scholarly journals Thermal Diffusion Performance of a Diffuser by various Guide Vanes configurations

2018 ◽  
Vol 225 ◽  
pp. 03018
Author(s):  
Aja O. Chikere ◽  
Hussain H. Al-Kayiem ◽  
Zainal Ambri A. Karim

The use of vane-less diffuser with large diffusion angle has shown a setback in the diffusion process of high temperature working fluids. The hot gas flow was characterized as a jet-like flow. This paper presents problem, encountered practically, using a vane-less diffuser with large diffusion angle and how the problem is solved by CFD simulation. The investigated thermal diffuser has a length of 0.3 m, an inlet to outlet crosssectional area ratio of 1:25 and diffusion angle of 115.44o. To resolve the jet-like flow problem and poor distribution of the flow temperature at the diffuser outlet, the study suggested the use of guide-vanes into the diffuser. The study employed CFD simulation by ANSYS-FLUENT software to analyze the flow and thermal process in the diffuser. Three different shapes of guide vanes; block-shaped, oval-shaped and airfoil-shaped were considered in this study and at different vanes diffusion angles, as well as vane-less case, which was adopted as the bench mark case. The simulation results of the velocity, temperature and pressure at the diffuser outlet were compared for all cases. It was found that the guide vanes with symmetrical airfoil profile provided the best performance with most uniform distribution at the outlet of the diffuser. Also, the airfoil-shaped guide vanes resulted in lower pressure losses compared to the block-shaped and oval-shaped guide vanes. According to the analysis results, the diffuser was redesigned to improve the diffusion and temperature distribution across the diffuser outlet.

Author(s):  
Michel Arnal ◽  
Christian Precht ◽  
Thomas Sprunk ◽  
Tobias Danninger ◽  
John Stokes

The present paper outlines a practical methodology for improved virtual prototyping, using as an example, the recently re-engineered, internally-cooled 1st stage blade of a 40 MW industrial gas turbine. Using the full 3-D CAD model of the blade, a CFD simulation that includes the hot gas flow around the blade, conjugate heat transfer from the fluid to the solid at the blade surface, heat conduction through the solid, and the coolant flow in the plenum is performed. The pressure losses through and heat transfer to the cooling channels inside the airfoil are captured with a 1-D code and the 1-D results are linked to the three-dimensional CFD analysis. The resultant three-dimensional temperature distribution through the blade provides the required thermal loading for the subsequent structural finite element analysis. The results of this analysis include the thermo-mechanical stress distribution, which is the basis for blade life assessment.


Author(s):  
Mahbub Ahmed ◽  
Cheng Zhang ◽  
Scott McKay ◽  
Vivek Shirsat ◽  
Jobaidur Khan

Hydrocarbon-based miniature power generators are promising any many application since hydrocarbon based fuels have higher power densities compared to conventional lithium batteries. A 40mm long meso-combustor of two different configurations, two-inlet and three-inlet, were used to investigate the combustion of methane in the meso-chamber. A non-premixed combustion of methane and oxygen was simulated numerically using a steady laminar flamelet model. The mesh generation and the CFD simulation were performed using ANSYS FLUENT software. A a finite volume approach was used for the simulation. The fuel-oxidizer mixing, thermal behavior and fuel burning efficiency were studied. An adequate mixing that supports the combustion was observed in certain locations. The exhaust gas was analyzed experimentally. The temperature distributions were also observed to predict the flame locations. According to the numerical analysis it was apparent that the flame would be anchored in the well mixed regions of the chamber the flames were found to be attached in two distinct locations. One in the upstream zone and the other one in the downstream zone. Another important finding was that the fuel lean condition produced higher efficiency than the fuel rich condition.


2018 ◽  
Vol 22 (6) ◽  
pp. 10-14 ◽  
Author(s):  
A.V. Dmitriev ◽  
I.N. Madyshev ◽  
O.S. Dmitrieva

In order to solve the problem of increasing the efficiency of purification of industrial gas emissions from aerosol particles, the authors developed a jet-film contact device, described the principle of its operation. The results of numerical studies to determine the efficiency of aerosol deposition on a fluid film of a jet-film contact device are presented. The study was carried out in the ANSYS Fluent software package, using the turbulence model of the k-ω SST model. Different variants of the ratio of the height to the width of the structure of the device are considered. The velocity of the gas flow and the sizes of the dispersed particles are changed. It is shown that to achieve high technical and economic performance of heat and mass transfer devices with jet-film contact devices, they should be designed taking into account the choice of optimum values for the height of the downcomer (kb = 0,46÷0,53).


2020 ◽  
Vol 315 ◽  
pp. 03003
Author(s):  
Vadim E. Zinurov ◽  
Oksana S. Dmitrieva ◽  
Oksana S. Popkova

The article deals with the problem of increasing the efficiency of dedusting the gas flow from the finely dispersed particles smaller than 10 μm. In order to solve this problem, a design of centrifugal separator with coaxially arranged pipes is proposed. The described principle of operation includes the large values of centrifugal forces, which take place inside the device when the flow is swirled, and these forces throw the finely dispersed particles to the walls of device. This scientific paper shows a numerical simulation of gas flow dedusting process by means of ANSYS Fluent software package. The efficiency of dedusting the gas from the finely dispersed particles of up to 10 μm in the device is on average within the range of 53.8–76.7%. The exponential function, describing the changes in the pressure loss from the input gas rate, is obtained. In the course of studies, it was found that the pressure loss in the device is not more than 800 Pa at the input gas rate from 3 to 19 m/s.


Author(s):  
V.B. Volovetskyi ◽  
Ya. Doroshenko ◽  
G. Kogut ◽  
A.P. Dzhus ◽  
I.V. Rybitskyi ◽  
...  

Purpose: The article implies theoretical and experimental studies of the liquid pollution accumulations impact on the efficiency of gathering gas pipelines operation at the Yuliivskyi oil and gas condensate production facility (OGCPF). Research of efficiency of gas pipelines cleaning by various methods. Design/methodology/approach: The research methodology consists of determining the hydraulic efficiency of gathering gas pipelines before and after cleaning of their internal cavity by different methods and comparing the obtained results, which allows to objectively evaluate the efficiency of any cleaning method. CFD simulation of gas-dynamic processes in low sections of gas pipelines with liquid contaminants. Findings: Experimental studies of cleaning efficiency in the inner cavity of the gas gathering pipelines of the Yuliivskyi OGCPF by various methods, including: supply of surfactant solution, creating a high-speed gas flow, use of foam pistons were performed. It was established that cleaning the inner cavity of gas gathering pipelines by supplying a surfactant solution leads to an increase in the coefficient of hydraulic efficiency by 2%-4.5%, creating a high-speed gas flow by 4%-7%, and under certain conditions by 8%-10 % and more. However, for two gas pipelines the use of foam pistons allowed to increase the coefficient of hydraulic efficiency from 5.7 % to 10.5 % with a multiplicity of foam from 50 to 90. be recommended for other deposits.The results of CFD simulation showed that the accumulation of liquid contaminants in the lowered sections of gas pipelines affects gas-dynamic processes and leads to pressure losses above the values provided by the technological regime. With the increase in liquid contaminants volume the pressure losses occur. Moreover, with a small amount of contamination (up to 0.006 m3), liquid contaminants do not have a significant effect on pressure loss. If the contaminants volume in the lowered section of the pipeline is greater than the specified value, the pressure loss increases by parabolic dependence. The increase in mass flow leads to an increase in the value of pressure loss at the site of liquid contamination. Moreover, the greater the mass flow, the greater the impact of its changes on the pressure loss. The CFD simulation performed made it possible not only to determine the patterns of pressure loss in places of liquid contaminants accumulation in the inner cavity of gas pipelines, but also to understand the gas-dynamic processes in such places, which is an unconditional advantage of this method over experimental. Research limitations/implications: The obtained simulation results showed that the increase in the volume of liquid contaminants in the inner cavity of gas gathering pipelines leads to an increase in pressure losses above the value provided by the technological regime. To achieve maximum cleaning of gas gathering pipelines, it is necessary to develop a new method that will combine the considered. Practical implications: The performed experimental results make it possible to take a more thorough approach to cleaning the inner cavity of gas gathering pipelines and to forecast in advance to what extent the hydraulic efficiency of gas gathering pipelines can be increased. Originality/value: The obtained results of CFD simulation of gas-dynamic processes in lowered sections of gas pipelines with liquid contaminants, experimental studies of the effectiveness of various methods of cleaning the inner cavity of gas gathering pipelines has original value.


Author(s):  
Jorge Contreras-Serna ◽  
Arturo Schiaffino ◽  
V. M. Krushnarao Kotteda ◽  
Alejandro J. García-Cuéllar ◽  
Vinod Kumar

Fragmentation of molten metal droplets is an important process in steam explosions caused by melt-coolant interactions. Ciccarelli and Frost (1994) found the formation of melt jets (or spikes) in hot melt drops immersed in water. In order to gain insight into this mechanism, they carried out experiments where melt jets were formed in a stratified water/liquid metal system with local generation of high-pressure vapor at the interface. This paper is dedicated to investigating how melt jets are formed in this mechanism when a stratified water/liquid metal system is analyzed. Also, a study of the most significant parameters in this process is performed. A 2D computational fluid dynamics (CFD) simulation is carried out using ANSYS Fluent software to study these phenomena by having water above hot liquid metal, a vapor film in between and a pressure pulse in the vapor film. The results show that the larger the pressure or density, the greater the melt jet length. In order to confirm this, deep neural network algorithm created by TensorFlow library was implemented to facilitate the understanding of the studied phenomena. The formation of melt jets observed in Ciccarelli and Frost’s experiments is also observed in current simulation.


Author(s):  
Rosyida Permatasari ◽  
Muhammad Alwan Ridhoarto ◽  
Sally Cahyati ◽  
Martinus Bambang Susetyarto

Various, different evaporator placements in a room have produced different airflow patterns, temperature distribution, and airflow velocities. In this study, the average room temperature and airflow velocity measured at 27 points of the CFD simulation for 4 positions of the planned evaporator placements were compared to determine the most ideal position based on the comfortable temperature and the maximum airflow velocity pursuant to the SNI 03-6572-2001 recommendation. On Position 1, two evaporators were given to the west wall. Position 2, two evaporators were placed on the south wall. On Position 3, two evaporators were given to the north wall. Moreover, on Position 4, two evaporators were placed opposite to each other where an evaporator was placed on the south wall, and the other evaporator was placed on the north wall. An ANSYS Fluent software was employed to make the CFD simulation. Based on the results of the study, it was found out that Position 2 was the most ideal evaporator placement position since it met the comfortable temperature limit and has the highest number of airflow velocity points meeting the recommended maximum airflow velocity pursuant to the SNI 03-6572-2001 recommendation.


2021 ◽  
Vol 1209 (1) ◽  
pp. 012019
Author(s):  
J Hrudka ◽  
M Šutúš ◽  
M Csóka ◽  
A Raczková ◽  
I Škultétyová

Abstract The paper deals with CFD simulation of a real combined sewer overflow chamber using Ansys fluent software. Simulations are created for various structural modifications. Within the results, the hydraulic parameters of the individual are evaluated with a proposal for optimal operation of the given relief chamber.


2019 ◽  
Vol 7 (1) ◽  
pp. 43-53
Author(s):  
Abbas Jassem Jubear ◽  
Ali Hameed Abd

The heat sink with vertically rectangular interrupted fins was investigated numerically in a natural convection field, with steady-state heat transfer. A numerical study has been conducted using ANSYS Fluent software (R16.1) in order to develop a 3-D numerical model.  The dimensions of the fins are (305 mm length, 100 mm width, 17 mm height, and 9.5 mm space between fins. The number of fins used on the surface is eight. In this study, the heat input was used as follows: 20, 40, 60, 80, 100, and 120 watts. This study focused on interrupted rectangular fins with a different arrangement and angle of the fins. Results show that the addition of interruption in fins in various arrangements will improve the thermal performance of the heat sink, and through the results, a better interruption rate as an equation can be obtained.


2003 ◽  
Vol 3 ◽  
pp. 208-219
Author(s):  
A.M. Ilyasov

In this paper we propose a model for determining the pressure loss due to friction in each phase in a three-layer laminar steady flow of immiscible liquid and gas flow in a flat channel. This model generalizes an analogous problem for a two-layer laminar flow, proposed earlier. The relations obtained in the final form for the pressure loss due to friction in liquids can be used as closing relations for the three-fluid model. These equations take into account the influence of interphase boundaries and are an alternative to the approach used in foreign literature. In this approach, the wall and interphase voltages are approximated by the formulas for a single-phase flow and do not take into account the mutual influence of liquids on the loss of pressure on friction in phases. The distribution of flow parameters in these two models is compared.


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