Study On Flow Field Characteristics Of Adjusting Window In Roadway Based On PIV Experiment

In mine ventilation,adjusting the window is one of the most important adjustment and optimization of ventilation system.Due to the local resistance of the wind window,the flow field of the air flow is complicated and disordered after the regulating window.So that the relevant parameters of mine ventilation test are not accurate,resulting in the optimization of ventilation system is not reasonable and the hidden danger of accidents is not found in time.The traditional contact point velocity measurement technique is limited by its own precision,which leads to inaccurate measurement and can't reflect the distribution characteristics of the transient flow field.However,the particle image velocimetry(PIV)is used to test the flow field and the results are compared and verified by numerical simulation and experiment mine.It can be used to reflect the instantaneous velocity distribution structure of the whole flow field in the wind tunnel.The characteristics of airflow distribution and the relationship between the parameters of adjusting the window are obtained,which provides guidance for the production site and the regulation of the window.PIV experiment and numerical simulation results show that the air flow field remains stable before the regulating window,and the flow field becomes very disordered after regulating window,which produce recirculation zone in the corner of regulation window.The length of the recirculation zone is independent of the inlet air velocity,and has a logarithmic relationship with the cross-sectional area ratio.The local resistance coefficient is not affected by the Reynolds number,and the influence of the sectional area ratio on the local resistance coefficient is larger.Moreover,the two relations are linearly decreasing,and the fitting function relation is obtained.On the basis of theoretical and experimental research,using the relationship between the length of recirculation zone and the coefficient of local resistance,the test results are verified.The results show that the length of the regulating window recirculation zone obtained from the test mine is basically consistent with the calculated values of the PIV experimental formula.Local resistance test and PIV test value of local resistance coefficient of the formula of local resistance is small relative error and verify the correctness of the local resistance coefficient formula,which can be used in the relation between the regulating window of local resistance determination of the production site.