Abstract

The aim of our research project is to develop a Kalman filter system which estimates unsteady flowrate of a pipe using a laminar flowmeter. In this study, incompressible flow is assumed as working fluid. When the flow becomes turbulent, it is difficult to establish flow model for turbulent friction. In this study, a laminar flowmeter is constructed in which thirty-two narrow pipes of 1mm in inner diameter are bundled and inserted in main flow path. When fluid flow in the narrow pipe is laminar flow, the Kalman filter theory can be applied to the flow of the narrow pipe. Kalman filter is applied to one of narrow pipes of laminar flowmeter. Both upstream and downstream pressure signals of the targeted narrow pipe are input to the Kalman filter. Midpoint pressure measured by a pressure sensor is compared with midpoint pressure signal which is estimated by the Kalman filter. When flow is laminar flow or the system has linear characteristics, an error signal between estimated pressure and measured pressure decreases according to Kalman filter principle. As a result, because the state variables of the Kalman filter converge to real variables, unsteady flowrate is estimated from the state variables of the Kalman filter. Experimental calibration of the Kalman-filtering laminar flowmeter under steady-state flow condition has been performed. In this study, experiments of step response of flowrate in a pipe are conducted by constructing an experimental circuit using solenoid valves. The purpose of experiment is confirmation of a response time of the Kalman-filtering laminar flowmeter. As a result of experiments, it was shown that the response time is 0.05s.

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