Abstract
The paper describes a method for determining the ‘time constants’ of turbine type flowmeters, in response to step inputs.
The equation of motion of the rotor during the speeding-up process was formed by equating the impressed torque to the inertia forces. This equation was then solved numerically, using a step-by-step process, and the response curves and hence the time constants found. The torque impressed on the rotor's cascade of blades owing to impingement of liquid was estimated using experimental lift and drag data which had been modified for the cascade effect.
The above approach was used to estimate the time constants of an Elliott 3/4-in helical flowmeter, since its dimensions were accurately known and experiments had been performed on the meter which enabled the calculated and experimental values to be compared.
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