Optimization Of The Differential-pressure Based Vortex Flowmeter And Research Of Vortex Signal Process

Designed based on the Karman shedding theory, vortex fiowmeter has been applied widely in the industry pipe flowrate measurement. In order to overcome the low anti-interference ability of vortex fiowmeter, according to the typical character of Karman vortex, our research group put forward the duct-wall differential pressure method (DDPM) to measure the mass flowrate in the pipe directly by equipping a differential pressure sensor on the pipe duct and made a DDPM vortex mass fiowmeter. In order to extend the application areas such as: water, air, and steam, etc, this thesis optimizes the DDPM vortex mass fiowmeter and studies the signal process method. The thesis mainly focuses on the following contents:(1) A detailed summary of the character, development history and measurement methods of the vortex fiowmeter were presented. The principle of the DDPM vortex mass fiowmeter and its advantage over traditional methods were introduced. Analyses of the difficulties of the DDPM vortex in the real application and the solutions were also given.(2) A DDPM vortex mass fiowmeter was optimized designed. The dynamic frequency response character of the pressure probe system was studied to optimize the pressure probe system structure through the study of the fluid network theory. The working temperature of the DDPM vortex fiowmeter was analyzed by heat transfer theory to prove the feasibility of the steam flowrate measurement.(3) Experiments were conducted by water and air. The causes of the error in the low mass flowrate measurement were studied. The experiment data shows that the optimized fiowmeter has a good measurement precise and can reduce the low limit in the water volume flowrate measurement.(4) In order to overcome the error in the low flowrate measurement, this thesis uses the temperature compensation to reduce the zero point drift and applies the Wigner-Hough transform (WHT) into the vortex signal process.The innovation of this thesis are listed as below: applied the fluid network theory on the research of the dynamic frequency response character of the DDPM probe system and proposed a new method of vortex signal process by using wigner-hough transformation to improve the anti-interference ability and the accuracy of the measurement...