洪水作用下汽车的起动流速研究

Estimation of Incipient Velocity of Flooded Vehicles

针对洪水作用下汽车的起动条件开展了一系列的研究:首先分析部分淹没状态下汽车的受力情况,结合滑动平衡的临界起动条件建立相关方程,导出了洪水中汽车起动流速公式;然后在室内水槽中对三款模型车进行了一系列的起动试验。试验结果表明:对于同一款模型车,平行于水流方向放置时,起动流速与水深的相关性较好;并且水深越大,起动流速越小。接着运用试验资料率定了起动流速公式中的相关参数。最后采用模型相似率及率定后的计算公式估算了原型车辆在不同水深下的起动流速,两种方法所得的结果较为接近,故预测结果较为可靠。

A series of flume experiments were conducted to investigate incipient velocity of flooded vehicles. Firstly, all forces acting on a partially submerged vehicle are presented. Integrated with the critical motion conditions, a formula of incipient velocity of flooded vehicles is derived. Secondly, a series of flume experiments on incipient velocity of flooded vehicles were conducted using three types of scaled die-cast model vehicles. These flume tests show that for a certain vehicle, the correlation between the water depth and the corresponding incipient velocity is high when a model vehicle is put parallel to the incoming flow. A lower incipient velocity is required for a flooded vehicle to start sliding under a larger water depth. Then the experimental data obtained for the model vehicles are used to determine the two parameters in the derived formula. Finally, two different approaches are used to estimate the critical conditions for partially submerged vehicles in flood water, including the prediction by the model scale ratios and the computation by the derived formula. The obtained incipient velocities by the first method are of close agreement with the results from the second method, which guarantee the reliability of the estimation of incipient velocity for partially submerged prototype vehicles.