考虑俯仰角的消防水炮射流轨迹理论模型

Pitching Angle-based Theoretical Model for the Track Simulation of Water Jet out from Water Fire Monitors

消防水炮要实现智能化,需要根据火情的方位确定其俯仰角和回转角,其中俯仰角的确定十分关键,它有赖于对其射流轨迹的准确预测。现有研究中对常用消防水炮射流轨迹的模拟,其射程的相对误差甚至超过40%,致使消防水炮的控制经常需要人的参与。基于牛顿第二运动定律和空气阻力与速度平方成比例的关系,提出一种消防水炮射流轨迹模拟的新理论模型,模型中考虑空气阻力对不同俯仰角下水射流分速度的影响。计算时只需给定两个俯仰角下的射程数据通过牛顿法确定模型中的未知参数,采用求解初值问题的四阶Runge-Kutta法求解微分方程组。通过实际算例和试验证明,采用该模型模拟出的射流轨迹与实际的射流轨迹比较吻合,射程相对误差在4%以内,可为消防水炮的智能控制研发提供借鉴意义。

The key to intellectualize water fire monitors is to determine their revolving and pitching angle according to the position of fire.The latter angle is more important since it depends on the correct simulation of the monitors＇ jet tracks.The range relative error of the simulated water jet track in literature even reaches 40%,which means that the monitor must be controlled manually to let its water jet reach the fire efficiently.Based on the second law of Newton and the proportional relationship between the air drag and the power law of velocity,a new theoretical model to predict the jet tracks out from water fire monitors is proposed.In the model,the effect of air drag to velocity division is considered by pitching angle.During computation,two ranges corresponding to two pitching angles must be supplied to solve the two unknown parameters in the model by Newton iteration method.The conventional primary value problem solver,four-step Runge-Kutta method is applied to solve the differential equations.Examples and experiments show that the jet tracks calculated by this model agree well with the actual ones.And the relative error of range is below 4%.The model can be of great help for the intellectualization of water fire monitors.