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51.
激波在异种气体中传播及诱导的剪切混合研究 总被引:1,自引:0,他引:1
利用二阶迎风TVD格式求解多组分,层流全N-S方程,针对直通道和突扩直通道,研究了马赫数为2和4的激波在H2和空气界面上的传播及诱导的燃料剪切混合,计算结果表明:(1)直通道中,剪切层中的激波阵面要发生畸变,存在对混合起主要作用的卷吸涡,激波马赫数不同,卷吸涡结构和横向混合的尺寸也不同,激波马赫数低,剪切混合效果好,(2)在突扩直通道中,马赫数为2和4的激波在H2中产生不同强度激波,在剪切层中都能产生顺时针,尺度较大的卷吸涡,后台阶增强了剪切层的混合。 相似文献
52.
针对一类变截面管内的轴对称弱螺旋流情况,讨论了其沿下游的演变规律,对于层流情况得到了指数衰减性的结论,对于湍流情况,则在Boussinesq涡粘性假设下得到了局部环量放大的必要条件。 相似文献
53.
54.
The objective of the present work is to predict compressible swirl flow in the nozzle of air‐jet spinning using the realizable k–ε turbulence model and discuss the effect of the nozzle pressure. The periodic change of flow patterns can be observed. The recirculation zone near the wall of the injectors upstream increases in size and moves gradually upstream, whereas the vortex breakdown in the injector downstream shifts slowly towards the nozzle outlet during the whole period. A low axial velocity in the core region moves gradually away from the centerline, and the magnitude of the center reverse flow and the area occupied by it increase with axial distance due to the vortex breakdown. From the tangential velocity profile, there is a very small free‐vortex zone. With increasing nozzle pressure, the velocity increases and the location of vortex breakdown is moved slightly downward. However, the increase in the velocity tends to decline at nozzle pressure up to a high level. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
55.
This paper studies the properties of turbulent swirling decaying flow induced by tangential inlets in a divergent pipe using the realizable k–ε turbulence model and discusses the effects of the injector pressure and injection position. The results of transient solutions show that both the recirculation zone near the wall in upstream of the injectors and the vortex breakdown in downstream of the injectors increase in size during the whole period. A nearly axisymmetric conical breakdown is formed and its internal structure consists of two asymmetric spiral‐like vortices rotating in opposite directions. The stagnation point shifts slowly toward the pipe outlet over time. The maxima of the three velocity components, which are located near the wall, decrease gradually with streamwise direction. It can also be inferred that Mach number approaches 1.0 near the injector outlets. The velocities increase with the increasing injector pressure. However, its increasing trend is not significant. With the increase of the injection position, vortex breakdown moves in downstream direction and the pitch along the streamwise direction increases. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
56.
Milan Miklav?i? 《Journal of Mathematical Analysis and Applications》2004,294(1):24-33
Existence of an exact solution of the Navier-Stokes equations representing swirling flow consisting of two fluid layers is proven. It is assumed that the fluid in the bottom layer is injected into the swirl from a rotating disk. This describes the case when a disk melts in an ambient fluid and the melted fluid is removed by rotation of the disk. 相似文献
57.
The results of an experimental investigation of the periodic pressure oscillations developing in a submerged swirling jet flowing out into an open space are presented. The main governing parameters of the process are determined and a general dependence relating the oscillation frequency with the governing parameters over a wide range of parameter variation is established experimentally. On the basis of this dependence, an empirical formula for calculating the oscillation frequency is proposed. 相似文献
58.
The present study addresses experimental results for investigating the details of the near field flow characteristics produced in an under-expanded, dual, coaxial, swirling jet. The under-expanded swirling jet is discharged from a sonic inner nozzle. An outer annular nozzle produces co- and counter-swirling streams relative to the inner primary swirling jet. The interaction between both the outer annular swirling stream and inner under-expanded swirling jet is quantified by impact and static pressure measurements, and visualized by using the shadowgraph method. Experiments are performed for several different pressure ratios. The results show that the outer secondary co-swirling jet significantly changes the structure of the inner under-expanded swirling jet, such as the shock structures and the recirculation region generated at the jet axis. The effect of the outer secondary stream on the major structures of the inner primary swirling jet is strongly dependent on the pressure ratio of the inner swirling jet, regardless of the swirl direction of the outer stream.Received: 17 May 2004, Accepted: 27 September 2004, Published online: 26 November 2004[/PUBLISHED]H.D. Kim: Correspondence to 相似文献
59.
螺旋管油气水多相流动与原油管流除砂理论 总被引:4,自引:2,他引:2
本文介绍了有关螺旋管内油气水多相流动的研究成果及原油井口螺旋管旋流除砂工艺技术发明的原理与实效. 相似文献
60.
The boundary layer integral method is used to investigate the development of the turbulent swirling flow at the entrance region
of a conical nozzle. The governing equations in the spherical coordinate system are simplified with the boundary layer assumptions
and integrated through the boundary layer. The resulting sets of differential equations are then solved by the fourth-order
Adams predictor-corrector method. The free vortex and uniform velocity profiles are applied for the tangential and axial velocities
at the inlet region, respectively. Due to the lack of experimental data for swirling flows in converging nozzles, the developed
model is validated against the numerical simulations. The results of numerical simulations demonstrate the capability of the
analytical model in predicting boundary layer parameters such as the boundary layer growth, the shear rate, the boundary layer
thickness, and the swirl intensity decay rate for different cone angles. The proposed method introduces a simple and robust
procedure to investigate the boundary layer parameters inside the converging geometries. 相似文献