Some Consideration on the Unsteady Flow Rate Measurement Using Wave Propagation Model in Pipeline

抄録

The three-transducer method using the wave propagation model is a promising method for estimating the instantaneous flow rate in a pipe that can reduce the influence of the half-wavelength spacing problem. This paper extends the correction equation to flow rate and deals with the optimizations of the correction coefficients and their verification by experiments. The error reduction mechanism of the original method is discussed based on the principle of the Method of Characteristics, and the correction equation is extended to flow rate. A numerical experiment for small amplitude waves in a pneumatic pipeline is conducted, and numerical optimizations assuming realistic pressure calibration errors were performed for a flow chirp. The optimization results showed that the coefficient of flow rate correction was almost unity, indicating the validity of introducing flow rate correction. A transient response experiment was carried out on an actual pneumatic pipeline, using a laminar flowmeter with a fast response as a flow rate measurement. Comparison with the flow rate measurements and the flow rate estimation utilizing the pressure measurements showed the difference in the trend of absolute errors depending on the coefficients. Considering robustness, the optimized coefficient under ideal conditions was the best. On the other hand, the optimized coefficient under realistic conditions was found to be the best for unsteady flow with no change in line pressure.