Laminar/turbulent oscillating flow in circular pipes

Abstract

A two-dimensional oscillating flow analysis was conducted simulating the gas flow inside Stirling engine heat exchangers. Both laminar and turbulent oscillating pipe flow were investigated numerically for Remax=l,920 (Va=80), 10,800 (Va=272), 19,300 (Va = 272), and 60,800 (Va = 126). The results are here compared with experimental results of previous investigators. Predictions of the flow regime on present oscillating flow conditions are also checked by comparing velocity amplitudes and phase difference with those from laminar theory and quasi-steady profile. A high Reynolds number k-e turbulence model was used for turbulent oscillating pipe flow. Finally, the performance of the k-e model was evaluated to explore the applicability of quasi-steady turbulent models to unsteady oscillating flow analysis.

Numerical correlation for the pressure drop in Stirling engine heat exchangers

“…6(a) where no trace of a transition is identified, the evolution of the turbulence kinetic energy is smooth with its amplitude proportional to the sinusoidal cross-sectional velocity. Similar results are previously reported by Ahn and Ibrahim [22]. In the derivation of the standard keε turbulence model, the assumption is that the flow is fully turbulent, and that the effects of molecular viscosity are negligible, therefore, the model is only valid for fully turbulent flow.…”

“…The transition from laminar to turbulent flow has been given a great deal of attention in the existing literature [11,17,18,20,22,32]. Experimental measurements show that the onset of turbulence in a reciprocating flow is different from that of a steady flow.…”

“…They identified an early prediction of laminar to turbulent transition. Ahn and Ibrahim [22] performed calculations for laminar, transition and turbulent regimes with the standard keε turbulence model. They obtained good results predicting laminar flow and fully turbulent regime, but they did not obtain adequate results for transition flow regime.…”

Numerical analysis of heat transfer in pulsating turbulent flow in a pipe

“…Fortunately, Seume and Simon [36] have experimentally observed that no flow separation occurred in oscillating turbulent flows. In fact, Ahn and Ibrahim [37] successfully used the standard k-e model with the help of the wall function method for such an oscillating turbulent flow. Although flow reversal may occur in a pulsating turbulent flow with a large velocity oscillating amplitude, it can be confidently inferred that no flow separation would develop in the pulsating turbulent flow.…”

Longitudinal dispersion of turbulent oscillatory pipe flows

“…According to the previous studies on the transition to turbulence of oscillatory pipe flows, the critical boundary Reynolds number for transition,  Re , was unanimously found to be around 500-550 [34][35][36][37], where…”