-
Natural Convection in a Partially Heated and Cooled Square Enclosure Containing a Diamond Shaped Heated Block
Kakali Chowdhury,
Abdul Alim,
Murad Hossen
Issue:
Volume 6, Issue 1, March 2020
Pages:
1-8
Received:
20 November 2019
Accepted:
11 December 2019
Published:
6 January 2020
Abstract: Finite element method is used to solve the two dimensional governing mass, momentum and energy equations for steady state, natural convection problem inside a square enclosure. The enclosure consists of adiabatic vertical walls, heated middle part of bottom wall and the cold (top wall and the rest part of bottom wall) walls and a uniformly heated diamond shaped solid body located somewhere inside the enclosure. The aim of this study is to describe the effect of different sizes and positions of diamond shaped heated block on natural convection. The investigations are conducted for different values of Rayleigh number (Ra), block length (l) and location of block center (Cx, Cy) inside the enclosure by using COMSOL multiphysics. Various results such as streamlines, isotherms, heat transfer rate in terms of the average Nusselt number and average fluid temperature inside the enclosure are presented for different parameters. The results indicate that the average Nusselt number at the heated surface and average temperature of the fluid inside the enclosure are strongly dependent on the configuration of the system under different geometrical and physical conditions. The average Nusselt number decreases with the increasing value of block size and increases in the free convection dominated region, it is maximum for Ra=106 and minimum for Ra=103. Block size also has significant effect on thermal fields. Average temperature increases with the increasing value of heated block.
Abstract: Finite element method is used to solve the two dimensional governing mass, momentum and energy equations for steady state, natural convection problem inside a square enclosure. The enclosure consists of adiabatic vertical walls, heated middle part of bottom wall and the cold (top wall and the rest part of bottom wall) walls and a uniformly heated d...
Show More
-
Oscillating Flow of Viscous Incompressible Fluid Through Sinusoidal Periodic Tube at Low Reynolds Number
Tithi Sikdar,
Nusrat Jahan Pinky,
Avijit Roy,
Shahid Shafayet Hossain,
Nazmul Islam
Issue:
Volume 6, Issue 1, March 2020
Pages:
9-18
Received:
28 October 2019
Accepted:
28 November 2019
Published:
7 January 2020
Abstract: The flow in tubes with periodically varying cross-section has many interests due to its various practical applications such as it can be used as particle separation devices. In this paper, we have examined the oscillatory flow of a viscous incompressible fluid in a sinusoidal periodic tube at low Reynolds number. The numerical study is undertaken to examine fluid movement at different cross-sections for different time. The boundary element method (BEM) has been formulated for the infinite sinusoidal periodic tube to solve the governing equations for obtaining components of surface force on the tube wall. We have calculated the axial and radial velocities at different cross-sections for different time and compared them. We find that the behaviors of the velocity curves for different cross-sections remain the same for the same phase of time over the oscillation. On the contrary, the behavior of the velocity curves become different for different phase of time. For the tube geometry, the axial velocity at the converging and diverging regions are the same while the radial velocity at these regions are the same in magnitudes but in opposite direction. In addition, the radial velocity is maximum in the half way between the tube axis and the tube wall, and it is minimum on the tube axis and on the tube wall. The obtained velocity indicates that the net fluid movement after each complete oscillation is zero, which is an assumption to separate particles in such periodic tube.
Abstract: The flow in tubes with periodically varying cross-section has many interests due to its various practical applications such as it can be used as particle separation devices. In this paper, we have examined the oscillatory flow of a viscous incompressible fluid in a sinusoidal periodic tube at low Reynolds number. The numerical study is undertaken t...
Show More
-
Design of a Radial Turbine for Wastegated Turbocharger
Hanqin Yang,
Qingbin Li,
Liaoping Hu,
Xiong Meng,
Guangqing He,
Lin Liu
Issue:
Volume 6, Issue 1, March 2020
Pages:
19-26
Received:
28 January 2020
Accepted:
21 February 2020
Published:
28 February 2020
Abstract: With the increasing popularity of turbocharging technology in the automotive industry, and people's increasing awareness of environmental protection, engineers are paying more attention to the technical development of turbochargers, while more advanced tools and methods are being used in the actual turbocharged design process to improve the accuracy and efficiency of research and design. Traditional turbocharger design methods are often based on experimental data and empirical models, and long development cycles conflict with market demand, and high performance conflict with high reliability. In this paper, in order to resolve this significant contradiction, a design process based on a variety of CAE methods and tools is proposed for the design of turbines, which are key components of turbochargers. This process was early applied to the design of turbocharger compressor, and then under the original boundary conditions, considering the challenges of high temperature and high engine demand, it has been improved and applied to the design of a 9L off-road country Tier-IV engine turbine in the Chinese market. The analysis shows that the turbine has good aerodynamic performance and structural reliability. The turbine performance was tested in gas stand the also verified on the engine test. This study demonstrated that the design was successful and future new turbine design can use similar procedure.
Abstract: With the increasing popularity of turbocharging technology in the automotive industry, and people's increasing awareness of environmental protection, engineers are paying more attention to the technical development of turbochargers, while more advanced tools and methods are being used in the actual turbocharged design process to improve the accurac...
Show More
-
Centrifugal Compressor Design for a Gasoline Engine Turbocharger
Qingbin Li,
Hanqin Yang,
Liaoping Hu,
Guangqing He,
Lin Liu,
Tao Feng
Issue:
Volume 6, Issue 1, March 2020
Pages:
27-35
Received:
10 February 2020
Accepted:
25 February 2020
Published:
6 March 2020
Abstract: With increasing challenges in both fuel consumption and emission, the turbochargers have played a very important role for gasoline engines. Turbochargers can increase engine power density, reduce physical dimensions and reduce engine weight. Most of the turbochargers have a rotor system including a centrifugal compressor and a turbo turbine. Centrifugal compressors is a turbomachine which increases the gas pressure with the help of a turbine. Centrifugal compressors dominate the turbocharger applications. Centrifugal compressor performances are very critical for turbocharger performance. Gasoline engines need compressor not only to have high efficiency at whole operating range but also have a wide operating range. This paper discussed a centrifugal compressor design for gasoline engine turbocharger. The modern compressor design process developed recently was used for this new compressor design. The performance of the new design was compared with original compressor in CFD (Computational Fluid Dynamics) analysis, gas stand test and engine test. It demonstrated that the newly developed compressor has better performance and also meet the engine operating needs from both numerical analysis and test. The new centrifugal compressor development is successful.
Abstract: With increasing challenges in both fuel consumption and emission, the turbochargers have played a very important role for gasoline engines. Turbochargers can increase engine power density, reduce physical dimensions and reduce engine weight. Most of the turbochargers have a rotor system including a centrifugal compressor and a turbo turbine. Centri...
Show More
