A computational optimization was performed for a direct-injection diesel engine using three-dimensional modeling. Fully transient CFD analyses of different valve profile strategies for the intake and compression strokes were performed to evaluate the effects on both engine performance and in-cylinder flow-field evolution. The turbulence model was used along with the second order linear upwin...

Abstract: To improve the stability and reliability of the piezoelectric micro-pump, the cause of air block phenomenon is analyzed on the structure of wheel check valve. During the movement of the bubble in the micro-channel, pressure drop occurs, the main factor which influences the bubble going through is opening height of the wheel check valve. Five groups of wheel check valves with different...

a computational optimization was performed for a direct-injection diesel engine using three-dimensional modeling. fully transient cfd analyses of different valve profile strategies for the intake and compression strokes were performed to evaluate the effects on both engine performance and in-cylinder flow-field evolution. the turbulence model was used along with the second order linear upwind s...

We present a low power, on demand Parylene MEMS electrothermal valve. A novel Omega-shaped thermal resistive element requires low power (approximately mW) and enables rapid valve opening (approximately ms). Using both finite element analysis and valve opening experiments, a robust resistive element design for improved valve opening performance in water was obtained. In addition, a thermistor, a...

The physiologic correlates of ejection sounds have been studied by simultaneous phonocardiograms, echocardiograms and high fidelity pressure tracings. Ejection sounds associated with semilunar valve stenosis or hypertension of the systemic or pulmonary circulation occur at the moment of complete opening of the aortic or pulmonary valve recorded echocardiographically. The start of opening of the...

Premature opening of the pulmonary valve (opening independent of atrial or ventricular systole) was originally described in a case of sinus of Valsalva rupture into the right atrium. Since that time we have observed five additional cases in which the pulmonary valve opened prematurely. Entities encountered included: 1) constrictive pericarditis; 2) Loeffler's endocarditis; 3) Ebstein's anomaly ...

The hot gases produced by the internal combustion engines passes through the exhaust valve and causes high temperatures in the exhaust valve and its seat. To avoid damaging the exhaust valve, heat must be transferred from the valve to its seat during the contact they make at the opening and closing cycle. Heat transfer rate from the exhaust valve to its seat is a function of many factors. One o...

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...

BACKGROUND AND AIM OF THE STUDY In-vitro studies on the ATS heart valve have indicated that valve opening is less in an expanding conduit than in a straight conduit. METHODS Bileaflet valve behavior was studied using a new computational fluid-structure interaction model. A three-dimensional model of the ATS valve was studied in two geometries, simulating the valve in a geometry with sudden ex...

BACKGROUND The closure sound of the ATS bileaflet mechanical valve is said to be quieter than that of the other mechanical valves. However, the reasons for this are still unknown. In this study, we investigated the reasons for the quietness of the ATS valve closure sound. PATIENTS AND METHODS The valve closure sound was evaluated in 70 patients and in another 70 patients in whom the SJM valve...