超声波体积流量计声场混合计算方法

Hybrid determination method for acoustic field of ultrasonic volumetric flowmeter

超声波体积流量计测量空间内声场分布主要由换能器性能和实际工况下的流场共同决定.在进行相关声场研究时,为了解决仅使用数值法难以对实际换能器重要计算参数进行准确建模的问题,提出联合测量边界条件和数值法的混合计算方法对声场进行求解.计算模型的振动边界条件通过使用扫描式激光测振仪测量换能器表面离散点的振动速度并对其进行数据拟合来准确获取,实现以实验测量的数据对建模不确定性最大的换能器进行表征.由计算流体动力学对超声体积流量计在不同体积流量下的流场进行求解,并将获取的流场导入数值计算模型中作为背景流场.借助有限元软件COMSOL求解由非均匀流中线性声学式推导的控制式对声场进行预测.比较预测和实验结果,对混合计算方法进行验证.

Acoustic field distribution in the measuring space of ultrasonic volumetric flowmeter is mainly determined by the performance of the transducer and the flow field under actual conditions.A hybrid approach combining measured boundary conditions and numerical method was used to predict the acoustic field,in order to solve the problem that only using numerical method has the difficulty in accurately modeling important calculation parameters of actual transducer.The vibration boundary condition of calculation model is accurately obtained by using a laser scanning vibrometer to measure vibration velocity of discrete points on transducer surface and following a data fitting computation,which means that the transducer with the most modelling uncertainty is replaced by the experimental data.The flow fields inside the ultrasonic volumetric flowmeter under different volume flowrates were calculated by computational fluid dynamics,and then the simulation results were inserted into the numerical calculation model as the background field.The acoustic field can be predicted by solving the governing equation derived from linear wave acoustic equations in non-uniform flow with the help of the finite element software COMSOL.The proposed hybrid approach is validated by comparing the predicted and experimental data.