Volume: 6
Number: 2
July-December 2007

To see an article directly, click its Title. To see abstract, click its [Abstract] link.

• ENERGY AND EXERGY ANALYSIS FOR MIXED CONVECTION IN A MICROSTRUCTURE FILLED VENTED CAVITY: EFFECT OF CHANGE OF ASPECT RATIO
  M.H. Banna, S.F. Bama, A.K.M.S Islam
  Abstract PDF
  ENERGY AND EXERGY ANALYSIS FOR MIXED CONVECTION IN A MICROSTRUCTURE FILLED VENTED CAVITY: EFFECT OF CHANGE OF ASPECT RATIO
  M.H. Banna, S.F. Bama, A.K.M.S Islam

  Abstract

  In this study, an enclosure filled with fluid saturated porous medium is considered. Initial observations are taken with all walls being isothermal. Imposing adiabatic conditions on three walls and isothermal condition on left vertical wall, a second stage of observations are carried out. Natural convection takes place due to the temperature difference between the isothermal wall and the fluid. Forced convection is induced by providing an inlet at the bottom surface and a vent at the top, facing the inlet. The problem is solved using the modified Darcy flow model and energy equation for five different Rayleigh Numbers (1, 50, 100, 500, and 1000) and seven different Peclet Numbers (0.1, 1, 5, 10, 20, 50 and 100). The equations are solved using standard Finite Element Method for considering three different Aspect Ratios of the cavity.
• NUMERICAL AND EXPERIMENTAL STUDY OF SHOCK/TURBULENT FLOW INTERACTION-A CODE VALIDATION TEST
  Mohammad Ali Jinnah, Kayzuyoshi Takayama
  Abstract PDF
  NUMERICAL AND EXPERIMENTAL STUDY OF SHOCK/TURBULENT FLOW INTERACTION-A CODE VALIDATION TEST
  Mohammad Ali Jinnah, Kayzuyoshi Takayama

  Abstract

  Anumerical code has been developed to solve the shock/turbulence interaction using grid adaptation technique. For the code validation test, shock wave propagations through nozzle are studied experimentally and numerically for the incident shock Mach number 1.60. The experimental photographs, taken by double exposure holographic interferometry, are used for the code validation test and a comparison is conducted between the experimental photographs and the numerical images. The shock wave propagation through a nozzle of small throat area is selected where laminar flow structures, transition phenomena, flow separation line as well as viscous boundary layer separation, wave propagation through the throat of the nozzle and shock wave reflection from converging area of the nozzle are observed numerically. The numerical results agree well with the experiment. The numerical code is used to solve the two-dimensional Navier-Stokes equations with k-i: turbulence model for the solution of the shock wave propagation through the nozzle and this code later has been extended to develop a three-dimensional code. The three-dimensional code is used to solve the shock/turbulence interaction for a compressible fluid. A grid convergence study has been performed to validate the interaction results. The Navier-Stokes Simulation (NS) results for the shock wave interaction with turbulence are compared with the Navier-Stokes Simulation (NS) results with k-e turbulence model and the comparison results are good enough to validate the present simulation works.
• EFFECT OF EVAPORATOR SURFACE ROUGHNESS ON THE PERFORMANCE OF A TWO PHASE CLOSED LOOP THERMOSYPHON
  S.L. Mahmood, M.A.R. Akhanda, M.A. Banna, N. Bagha
  Abstract PDF
  EFFECT OF EVAPORATOR SURFACE ROUGHNESS ON THE PERFORMANCE OF A TWO PHASE CLOSED LOOP THERMOSYPHON
  S.L. Mahmood, M.A.R. Akhanda, M.A. Banna, N. Bagha

  Abstract

  A two-phase closed loop thermosyphon has been designed, fabricated and tested. This thermosyphon consists of four components in its loop, an evaporator with boiling enhancement structure, vapor rising tube, condenser and condensate return tube. Evaporator surface is heated by using an electric capsule heater which is connected to the A.C power supply. Heat supply is varied using a voltage regulator which is measured by a precision ammeter and a voltmeter. The condenser section is cooled by natural convection of air. Temperatures at different locations of the evaporator surface are measured using five calibrated K type thermocouples. Three different evaporator surfaces namely semi circular ribbed surface (SCRS), triangular ribbed surface (TRS) & smooth surface (SS) are tested in this study to assess the effects of evaporator surface geometry using three working fluids (acetone, ethanol and methanol). Triangular ribbed surface can dissipate maximum heat flux among all the evaporator surfaces used and among the working fluids ethanol’s performance is the best.
• DESIGN OF THE RICKSHAW TO IMPROVE SAFETY AND COMFORT OF PASSENGERS
  M. Iqbal Mahmud, M.A. Satter, Mahmudur Rahman
  Abstract PDF
  DESIGN OF THE RICKSHAW TO IMPROVE SAFETY AND COMFORT OF PASSENGERS
  M. Iqbal Mahmud, M.A. Satter, Mahmudur Rahman

  Abstract

  The aim of the project is to present a complete picture of the knowledge and skills needed for “Design of the rickshaw to improve safety and comfort of passengers”. For safety and comfortability the height of Centre of Gravity (C.G.) and length of C.G is taken into account. For this case the height of rickshaw decreased and the length increased. For comfort the stiffness of the leaf spring which supports the seat, decreased from the current value. The major challenge in this design is to lowering the C.G. into appropriate value, which increases the stability of the rickshaw. For the comfort purpose the seat is widens and make soft to sit. Several systems and options are added for the increase in safety and comfort for both the passenger and rickshaw puller.