-
Numerical Solution of Solar Energy Absorbed in Porous Medium with a New Approach for Vapor Pressure Calculation and Consideration of Solute Crystallization
Sherif A. Mohamed
,
Ibrahim S. Taha
,
Mahmoud G. Morsy
,
Hany A. Mohamed
,
Mahmoud S. Ahmed
Issue: Volume 2, Issue 1-1, January 2015
Pages: 93-105
Received: 29 October 2014
Accepted: 17 November 2014
Published: 25 November 2014
DOI:
10.11648/j.ajae.s.2015020101.18
Downloads:
Views:
Abstract: The goal of the study is to enhance the productivity of solar stills using an unsaturated porous medium initially saturated by salty water and using concentrating reflector. This paper concentrates only on the mathematical model for the porous medium and its solution using a finite-volume approach. The previous studies dealt with wick medium with high water content and liquid saturation in the wick medium was not determined. A physical model for the initially saturated porous medium was developed. The model takes into consideration the salt concentration in the solution, surface and internal water diffusions to humid air with vapor pressure determined from vapor mass balance. The system of transient one-dimensional differential equations was developed together with the boundaries and initial conditions. A finite-volume method was used for discretisation of the differential equations. A fully-implicit scheme was used for unsteady term discretisation while the convective terms (liquid solution, vapor and dry air) in the energy equation are handled by an upwind scheme method. The nonlinear equations are solved simultaneously by updating the coefficients matrix at one time step until the five variables converge to prescribed tolerance. Matlab was used as a programming tool. Solution of the model is obtained and discussed.
Abstract: The goal of the study is to enhance the productivity of solar stills using an unsaturated porous medium initially saturated by salty water and using concentrating reflector. This paper concentrates only on the mathematical model for the porous medium and its solution using a finite-volume approach. The previous studies dealt with wick medium with h...
Show More
-
Performance Evaluation of the Tandem C4 Blades for Axial-Flow Compressors
Atef Mohamed Alm-Eldien
,
Ahmed Farouk Abdel Gawad
,
Gamal Hafaz
,
Mohamed Gaber Abd El Kreim
Issue: Volume 2, Issue 1-1, January 2015
Pages: 74-92
Received: 5 October 2014
Accepted: 10 October 2014
Published: 17 October 2014
DOI:
10.11648/j.ajae.s.2015020101.17
Downloads:
Views:
Abstract: The purpose of this work is to study the aerodynamic performance of a tandem C4 base-profile compressor blade using numerical tools. In this paper, the flow along the tandem blade is studied for various relative blade positions. In all the studied cases, the front blade is fixed and the position of the rear blade is varied as a function of the axial and tangential displacements. A computer code was developed in "Visual Basic" using linear strength vortex-panel method to predict the aerodynamic performance of the tandem blade.
Abstract: The purpose of this work is to study the aerodynamic performance of a tandem C4 base-profile compressor blade using numerical tools. In this paper, the flow along the tandem blade is studied for various relative blade positions. In all the studied cases, the front blade is fixed and the position of the rear blade is varied as a function of the axia...
Show More
-
Erosion of an Axial Transonic Fan due to Dust Ingestion
Ahmed Fayez EL-Saied
,
Mohamed Hassan Gobran
,
Hassan Zohier Hassan
Issue: Volume 2, Issue 1-1, January 2015
Pages: 47-63
Received: 29 September 2014
Accepted: 5 October 2014
Published: 16 October 2014
DOI:
10.11648/j.ajae.s.2015020101.15
Downloads:
Views:
Abstract: This paper deals with the prediction of the particle dynamic and erosion characteristics due to dust ingestion in an axial flow fan, installed in a high bypass-ratio turbofan engine that operates in a dusty environment. Dynamic behavior comprises the particle trajectory and its impact velocity and location. While the erosion characteristics are resembled by the impact frequency, erosion rate, erosion parameter and the penetration rate. The study was carried out in two flight regimes, namely, takeoff, where the sand particles are prevailing, and cruise, where the fly ashes are dominated. In both cases, the effect of the particle size on its trajectory, impact location, and the erosion characteristics was studied. To simulate the problem in a more realistic manner, a Rosin Rambler particle diameter distribution was assumed at takeoff and cruise conditions. At takeoff, this distribution varies from 50 to 300 μm with a mean diameter of 150 μm sand particles. While at cruise, this distribution varies from 5 to 30 μm with a mean diameter of 15 μm fly ash particles. The computational domain employed was a periodic sector through both the fan and its intake bounding an angle of (360/38) where the number of fan blades is (38). The intake is a stationary domain while the fan is a rotating one and the FLUENT solver is used to solve this problem. Firstly, the flow field was solved in the computational domain using the Navier-Stokes finite- volume supported by the Spalart-Allmaras turbulence model. The governing equations, representing the particle motion through the moving stream of a compressible flow are introduced herein to calculate the particle trajectory. The solution of these equations is carried out based on the Lagrangian approach. Next, empirical equations representing the particle impact characteristics with the walls are introduced to calculate the rebound velocity, the erosion rate, erosion parameter, impact frequency and penetration rate. Moreover, a method to smoothen the irregularity in the calculated scattered data was discussed as well. During takeoff flight regime, the pressure side of fan blade experienced higher particle impact and erosion damage. The highest erosion rate was found at the corner formed by blade tip and trailing edge of pressure side. During cruise conditions, less erosion rates resulted. Maximum erosion rates are found at the leading edge of the pressure side.
Abstract: This paper deals with the prediction of the particle dynamic and erosion characteristics due to dust ingestion in an axial flow fan, installed in a high bypass-ratio turbofan engine that operates in a dusty environment. Dynamic behavior comprises the particle trajectory and its impact velocity and location. While the erosion characteristics are re...
Show More
-
Computational Investigation of Aerodynamic Characteristics and Drag Reduction of a Bus Model
Eyad Amen Mohamed
,
Muhammad Naeem Radhwi
,
Ahmed Farouk AbdelGawad
Issue: Volume 2, Issue 1-1, January 2015
Pages: 64-73
Received: 29 September 2014
Accepted: 5 October 2014
Published: 16 October 2014
DOI:
10.11648/j.ajae.s.2015020101.16
Downloads:
Views:
Abstract: It is well-known that buses comprise an important part of mass transportation and that there are many types of buses. At present, the bus transportation is cheaper and easier to use than other means of transportation. However, buses have some disadvantages such as air pollution due to engine exhaust. This study is an attempt to reduce the gas emissions from buses by reducing the aerodynamic drag. Several ideas were applied to achieve this goal including slight modification of the outer shape of the bus. Thus, six different cases were investigated. A computational model was developed to conduct this study. It was found that reduction in aerodynamic drag up to 14% can be reached, which corresponds to 8.4 % reduction in fuel consumption. Also, Neuro-Fuzzy technique was used to predict the aerodynamic drag of the bus in different cases.
Abstract: It is well-known that buses comprise an important part of mass transportation and that there are many types of buses. At present, the bus transportation is cheaper and easier to use than other means of transportation. However, buses have some disadvantages such as air pollution due to engine exhaust. This study is an attempt to reduce the gas emiss...
Show More
-
CFD Modeling of the Atmospheric Boundary Layer in Short Test Section Wind Tunnel
Yassen El-Sayed Yassen
,
Ahmed Sharaf Abdelhamed
Issue: Volume 2, Issue 1-1, January 2015
Pages: 38-46
Received: 26 September 2014
Accepted: 27 September 2014
Published: 16 October 2014
DOI:
10.11648/j.ajae.s.2015020101.14
Downloads:
Views:
Abstract: The aim of this paper is to provide a contribution to algorithms for the numerical simulation of the atmospheric boundary layer (ABL) in short test section wind tunnel, with the lowest pressure loss possible, for large Re, similar to the high values observed in nature. Different turbulent models have been examined for their relative suitability for the atmospheric boundary layer airflow with and without the implementation of buoyancy effects with modified turbulence model constants for the atmosphere. Validation of turbulent models through comparison with wind tunnel experiments is essential for practical applications. It has been observed that the k-ε model is most suitable tool for generation of an ABL in short-chamber wind tunnel. A comparison has been made with the available experimental data, from literature, and the predicted CFD values are very close to the corresponding experimental measurements. The simulation results show the importance of turbulence model constant (Cµ), the non-uniform velocity and turbulence intensity profiles. Also, the significance of y+ for consistent assessment is confirmed. However, it has been found that the buoyancy force makes significant change in boundary layer thickness without a major impact on computation time.
Abstract: The aim of this paper is to provide a contribution to algorithms for the numerical simulation of the atmospheric boundary layer (ABL) in short test section wind tunnel, with the lowest pressure loss possible, for large Re, similar to the high values observed in nature. Different turbulent models have been examined for their relative suitability for...
Show More
-
Design of Mini Wind Tunnel Based on Coanda Effect
Yassen El-Sayed Yassen
,
Ahmed Sharaf Abdelhamed
Issue: Volume 2, Issue 1-1, January 2015
Pages: 31-37
Received: 26 September 2014
Accepted: 27 September 2014
Published: 7 October 2014
DOI:
10.11648/j.ajae.s.2015020101.13
Downloads:
Views:
Abstract: An experimental investigation and CFD treatment were employed to design mini-wind tunnel based on Coanda effect for model tests and basic research. The inlet source flow is efficiently creating smooth steady airflow with acceptable noise, achieving the possibility of placing the test target closer to the source of flow with reasonable estimates of turbulence intensity. The design aims at achieving flow uniformity in the working section midplane, preventing separation in the contraction and minimizing the boundary–layer thickness. Intensive measurements after construction demonstrate the significance of the design process and validate the CFD predictions. The results are represented in graphic form to indicate the aspects of the contraction ratio. The numerical and experimental results show the uniformity of velocity distribution inside the working section. Tracing of separation and backflow is crucial allowing a variety of realistic demonstrations to be performed. The numerical solution provides a powerful tool to demonstrate the rate of boundary–layer growth inside the working section and validate against the empirical correlations with insignificant wall–friction drag. Assessment study to address large–scale wind tunnel based on coanda effect would be considered.
Abstract: An experimental investigation and CFD treatment were employed to design mini-wind tunnel based on Coanda effect for model tests and basic research. The inlet source flow is efficiently creating smooth steady airflow with acceptable noise, achieving the possibility of placing the test target closer to the source of flow with reasonable estimates of ...
Show More
-
Hands-On Engineering Education by Construction and Testing of Models of Sailing Boats
Issue: Volume 2, Issue 1-1, January 2015
Pages: 11-30
Received: 26 September 2014
Accepted: 7 October 2014
Published: 7 October 2014
DOI:
10.11648/j.ajae.s.2015020101.12
Downloads:
Views:
Abstract: This paper introduces involvement of the hands-on learning method. According to the modern environment of technology, engineering students have to realize the multidisciplinary nature of engineering systems. This learning technique is essential to offer students the necessary skills to master practical, organizational and work-group cleverness. The work is concerned with the redesign, construction and operation of two models of sailing boats. The approach of the work and final outputs are illustrated.
Abstract: This paper introduces involvement of the hands-on learning method. According to the modern environment of technology, engineering students have to realize the multidisciplinary nature of engineering systems. This learning technique is essential to offer students the necessary skills to master practical, organizational and work-group cleverness. The...
Show More
-
Proposed Simple Electro-Mechanical Automotive Speed Control System
Ahmed Farouk AbdelGawad
,
Talal Saleh Mandourah
Issue: Volume 2, Issue 1-1, January 2015
Pages: 1-10
Received: 26 September 2014
Accepted: 7 October 2014
Published: 7 October 2014
DOI:
10.11648/j.ajae.s.2015020101.11
Downloads:
Views:
Abstract: Millions of people are killed or seriously injured on the roads due to terrified accidents every year. Most of these accidents are attributed to the over-speeding of the road vehicles. Thus, the road speed limiter (RSL) is a very important technique to reduce the possibility of road accidents. An interesting idea to control the speed of the vehicle is to apply electronic control of the air-supply that enters the vehicle carburetor according to road transmitters that are connected and operated either by local network or satellite. In the present paper, a control system was designed and implemented. It is consisted of a control mechanism and an electronic circuit to control the air-inlet to the carburetor according to pre-set programming based on the vehicle speed. Although, it is a challenging job to design and implement modifications to existing systems, the present speed control system was successfully implemented and tested. The present proposed mechanism is simple, inexpensive and suitable to be implemented in developing countries where a big number of cars still work using the traditional carburetor mechanism.
Abstract: Millions of people are killed or seriously injured on the roads due to terrified accidents every year. Most of these accidents are attributed to the over-speeding of the road vehicles. Thus, the road speed limiter (RSL) is a very important technique to reduce the possibility of road accidents. An interesting idea to control the speed of the vehicle...
Show More
