The comparison of experimental data of drag coefficients with analytical evaluations shows that, for most tip projections, the agreement of both results is poor. The fact that the assumption of constant pressure is not fulfilled in the separated region is because of the vortical motion set up by the entrainment of the fluid by the shear layer over the separated region. It is known from experiment that the assumptions made for the analysis are not valid in general, although a tendency toward constant pressure in the separated region is evident as the tip projection becomes very large. However, the magnitude of β is not yet known except for the case of laminar flow with no initial boundary layer therefore eqn. (16) the variation of t/ L with respect to cone angle and Mach number is determined for completely laminar and completely turbulent flows on the spike. If the value of a/ t is given, then from eqn. (16) t L = ( 2 / β ) ( a / t ) T c tan λ c + 2 β a t T c. Moreover, it is indicated that the average heat transfer for separated laminar boundary layer is reduced in accordance with the calculation of Chapman's analysis, and is apparently independent of the heater surface area lying beneath the separated boundary layer. The agreement between experiment and analysis up to transition is good.
#Axial symmetry not applicable on 2d boundaries comsol 5.3 full
Consequently, the full theoretical reduction of 44 percent is not to be expected. So for comparison with analysis, only that portion of the surface must be considered. At sufficiently high Reynolds numbers Re L > 2×10 6, where L is model length, an increase rather than a reduction in average heat transfer occurred.įor two-dimensional models at M e = 3 and M ∞ = 4, the rearward two-hirds chord of the separated flow model actually was exposed to separated flow. At higher Reynolds numbers, values of h S/h A increase in the transitional region, and separation is observed to induce premature transition.
Laminar heat transfer, two-dimensional flow įor axially symmetric flow, the measured data of h S/h A (the ratio of average heat transfer coefficient at separated boundary layer to attached boundary layer) are reasonably independent of Mach and Reynolds numbers up to the Reynolds number at which transition begins in the reattachment regions, and also appear to agree well with the analysis of Chapman.
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