Abstract: The steady-state temperature for one-dimensional transpiration cooling system has been conducted experimentally and numerically to investigate the heat transfer characteristics of combined convection and radiation. The Nickel –Chrome (Ni-Cr) open-cellular porous material having porosity of 0.93 and pores per inch (PPI) of 21.5 was examined. The upper surface of porous plate was heated by the heat flux of incoming radiation varying from 7.7 - 16.6 kW/m2 whereas air injection velocity fed into the lower surface was varied from 0.36 - 1.27 m/s, and was then rearranged as Reynolds number (Re). For the report of the results in the present study, two efficiencies including of temperature and conversion efficiency were presented. Temperature efficiency indicating how close the mean temperature of a porous heat plate to that of inlet air, and increased rapidly with the air injection velocity (Re). It was then saturated and had a constant value at Re higher than 10. The conversion efficiency, which was regarded as the ability of porous material in transferring energy by convection after absorbed from heat radiation, decreased with increasing of the heat flux and air injection velocity. In addition, it was then asymptotic to a constant value at the Re higher than 10. The numerical predictions also agreed with experimental data very well.
Abstract: In hydrocyclones, the particle separation efficiency is
limited by the suspended fine particles, which are discharged with the
coarse product in the underflow. It is well known that injecting water
in the conical part of the cyclone reduces the fine particle fraction in
the underflow. This paper presents a mathematical model that
simulates the water injection in the conical component. The model
accounts for the fluid flow and the particle motion. Particle
interaction, due to hindered settling caused by increased density and
viscosity of the suspension, and fine particle entrainment by settling
coarse particles are included in the model. Water injection in the
conical part of the hydrocyclone is performed to reduce fine particle
discharge in the underflow. The model demonstrates the impact of
the injection rate, injection velocity, and injection location on the
shape of the partition curve. The simulations are compared with
experimental data of a 50-mm cyclone.
Abstract: This paper addresses one important aspect of
combustion system analysis, the spray evaporation and
dispersion modeling. In this study we assume an empty
cylinder which is as a simulator for a ramjet engine and the
cylinder has been studied by cold flow. Four nozzles have the
duties of injection which are located in the entrance of
cylinder. The air flow comes into the cylinder from one side
and injection operation will be done. By changing injection
velocity and entrance air flow velocity, we have studied
droplet sizing and efficient mass fraction of fuel vapor near
and at the exit area. We named the mass of fuel vapor inside
the flammability limit as the efficient mass fraction. Further,
we decreased the initial temperature of fuel droplets and we
have repeated the investigating again. To fulfill the calculation
we used a modified version of KIVA-3V.
Abstract: This work is focused on the steady boundary layer flow
near the forward stagnation point of plane and axisymmetric bodies
towards a stretching sheet. The no slip condition on the solid
boundary is replaced by the partial slip condition. The analytical
solutions for the velocity distributions are obtained for the various
values of the ratio of free stream velocity and stretching velocity, slip
parameter, the suction and injection velocity parameter, magnetic
parameter and dimensionality index parameter in the series forms with
the help of homotopy analysis method (HAM). Convergence of the
series is explicitly discussed. Results show that the flow and the skin
friction coefficient depend heavily on the velocity slip factor. In
addition, the effects of all the parameters mentioned above were more
pronounced for plane flows than for axisymmetric flows.
Abstract: This paper addresses one important aspect of
combustion system analysis, the spray evaporation and
dispersion modeling. In this study we assume an empty
cylinder which is as a simulator for a ramjet engine and the
cylinder has been studied by cold flow. Four nozzles have the
duties of injection which are located in the entrance of
cylinder. The air flow comes into the cylinder from one side
and injection operation will be done. By changing injection
velocity and entrance air flow velocity, we have studied
droplet sizing and efficient mass fraction of fuel vapor near
and at the exit area. We named the mass of fuel vapor inside
the flammability limit as the efficient mass fraction. Further,
we decreased the initial temperature of fuel droplets and we
have repeated the investigating again. To fulfill the calculation
we used a modified version of KIVA-3V.