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Trial for the Development of a Non-Contact Type Density Meter by the Inversion Method for the Continuous Spatial Measurement of Internal Waves and Stratified Flow Fields

反演法非接触式密度计连续空间测量内波和分层流场的尝试

基本信息

批准号：
01850119
负责人：
HINO M.
金额：
$ 6.53万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B).
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

项目摘要

Generally, the density change of a liquid is measured using the change of electrical conductivity. The conventional density meter has the deficits that the probe itself disturbs the flow field and it can measure only the density change at the point.The ray path of a laser beam is deflected when it is shed into a stratified fluid due to the change of the deflection ratio of light by the density difference of liquid. In many cases, this is unfavorable property for the flow measurement. This research aims at the development of a new type density meter using this property.A functional form such as the polynominals, the Fourier series and other orthogonal functions which contain a few arbitrary parameters is assumed to express the density filed. The path of laser beams are calculated by solving the differential equitation of ray deflection. The true values of parameters are inversly estimated by the Marquardt method so as to minimize the squared errors between the calculated and measured points of laser ray emmission.The position of laser ray emmission is measured precisely and quickly by PSD (Position Sensing Device). The direction of laser beam is changed by the combination of a rotating mirror and reflection mirrors, in order to increase the amount of information, i. e. The number of laser rays.The density changes of stratified flow are correctly estimated for (a) one dimensional vertical density filed, (b) the internal waves of two-layered flow and (c) complicated density field around a isolated mountain model.

通常，液体的密度变化是利用电导率的变化来测量的。传统的密度计存在探头本身对流场有干扰，只能测量点处密度变化的缺点，当激光束射入分层流体时，由于流体密度差改变光的偏转比，使光路发生偏转。在许多情况下，这对于流量测量是不利的。利用该特性研制了一种新型的密度计，采用多项式、傅里叶级数等含有少量任意参数的正交函数来表示密度场。通过求解光线偏转微分方程，计算出激光束的路径。采用马夸特法反演参数的真值，使激光发射点的计算值与测量值的平方误差最小，并利用PSD（Position Sensing Device）对激光发射点的位置进行快速、精确的测量。通过旋转镜和反射镜的组合改变激光束的方向，以增加信息量。e.本文对（a）一维垂直密度场，（B）两层流内波和（c）孤立山脉模型周围的复杂密度场，正确地估计了分层流的密度变化。