EXPERIMENTAL AND NUMERICAL INVESTIGATIONS ON FLOW MEASUREMENT USING CLAMP-ON TYPE ULTRASONIC FLOWMETER

Abstract

Any small hydropower (SHP) station, which has been installed and commissioned recently, should be tested to confirm that all its parts and systems are performing their assigned functions correctly and that the generating units are operating efficiently. The Ministry of New and Renewable Energy (MNRE), Government of India, with its concern to improve the quality and performance of SHP stations in the country, felt for long a need to create a system of performance evaluation by a neutral agency at low costs. In July 2003, the MNRE issued a notification linking its subsidy support for SHP projects to their performance. The Alternate Hydro Energy Centre (AHEC) of the Indian Institute of Technology Roorkee (IITR) was identified as the test agency for this purpose. At IITR, a multi-disciplinary team was formed to carry out performance testing of SHP stations in India and necessary portable test equipment procured by the support of MNRE. Among those equipments UTTF is one type of the portable instrument which is used to measure discharge in the closed pipe during the testing of SHP stations to evaluate the performance and for the correct readings it is generally installed in horizontal plane of a 7 pipe which is laid nearly horizontal. I { But most of the small hydro power plants have water conductor system i.e. penstocks exposed in inclined position and are susceptible to give more errors as per the conventions. A practical problem is to take discharge in the inclined closed pipes (penstock) by UTTF. In this case, UTTF may not give correct measurement due to this inclination. In view of above, an attempt has been made to predict the effects on UTTF reading due to pipe inclination and to investigate the suitable plane for installation of sensors for measurement of the flow through penstock (closed pipe). Since the maximum angle of penstock is around 500 in most of the small hydro power plants, the pipe angle in the present work has been varied in the range of 00 - 450. An extensive experimental study has •been carried out by creating similar site conditions in Hydraulics Measurements. Laboratory, Alternate Hydro Energy Center at Indian Institute of Technology Roorkee. A numerical analysis also has been carried out by using commercial FLUENT code. The experimental and numerical results support that the variation of angle of penstock will not affect the discharge measurement by clamp-on type ultrasonic transit time flowmeter. The plane of measurement on inclined pipe will also not affect the discharge measurement by the flowmeter. iv