Valve with pneumatic actuator, working as the control valve andįlowmeter. Prototype was made in the laboratory using a 50-mm conventional control To present day intelligent controllers, to implement the scheme. Necessitates the use of a computer or a processor-based system, similar In order to obtain a particular flow rate using this method. Error analysis is performed for the expression and to suggest Valve position characteristics in order to measure and control the flow Temperature, the valve position, and the CνVs Of the differential pressure across the valve, the static pressure, A relationship for this wasĮstablished based on the equation for control valve capacity (Cν From the above, it is seen that if a relationship is developedīetween the differential pressure produced by the control valve and theįlow through it, the valve itself could function as a flowmeter also,Īpart from acting as a control valve. Of restricting the area for flow which in turn produces a differential Incidentally, a control valve uses the principle
Conventional flowmeters produce aĭifferential pressure in the flow, which is measured and suitably scaled The control valve depending upon the difference between the measuredįlow rate and the set flow rate. The controller gives an appropriate signal to The control of flow through a pipe requires mainly three devices-aįlowmeter for the measurement of flow, a control valve to control theįlow, and a controller. The magnitude of the oscillation pressure in intermittent mode could be evaluated from the difference between the throat static-pressure immediately prior to the occurrence of cavitation and that during cavitation. Oscillation pressure values in intermittent mode were much larger than those in continuous mode, peaking between 74 and 76 K. Occurrence of the intermittent mode accompanying very large pressure-oscillations was considered to be caused by a drastic reduction of the speed of sound in the single-component, vapor-liquid flow because the speed of sound restricted the throat velocity in the C-D nozzle during cavitation. This change occurred in both C-D nozzles when the temperature of the liquid reached approximately 76 K.
The cavitation mode changed from continuous mode to intermittent mode as the temperature of the subcooled liquid nitrogen decreased. Flow observations were also performed to clarify the instability phenomenon and the differences in cavitation behavior between the two nozzles. The cavitation flow instability of subcooled liquid nitrogen in two types of converging-diverging (C-D) circular nozzles with throat diameters of 1.5 and 2.0 mm was experimentally investigated.
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