Heat transfer from a flat plate to a turbulent axisymmetric impinging jet

Abstract

The heat transfer due to a single axisymmetric impinging jet at a Reynolds number of 20 000 and nozzle-to-plate spacings of 1—8 has been determined using a combined constant heat flux/constant temperature electrocaloric test plate. Both unconfined and semi-confined geometries have been considered for a uniform mean exit velocity. The exit conditions and axial development of the jet have been quantified using hot-wire anemometry. Careful design of the composite heater plate has reduced experimental uncertainties in the local Nusselt number to 5 per cent.

The effect of inflow conditions on the development of non-swirling versus swirling impinging turbulent jets

“…The potential core is commonly considered to end where the centreline velocity is 95 % of the velocity at the nozzle exit [12,14], and is found to extend over 4-6 nozzle diameters (D) when impingement occurs relatively far from the nozzle [11,16]. This aspect of impinging jet development appears to agree with the behaviour of (nonimpinging) free jets where the potential core typically ends at 2.5D -8D [17][18][19][20]. In the impingement region, jet impact causes deflection of the flow and a rapid decrease in axial velocity with a corresponding rise in static pressure.…”

Reynolds Number Effects on Fully-Developed Pulsed Jets Impinging on Flat Surfaces

“…(1) to obtain Eq. (2). Using this relation, the turbulent statics can be computed at each position x; r over the entire data range, N, using the equations shown in table 2, where N is the number of vector fields.…”

“…Because of the numerous practical applications of impinging jets, their study has been mainly focused on understanding their mass, momentum, and heat transfer characteristics [1][2][3][4]. However, an understanding of the underlying fluid mechanics behind these types of jet also offers significant benefits to the study of free shear layers and boundary layers.…”

Stagnation Heat Transfer on a Concave Surface Cooled by Unconfined Slot Jet

“…A multitude of previous studies have documented that the overall and local impinging jet heat transfer characteristics on a flat plate (as the most simplistic configuration in all impinging jet configurations) depend strongly on the jet-to-flat plate distance, H, among other parameters [5][6][7][8][9][10][11][12][13][14][15][16]. Depending on the longitudinal position relative to the length of potential core of the jet, either two peaks of local heat transfer (a primary peak at the stagnation point and a second peak off from the stagnation point) or a single peak (only at the stagnation point) exist on a flat plate.…”

“…All subsequent works [5][6][7][8][9][10][11][12][13][14][15][16][18][19][20][21][22] have referred to this argument as the fluidic mechanisms of the observed nonmonotonic variation of heat transfer at the stagnation point.…”