Ihsan Dagtekin

Comparison of position of a heated thin plate located in a cavity for natural convection

In this numerical study, natural convection heat transfer in a square cavity with a heated plate built-in vertically and horizontally was investigated. In order to obtain finite difference equations, transport and energy equations were integrated based a finite control volume with non-staggered grid arrangement. The discretized equations were solved with TDMA using SIMPLEM algorithm iteratively. The study was performed for different Rayleigh number values ranging from 10 4 to 10 6 and for different aspect ratios and position of heated plate. Air was chosen as a working fluid (Pr=0.71). The effect of the position and aspect ratio of heated plate on heat transfer and flow were addressed

Natural convection heat transfer by heated partitions within enclosure

Abstract In this study, natural convection heat transfer and fluid flow of two heated partitions. within an enclosure have been analysed numerically. The right side wall and the bottom wall of the enclosure were insulated perfectly while the left side wall and top wall were maintained at the same uniform temperature. The partitions were placed on the bottom of the enclosure and their temperatures were kept higher than the non-isolated walls. The effects of position and heights of the partitions on heat transfer and flow field have been investigated. Computations for Rayleigh number in the range of 104 and 106 have been conducted. Using the control volume approach, finite difference equations are obtained with non-staggered grid arrangement, a computer program based on the SIMPLEM algorithm was developed. The finite difference equations were solved iteratively with a line-by-line Thomas algorithm.

Enhancement of heat transfer in a pipe with inner contraction-expansion-contraction pipe insertion

In this study, a numerical analysis was conducted in order to enhance heat transfer in a circular smooth pipe. As a physical configuration a partly heated circular pipe with an inner contraction-expansion-contraction (CEC) pipe insertion was considered. Due to the insertion of the CEC pipe some amount of fluid is deviated from the original path to the heated pipe, thus, the heat transfer increases from the heated wall to the fluid. A finite control volume approach was applied for discretisation of transport and energy equations in laminar flow regime. The calculations were performed for various Reynolds numbers ranging from 100 to 1000, various Prandtl numbers ranging from 0.1 to 10 and at the different CEC ratio β (=r 2 /r 1 ) values. It is found that Peclet number and p values affect the heat transfer enhancement significantly and average CEC β 1 (=r 3 /r 0 ) values should be less than 0.7 in order not give rise to severe pressure drop.

Abrasive Waterjet Cutting of Aluminum Alloys: Workpiece Surface Roughness

Abrasive waterjet machining is one of the non-traditional methods of the recent years which found itself a wide area of application in the industry for machining of different materials. In this paper, the surface roughness of 6061-T6 and 7075-T6 aluminum alloys are being cut with abrasive waterjet is examined experimentally. The experiments were conducted with different waterjet pressures and traverse speeds. It has been found that the surface roughness obtained by cutting material with high mechanical properties is better than that of obtained by cutting material with inferior mechanical properties.