Design of a Circular to Rectangular Transition Duct for 2D Exhaust Tail Pipe

Valeriya Komkov
Work towards M. Sc. degree under the supervision of Prof. Y. Levy and Prof. R. Arieli
Department of Aerospace Engineering
Technion – Israel Institute of Technology

A numerical parametric investigation for a circular to rectangular transition duct is presented for a 2D exhaust tail pipe. This research is focused on the influence of geometric parameters along the duct on the flow characteristics.  The impact the various geometries have on the drag and pressure losses is displayed in this work. The nine following geometry types were checked in this research: three different aspect ratio of exit section (2, 3 and 4) for three different duct lengths (1.5, 2.5 and 3.5 inlet diameters).

In all the geometries with aspect ratio of 2, no flow separations were found. In these cases the dominant parameter leading to the flow losses is the skin friction force. As for the geometries with aspect ratio of 3, flow separation was found at the two shortest tube lengths only. All geometries with aspect ratio of 4 displayed flow separation. In all these cases the shape of the flow separation remained almost unchanged. Cases with the exit section having an aspect ratio of 3 displayed a higher drag in geometries with flow separations compared to the one with the longest duct length and without the flow separations. Regarding the aspect ratio 4 cases, the minimum drag was detected in the medium length case. Shorter tube length showed the highest drag caused by the relative large flow separation.

Generally, it is clear that increase in the tube surface area (as a result of an increase in the tube’s length) causes only small increase in the overall drag and flow losses. Drastic increase in drag is caused by pressure drag due to flow separations.

The talk will be given in Hebrew

Wed, 26-11-2014, 16:30 (Gathering at 16:00)

Classroom 165, ground floor, Library, Aerospace Eng.

Light refreshments will be served before the lecture

Design of a Circular to Rectangular Transition Duct for 2D Exhaust Tail Pipe