The effect of initial disturbances in the Hagen–Poiseuille impact jet on the intensification of wall heat transfer

V. V. Lemanov, V. V. Lukashov, K. A. Sharov

S.S. Kutateladze Institute of Thermophysics, Siberian Division of the Russian Academy of Sciences, Novosibirsk, Russia

Abstract: An experimental study of heat transfer in an impact air jet flowing out of a long round pipe ($l/d>$ 100) at low Reynolds numbers of 250–12000 was conducted. Three variants of the pipe inlet geometry were studied: sudden narrowing, conical confuser, profiled nozzle. Instantaneous and statistical data on local heat transfer were obtained at large distances to the obstacle ($h/d$ = 20). Localization of heat transfer for laminar jets in the critical point region was found for three variants of the pipe inlet. Initial conditions with a lower level of disturbances increase the critical Reynolds number and also promote heat transfer intensification in the critical point region.

Keywords: Hagen–Poiseuille flow, laminar-turbulent transition, initial conditions, velocity pulsations.

Received: 02.10.2024
Revised: 19.10.2024
Accepted: 20.10.2024

DOI: 10.61011/PJTF.2025.04.59837.20135

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