非线性最小二乘法在多声道超声波流量计测量非理想流动中的应用

摘要

针对多声道超声波流量计在流量计算过程中应用的数值积分方法只适用于理想的充分发展流动的问题,提出在测量非理想流动时应用非线性二乘法计算最小的流速误差的平方和,流速误差平方和最小时计算得到的权重系数即为多声道超声波流量计在测量非理想流动时的最优权重系数,提高了流量计在测量非理想流动时的精度.应用计算流体力学仿真软件FLUENT对单弯管和异面双弯管下游5D和10D处的流速测量进行仿真验证,应用优化后的权重系数进行流速计算可以使测量误差减小到±0.5%以内.%In view of the application of the numerical integration method in the calculation of the flow rate of multi -path ul-trasonic flowmeter,it can only be applied to the problem of ideal fully developed flow,the nonlinear least square method for calcu-lating the sum of the least squares of the velocity error in the measurement of non-ideal flow was proposed.The weights coefficient calculated by the sum of the least squares of the velocity error were the optimal weights coefficient of the multi -path ultrasonic flowmeter in the measurement of non-ideal flow,the measurement precision of flowmeter in the measurement of non-ideal flow was improved.The simulation of flow velocity measurement of 5D and 10D at the downstream of single bend and double curved pipe were carried out by using computational fluid dynamics simulation software FLUENT,the application of the optimized weights co-efficient can reduce the measurement error to within ±0.5%.