Using the enterprise’s valve as the research object, the research shows the characteristics of the flow field and noise of the valve. The theory of LES and Lighthill acoustic analogy is applied to study the flow noise characteristics of 100% opening and 70% opening of valve in the same flow. The result shows that the region of variation about pressure and velocity is concentrated in the valve s...

Mitral valve closure during cardiopulmonary resuscitation may result from direct cardiac compression. An alternative hypothesis is that with a rise in intrathoracic pressure, mitral valve closure can occur but may be influenced by whether the lungs are inflated or deflated. To test this hypothesis, we placed a large-bore cannula into the thoraces of 11 dogs. Intrathoracic pressure was changed b...

In internal combustion engines, exhaust valve and its seat gain considerable temperature as the hot gases exit through them. So, the rate of heat transfer should be under control. In this study, the contact heat transfer coefficient has been estimated. An experimental study on an Air-Cooled internal combustion engine cylinder head has been considered. Using the measured temperatures of sensors ...

The mean pressure drop across the mitral valve and atrioventricular pressure half-time were measured noninvasively by Doppler ultrasound in 40 normal subjects, in 17 patients with mitral regurgitation, 32 patients with mitral stenosis and 12 with combined stenosis and regurgitation. In normal subjects pressure half-times were 20--60 msec, in patients with isolated mitral regurgitation 35--80 ms...

This paper presents a study of dynamic characteristics of spring loaded relief valve and the turbulent flow of water through it by using CFD in 2-Dimensions. Mesh deformation due to the fluid-solid interaction between the valve disc and the surrounding fluid and CEL expressions determined by solving a dynamics equation of forces acting on the valve disc, are used to account for the motion of th...

Novel latching microfluidic valve structures are developed, characterized, and controlled independently using an on-chip pneumatic demultiplexer. These structures are based on pneumatic monolithic membrane valves and depend upon their normally-closed nature. Latching valves consisting of both three- and four-valve circuits are demonstrated. Vacuum or pressure pulses as short as 120 ms are adequ...

A double coil magnetorheological (MR) valve with an outer annular resistance gap was designed and prototyped. The finite element modeling and analysis of double coil MR valve were carried out using ANSYS/ Emag software, and the optimal magnetic field distribution and magnetic flux density of the double coil MR valve were achieved. The mechanism of the pressure drop was studied by building a mat...

The flow-resistive characteristics of a variety of commercially available expiratory positive-pressure valve systems used to provide continuous positive airway pressure (CPAP) and positive end-expiratory pressure were evaluated. One flow-resistor and seven threshold-resistor expiratory pressure valve systems were set at 5, 10, 15, 20, and 25 cm H2O of expiratory pressure, and sinusoidal exhaled...

Heat exchangers are the critical components of refrigeration and liquefaction processes. Selection of appropriate operational conditions for cryogenic recuperative heat exchanger and expansion valve operating in Joule-Thomson cooling system results in improving the performance and efficiency. In the current study, a straightforward procedure is introduced to design an efficient Joule-Thomson co...

AIMS In experimental studies the recovery of pressure distal to stenotic valve orifices has been well described. We evaluated the extent, determinants, and clinical importance of pressure recovery in patients with aortic valve stenosis. METHODS AND RESULTS The study was performed in 37 patients with aortic valve stenosis, in whom cardiac catheterization was performed and left ventricular and ...