Influence of Inflow Direction on Thermal-Hydraulic Performance of Louvered Fin-Common Flow Down Vortex Generator

doi:10.12141/j.issn.1000-565X.220701

Abstract

Abstract:

In order to improve the thermal-hydraulic performance of louvered fin and flat tube heat exchangers (LFHE), by arranging common flow down vortex generator (CFDVG) on LFHE’s flat tubes, this paper proposes louvered fin-common flow down vortex generator (LF-CFDVG). Then, considering the use of active grille air shutter (AGS) may change the inflow direction of air at the core of LFHE, the influence of inflow direction on the thermal-hydraulic performance of LF-CFDVG is further studied at the air velocity of 3 m/s. The results show that the pressure drop Δp of LF-CFDVG is always greater than that of Baseline (namely the LFHE without CFDVG) due to the impact of minimum free flow area reduction after the appearance of CFDVG, the increase in frictional resistance caused by the air velocity increment and the differential pressure resistance caused by CFDVG. In the process of γ (inflow direction angle) increasing from 0° to 30°, under the influence of air velocity reduction, Δp of both Baseline and LF-CFDVG decreases, so that increasing γ helps to reduce the resistance to air flow. At the same time, under the impact of high-speed and low-temperature main stream transported by the longitudinal vortices on the tube wall between CFDVGs, the convective heat transfer ability of LF-CFDVG is significantly enhanced, as compared with the Baseline. Moreover, in the process of γ increasing from 0° to 30°, the convective heat transfer coefficients of Baseline and LF-CFDVG both reduce due to the decrease of longitudinal vortex strength and scale, so that increasing γ impairs heat exchange ability. It is also found that the comprehensive performance of LF-CFDVG continuously decreases in the process of γ increasing from 0° to 30°. Thus, increasing γ is not conducive to the improvement of comprehensive performance.

Key words: computational fluid dynamics, inflow direction, louvered fin-common flow down vortex generator, thermal-hydraulic performance

CLC Number:

U461.8

HU Xingjun, LUO Yufei, ZHANG Jinglong, et al.. Influence of Inflow Direction on Thermal-Hydraulic Performance of Louvered Fin-Common Flow Down Vortex Generator[J]. Journal of South China University of Technology(Natural Science Edition), 2023, 51(7): 12-20.

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参数	定义	取值
L_t/mm	冷却管长度	604
W_t/mm	冷却管宽度	50
H_t/mm	冷却管高度	8
T_t/mm	冷却管厚度	0.45
φ/（°）	百叶窗翅片开窗角度	10
P_LF/mm	百叶窗翅片间距	2.75
T_LF/mm	百叶窗翅片厚度	0.1
H_LF/mm	百叶窗翅片高度	12
L_P/mm	百叶间距	3
L_LF/mm	百叶窗翅片长度	50
L_H/mm	百叶高度	10.5

来流方向角 γ/（°）	x轴速度分量 v_x /（m·s^-1）	z轴速度分量 v_z /（m·s^-1）
0	3.00	0.00
10	2.95	0.52
20	2.82	1.03
30	2.60	1.50

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