Aero-Thermal Investigation of the Flow Developing in a 180-Degree Turn Channel

Infrared thermography: An optical method in heat transfer and fluid flow visualisation

“…Three relatively high heat transfer regions may be recognised: the first one is located by the end wall (in front of the partition wall towards the first outer corner) and is caused by the jet coming from the first duct which impinges on this wall; the second one is located at the outer wall downstream of the second corner and is due to the jet effect of the flow through the bend; the third one is located at about the half part of the partition wall, downstream of the second inner corner, where the flow rebounding from the outer wall, impinges before exhausting. The second zone attains Nu=Nu à values much greater than the other two due to the presence of strong secondary flows already found by Arts et al [32]. Two relatively low heat transfer zones are also observed, one just before the first corner of the outer wall and the other one in the neighbourhood of the tip of the partition wall; these zones constitute evidence for the existence of recirculation patterns.…”

Heat transfer measurements in a rotating two-pass square channel

“…The same figure shows also three zones with a high convective heat transfer coefficient: the first one extends almost on the whole frontal wall (most probably due to the jet effect); the second one is situated on the external wall immediately after second outer angle and extends for almost three diameters; the third one is situated roughly one diameter after the second inner angle, towards the partition wall. According to the hypothesis of the passage vortex made by Arts et al (Arts et al, 1992), in the outlet channel two vortices, symmetrical with respect to the channel middle plane and parallel to the measured surface, develop after the turn, first nearby the outer wall, then move to the other side and finally towards the center of the channel. These secondary flows increase the overall heat transfer coefficient and should produce the last two high heat transfer zones mentioned before.…”

Computation of Turbulent Heat Transfer on the Walls of a 180 Degree Turn Channel With a Low Reynolds Number Reynolds Stress Model

“…al. [3] among other places. For our purposes we will rewrite the above in the following form (25) rewriting using k and 0), we found the following form satisfactory for flow over flat plates.…”

“…The geometry and experimental measurements chosen come out of the work of Arts et al [3]. In this work we will explore the use of the Stress-ro model and contrast the solutions using the two models.…”