scholarly journals Transient flashing propellant flow models to predict internal flow characteristics, spray velocity, and aerosol droplet size of a pMDI

2017 ◽  
Vol 51 (5) ◽  
pp. 564-575 ◽  
Author(s):  
B. Gavtash ◽  
H. K. Versteeg ◽  
G. Hargrave ◽  
B. Myatt ◽  
D. Lewis ◽  
...  
Keyword(s):  
Droplet Size ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Flow Models ◽  
Aerosol Droplet ◽  
Spray Velocity

scholarly journals Effect of Air Injection on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1182
Author(s):  
Seung-Jun Kim ◽  
Yong Cho ◽  
Jin-Hyuk Kim
Keyword(s):  
Flow Rate ◽  
Draft Tube ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Air Injection ◽  
Low Flow ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Vortex Rope

Under low flow-rate conditions, a Francis turbine exhibits precession of a vortex rope with pressure fluctuations in the draft tube. These undesirable flow phenomena can lead to deterioration of the turbine performance as manifested by torque and power output fluctuations. In order to suppress the rope with precession and a swirl component in the tube, the use of anti-swirl fins was investigated in a previous study. However, vortex rope generation still occurred near the cone of the tube. In this study, unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted with a scale-adaptive simulation shear stress transport turbulence model. This model was used to observe the effects of the injection in the draft tube on the unsteady internal flow and pressure phenomena considering both active and passive suppression methods. The air injection affected the generation and suppression of the vortex rope and swirl component depending on the flow rate of the air. In addition, an injection level of 0.5%Q led to a reduction in the maximum unsteady pressure characteristics.

Internal Flow Characteristics of a Plastic Kaolin Suspension During Extrusion

2011 ◽  
Vol 95 (2) ◽  
pp. 494-501 ◽  
Author(s):  
Brooks D. Rabideau ◽  
Pascal Moucheront ◽  
François Bertrand ◽  
Stéphane Rodts ◽  
Yannick Mélinge ◽  
...  
Keyword(s):  
Flow Characteristics ◽  
Internal Flow ◽  
Kaolin Suspension

Numerical Simulation of Transient Flow Inside Nozzle on Gasoline Direct Injection Engine

2012 ◽  
Vol 466-467 ◽  
pp. 1237-1241
Author(s):  
Yan Hua Wang ◽  
Shi Chun Yang ◽  
Yun Qing Li
Keyword(s):  
Kinetic Energy ◽  
Transient Flow ◽  
Direct Injection ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Turbulence Kinetic Energy ◽  
Gasoline Direct Injection ◽  
Injection Hole ◽  
Gasoline Direct Injection Engine ◽  
Nozzle Configuration

To achieve transient flow characteristics at exit of nozzle orifice on gasoline direct injection engine, two phase Euler-Euler schemes was used to simulate the internal flow of the swirl nozzle. Different flow characteristics were calculated in the simulation. Different kinds of nozzle configuration were studied. Cavitaion and swirl flow occured in the nozzles. Injection hole configuration matters more than area variation of swirl tangential slot to discharge coefficient of the studied nozzle. Discharge coefficient changes a little along the injection hole length. The area of the swirl tangrntial slot plays an important throttling action in nozzle internal flow. Smaller area of swirl tangential slot generates larger degree cavitation but smaller mean injection velocity. Turbulence kinetic energy changes with the time of cavitation and swirl field occurring and the nozzle configuration. Before the appearance of cavitation, smaller inclination angle of orifice can generate more turbulence kinetic energy. After that moment, turbulence kinetic energy varies with different configuration. Along injection hole length, turbulence kinetic energy obviously varies. These flow characteristics affect primary atomization and will be as input for next spray simulation. They are also applied to design reference for injection nozzle.

scholarly journals Numerical Simulation and Experimental Study on Flow Field in a Swirl Nozzle

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yicheng Sun ◽  
Yufan Fu ◽  
Baohui Chen ◽  
Jiaxing Lu ◽  
Wanquan Deng
Keyword(s):  
Flow Field ◽  
Velocity Distribution ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Low Pressure ◽  
External Flow ◽  
Droplet Velocity ◽  
Inlet Pressure ◽  
Outlet Section ◽  
Local Pressure

In order to study the internal flow characteristics and external droplet velocity distribution characteristics of the swirl nozzle, the following methods were used: numerical simulations were used to study the internal flow characteristics of a swirl nozzle and phase Doppler particle velocimetry was used to determine the corresponding external droplet velocity distribution under medium and low pressure conditions. The distributions of pressure and water velocity inside the nozzle were obtained. Meanwhile, the velocities of droplets outside the nozzle in different sections were discussed. The results show that the flow rate in the swirl nozzle increases with the increase in inlet pressure, and the local pressure in the region decreases because of the excessive velocity at the internal outlet section of the swirl nozzle, resulting in cavitation. The experimental results show that under an external flow field, the minimum droplet velocity occurs in the axial direction; starting from the axis, the velocity first increases and then decreases along the radial direction. Swirling motion inside the nozzle and velocity variations in the external flow field occur under medium and low pressure conditions. The relationship between the inlet pressure and the distributions of water droplets’ velocities was established, which provides a reference for the research and development of the swirl nozzle.

scholarly journals A Study on Internal Flow Characteristics of T Branch using CFD Analysis

2015 ◽  
Vol 26 (5) ◽  
pp. 438-444
Author(s):  
CHUL HEE JO ◽  
MYEONG JOO KIM ◽  
SEOK JIN CHO ◽  
SU JIN HWANG
Keyword(s):  
Flow Characteristics ◽  
Internal Flow ◽  
Cfd Analysis

scholarly journals The temporal evolution of neutral modes in the impulsively started flow through a circular pipe and their connection to the nonlinear stability of Hagen–Poiseuille flow

2002 ◽  
Vol 457 ◽  
pp. 339-376 ◽  
Author(s):  
ANDREW G. WALTON
Keyword(s):  
Poiseuille Flow ◽  
Multiple Scales ◽  
Stability Boundary ◽  
Circular Cross Section ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Bypass Transition ◽  
Flow Through ◽  
High Reynolds ◽  
Wave Limit

The linear stability of the impulsively started flow through a pipe of circular cross-section is studied at high Reynolds number R. A crucial non-dimensional time of O(R7/9) is identified at which the disturbance acquires internal flow characteristics. It is shown that even if the disturbance amplitude at this time is as small as O(R−22/27) the subsequent evolution of the perturbation is nonlinear, although it can still be followed analytically using a multiple-scales approach. The amplitude and wave speed of the nonlinear disturbance are calculated as functions of time and we show that as t → ∞, the disturbance evolves into the long-wave limit of the neutral mode structure found by Smith & Bodonyi in the fully developed Hagen–Poiseuille flow, into which our basic flow ultimately evolves. It is proposed that the critical amplitude found here forms a stability boundary between the decay of linear disturbances and ‘bypass’ transition, in which the fully developed state is never attained.

Study on Characteristics and Operating Parameters of Axial Rotating Hydrocyclone

2009 ◽  
Author(s):  
Yan Xu ◽  
Zunce Wang ◽  
Fengxia Lv ◽  
Sen Li
Keyword(s):  
Pressure Drop ◽  
Laboratory Experiments ◽  
Separation Efficiency ◽  
Rotation Speed ◽  
Tangential Velocity ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Axial Rotation ◽  
Rotating Wall ◽  
Simulation Results

The axial rotation of the hydrocyclone affects its internal flow characteristics and separating effect directly, as some local applications require the static hydrocyclone rotates about its own axis. Based on CFD, velocity distribution in the axial rotating hydrocyclone is studied. It is shown that as the rotation speed increasing, the tangential velocity improves and its gradient reduces in free vortex region observably, while the radial velocity has an incremental trend in the section of the small cone. The laboratory experiments are carried out for the static hydrocyclone of disposal capacity of 4 m3/h at 100r/min ∼ 300r/min. The relationships among rotation speed, flowrate, pressure drop and separated efficiency are achieved, which agree well with the numerical simulation results. The results indicate that the disposal capacity of hydrocyclone subjected to the rotation wall can be more flexible than that with no-rotating wall, the scope of best disposal capacity gradually enlarges with the increase of rotation speed of wall. Appropriate rise of the rotation speed is favor of the separation efficiency at the steady flowrate, however the increase of the flowrate and rotation speed induces the growth of the hydrocyclone’s pressure drop correspondingly to some extent.

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