Aerospace Science and Technology
Mohammad Reza Salimi; Mohammad Taeibi Rahni; Abolfazl Amiri Hezaveh; Mehdi Zakyani Rodsari
Abstract
In present research, the interaction between single liquid droplet with particles inside a porous media is investigated numerically in two dimensions. The He’s model is used to simulate two phase flow and multiple relaxation time collision operator is implemented to increase numerical stability. ...
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In present research, the interaction between single liquid droplet with particles inside a porous media is investigated numerically in two dimensions. The He’s model is used to simulate two phase flow and multiple relaxation time collision operator is implemented to increase numerical stability. Simulations have performed in three non-dimensional body forces of 0.000108, 0.000144, 0.000180, porosity values of 0.75, 0.8, 0.85 and Ohnesorge range of 0.19-0.76. In the range of investigated non-dimensional parameters, two distinct physics of droplet trapping and break up have observed. The related results revels that for every values of investigated non-dimensional body forces and porosity, there is a critical Ohnesorge number that droplet breaks up occurs for larger values. This critical value decreases as non-dimensional body force and porosity increases. Based on these results, a droplet trapping or break up behavioral diagram is drown with respect to the investigated density ratio, Ohnsorge, Reynolds and Capilary numbers.
Aerospace Science and Technology
Mohammad Reza Salimi; Mohsen Rostami; Amir Hamzeh Farajolahi; Morteza Ghanbari
Abstract
In this paper, flow and heat transfer inside a helicopter shell and tube heat exchanger is simulated in three dimensions. This converter consists of a shell with 90 U-shaped tubes inside. For further heat transfer, the tubes were simulated and compared once without fins and again with fins, which are ...
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In this paper, flow and heat transfer inside a helicopter shell and tube heat exchanger is simulated in three dimensions. This converter consists of a shell with 90 U-shaped tubes inside. For further heat transfer, the tubes were simulated and compared once without fins and again with fins, which are produced longitudinally and integrally with the tube body. The current flowing in the shell is MIL-PRF 23699 oil and the flowing fluid in the tubes is JP-4 fuel. These two fluids flow in opposite directions and exchange heat with each other. Using Aspen software, the design is done in such a way that the heat exchanger has minimum length and weight to have a better and higher effect on the efficiency of the helicopter. To investigate the effect of tube geometry and oil mass flow on the heat transfer between fuel and oil, simulation has been performed in ANSYS Fluent program. In this simulation, a part of the whole heat exchanger is selected as the geometry and the effect of changing the geometry of the tubes, mass flow of fuel and oil on the heat transfer coefficient, Colburn coefficient, coefficient of friction and their ratio, and outlet temperature changes are investigated. The results of this simulation show that the heat transfer rate between fuel and oil for a heat exchanger with finned tubes is about 11% higher than without a fin. Also, reducing the mass flow of oil entering the shell increases the efficiency of the heat exchanger.
