Numerical simulation and experiment research on inner-flow of axial flow fan under low flow rate condition

2004 ◽  
pp. 825-829
Author(s):  
Lihong Jia ◽  
Yimin Li ◽  
Xiaodong Wang ◽  
Xiaodong Huang
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Axial Flow ◽  
Low Flow ◽  
Experiment Research ◽  
Axial Flow Fan ◽  
Rate Condition ◽  
Simulation And Experiment ◽  
Low Flow Rate

Numerical Simulation of Cavitation in a Centrifugal Pump at Low Flow Rate

2012 ◽  
Vol 29 (1) ◽  
pp. 014702 ◽  
Author(s):  
Lei Tan ◽  
Shu-Liang Cao ◽  
Yu-Ming Wang ◽  
Bao-Shan Zhu
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Low Flow ◽  
Low Flow Rate

scholarly journals Investigation of the Flow Field in the Vicinity of an Axial Flow Fan During Low Flow Rates

2014 ◽  
Author(s):  
Francois G. Louw ◽  
Theodor W. von Backström ◽  
Sybrand J. van der Spuy
Keyword(s):  
Flow Field ◽  
Numerical Simulations ◽  
Flow Rate ◽  
Axial Flow ◽  
Operating Conditions ◽  
Design Flow ◽  
Low Flow ◽  
Axial Flow Fan ◽  
Free Vortex ◽  
Flow Rates

Large axial flow fans are used in forced draft air cooled heat exchangers (ACHEs). Previous studies have shown that adverse operating conditions cause certain sectors of the fan, or the fan as a whole to operate at very low flow rates, thereby reducing the cooling effectiveness of the ACHE. The present study is directed towards the experimental and numerical analyses of the flow in the vicinity of an axial flow fan during low flow rates. This is done to obtain the global flow structure up and downstream of the fan. A near-free-vortex fan, designed for specific application in ACHEs, is used for the investigation. Experimental fan testing was conducted in a British Standard 848, type A fan test facility, to obtain the fan characteristic. Both steady-state and time-dependent numerical simulations were performed, depending on the operating condition of the fan, using the Realizable k-ε turbulence model. Good agreement is found between the numerically and experimentally obtained fan characteristic data. Using data from the numerical simulations, the time and circumferentially averaged flow field is presented. At the design flow rate the downstream fan jet mainly moves in the axial and tangential direction, as expected for a free-vortex design criteria, with a small amount of radial flow that can be observed. As the flow rate through the fan is decreased, it is evident that the down-stream fan jet gradually shifts more diagonally outwards, and the region where reverse flow occur between the fan jet and the fan rotational axis increases. At very low flow rates the flow close to the tip reverses through the fan, producing a small recirculation zone as well as swirl at certain locations upstream of the fan.

Pressure Fluctuation on Casing Wall of Isolated Axial Compressor Rotors at Low Flow Rate

1993 ◽  
Vol 115 (1) ◽  
pp. 19-26 ◽  
Author(s):  
M. Inoue ◽  
M. Kuroumaru ◽  
Y. Ando
Keyword(s):  
Flow Rate ◽  
Pressure Fluctuation ◽  
Correlation Functions ◽  
Pressure Fluctuations ◽  
Axial Compressor ◽  
Axial Flow ◽  
Tip Clearance ◽  
Low Flow ◽  
Flow Compressor ◽  
Low Flow Rate

The pressure fluctuations on the casing wall of two axial flow compressor rotors with various tip clearances have been analyzed by the use of two kinds of correlation functions. The behavior of the pressure fluctuation varies depending on tip clearance and blade solidity. In the case of small tip clearance, the nature of disturbances becomes random as the flow rate is reduced to a stall condition. For moderate tip clearance, coherent-structured disturbances appear intermittently at low flow rate. They appear more frequently as the solidity is increased and the flow rate becomes lower. For large tip clearance, the coherent structured disturbances exist even at considerably higher flow rates. Corresponding to these features, there are peculiar patterns in the correlation designated as “phase-locked correlation functions.”

scholarly journals Pore-Scale Simulations of Particles Migration and Deposition in Porous Media Using LBM-DEM Coupling Method

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 465
Author(s):  
Yanjie Zhou ◽  
Liping Chen ◽  
Yanfeng Gong ◽  
Shilin Wang
Keyword(s):  
Porous Media ◽  
Critical Velocity ◽  
Flow Rate ◽  
Shear Force ◽  
Particle Deposition ◽  
Moving Boundary ◽  
Low Flow ◽  
Rate Condition ◽  
Groundwater Source ◽  
Low Flow Rate

This paper studies the migration and deposition of suspended particles in porous media. This problem results from the fact that during the operation of a groundwater source heat pump, the recharging process will contribute to the impairment of soil permeability. A coupling lattice Boltzmann method, discrete element method and immersed moving boundary method were used to investigate the migration of particles in porous media. The DKT (Drifting, Kissing, Tumbling) phenomena were employed to validate our program. The coupled effects of concentration, flow rate and pH on the clogging mechanism of the porous media were analyzed. Results show that, due to the repulsive barrier between the particles and porous media, there is a critical velocity. At a low flow rate, the deposition ratio increases with the increase in velocity. Beyond the critical velocity, the deposition ratio decreases when the velocity increases due to higher shear force. Permeability impairment increases with the increase in concentration, especially in the low flow rate condition. Changes in pH mainly affect the repulsive barrier. For a low flow rate, the decrease in repulsive barrier greatly promotes the deposition of particles. Under the condition of favorable deposition, the increase in flow rate reduces the deposition phenomenon. Under the condition of unfavorable deposition, the lower flow rate condition has a lower deposition ratio. The process of particle deposition and the dynamic motion after deposition were observed such as particles gliding over the surface. Accumulated particles in the downstream form bridges and hinder fluid flow. At a high flow rate, strong shear force is more capable of destroying bridges and recovering permeability. Adsorbed particles glide on the surface of the grain and deposit in the downstream. This paper aims to help understanding of the micro-events of particle deposition and the clogging process.

Abstract 295: Importance of the Rate of Platelet Activation by Thrombin for Regulating the Size of Thrombi Formed Under Low Blood Flow Velocity Conditions

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Shinichi Goto ◽  
Kengo Ayabe ◽  
Youth Kawamura ◽  
Noriko Tamura ◽  
Shinya Goto
Keyword(s):  
Blood Flow ◽  
Flow Velocity ◽  
Platelet Activation ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Low Flow ◽  
Coagulation Cascade ◽  
Computer Simulation Model ◽  
Rate Condition ◽  
Low Flow Rate

Background: Platelets, coagulation cascade including thrombin and fibrin, and fibrinolysis by plasmin along with blood flow are known to play regulatory roles in thrombogenesis. However, quantitative and interactive contribution of these factors are not fully understood. Method: We developed a computer simulation model of thrombi at sites of vessel injury by implementing quantitative parameters of blood flow, platelet, coagulation cascade and fibrinolysis. In this model, we defined thrombi as the area where the amount of activated platelet become 80% or more of the global platelet count of 3.0х10 5 /mm 3 upon vessel damage We have measured the 3-dimensional size of thrombi as defined in various conditions with various parameters of flow velocity, rate of platelet activation by thrombin, rate of thrombin production on the surface of activated platelets, rate of fibrinolysis and rate of plasmin production. Results: Rate of platelet activation by thrombin had the largest influence on the size of thrombi under low flow rate condition of 0.5 (cm/sec) (Fig1 A). When blood flow rate increased to 2.0 (cm/sec), the absolute importance of this parameter decreased (Fig1 B). Conclusion: Our results show that the rate of platelet activation by thrombin, which are signaled with PAR-1 receptor in human, has a marked effect on the size of thrombi in low flow rate condition suggesting the benefit of blocking this receptor in low blood flow condition such as venous thrombosis.

Performance Research on the Axial Flow Fan Adding Guide Vane

2011 ◽  
Vol 228-229 ◽  
pp. 204-208
Author(s):  
Wang Rui ◽  
Yi Chun Wang ◽  
Hong Fei Zheng ◽  
Chao Qing Feng
Keyword(s):  
Numerical Simulation ◽  
Mass Flow ◽  
Cooling System ◽  
Guide Vane ◽  
Axial Flow ◽  
Experiment Research ◽  
Axial Flow Fan ◽  
Result Show ◽  
Performance Research ◽  
Better Than

Fan is a major part of the cooling system in the vehicle, axial flow fan is used very common recently. In order to improve the cooling capability, cooling fan’s structure has been changed; experiment research and numerical simulation are done for it. The result show that after adding guide vane to axial flow fan, its mass flow increases. At the same speed, the mass flow is increased by 20% when a rear guide vane is installed, and 15% of mass flow increase when the front guide vane is installed, which indicates that a mixed flow fan could be increased in flow and improved in performance if the guide vanes are installed. Rear guide vane is better than front guide vane in the aspect of improving mass flow. Take front guide vane as an example, adopting the NUMECA for numerical simulation, the result is as similar as the experiment’s.

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