Sakhaeimanesh A A
Biomedical Engineering Group, Faculty of Engineering, University of Isfahan, Isfahan, Iran.
J Med Eng Technol. 2008 Nov-Dec;32(6):434-9. doi: 10.1080/03091900701543832.
The effect of oscillation on elevating turbulent shear stresses through the Jellyfish and St. Vincent valves has been investigated. Laser Doppler anemometry was employed to determine the velocity and shear stress distributions at various locations downstream of the valves. Comparison between two valves revealed that at 0.5D downstream of the valves the magnitude of shear stresses in the Jellyfish valve were much higher than those of the St. Vincent valve at cardiac outputs of 4, 5.5 and 7 l min(-1). The cause of high shear stresses in close proximity to the Jellyfish valve could be attributed to the oscillation of the membrane which in turn generated a wake downstream of the valve (in the core of valve chamber) and produced a wide region of disturbance further downstream. This resulted in further pressure drag, and consequently higher pressure drops across the valve and higher shear stresses downstream of the valve.
研究了水母瓣膜和圣文森特瓣膜振荡对提高湍流剪应力的影响。采用激光多普勒测速仪测定瓣膜下游不同位置的速度和剪应力分布。两个瓣膜的比较表明，在瓣膜下游0.5D处，当心输出量为4、5.5和7 l min(-1)时，水母瓣膜处的剪应力大小远高于圣文森特瓣膜。水母瓣膜附近剪应力高的原因可能是膜的振荡，这反过来又在瓣膜下游（瓣膜腔核心处）产生了尾流，并在更下游产生了广泛的扰动区域。这导致了进一步的压力阻力，从而导致瓣膜两端的压降更高，瓣膜下游的剪应力也更高。
