基于热源权重参数反演优化的新权重多点源热辐射模型

A novel weighted multi-point source thermal radiation model based on inversion optimization of heat source weight parameters

为了解决原权重多点源模型中热源权重分配过于简化的问题,开展了一系列火焰热释放速率达3.5 MW、火焰弗劳德数达4.46的中度尺寸天然气喷射火实验,获得了各种工况下喷射火的长度特征参数及近场热辐射实验数据,进而采用基于鸡群优化算法(CSO)的热源权重参数反演优化研究思路,探究了热源权重参数与出口工况参数之间的影响规律。研究结果表明:①随着出口火焰弗劳德数的增大,热源权重峰值出现的轴向相对位置逐渐下降,峰值两侧的热源权重分配逐渐变得均衡;②热源权重沿火焰轴向相对位置呈现双指数函数分布特征,并且该双指数函数中常系数与各种工况下的火焰弗劳德数之间呈现出较好的线性变化关系;③根据优化结果,提出基于火焰弗劳德数的热源权重分布关系式,建立了基于该分布关系式的新权重多点源模型(以下简称新模型)。结论认为,较之于原权重多点源模型,新模型在预测喷射火近场热辐射准确度方面有着明显的提高,预测结果平均相对偏差的平均值由原模型的12.87%降至7.68%,最大相对偏差的平均值由原模型的19.83%降至14.69%。

In order to solve the problem of over-simplified weight distribution of heat source in the original weighted multi-point source thermal radiation model(WMPM),a series of medium-scale natural gas jet fire experiments were conducted,in which heat release of 3.5 MW and the flame Froude number of 4.46 were both considered.Based on the experimental data about the length characteristic parameters and near field thermal radiation of jet fire,the Chicken Swarm Optimization(CSO)algorithm was utilized to invert and optimize the weight distribution parameters of heat sources in the WMPM and explore the influence of test conditions on weight parameters.The optimization results showed that with an increase in flame Froude number,the axial position for peak weight of heat source decreases gradually and the weight distribution of heat source at the both sides of the peak weight becomes balanced gradually.In addition,it was found that the weight distribution of heat source along the relative axial position of the flame can be characterized properly by a double exponential function.The constant coefficients in the double exponential function vary linearly with flame Froude number.Furthermore,a correlation describing weight distribution of heat source associating with flame Froude number was proposed.On this basis,a novel WMPM was thus developed.Compared to the original WMPM,the novel WMPM can significantly improve the prediction accuracy of thermal radiation in the near field of jet fire.In this test,the relative average deviation of prediction results was found to be reduced to 7.68%from the previous 12.87%,while the maximum relative deviation was down to 14.69%from the previous 19.83%.