Abstract: Due to the presence of air intakes outside the body of some missiles with research objectives as well as some unmanned aerial, the use of the air intake duct in S-shaped is necessary and therefore the air flow quality must be determined, with the most important parameters being the total drop and distortion is from the beginning of the air intake until the delivery phase to the engine. In this research, it has been determined that the optimum air intake geometry is determined according to the dimensions of a unmanned aerial. Therefore, we first tried to optimize the geometry of S-shaped air intake and then optimize this geometry based on the reduction of total pressure drop. The computational grid with ICEM software and mesh analysis by computational fluid dynamics (Fluent software) has been done. Given that the intake of unmanned aerial was considered in this study, Mach flight is considered 0.3. Since the output section is actually the same section of the motor, whose cross section is constant, it has been considered in optimizing the inlet section and the wall. By optimizing geometry, the total pressure drop dropped to about half. Given the fact that the optimization repetition resulted in undesirable changes in geometry, optimization of geometry was not repeated. Additionally, by comparing the optimized geometry with the initial geometry, It is known that the slow rotation of the flow (the lower rotation angle) reduces the total pressure drop and reduces the amount of distortion. In the end, the results of the numerical solution with the experimental results presented by NASA have been investigated, which indicates that the numerical solution is desirable.Abstract: Due to the presence of air intakes outside the body of some missiles with research objectives as well as some unmanned aerial, the use of the air intake duct in S-shaped is necessary and therefore the air flow quality must be determined, with the most important parameters being the total drop and distortion is from the beginning of the air intake u...Show More
Abstract: In the article, the differential method of thermal calculation of a furnace is used to determine the aerodynamic and thermal characteristics in the chambers of radiation of tube furnaces with wall burners of two types located on several tiers. In the methane steam reforming furnace, the acoustic burners of the near-wall flame gas fuel are arranged in three tiers on the side walls of the radiation chamber. In the primary reforming furnace for the production of ammonium nitrate, wall-mounted burners are located on six tiers. The method implies joint numerical solution of 2D radiation transfer equations using the S2-approximation of the discrete ordinate method, of energy equations, flow equations, k-e turbulence model, and two stage modeling of gas fuel combustion. Is it given a brief description of the boundary conditions for differential equations and the method of their numerical solution. The results of the calculation of the temperature fields and the flow of combustion products in the radiation chamber of the furnace obtained with the help of a computer program that implements the described method are given.Abstract: In the article, the differential method of thermal calculation of a furnace is used to determine the aerodynamic and thermal characteristics in the chambers of radiation of tube furnaces with wall burners of two types located on several tiers. In the methane steam reforming furnace, the acoustic burners of the near-wall flame gas fuel are arranged ...Show More
Abstract: The idea of introducing artificial roughness on absorber plate to improve the thermal performance of a solar air heater is very common now days. The technique uses the concept of providing artificial roughness by imbedded element in the absorber plate of the heater. Diagonally chamfered cuboids have been used as roughness element in the current study. A numerical study is performed to investigate the enhancement of the thermo-hydraulic performance of the heater for the various affecting parameters such as Relative Roughness Pitch (Transverse and Longitudinal) of 6 to 14, cross section of cuboids from 8 mm to 14 mm and relative roughness height of 0.44 to 0.088. The range of Reynolds number used in this study was 5000 to 22500. During the study a constant heat flux of 1000 W/m2 on the absorber plate was considered. The standard k-ε turbulence model with enhanced wall treatment of the ANSYS FLUENT software has been used for numerical computation and to handle the flow turbulence. The Nusselt number and the average friction factor are determined for different values of relative roughness pitch and cross sectional areas of the roughness element. Using calculated computational data correlations for Nusselt number as well as friction factor have been developed as a function of flow and roughness parameters for solar air heaters. The predicted and computational values of Nusselt number and friction factor show a good agreement.Abstract: The idea of introducing artificial roughness on absorber plate to improve the thermal performance of a solar air heater is very common now days. The technique uses the concept of providing artificial roughness by imbedded element in the absorber plate of the heater. Diagonally chamfered cuboids have been used as roughness element in the current stu...Show More