PC BASED MEASUREMENT OF VELOCITY DISTRIBUTION IN AN OPEN CHANNEL

Abstract

The present work deals with the interfacing of a hydraulic open channel process with a personal computer. The inductive type pressure transducer has been used to measure the velocity of flow. The interface between the transducer and the PC is provided by a data acquisition device, System 570 manufactured by Keithley Instruments, USA. The analog input circuitry of the device is used for this purpose. A samping rate of about 2000 samples/sec has been obtained using a PC XT. This rate may be increased if a PC AT is used. A stepper motor positions the transducer at different locations, along the depth, in an open channel. The digital output circuitry present on the data acquisition device is used to send a sequence of digital pulses to the stepper motor. An experiment has also been carried out to determine the maximum speed of rotation of a stepper motor. The instantaneous velocity values acquired are stored in various data files and are used later for computation of the mean velocity distribution and the turbulence intensity. A user friendly and interactive software has been developed using the C programming language-the compiler used being Turbo C. The inline assembly language programming facility provided with Turbo C has also been used.