scholarly journals Numerical simulation of vortices with axial velocity deficits

1995 ◽  
Vol 7 (3) ◽  
pp. 549-558 ◽  
Author(s):  
Saad Ragab ◽  
Madhu Sreedhar
Keyword(s):  
Numerical Simulation ◽  
Axial Velocity ◽  
Velocity Deficits

scholarly journals Effects of Shell on Bore center Annular Shaped Charges Formation and Penetrating into Steel Targets

2020 ◽  
Vol 70 (1) ◽  
pp. 35-40
Author(s):  
Wenlong Xu ◽  
Cheng Wang ◽  
Jianming Yuan ◽  
Weiliang Goh ◽  
Bin Xu
Keyword(s):  
Numerical Simulation ◽  
Radial Velocity ◽  
Numerical Simulations ◽  
Penetration Depth ◽  
Axial Velocity ◽  
Shaped Charge ◽  
Shell Structures ◽  
Steel Shell ◽  
Simulation Results ◽  
Good Agreement

Annular shaped charge can efficiently create large penetration diameter, which can solve the problem of small penetration diameter of a traditional shaped charge, and thus meeting the requirements of large penetration diameter in some specific situations. In this paper, the influence of five kinds shell structures, i.e. no shell, aluminum shell with thickness of 2.0 mm and steel shell with thickness of 2.0 mm, 3.0 mm and 4.0 mm, on bore-center annular shaped charges (BCASCs) formation and penetrating steel targets was investigated by numerical simulations and experiments. The numerical simulation results are in good agreement with the experimental results. The results showed that, from no shell to aluminum shell of 2.0 mm and then to steel shell of 2.0 mm, 3.0 mm and 4.0 mm for BCASCs, the diameter and radial velocity of projectile head decrease, the axial velocity of BCASC projectiles increases gradually, the penetration diameter of the targets decreases, and the penetration depth increases. The penetration diameter caused by the BCASC with no shell is the largest, being 116.0 mm (1.16D), D is the charge diameter. The penetration depth caused by the BCASC with steel shell of 4.0 mm thickness is the deepest, being 76.4 mm (0.76D).

Three-dimensional numerical simulation of air flow and fiber dynamic in carding region in carding machine

2019 ◽  
Vol 89 (19-20) ◽  
pp. 3916-3926
Author(s):  
Shanshan He ◽  
Longdi Cheng ◽  
Wenliang Xue ◽  
Zhong Lu ◽  
Liguo Chen
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Finite Element ◽  
Flow Field ◽  
Axial Velocity ◽  
Three Dimensional ◽  
Tangential Velocity ◽  
Element Model ◽  
Mechanical Analysis ◽  
Field Simulation

Regular cylinder metallic card clothing has a limited carding efficiency. As a result of the limited dimensions, any measurement between the cylinder and flat area is difficult to make. In this study, an approach is first proposed to simulate the flow field and a fiber finite-element model on the moving surface of the teeth and produce a new design of misaligned-teeth card clothing, with the aim of improving the carding efficiency. A comparison is made between regular and misaligned-teeth card clothing types with respect to flow field simulation and fiber mechanical properties. The results show that the force resulting from the tangential velocity between the cylinder and flat is as great as 1.86 × 10−3 N, sufficient to pull fiber out of tufts, and that the tangential velocity (from 3880 to 2500 mm/s) plays a major role in this area, as opposed to the axial velocity (from 0 to 190 mm/s). Through this comparison, the misalignment design can result in a different tangential velocity distribution from that of traditional card clothing, which helps fibers between two lines of teeth move into neighboring lines of teeth, thereby increasing the likelihood that fibers will be carded. For fiber mechanical analysis, different air forces are loaded on fibers. This comparison shows that for fibers in the channel, the misalignment can help fibers move toward the teeth. Therefore, this misaligned-teeth card clothing is thought to prove more effective in practice.

Comparison of the Numerical and Experimental Flowfield Downstream of a Plate Array

2001 ◽  
Vol 124 (1) ◽  
pp. 284-286 ◽  
Author(s):  
D. W. Guillaume ◽  
J. C. LaRue
Keyword(s):  
Numerical Simulation ◽  
Axial Velocity ◽  
Thickness Ratio ◽  
Velocity Increase ◽  
Trailing Edges ◽  
Recirculation Zones ◽  
Plate Array ◽  
Adjacent Channels ◽  
Previous Experimental Study ◽  
Velocity Decrease

The findings of a numerical solution of the flowfield downstream of a six-plate array are compared to a previous experimental study. In both studies, the chord-to-thickness ratio, c/t, is 6.67, the Reynolds number, Re, is 500, and the spacing-to-thickness ratio, H/t, is 3.67. Consistent with experimental results, the numerical simulation shows that the recirculation zones formed at the trailing edges of the surfaces that form channels in the plate array are in-phase. Also consistent, they are nearly 180 deg out-of-phase with the recirculation zones formed at the trailing edges of the surfaces of adjacent channels. Comparison of the locations of recirculation zones and peaks in the downstream variation in axial velocity confirms that “vortex pumping” is described by 1) the axial velocity increase on the midplane of the channel in the region where the separation between pairs of recirculation zones is a minimum and 2) the axial velocity decrease in the region where the separation between pairs of recirculation zones is a maximum.

Numerical Simulation of Flow Field and Separation Efficiency of Inclined Cut-In Double-Inlet Cyclone

2012 ◽  
Vol 184-185 ◽  
pp. 341-347
Author(s):  
Cai Jin Wu ◽  
Zheng Fei Ma ◽  
Yong Yang
Keyword(s):  
Numerical Simulation ◽  
Pressure Drop ◽  
Flow Field ◽  
Axial Velocity ◽  
Separation Efficiency ◽  
Tangential Velocity ◽  
Reynolds Stress Model ◽  
Stress Model ◽  
Three Dimension ◽  
Inclined Angle

The three-dimension flow field and the separation efficiency of the inclined cut-in double-inlet cyclone were simulated numerically with Reynolds Stress Model (RSM). Numerical results show that the flow field nonsymmetry is improved in the inclined cut-in double-inlet cyclone and the swirl in the flow field was decreased greatly compared to that in the single-inlet cyclone. With the increase of inclined angle, both the tangential velocity and the axial velocity first increase and then decrease, reaching a peak at inclined 12 ° angle and at inclined 10 ° angle, respectively. The pressure drop in the inclined cut-in double-inlet cyclone increases first and then decreases with the increase of inclined angle, reaching a maximum far lower than that in the single-inlet cyclone, while the change of the radial velocity is not obvious. The separation efficiency of the inclined cut-in double-inlet cyclone could be effectively improved and the optimum inclined angle is 10 °.

Investigations of Unsteady Flow Field Characters in Axial Flow Pump Based on Numerical Simulation

2011 ◽  
Author(s):  
De-sheng Zhang ◽  
Wei-dong Shi ◽  
Xing-fan Guan ◽  
Jie Yao
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Unsteady Flow ◽  
Velocity Distribution ◽  
Axial Velocity ◽  
Axial Flow ◽  
Pressure Amplitude ◽  
Axial Velocity Distribution ◽  
Axial Flow Pump ◽  
Flow Pump

Investigations of the unsteady flow field characters in a axial-flow pump at different conditions are presented in the paper. The numerical simulation of the unsteady flow field is performed with FLUENT codes based on RNG k-ε model and SIMPLEC arithmetic. Numerical results show that the strong-coupling evolutions of static pressure and axial velocity distribution between rotor and stator in multi-conditions are periodic with the rotation of rotor. The interaction of stationary and rotating pressure field leads to periodic flow field distortions and induces pressure fluctuation. It is found that the maximum pressure amplitude of blade passing frequency occurs in the rotor inlet zone, but it deceases very fast backward to the stator. The dominant frequency at monitoring points located at rotor inlet, outlet and stator outlet, corresponds to the blade passage frequency. The axial velocity distortion resulting from the modulation of the interacting stationary and rotating flow field is affected by the blade numbers and thickness of both rotor and stator. The axial velocity has different distributions at different conditions, and the phase of it changes cyclically. However, the axial velocity distribution at stator outlet is also mainly affected by the stator blade numbers, but its phase does not change cyclically.

scholarly journals Effect of the Preheating Inlet Air on the G222 Fuel Combustion

2019 ◽  
Vol 3 (2) ◽  
pp. 29
Author(s):  
Mohammed El Hadi Attia
Keyword(s):  
Numerical Simulation ◽  
Carbon Monoxide ◽  
Axial Velocity ◽  
Mass Fraction ◽  
Three Dimensional ◽  
Special Treatment ◽  
Inlet Temperature ◽  
Governing Equations ◽  
Characteristic Parameters ◽  
Air Inlet

In this paper, a numerical simulation is developed to study the preheating effect of the air in a three-dimensional cylindrical combustion chamber using the FLUENT-CFD code. Particularly, we are interested on the calculation of the characteristic parameters such as the axial velocity, the temperature and the mass fraction of carbon monoxide. This study consists of a special treatment of mathematical models. The considered approaches resolve the governing equations of system. The main objective of this work is to study the behavior of the parameters considered previously during the variation of the air inlet temperature. The obtained results show that the variation of the inlet temperature presents a direct effect on the considered parameters. 

Effect of Produced Liquid Viscosity on Flow Characteristics and Separating Property of Downhole Hydrocyclone Desander

2014 ◽  
Vol 933 ◽  
pp. 250-254 ◽  
Author(s):  
Yue Juan Yan ◽  
Zun Ce Wang ◽  
Yan Xu Shang ◽  
Sen Li ◽  
Yan Xu
Keyword(s):  
Numerical Simulation ◽  
Pressure Drop ◽  
Radial Velocity ◽  
Axial Velocity ◽  
Separation Efficiency ◽  
Tangential Velocity ◽  
Flow Characteristics ◽  
Liquid Viscosity ◽  
Separating Property ◽  
Viscosity Changes

A new style single outlet downhole hydrocyclone desander with spiral deflectors was designed according to the working characters of downhole desander, which combined hydrocyclone separation and sediment separation. Numerical simulation was conducted to analysis effect of produced liquid viscosity on flow characteristics and separating property. The results show that the tangential velocity of hydrocyclone desander decreases rapidly and the axial velocity and radial velocity of hydrocyclone desander changes slightly when the produced liquid viscosity changes in the range of 1.5mPa·s ~ 30mPa·s. Separation efficiency drops sharply and pressure drop decreases slightly with the increasing of produced liquid viscosity.

Water uptake by substituted amylose tablets: experimentation and numerical simulation

2009 ◽  
Vol 00 (00) ◽  
pp. 090904073309027-8
Author(s):  
H.W. Wang ◽  
S. Kyriacos ◽  
L. Cartilier
Keyword(s):  
Numerical Simulation ◽  
Water Uptake
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