Research On Flow Regulation Characteristics Of A Swirlmeter Adjustment Device

Flow adjustment device is a kind of actuators in automatic instruments,which is also called flow regulator valve or flow control valve. With the continuallyincreasing of automation degree in production process, flow adjustment valve, as akind of terminal elements in process control, has been widely used in metallurgy,electric power, chemical industry, petroleum, construction and other industrial fields.Due to the restriction in pipeline layout, the interaction between the regulate valveand the flow rate transmitter, and other influence factors, the regulating precision ofmost of cite used flow adjustment valves is difficult to reach a high level. In responseto above technical issues, a new type flow adjustment device was developed in thisthesis, which is a combination of a swirlmeter and a regulate valves. Since theswirlmeter has the ability to make the internal flow become uniform, it has goodanti-interference performance. Therefore, if the signal of swirlmeter is used for flowcontrol, the regulation accuracy can be increased.The flow measurement and regulating characteristics of this combinational flowcontrol device are investigated in the thesis. The main works are as following:（1） A design of an air flow control device which combined swirlmeter andcontrol valve is brought forward, with the nominal diameter of DN50. In the design,a conical valve core is used in the valve parts. Flow regulating is achieved byadjusting the position of valve core to change the effective flow area. The swirlmeteris at the downstream of the valve. Flow rate signals measured by the swirlmeter areused for flow adjusting. In the study, several works have been completed, includingthe structural design of the device, manufacturing, design of using step motor todrive the valve core, establishment of the mathematic model of control parts. Bytheoretical analysis and tests, relationships between important structural parametersand main performance parameters have been abtained.（2） Experiments were carried out on flow measurement and controlcharacteristics of the developed swirlmeter regulating device. For the purpose ofdeeply understanding the characteristics of swirlmeter, experiments were carried out for the cases of two and three probes, respectively. The results show that thecapability of the flowmeter for the small flow rate measurement can be furtherimproved in the case of three probes compared with the two probes. Then, measuredwere taken for the case of assembling the swirlmeter and regulating valve. Thedynamic pressure of the flow inside the flowmeter is measured. The characteristics ofthe swirl precession frequency and the amplitude of the pressure fluctuation aremainly analyzed. The results show that the upstream valve has almost no effect to theflow rate curve of the swirlmeter. In terms of adjusting characteristics of the device,measurements have been taken at inlet pressures varies from0.110to0.230MPa andvalve opening from0～8mm, respectively. The data of pressure loss and volumeflow rate are obtained. It is found that if inlet pressure is the same, the intensity ofpressure fluctuation and the precession frequency increases with the increasing valveopening, and the flow rate shows linear relationship with the valve opening. As theinlet pressure increasing, the flow rate increased.