Numerical Study of Classification of Ultrafine Particles in a Gas-Solid Field of Elbow-Jet Classifier

2005 ◽  
Author(s):  
Shibin Liang
Keyword(s):  
Flow Field ◽  
Ultrafine Particles ◽  
High Speed ◽  
Numerical Study ◽  
Experimental Results ◽  
Speed Flow ◽  
Fluent Software ◽  
Air Classifier ◽  
Different Diameters

Computational fluid dynamics (CFD) is applied to develop a novel submicron air classifier. Based on different inner structure sizes and positions in the elbow-jet classifier, the two-dimensional air flow field has been simulated by the Fluent software. The Coanda-effect plays a paramount role in the separation of ultrafine particles in the high-speed flow field of the elbow-jet classifier. The effects on the features of the Coanda element, i.e. a half-cylinder, have been analyzed and discussed. The trajectories of moving particles with different diameters in the channels and chambers of the classifier have been calculated under the velocity field simulation results obtained by the CFD analysis. The cut sizes of three products at the related outlets of the classifier are obtained based on the trajectories calculation of the particles and compared with the corresponding experimental results. The ground/classified experiment has been conducted by using the products outlet of a vortex jet mill as the particles feed of the elbow-jet classifier. The experimental results show that the external classifier for the vortex jet mill improves the classification of the mill significantly. The combination of the vortex jet mill with the external classifier provides a new choice of the grinding equipment for the multiple size products of fine/medium/coarse powders. A centrifugal channel has been added between the vortex jet mill and the elbow-jet classifier to improve the performance of the air classifier. Both numerical and experimental results show that the pre-distributed feed powders at the exit of the centrifugal channel have a strong effect on the fine powders separation and a less effect on the coarse powders separation.

Experimental Study of Turbulent Macroinstabilities in an Agitated System with Axial High-Speed Impeller and with Radial Baffles

1996 ◽  
Vol 61 (6) ◽  
pp. 856-867 ◽  
Author(s):  
Oldřich Brůha ◽  
Ivan Fořt ◽  
Pavel Smolka ◽  
Milan Jahoda
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
High Speed ◽  
Experimental Results ◽  
Turbulent Regime ◽  
Frequency Of Occurrence ◽  
Visualization Method ◽  
Entire Flow

The frequency of turbulent macroinstability occurrence was measured in liquids agitated in a cylindrical baffled vessel. As it has been proved by preceding experimental results of the authors, the stochastic quantity with frequency of occurrence of 10-1 to 100 s-1 is concerned. By suitable choosing the viscosity of liquids and frequency of impeller revolutins, the region of Reynolds mixing numbers was covered from the pure laminar up to fully developed turbulent regime. In addition to the equipment making it possible to record automatically the macroinstability occurrence, also the visualization method and videorecording were employed. It enabled us to describe in more detail the form of entire flow field in the agitated system and its behaviour in connection with the macroinstability occurrence. It follows from the experiments made that under turbulent regime of flow of agitated liquids the frequency of turbulent macroinstability occurrence is the same as the frequency of the primary circulation of agitated liquid.

scholarly journals Numerical simulation and experimental research of cavitation nozzle based on equation curve

2021 ◽  
Author(s):  
Lifu Wang ◽  
Dongyan Shi ◽  
Zhixun Yang ◽  
Guangliang Li ◽  
Chunlong Ma ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Flow Field ◽  
High Speed ◽  
Quadratic Equation ◽  
Outer Contour ◽  
Study Results ◽  
Fluent Software ◽  
The Impact ◽  
Better Than

Abstract To further investigate and improve the cleaning ability of the cavitation nozzle, this paper proposes a new model that is based on the Helmholtz nozzle and with the quadratic equation curve as the outer contour of the cavitation chamber. First, the numerical simulation of the flow field in the nozzle chamber was conducted using FLUENT software to analyze and compare the impact of the curve parameters and Reynolds number on the cleaning effect. Next, the flow field was captured by a high-speed camera in order to study the cavitation cycle and evolution process. Then, experiments were performed to compare the cleaning effect of the new nozzle with that of the Helmholtz nozzle. The study results demonstrate that effective cavitation does not occur when the diameter of the cavitation chamber is too large. For the new nozzle, with the increase of the Reynolds number, the degree of cavitation in the chamber first increases and then decreases; the cleaning effect is much better than that of a traditional Helmholtz nozzle under the same conditions; the nozzle has the best cleaning effect for the stand-off distance of 300 mm.

The effect analysis of an engine jet on an aircraft blast deflector

2018 ◽  
Vol 41 (4) ◽  
pp. 990-1001
Author(s):  
Song Ma ◽  
Jianguo Tan ◽  
Xiankai Li ◽  
Jiang Hao
Keyword(s):  
High Temperature ◽  
Flow Field ◽  
High Speed ◽  
Deflection Angle ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Aircraft Engine ◽  
Experimental Results ◽  
Exhaust Gases ◽  
The Impact

This paper establishes a novel mathematical model for computing the plume flow field of a carrier-based aircraft engine. Its objective is to study the impact of jet exhaust gases with high temperature, high speed and high pressure on the jet blast deflector. The working condition of the nozzle of a fully powered on engine is first determined. The flow field of the exhaust jet is then numerically simulated at different deflection angle using the three-dimensional Reynolds averaged Navier–Stokes equations and the standard [Formula: see text]-[Formula: see text] turbulence method. Moreover, infra-red temperature tests are further carried out to test the temperature field when the jet blast deflector is at the [Formula: see text] deflection angle. The comparison between the simulation results and the experimental results show that the proposed computation model can perfectly describe the system. There is only 8–10% variation between them. A good verification is achieved. Moreover, the experimental results show that the jet blast deflector plays an outstanding role in driving the high-temperature exhaust gases. It is found that [Formula: see text] may be the best deflection angle to protect the deck and the surrounding equipment effectively. These data results provide a valuable basis for the design and layout optimization of the jet blast deflector and deck.

Analysis of the Behavior of Droplet Impinging on a Curved Dry Wall in a Rotating Flow Field

2020 ◽  
Author(s):  
Shuo Ouyang ◽  
Zhenqin Xiong
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Nuclear Power ◽  
Rotating Flow ◽  
Droplet Deformation ◽  
Wind Speeds ◽  
Boundary Information ◽  
Different Diameters ◽  
The Impact ◽  
Steam Separator

Abstract Steam water separator is the core equipment of nuclear power plant. It is very vital for improving the efficiency of the steam separator to study the impact characteristics between the droplets and the curved dry wall of the steam separator under the action of the rotating air flow. In this paper, the characteristics of droplet impinging on the dry wall in the rotating flow field are analyzed by establishing a visualization experimental device. A high-speed camera was used to capture the impact of droplets with different diameters on the dry wall of a non-wetting curved surface at different gas velocities. At the same time, using image processing tool in MATLAB to obtain image boundary information. The characteristics of spreading factor, droplet deformation factor and initial diffusion velocity of droplets impacting the surface dry wall under different wind speeds are studied.

Numerical and Experimental Study on Soot Accumulation on the Wall of Falling Fuel Film Micro-Combustor

2010 ◽  
Author(s):  
Ning Mei ◽  
Xiaoyan Wang ◽  
Hongming Zhao ◽  
Yan Li ◽  
Hongyu Si
Keyword(s):  
Flow Field ◽  
Combustion Chamber ◽  
Turbulence Model ◽  
Complex Structure ◽  
Flow Distribution ◽  
Experimental Results ◽  
Fuel Film ◽  
Numerical Result ◽  
Different Diameters ◽  
Micro Combustor

Fluid flow contributes much to fuel-air mixture formation in a micro-combustor, the RNG k-ε turbulence model was used to simulate the cold flow field of a falling fuel film microcombustor, and comparison was made between numerical result and experimental results. It is shown that the RNG k-ε turbulence model translated the flow field of a complex structure micro-combustor and the soot accumulation on the wall of combustion chamber. The experimental results showed that soot accumulation occurs in vortex backflow area near the wall of combustion chamber and the numerical methods is helpful for understanding the way of soot accumulation in the wall of combustion chamber. Therefore, modifications on the flow field with different diameters and entrance direction of the air flow into the primary combustion chamber were made. The numerical simulation of flow distribution showed that the flow field of micro-combustor could be ideal for eliminated soot accumulation.

Condensation Phenomena in High Speed Flow of Steam—Experimental Apparatus

1973 ◽  
Vol 187 (1) ◽  
pp. 199-205 ◽  
Author(s):  
B. A. Campbell ◽  
F. Bakhtar
Keyword(s):  
Cross Section ◽  
Test Section ◽  
High Speed ◽  
Rectangular Cross Section ◽  
Experimental Results ◽  
Theoretical Treatment ◽  
Wet Steam ◽  
High Speed Flow ◽  
Speed Flow ◽  
Experimental Apparatus

The paper describes a steam circuit for studies of nucleation and behaviour of wet steam. The test section is a duct of rectangular cross-section in which particular geometries are produced by fitting shaped profiles to its sides. To deliver steam to the test section, at required conditions, a turbine, cooler and superheater are included in the circuit. The experimental results presented are concerned with the variations of Wilson point as a function of pressure. Comparisons are made with the results of a theoretical treatment already published (1)‡ and agreement is shown to be good.

Numerical Study of Interior Trajectory of Missile Ejection Based on Mechanics

2012 ◽  
Vol 485 ◽  
pp. 616-619 ◽  
Author(s):  
Yong Quan Liu ◽  
An Min Xi ◽  
Hong Fei Liu
Keyword(s):  
Flow Field ◽  
Test Data ◽  
Numerical Study ◽  
Phase Problem ◽  
Source Terms ◽  
Two Phase ◽  
Trajectory Simulation ◽  
Fluid Equations ◽  
Fluent Software ◽  
Good Agreement

An interior trajectory simulation of the gas-steam missile ejection has been developed with the help of FLUENT software. One of the special features of this simulation is the method by which the coupled two-phase problem is reduced to solving the fluid equations only. The calculation has been done efficiently in FLUENT after setting all the required parameters and adding the source terms. Several figures of the velocity and pressure have been given to show the flow field in the reservoir. The distribution curves of the velocity and acceleration of the missile show that the results of the simulation are in good agreement with the test data of the experiments. This model can be used to analyze the similar launch procedures in practice.

Effect of housing surface roughness on the performance of a centrifugal compressor for turbocharger: Experimental and numerical study

2021 ◽  
pp. 146808742110475
Author(s):  
Ealumalai Karunakaran ◽  
Sanket Mulye ◽  
Jawali Maharudrappa Mallikarjuna
Keyword(s):  
Surface Roughness ◽  
Numerical Analysis ◽  
Centrifugal Compressor ◽  
High Speed ◽  
Numerical Study ◽  
Experimental Results ◽  
Wall Turbulence ◽  
Low Flow ◽  
Pressure Losses ◽  
Compressor Performance

Centrifugal compressor plays a vital role in the performance of a turbocharger. The compressor contains an impeller and housing, including the vaneless diffuser and a volute. The high-speed flow from the impeller is diffused in the diffuser and volute, before being delivered to the engine. Hence, the housing flow characteristics affect the compressor performance and operating range. Generally, housing has noticeable surface roughness, especially in the volute. This study evaluates the effect of the volute surface roughness on the compressor performance by experimental and numerical analysis. The experiments are conducted for three different volute surface roughness levels to measure the overall compressor pressure ratio and efficiency. The uncertainty in the efficiency for experimental results is within ±0.5% pts. Also, steady-state numerical simulations are performed to analyse the flow mechanisms causing pressure losses. Then, a numerical analysis is done to understand the effect of roughness of the diffuser hub and shroud walls on the compressor performance. From the experimental results, it is found that the increase in the roughness level of the volute from the smooth surface by circa 900% and 1400% shows a significant reduction in the compressor efficiency at the design speed (N) and off-design speeds (0.87 and 1.13 N). The reductions of efficiency are about 0.5%–1% pts at the near surge point, 1%–1.5% pts at the peak efficiency point and 2%–2.5% pts at the near choke flow point. The CFD analyses show significantly higher near-wall turbulence and wall shear resulting in additional pressure losses. Also, it is found that the pressure losses are more sensitive to roughness of the diffuser shroud-wall than that of the hub-wall. On the other hand, the diffuser hub-wall roughness increases the radial momentum in the diffuser passage which suppress the flow separation at low flow rates.

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