular bisector of the instantaneous velocity value although with turbulent pulsation,but after averaging process,distribution curve was relatively smooth,indicating that perpendicular velocity distribution obeys the exponential function relationship.The contour map of the whole section is approximate to the closed rectangular ring,and the center area is large,and the center to the edge wall is gradually reduced.The average wind speed in different wind speed is close to the wall of the tunnel,the average wind speed is greater,and its position is close to the wall.The average wind speed can be obtained by using the inverse calculation of the average wind speed in any rectangular tunnel.The results show that the laser Doppler velocity measurement technique can avoid the disturbance of the airflow state and can be used to test the turbulence characteristics of the tunnel,and can better reflect the flow characteristics of the air flow in the experimental tunnel.LDA testing technology can be used as an important means to further understand and study a series of complex flow of mine ventilation,so as to provide basic parameters for determining the average wind speed in the underground.