基于CFD技术的远射程消防水炮性能优化

发布时间：2018-03-15 20:59

本文选题：消防水炮　切入点：数值模拟　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：为提高远射程消防水炮的射程,本文对水炮的内流场、外流场及后坐力这三部分进行分析。对内部结构进行优化,尤其是对整流器、弯管及喷嘴结构的优化,以减小内部流动损失,改善内流场流动状态,提高射流的集束性,使水炮达到最远射程。本文主要研究内容如下:(1)通过对原水炮模型进行仿真模拟,发现水炮喷嘴来流紊乱,有切向和轴向速度分量,造成喷嘴射流水柱过早破碎,需要对水炮关键结构进行整流及优化。首先对喷嘴收缩角及具有微整流作用的喷嘴出口圆柱段,进行结构设计及流场分析,确定出喷嘴最佳收缩角及喷嘴出口圆柱段长度。(2)结合正交试验与流场数值计算的方法,对U型管的直管进行研究,结合水炮工作的平衡性及结构的紧凑性,确定直管的最佳长度。为了确定弯管导流片的安放位置及数量,对180°弯管做了详细分析,确定弯管造成的速度偏移,并找出偏移量与水炮仰角的关系,最终得到获得良好弯管流动的最佳导流片安放位置为弯管内壁面附近。(3)为获得较好的喷嘴来流,在直管段内安放整流器。本文重点研究了整流器截面形状、整流器进出口处理方式、整流器长度对内流场的影响,以压力损失、出口速度分布、出口湍动能及出口轴线速度为考核标准。得到整流器分割流道数量越多,整流效果越好,越有利于提高射程。考虑到普通整流器的肋片为直板结构,会产生较大的冲击损失,因此本文设计了含有螺旋形肋片的双层圆管整流器及正六边形流道的螺旋蜂窝整流器。从流线图、压力损失及与普通整流器的对比得出,当安放角等于液流角时,整流器损失及水炮进出口压力损失最小,能量损失少。与普通整流器相比,螺旋蜂窝整流器在螺旋流道的引流下,部分切向和径向速度能转化为轴向速度,获得较大的出口平均速度。同时采用实验和模拟相结合的方法研究了三种不同螺距变化方式对整流器性能的影响。安装螺旋形整流器后,整流器损失及水炮总压损失比普通整流器的小,整流效果较好,整流器压损少,可有效提高射程,为整流器的设计提供技术参考。(4)最后又对水炮外流场进行分析,通过算例验证了模拟方法的可靠性。从内流场的分析,得到最佳水炮结构。并分析了仰角及喷嘴出口速度分布对射流的影响,得出对射流有利的喷嘴出口速度分布规律。在此基础上,对水炮的后坐力做了流固耦合分析,证明本文设计的水炮结构满足实际工作的受力要求。
[Abstract]:In order to improve the range of the long range fire water gun, this paper analyzes the internal flow field, the outflow field and the recoil force of the water gun, and optimizes the internal structure, especially the structure of rectifier, elbow and nozzle. In order to reduce the internal flow loss, improve the flow state of the internal flow field, improve the concentration of the jet, and make the water gun reach the farthest range. The main research contents of this paper are as follows: 1) through the simulation of the original water gun model, it is found that the nozzle flow of the water gun is disordered. Due to the tangential and axial velocity components, the nozzle jet water column is broken prematurely, so the key structure of the water gun needs to be rectified and optimized. Firstly, the nozzle shrinkage angle and the nozzle outlet cylinder with micro-rectifying action are studied. Through structural design and flow field analysis, the optimum shrinkage angle of the nozzle and the length of the cylinder section at the nozzle outlet are determined. Combining with the orthogonal test and the numerical calculation method of the flow field, the straight tube of the U-shaped tube is studied. Combined with the balance and compact structure of the water gun, the optimum length of the straight pipe is determined. In order to determine the position and quantity of the deflector, the 180 掳bend is analyzed in detail, and the velocity offset caused by the bend is determined. The relationship between offset and elevation angle of water gun is found out. Finally, the best position of the guide piece for obtaining good flow of bends is near the inner surface of the bend pipe. In this paper, the effect of rectifier section shape, rectifier inlet and outlet treatment mode and rectifier length on the internal flow field is studied. The higher the number of separated channels, the better the rectifier effect is and the better the range is. Considering that the ribbed plate of the ordinary rectifier is a straight plate structure, the larger the impact loss will be. Therefore, a double-layer circular tube rectifier with helical ribs and a helical honeycomb rectifier with hexagonal flow channel are designed in this paper. From the streamline diagram, pressure loss and comparison with the ordinary rectifier, it is concluded that when the angle of placement is equal to the liquid flow angle, The loss of rectifier and the pressure loss of water gun inlet and outlet are minimum and the energy loss is less. Compared with the conventional rectifier, the partial tangential and radial velocity of the spiral honeycomb rectifier can be converted to axial velocity under the drainage of the spiral channel. At the same time, the effects of three different pitch variations on the performance of the rectifier are studied by the combination of experiment and simulation. The rectifier loss and the total pressure loss of water gun are smaller than those of the ordinary rectifier, the rectifier has better rectifying effect and the voltage loss of the rectifier is less, which can effectively improve the range, and provide a technical reference for the design of the rectifier. Finally, the flow field of the water gun is analyzed. An example is given to verify the reliability of the simulation method. From the analysis of the internal flow field, the optimum structure of the water gun is obtained, and the influence of elevation angle and velocity distribution of the nozzle outlet on the jet flow is analyzed. On the basis of this, the fluid-solid coupling analysis of the recoil force of the water gun is made, which proves that the structure of the water gun designed in this paper can meet the requirements of the actual work.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU998.1

【参考文献】