scholarly journals Numerical Analysis of Supersonic Impinging Jet Flows of Particle-Gas Two Phases

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 191
Author(s):  
Zhang ◽  
Ma ◽  
Kim ◽  
Lin
Keyword(s):  
Shear Stress ◽  
Supersonic Nozzle ◽  
Particle Diameter ◽  
Impinging Jet ◽  
Continuous Phase ◽  
Jet Flows ◽  
Discrete Phase Model ◽  
Sonic Nozzle ◽  
Supersonic Impinging Jet ◽  
Two Phases

Supersonic impinging jet flows always occur when aircrafts start short takeoff and vertical landing from the ground. Supersonic flows with residues produced by chemical reaction of fuel mixture have the potential of reducing aircraft performance and landing ground. The adverse flow conditions such as impinging force, high noise spectrum, and high shear stress always take place. Due to rare data on particle-gas impinging jet flows to date, three-dimensional numerical simulations were carried out to investigate supersonic impinging jet flows of particle-gas two phases in the present studies. A convergent sonic nozzle and a convergent-divergent supersonic nozzle were used to induce supersonic impinging jet flows. Discrete phase model (DPM), where interaction with continuous phase and two-way turbulence coupling model were considered, was used to simulate particle-gas flows. Effects of different particle diameter and Stokes number were investigated. Particle mass loading of 10% were considered for all simulations. Gas and particle velocity contours, wall shear stress, and impinging force on the ground surface were obtained to describe different phenomena inside impinging and wall jet flows of single gas phase and gas-particle two phases.

Electrowetting Induced Droplet Generation in T-junctions

2021 ◽  
Author(s):  
Arshia Merdasi ◽  
Ali Moosavi
Keyword(s):  
Shear Stress ◽  
Continuous Phase ◽  
Droplet Breakup ◽  
Droplet Generation ◽  
The Finite Element Method ◽  
Fluidic Channel ◽  
Generation Frequency ◽  
Two Phases ◽  
Breakup Time ◽  
Good Agreement

Abstract In the current study, droplet generation in a T-junction fluidic channel device was studied through using electrowetting actuation with the consideration of different droplet forming regimes. For this purpose, the finite element method (FEM) was used to solve the unsteady Naiver-Stokes equation. In addition, the level set method was applied to capture the interface between two phases. It was shown that there was a good agreement between obtained data and other work during the process of droplet generation in the absence of electrowetting actuation which results in decrease in the size of droplet with increasing the velocity ratios. In shearing regime, the effectiveness of electrowetting on the droplet generation frequency as well as droplet size is visible in a T-junction fluidic channel since after applying voltages, specified with non-dimensional electrowetting numbers of ?=0.5 and 1.2, dispersed phase is pulled out into the oil phase. In fact, with applying the voltage on the top wall, the droplet breakup time was decreased and smaller droplets were produced. Finally, different important parameters such as pressure difference across the interface as well as Shear Stress exerted from the continuous phase shear stress were examined in a detail.

Control of supersonic impinging jet flows using microjets

2000 ◽  
Author(s):  
F. Alvi ◽  
R. Elavarasan ◽  
C. Shih ◽  
G. Garg ◽  
A. Krothapalli
Keyword(s):  
Impinging Jet ◽  
Jet Flows ◽  
Supersonic Impinging Jet

Study on Drug Powder Acceleration in a Micro Shock Tube

2015 ◽  
Author(s):  
Guang Zhang ◽  
Heuy Dong Kim ◽  
Yingzi Jin ◽  
Toshiaki Setoguchi
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
Shock Tube ◽  
Gas Flow ◽  
Stokes Equations ◽  
Supersonic Nozzle ◽  
Particle Diameter ◽  
Shock Wave Propagation ◽  
Finite Volume Scheme ◽  
Discrete Phase Model

Recently, needle-free drug delivery systems have been widely used for delivering drug particles into human body without any external needles in medical fields. Drug powders should be accelerated to obtain enough momentum to be delivered into the suitable layer of the skin. This is achieved by accelerating drug particles in a Contoured Shock Tube (CST) which consists of a micro shock tube and an expanded supersonic nozzle. Shock wave happens in micro shock tube, and supersonic flow with particles is induced by the shock wave and accelerated in the expanded nozzle. Even though micro shock tubes have been studied for a long time, detailed experimental data for shock waves and particle-gas flows are sparse to date and it is very important to investigate the complicated particle-gas flow fields for practical applications. In the present study, Particle Tracking Velocimetry (PTV) was used to measure the average velocity of the gas-particle flow behind the propagating shock wave. Unsteady flow properties and shock wave propagation were analyzed by this instantaneous particle velocity fields. Numerical simulation was performed with unsteady compressible Naver-stokes equations which were solved by using a fully implicit finite volume scheme. Discrete Phase Model (DPM) has been used for simulating particle-gas two-phase flows. Different particle diameter and density were performed in present numerical studies. Unsteady particle-gas flow characteristics and shock wave propagation have been studied and analyzed in details in present micro shock tube model.

Control of Supersonic Impinging Jet Flows Using Supersonic Microjets

AIAA Journal ◽  
2003 ◽  
Vol 41 (7) ◽  
pp. 1347-1355 ◽  
Author(s):  
F. S. Alvi ◽  
C. Shih ◽  
R. Elavarasan ◽  
G. Garg ◽  
A. Krothapalli
Keyword(s):  
Impinging Jet ◽  
Jet Flows ◽  
Supersonic Impinging Jet

Oscillatory behavior of supersonic impinging jet flows

Shock Waves ◽  
2005 ◽  
Vol 14 (4) ◽  
pp. 259-272 ◽  
Author(s):  
S. I. Kim ◽  
S. O. Park
Keyword(s):  
Impinging Jet ◽  
Oscillatory Behavior ◽  
Jet Flows ◽  
Supersonic Impinging Jet

scholarly journals Effects of Blade Parameters on the Flow Field and Classification Performance of the Vertical Roller Mill via Numerical Investigations

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Chang Liu ◽  
Zuobing Chen ◽  
Weili Zhang ◽  
Chenggang Yang ◽  
Ya Mao ◽  
...  
Keyword(s):  
Flow Field ◽  
Pressure Difference ◽  
Continuous Phase ◽  
Classification Performance ◽  
Field Analysis ◽  
Discrete Phase Model ◽  
Roller Mill ◽  
Discrete Phase ◽  
Vertical Roller ◽  
Classification Efficiency

The vertical roller mill is an important crushing and grading screening device widely used in many industries. Its classification efficiency and the pressure difference determine the entire producing capacity and power consumption, respectively, which makes them the two key indicators describing the mill performance. Based on the DPM (Discrete Phase Model) and continuous phase coupling model, the flow field characteristics in the vertical roller mill including the velocity and pressure fields and the discrete phase distributions had been analyzed. The influence of blade parameters like the shape, number, and rotating speed on the flow field and classification performance had also been comprehensively explored. The numerical simulations showed that there are vortices in many zones in the mill and the blades are of great significance to the mill performance. The blade IV not only results in high classification efficiency but also reduces effectively the pressure difference in the separator and also the whole machine. The conclusions of the flow field analysis and the blade effects on the classification efficiency and the pressure difference could guide designing and optimizing the equipment structure and the milling process, which is of great importance to obtain better overall performance of the vertical roller mill.

scholarly journals Enhanced discrete phase model for multiphase flow simulation of blood flow with high shear stress

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042110080
Author(s):  
Zheqin Yu ◽  
Jianping Tan ◽  
Shuai Wang
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Multiphase Flow ◽  
Experimental Verification ◽  
Flow Simulation ◽  
Turbulence Models ◽  
Phase Model ◽  
Force Model ◽  
Discrete Phase Model ◽  
Discrete Phase

Shear stress is often present in the blood flow within blood-contacting devices, which is the leading cause of hemolysis. However, the simulation method for blood flow with shear stress is still not perfect, especially the multiphase flow model and experimental verification. In this regard, this study proposes an enhanced discrete phase model for multiphase flow simulation of blood flow with shear stress. This simulation is based on the discrete phase model (DPM). According to the multiphase flow characteristics of blood, a virtual mass force model and a pressure gradient influence model are added to the calculation of cell particle motion. In the experimental verification, nozzle models were designed to simulate the flow with shear stress, varying the degree of shear stress through different nozzle sizes. The microscopic flow was measured by the Particle Image Velocimetry (PIV) experimental method. The comparison of the turbulence models and the verification of the simulation accuracy were carried out based on the experimental results. The result demonstrates that the simulation effect of the SST k- ω model is better than other standard turbulence models. Accuracy analysis proves that the simulation results are accurate and can capture the movement of cell-level particles in the flow with shear stress. The results of the research are conducive to obtaining accurate and comprehensive analysis results in the equipment development phase.

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