Dynamic Estimating measurement of Instantaneous Flow Rate Using Automatically Generated Fluid Line Model.

本研究的目的是通过基于模型的速度分布估计，将管道瞬时流量测量方法的应用范围扩展到更一般的情况，即流体流线的分析模型未知或难以知道的情况，建立一种自动生成流线模型的方法，并与束流扫描LDV的方法有效地结合起来，从而实现高精度的瞬时流量计。提出了两种流体管路模型的自动生成方法，它们在包含一组未知参数的线性化动态模型的推导过程中各有特点。利用扩展卡尔曼滤波技术，从流体线横截面上代表性点处的流速数据中同时估计出速度剖面和模型参数值，并对所需点数和最优布置以及模型对流动边界条件的适应性等问题进行了研究。改进了束流扫描激光测速系统和流量信号产生系统。开发了一套非定常层流管道/管道流动有限差分数值模拟软件。将文献[2]中提出的方法应用于圆形管内整个入口区的非定常层流流动的测量，并与文献[3]和[4]中的实验结果进行了比较，验证了该方法的有效性。将该方法推广到矩形管道流动，并进行了实验验证。下一步是将该方法应用于湍流或层流-湍流流动。

The aim of this study is to extend the application area of the measuring method of instantaneous flow rate in a pipe through model-based estimation of velocity profiles to more general cases, where the analytical model of fluid lines is unknown or hard to know, by establishing a method to generate the fluid line model automatically in effective combination with approaches by beam scanning LDV, which leads to realization of a precision instantaneous flowmeter.The summary of the results is as follows:1. Finite element method to derive lumped-parameter models of fluid lines was introduced.2. Two kinds of automatic generation method of fluid line models, each has features in derivation process of a linearized dynamical model including a set of unknown parameters, has been proposed. Simultaneous estimation of velocity profiles and value of the model parameters are executed using extended Kalman filering technique from flow velocity data at representative points in the cross-sectional area of the fluid line.Some problems, such as necessary number and optimum arrangement of the points and fitness of the model to flow boundary conditions, are also examined.3. Beam scanning LDV and flow signal generating system have been improved.4. A flow simulator, as numerical experiments, for the unsteady laminar pipe/duct flow by finite difference method has been developed.5. By applying the proposed method of item 2 to the measurement of unsteady laminar flow over the whole entrance region in a circular pipe, and comparing the estimated velocity profiles with the experimental results from items 3 and 4, the methods are proved to be effective.6. Extension of the method to rectangular duct flows was made and confirmed experimentally.7. Next step is to apply the method to turbulent or laminar-turbulent flows.