Rate of flow measuring with cross correlation
For years the acoustical Doppler-effect has been used to measure the velocity and flow rates of water and waste water in pipes and open canals. The systeM defines the speed of scattering particles; this speed is equated with the water speed and converted into a volumetric flow rate. Since this method does not allow a spatial/physical correlation, the determination of the volumetric flow is usually not very accurate. Statistical corrections and calibration can increase the achievable accuracy still a higher accuracy can only be obtained in individual cases. Using the pulse Doppler method the accuracy can be increased because a local correlation of the scatter speed is possible. Because the typical measuring window size is more than 0,3M this method is preferably used with larger bodies of waters. Measuring devices, whilst taking the normal dimension of the sewage plant range into account, record the measured speed and deliver the desired accurate data of pipes and canals. More recently there have been measuring devices on the market which, with the help of cross correlation, allow measuring on an ultrasonic wave basis. With the appropriate conditions provided, e.g. sufficient and undisturbed inlet and outlet water flow, an accuracy of ± 2% of the measured value can be obtained. Even with slightly disturbed, irregular velocity profiles, a useful determination of flow can be achieved. However, if the inlet distances are to short or in the case that a back flow occurs and/or low water and current velocity coincide, the degree of disturbance of the velocity profile increases. In that case it is very difficult to make any statements regarding the accuracy.
M. Teufel H. G Hohnecker
Governmental Master Architect, Institute of river and lake protection, Stuttgart University of Applied sciences
国际会议
2009 Beijing International Environmental Technology Conference(2009北京国际环境技术会议暨第五届“中、德、波环境技术研讨会)
北京
英文
383-395
2009-10-16（万方平台首次上网日期，不代表论文的发表时间）