scholarly journals Numerical investigation on the effect of second throat diameter on two-throat nozzle ejector

2021 ◽  
Vol 2047 (1) ◽  
pp. 012020
Author(s):  
F T Jia ◽  
D Z Yang ◽  
J Xie
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Simulation Model ◽  
Flow Velocity ◽  
Working Conditions ◽  
Static Pressure ◽  
Two Phase ◽  
Entrainment Ratio ◽  
Mixing Chamber ◽  
Throat Diameter

Abstract The employment of two-phase ejectors in the CO2 refrigeration systems is widely developed recently. Due to the lack reports on the two-throat nozzle ejectors, the performance of CO2 two-throat nozzle ejector varied with different second throat diameter (D t ) was numerically investigated under different primary pressures (P p ). The accuracy of established numerical simulation model was confirmed with the assistance of experimental data summarized in the literature. The simulated results show that the two-throat nozzle ejector performance corresponding to entrainment ratio (Er) is of better stability with relatively bigger D t under different working conditions. Next, the axial static pressure corresponding to bigger D t is lower than that of smaller one at pre-mixing chamber. And the secondary flow velocity of bigger D t is accelerated better as compared to that of smaller one.

Numerical Simulation of Performance of Steam Ejector Influenced by the Distance between Nozzle Outlet and Mixing Chamber Inlet

2011 ◽  
Vol 299-300 ◽  
pp. 970-973
Author(s):  
Xiao Chun Dai ◽  
Guo Jin Liao
Keyword(s):  
Numerical Simulation ◽  
Geometric Parameters ◽  
Experimental Results ◽  
Nozzle Outlet ◽  
Entrainment Ratio ◽  
Optimum Range ◽  
Steam Ejector ◽  
Mixing Chamber ◽  
Throat Diameter

The performance of a steam ejector was simulated using FLUENT. The performance of steam ejector was studied by changing the distance between primary nozzle outlet and mixing chamber inlet (DPM) while operating pressures and other geometric parameters were not varied. The entrainment ratios of the steam ejector with different values of DPM were calculated. The optimum range of DPM was given, which is changed from 1.8 to 2 times of the throat diameter of hybrid diffuser pipe. The errors of the CFD results to the experimental results of the entrainment ratio are not more than 15%.

Numerical Simulation on Flow Structure of a Steam-Jet Pump Influenced by Primary Nozzle Geometries

2011 ◽  
Vol 130-134 ◽  
pp. 1703-1707 ◽  
Author(s):  
Xiao Chun Dai ◽  
Jian Huo
Keyword(s):  
Fluid Dynamics ◽  
Flow Structure ◽  
Mixing Process ◽  
Nozzle Outlet ◽  
Jet Pump ◽  
Entrainment Ratio ◽  
Great Loss ◽  
Mixing Chamber ◽  
Throat Diameter ◽  
Nozzle Geometries

The aim of the paper is to reveal the flow structure and the mixing process of a steam-jet pump by using a computational fluid dynamics code FLUENT. Discusses the effect on a steam-jet pump’s entrainment ratio when the throat diameter of the primary nozzle as well as the outlet diameter of the primary nozzle is varied. Analyzes the position of shock wave which will bring the steam-jet pump’s performance a great loss. The performances of a steam-jet pump are studied by changing back pressures while the distance between primary nozzle outlet and mixing chamber inlet (DPM) is varied. The entrainment ratios of a steam-jet pump with different values of DPM and different back pressures are calculated.

Research of NOx Emissions Characteristic of Engine Fuelled with M40

2011 ◽  
Vol 382 ◽  
pp. 22-25
Author(s):  
Xin Guang Li ◽  
Bing Yuan Han ◽  
Rong Hai Yang
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Simulation Model ◽  
Compression Ratio ◽  
Gasoline Engine ◽  
Volume Ratio ◽  
Nox Emissions ◽  
Cylinder Pressure ◽  
Variable Parameters ◽  
Vehicle Engine

A numerical simulation model for gasoline engine was established by GT-POWER in order to study the NOx emissions characteristic of vehicle engine fuelled with M40 (the methanol and the gasoline in volume ratio 40∶60) and was validated by Experimental data. Based on the model, the variable parameters study including air-fuel radio, compression radio and ignition advance angle were carried out. The model results showed that the compression radio and the air-fuel radio played an important role during the NOx emissions characteristic. There is a significant improvement of the NOx emissions with the compression ratio increases. The cylinder pressure increased with the improvement of the compression ratio brought out the NOx emissions rise. With the improvement of the air-fuel ratio, NOx emissions increased first and then decreased. A larger ignition advance angle can increase the pressure and the temperature of the cylinder.

Paper 30: A Theory for the Prediction of Local Phase Velocity, Static Pressure and Amount Condensed for Condensing Annular Flow in Tubes

1969 ◽  
Vol 184 (7) ◽  
pp. 64-69
Author(s):  
A. Porteous
Keyword(s):  
Experimental Data ◽  
Phase Velocity ◽  
Annular Flow ◽  
Static Pressure ◽  
Interfacial Shear ◽  
Phase Flow ◽  
Local Phase ◽  
Two Phase ◽  
Condensate Film ◽  
Comparison With Experimental Data

This paper presents a theory for condensing fluid flow in pipes. The theory incorporates the Reynolds flux concepts, advanced by Silver and Silver and Wallis, to account for the modification of interfacial shear when a phase change occurs across an interface. The basic theory is applicable to any fluid condensing in the annular two-phase flow régime and enables good predictions to be made for the local values of phase velocity, static pressure, and amount condensed. A comparison has been made with published experimental data for steam condensing with velocities in the range 380–730 ft/s, i.e. turbulent vapour core and a laminar/turbulent condensate film. A further outcome of the comparison with experimental data is a rationalization of the Reynolds flux concept with less empirical modification.

Numerical Simulation for Peripheral Milling of Aero-Aluminum Alloy Based on 3D FE Model

2013 ◽  
Vol 589-590 ◽  
pp. 3-7
Author(s):  
Kui Hu Cui ◽  
Cheng Zu Ren ◽  
Guang Chen
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Aluminum Alloy ◽  
Simulation Model ◽  
Depth Of Cut ◽  
Fe Model ◽  
Peripheral Milling ◽  
Side Edge ◽  
Simulation Results ◽  
Aluminum Alloy 7075

In this paper, an advanced 3D FE model was established using ABAQUS Explicit to simulate the process of milling aluminum-alloy 7075-T7451. Taking the end edge and the side edge of single flute into consideration, the model simulated the interaction between the spiral flute and wokpiece at full depth of cut. In addition, by defining automatic element deletion criterion and locally refining mesh, this model realized chip separating from workpiece without defining of cutting layer. The simulation results were compared with experimental data to verify the correctness of the simulation model.

TWO-PHASE MODEL IN VISCOELASTICITY AND VISCOPLASTICITY OF SEMICRYSTALLINE POLYMERS

2012 ◽  
Vol 01 (02) ◽  
pp. 1250015
Author(s):  
A. D. DROZDOV ◽  
N. DUSUNCELI
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Constitutive Model ◽  
Isotactic Polypropylene ◽  
Mechanical Response ◽  
Semicrystalline Polymers ◽  
Two Phase ◽  
Amorphous Phases ◽  
Characteristic Features ◽  
Tensile Relaxation

Observations are reported on isotactic polypropylene in tensile relaxation tests and in loading–unloading tests followed by relaxation after retraction at temperatures ranging from room temperatures up to 100°C. A two-phase constitutive model is developed for the mechanical response of semicrystalline polymers where crystalline and amorphous phases are treated as viscoelastoplastic continua with different laws of plastic flow. Adjustable parameters in the stress–strain relations are found by fitting the observations. Ability of the model to describe characteristic features of the viscoelastic and viscoplastic behavior of polypropylene at various temperatures is confirmed by numerical simulation and comparison of its results with experimental data in additional tests.

Comparison of experimental data and numerical simulation of two-phase flow pattern in vertical minichannel

2012 ◽  
Vol 33 (1) ◽  
pp. 63-71
Author(s):  
Jarosław Sowiński ◽  
Marek Krawczyk ◽  
Marek Dziubiński
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Boundary Conditions ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Computational Domain ◽  
Two Phase ◽  
Ansys Fluent ◽  
Satisfactory Description

Comparison of experimental data and numerical simulation of two-phase flow pattern in vertical minichannel The aim of the study was the implementation of a numerical simulation of the air-water two-phase flow in the minichannel and comparing results obtained with the values obtained experimentally. To perform the numerical simulations commercial software ANSYS FLUENT 12 was used. The first step of the study was to reproduce the actual research installation as a three-dimensional model with appropriate and possible simplifications - future computational domain. The next step was discretisation of the computational domain and determination of the types of boundary conditions. ANSYS FLUENT 12 has three built-in basic models with which a two-phase flow can be described. However, in this work Volume-of-Fluid (VOF) model was selected as it meets the established requirements of research. Preliminary calculations were performed for a simplified geometry. The calculations were later verified whether or not the simplifications of geometry were chosen correctly and if they affected the calculation. The next stage was validation of the chosen model. After positive verification, a series of calculations was performed, in which the boundary conditions were the same as the starting conditions in laboratory experiments. A satisfactory description of the experimental data accuracy was attained.

Numerical Simulation and Experimental Research on a Splash-Proof Water Injector

2011 ◽  
Vol 291-294 ◽  
pp. 2866-2870
Author(s):  
Zhong Yi Wang ◽  
Jia Han ◽  
Xu Yang ◽  
Tao Sun
Keyword(s):  
Numerical Simulation ◽  
Working Conditions ◽  
Domain Model ◽  
Calculation Methods ◽  
Two Phase ◽  
Simulation Research ◽  
Vof Model ◽  
Velocity Flow ◽  
Simulation Results ◽  
Experimental Researches

In this thesis, a model of water injector is established, which can prevent water from splashing when high-velocity flow pours into a container. With the periodic boundary, the 1/18 calculation domain model is built. Then two-phase flow numerical simulation research is done on the device with the steady VOF model. The influencing factors of water injector's performance and the variation laws under different working conditions are obtained. The reliability of the results is improved by comparing the results from different calculation methods with that from steady-state VOF method. And through the experimental researches on the splash-proof water injector, the accuracy of the numerical simulation results is validated.

scholarly journals Mathematical modeling of heat transfer in a closed two- phase thermosyphon

2019 ◽  
Vol 21 (3) ◽  
pp. 3-13
Author(s):  
V. I. Maksimov ◽  
A. Е. Nurpeiis
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Heat Flow ◽  
Problem Solution ◽  
Two Phase ◽  
Evaporation Zone ◽  
Characteristic Temperatures ◽  
Simulation Results

We suggested a new approach for describing heat transfer in thermosyphons and determining the characteristic temperatures. The processes of thermogravitation convection in the coolant layer at the lower cap, phase transitions in the evaporation zone, heat transfer as a result of conduction in the lower cap are described at the problem statement. The main assumption, which was used during the problem formulation, is that the characteristic times of steam motion through the thermosyphon channel are much less than the characteristic times of thermal conductivity and free convection in the coolant layer at the lower cap of the thermosyphon. For this reason, the processes of steam motion in the thermosyphon channel, the condensate film on the upper cap and the vertical walls were not considered. The problem solution domain is a thermosyphon through which heat is removed from the energy-saturated equipment. The ranges of heat flow changes were chosen based on experimental data. The geometric parameters of thermosyphon and the fill factors were chosen the same as in the experiments (height is 161 mm, diameter is 42 mm, wall thickness is 1.5 mm, ε=4-16%) for subsequent comparison of numerical simulation results and experimental data. In the numerical analysis it was assumed that the thermophysical properties of thermosyphon and coolant caps do not depend on temperature; laminar flow regime was considered. The dimensionless equations of vortex, Poisson and energy transfer for the liquid coolant under natural convection and the equations of thermal conductivity for the lower cap wall are solved by the method of finite differences. Numerical simulation results showed the relationship between the characteristic temperatures and the heat flow supplied to the bottom cap of thermosyphon. The results of the theoretical analysis are in satisfactory agreement with the known experimental data. 

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