Experimental Study and Conjugate Heat Transfer Simulation of Pulsating Flow in Straight and 90° Curved Square Pipes

Guo, Guanming; Kamigaki, Masaya; Inoue, Yuuya; Nishida, Keiya; Hongou, Hitoshi; Koutoku, Masanobu; Yamamoto, Ryō; Yokohata, Hideaki; SUMI, Shinji; Ogata, Yoichi

doi:10.3390/en14133953

Cited by 8 publications

(3 citation statements)

References 30 publications

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“…The inspection of this study explained that eight-vortex chaotic flow enhanced the HC more than the two-vortex steady-state solution. Experimental observation of conjugate HT of turbulent flow is performed by Guo et al [36] in a 90 o curved square tube, where it was suggested the HT in a 90 o bent channel is 20% higher rather than in a straight channel. In the present work, Dolon et al [33] completed spectral-based computational modeling on flow and heat transition for a CRD of strong curvature (0.5) and large aspect ratio (Ar = 4.0) where various flow regimes are obtained and CHT is substantially enhanced by the centrifugal instability in their study.…”

Section:  mentioning

confidence: 99%

A Computational Study on Fluid Flow and Energy Distribution through a Bending Duct with Longitudinal Vortex Generation

Adhikari¹,

Chanda²,

Mondal³

2022

Preprint

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Since studies on fluid flow and energy dissemination through a bending duct (BD) plays prodigious contribution to both engineering and industrial standpoint, scientists have paid considerable attention to disclose new features of fluid flow through a BD. Taking this factor into account, the current work explores a computational approach on flow features and energy distribution through a bending rectangular duct of curvature 0.001 applying a spectral-based numerical scheme over a wide domain of the Dean number 0 < Dn ≤ 3000.The geometry is such that the bottom and outer side walls are thermally heated while the other walls are kept in room temperature. Newton-Raphson iteration method (N-R method) is adopted to inspect the branching structure of steady solutions (SS) which explores that there exist four branches of asymmetric steady solutions comprising 2- to 14-vortex solutions. The axial and secondary velocity distribution for each branch is investigated through different grid points by using different values of Dn. Unsteady flow characteristics are analyzed exquisitely by performing time-advancement of the solutions and flow transition is well determined by analyzing power spectrum (P-S) of the solutions. Axial flow, secondary flow, and temperature profiles have been depicted in accordance with Dn to wander the flow pattern, and it is predicted that the time-dependent flow (TDF) consists of asymmetric 2- to 10-vortex solutions. Finally, convective heat transfer (CHT) is analyzed by acquiring temperature contours for various types of physically realizable solutions. The study also demonstrates that centrifugal force comprehensively influences the fluid nature of the bending channel and CHT is more intensified due to chaotic phenomena of the flow.

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Section:  mentioning

confidence: 99%

A Computational Study on Fluid Flow and Energy Distribution through a Bending Duct with Longitudinal Vortex Generation

Adhikari¹,

Chanda²,

Mondal³

2022

Preprint

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“…They concluded that the Nusselt number increased under the pulsation frequency where the structural resonance of the pipe occurred. In a separate study, Guo et al [18] induced a pulsating flow (Rem=60000, fp=30 Hz) by installing a rotating disk in a pipe, and evaluated the heat flux for both curved and straight pipes. Their findings suggest that the bend augments the heat transfer, a trend that persists even in the presence of pulsation.…”

Section: Introductionmentioning

confidence: 99%

An Examination of Heat Transfer Dynamics in Pulsating Air Flow within Pipes: Implications for Automotive Exhaust Engines

Kato,

Guo,

Kamigaki

et al. 2023

IJHT

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The detailed understanding of heat transfer in the pulsating airflow in the pipe is critical to reducing heat losses in the engine exhaust stream and improving catalyst performance. In the present investigation, we have scrutinized the impact of pulsation frequencies ranging from 0-90 Hz on the flow velocity field and the consequent heat transfer through a horizontal pipe wall. The Nusselt numbers were evaluated at three distinct cross-sectional points moving from upstream to downstream, by systematically modulating the frequency. Temporal variations in the velocity field and temperature were captured utilizing particle image velocimetry (PIV) and dual-thermocouple probes, respectively. Intriguingly, while the Nusselt number for steady flow at 0 Hz closely adhered to Gnielinski’s equation, the pulsating flow demonstrated a peak between 25-35 Hz, a pattern not predicted by the prevailing quasi-steady-state theory. The observed frequency response of turbulence was found to be congruous with the Nusselt number, indicating that the heightened heat transfer at frequencies of 25-35 Hz could be attributed to the enhanced turbulence and the temperature gradient between the fluid and the wall surface during the deceleration phase in the hysteresis of turbulence in the pulsating flow. The unique frequency characteristics of heat transfer that were uncovered in this study, with respect to both flow velocity and temperature, offer valuable insights for devising strategies to mitigate heat loss during ignition and idling. Furthermore, these findings provide robust benchmarks for validating numerical simulations of pulsating flows in real-life automotive engines.

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“…Basiak et al [ 16 ] investigated two-phase flow, with an emphasis on velocity visualization and assessment. While Guo et al [ 17 ] performed thermal analysis, it was only for one frequency at a high flow rate.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Assessment of Iso-Flux Cooling with Low Reynolds Pulsating Water Flow

Szodrai

2022

Sensors

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Almost every scale in thermal engineering requires performance optimization to lessen energy demand. The possibility of using pulsating flow for water cooling was investigated both experimentally and numerically. The experiments were conducted below a 60 mL∙min−1 flow rate and frequencies of 3.3, 4, 5, 6.6, and 10 Hz. The flow rate and temperatures were monitored while the solenoid valve was actuated and cooled with thermoelectric coolers. The measurements were replicated by using commercially available software capable of doing large-eddy simulations with coupled thermal modelling. Thermal boundaries were created by using steady inflow temperature and iso-flux conditions. The experimental and numerical results were compared and evaluated. The results show that the Nusselt number of the examined pulsating flow was lower when compared to constant flow scenarios at the corresponding averaged flow rate.

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Experimental Study and Conjugate Heat Transfer Simulation of Pulsating Flow in Straight and 90° Curved Square Pipes

Cited by 8 publications

References 30 publications

A Computational Study on Fluid Flow and Energy Distribution through a Bending Duct with Longitudinal Vortex Generation

A Computational Study on Fluid Flow and Energy Distribution through a Bending Duct with Longitudinal Vortex Generation

An Examination of Heat Transfer Dynamics in Pulsating Air Flow within Pipes: Implications for Automotive Exhaust Engines

Experimental and Numerical Assessment of Iso-Flux Cooling with Low Reynolds Pulsating Water Flow

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