隧道通风阻力格栅局部阻力试验

由于试验场地和试验条件的限制，通常难以建立1：1比例模型或同比例尺缩小模型，因此在保证原形与模型阻力相似的前提下，根据等效设计理论，在隧道通风模型中安装阻力格栅可以有效缩短隧道模型的长度。为了解决阻力格栅在通风模型中的选取和设置问题，建立物理模型进行试验测试，并将试验结果进行了分析对比，研究了不同的阻力格栅串联间距、串联数量以及格栅类型的变化对通风试验局部阻力的影响。模型试验结果表明：加入阻力格栅后通风模型仍存在自模区，且阻力格栅的串联间距、组数、规格对模型进入自模区的临界风速几乎没有影响；当格栅间距大于3倍断面当量直径时，格栅之间的相互影响可以忽略不计，故阻力格栅串联间距应不小于3倍模型当量直径；每组格栅局部阻力损失系数随格栅组数的增多而降低，降低的速率随着格栅组数的增多而减小；在选择阻力格栅时，格栅局部阻力系数要求较大时，可选择多孔板作为阻力格栅，并优先考虑方孔多孔板；当格栅局部阻力系数要求较小时，可选择铁丝网作为阻力格栅。研究成果可以为模型试验阻力格栅的选取和设置提供指导建议，同时介绍了阻力格栅在隧道通风模型试验中的具体应用。

Experiment on Local Resistant of Grid in Tunnel Ventilation Model Test

Due to the limitation of the test site and test conditions, it is usually to build a 1:1 scale model or a reduced model at the same scale. Therefore, on the premise that the prototype is similar to the model resistance, according to the equivalent design theory, the installation of resistance grid in the tunnel ventilation model can effectively shorten the length of the tunnel model. In order to solve the problem of selecting and setting the resistance grid in the ventilation model, the physical model is established for experimental test, and the experimental results are analyzed and compared. Among them, the influence of different resistance grid series spacing, series number and grid type on the local resistance of ventilation test is studied. The results show that adding resistance rack in the model, the automatic zone still exists, its critical speed of the wind is almost equal to the wind speed of the model; when the grid spacing is greater than three times of the model section, the interaction between the grid can be neglected, so the gap of the resistance rack should be longer than triple equivalent diameter of the section of the model; every rack of the part of the resistance loss factor is getting lower with the rising of the rack number, the lowing speed is getting smaller with the rising of the rack number. When selecting resistance grid, when the local resistance coefficient of grid is required to be large, porous plate can be selected as resistance grid, and square porous plate is preferred; when the local resistance coefficient of grid is required to be small, wire mesh can be selected. The research results provided guidance for the selection and setting of resistance grid in model test, and introduced the specific application of resistance grid in tunnel ventilation model test.