Numerical study on heat transfer of supercritical RP-3 aviation kerosene in vertical helical tubes
-
摘要:
针对空-油换热器的冷却换热问题,开展了竖直螺旋管中超临界RP-3航空煤油换热的数值研究。探究了不同运行参数和结构参数下的换热特性和换热机理,包括沿流动方向的平均换热情况和沿管道周向的局部换热情况。考察管截面温度和二次流的分布情况,通过流速和湍动能径向差别阐述了离心力对换热的作用机制,基于误差分析得到合理的换热关联式。结果表明:管下游表现为强化换热机制,低压力下还观察到局部传热恶化问题;离心力导致流体域温度横向异常分层,边界层厚度周向不均匀,管截面出现二次流;管外侧流速和湍动能高,换热显著优于管内侧;提高运行压力、降低热质比、增大绕径、增大螺距均抑制离心力作用,致使二次流强度减弱;Merkel换热公式可以较好实现螺旋管内航空煤油的换热预测。
Abstract:To understand the cooling heat transfer problem in air-kerosene heat exchangers, numerical study on the heat transfer of supercritical RP-3 aviation kerosene in vertical helical tubes has been conducted. The heat transfer characteristics and mechanisms under different operating parameters and structural parameters were investigated, including the average heat transfer along the flow direction, and the local heat transfer along the circumferential direction. The temperature and secondary flow distributions in tube cross-sections were discussed. The effect mechanism of centrifugal force on heat transfer was analyzed through radial differences of velocity and turbulent kinetic energy. Based on the error analysis, an effective heat transfer correlation was obtained. The results show that the enhanced heat transfer appears in the downstream section, and the local deteriorated heat transfer is observed at low-pressure condition. The centrifugal force results in the abnormal lateral stratification of temperature in the fluid domain, the uneven thickness of boundary layer in the circumferential direction, and the secondary flow in tube cross-sections. The outer position has the large fluid velocity and turbulent kinetic energy. Hence, the heat transfer of the outer position. is significantly better than that the inner position. Increases the pressure, decreases the heat-mass radio, increases the helical diameter, and increases the pitch could suppress the effect of centrifugal force, leading to the weakened secondary flow intensity. The Merkel heat transfer formula can better realize the heat transfer prediction of aviation kerosene in vertical helical tubes.
-
Key words:
- helical tube /
- supercritical kerosene /
- nonuniform heat transfer /
- centrifugal force /
- secondary flow
-
-
[1] FU Y C, WEN J, TAO Z, et al. Experimental research on convective heat transfer of supercritical hydrocarbon fuel flowing through U-turn tubes[J]. Applied Thermal Engineering, 2017, 116: 43-55. doi: 10.1016/j.applthermaleng.2017.01.058 [2] LIU S B, BAO Z W, HUANG W X, et al. Numerical investigation of boundary grid effect on heat transfer computation of RP-3 at supercritical temperature of helical tube wall[J]. Journal of Thermal Science, 2021, 30(2): 504-516. doi: 10.1007/s11630-021-1355-1 [3] ZHAO H J, LI X W, WU X X. Numerical investigation of supercritical water turbulent flow and heat transfer characteristics in vertical helical tubes[J]. The Journal of Supercritical Fluids, 2017, 127: 48-61. doi: 10.1016/j.supflu.2017.03.016 [4] LI F B, BAI B F. Flow and heat transfer of supercritical water in the vertical helically-coiled tube under half-side heating condition[J]. Applied Thermal Engineering, 2018, 133: 512-519. doi: 10.1016/j.applthermaleng.2018.01.047 [5] ZHANG S J, XU X X, LIU C, et al. The buoyancy force and flow acceleration effects of supercritical CO2 on the turbulent heat transfer characteristics in heated vertical helically coiled tube[J]. International Journal of Heat and Mass Transfer, 2018, 125: 274-289. doi: 10.1016/j.ijheatmasstransfer.2018.04.033 [6] WANG K Z, XU X X, WU Y Y, et al. Numerical investigation on heat transfer of supercritical CO2 in heated helically coiled tubes[J]. The Journal of Supercritical Fluids, 2015, 99: 112-120. doi: 10.1016/j.supflu.2015.02.001 [7] XU J L, YANG C Y, ZHANG W, et al. Turbulent convective heat transfer of CO2 in a helical tube at near-critical pressure[J]. International Journal of Heat and Mass Transfer, 2015, 80: 748-758. doi: 10.1016/j.ijheatmasstransfer.2014.09.066 [8] LIU X X, XU X X, LIU C, et al. Numerical study of the effect of buoyancy force and centrifugal force on heat transfer characteristics of supercritical CO2 in helically coiled tube at various inclination angles[J]. Applied Thermal Engineering, 2017, 116: 500-515. doi: 10.1016/j.applthermaleng.2017.01.103 [9] 李洪瑞, 徐肖肖, 刘朝, 等. 螺旋管内超临界CO2流动方向对换热的影响[J]. 航空学报, 2016, 37(7): 2123-2131.LI H R, XU X X, LIU C, et al. Flow direction effect on heat transfer of supercritical CO2 in helically coiled tube[J]. Acta Aeronautica et Astronautica Sinica, 2016, 37(7): 2123-2131(in Chinese). [10] 黄小锐, 张震, 杨星团, 等. 超临界CO2在螺旋管中的流动换热特性研究[J]. 原子能科学技术, 2018, 52(5): 769-775.HUANG X R, ZHANG Z, YANG X T, et al. Numerical study on heat transfer characteristic of CO2 in helical tube at supercritical pressure[J]. Atomic Energy Science and Technology, 2018, 52(5): 769-775(in Chinese). [11] FU Y C, HUANG H R, WEN J, et al. Experimental investigation on convective heat transfer of supercritical RP-3 in vertical miniature tubes with various diameters[J]. International Journal of Heat and Mass Transfer, 2017, 112: 814-824. doi: 10.1016/j.ijheatmasstransfer.2017.05.008 [12] CHENG Z Y, TAO Z, ZHU J Q, et al. Diameter effect on the heat transfer of supercritical hydrocarbon fuel in horizontal tubes under turbulent conditions[J]. Applied Thermal Engineering, 2018, 134: 39-53. doi: 10.1016/j.applthermaleng.2018.01.105 [13] WEN J, HUANG H R, FU Y C, et al. Heat transfer performance of aviation kerosene RP-3 flowing in a vertical helical tube at supercritical pressure[J]. Applied Thermal Engineering, 2017, 121: 853-862. doi: 10.1016/j.applthermaleng.2017.04.055 [14] BAI W J, ZHANG S J, LI H R, et al. Effects of abnormal gravity on heat transfer of supercritical CO2 in heated helically coiled tube[J]. Applied Thermal Engineering, 2019, 159: 113833. [15] FU Y C, TAO Z, XU G Q, et al. Experimental study of flow distribution for aviation kerosene in parallel helical tubes under supercritical pressure[J]. Applied Thermal Engineering, 2015, 90: 102-109. doi: 10.1016/j.applthermaleng.2015.06.082 [16] 程泽源, 朱剑琴, 金钊. 吸热型碳氢燃料RP-3替代模型研究[J]. 航空动力学报, 2016, 31(2): 391-398. doi: 10.13224/j.cnki.jasp.2016.02.018CHENG Z Y, ZHU J Q, JIN Z. Study on surrogate model of endothermic hydrocarbon fuel RP-3[J]. Journal of Aerospace Power, 2016, 31(2): 391-398(in Chinese). doi: 10.13224/j.cnki.jasp.2016.02.018 [17] TAO Z, LI L W, ZHU J Q, et al. Numerical investigation on flow and heat transfer characteristics of supercritical RP-3 in inclined pipe[J]. Chinese Journal of Aeronautics, 2019, 32(8): 1885-1894. doi: 10.1016/j.cja.2019.05.007 [18] 王淑香, 张伟, 牛志愿, 等. 超临界压力下CO2在螺旋管内的混合对流换热[J]. 化工学报, 2013, 64(11): 3917-3926.WANG S X, ZHANG W, NIU Z Y, et al. Mixed convective heat transfer to supercritical carbon dioxide in helically coiled tube[J]. CIESC Journal, 2013, 64(11): 3917-3926(in Chinese). [19] SCHHUKIN V K. Correlation of experimental data on heat transfer in curved pipes[J]. Thermal Engineering, 1969, 16: 72-76. [20] MORI Y S, NAKAYAMA W. Study of forced convective heat transfer in curved pipes(2nd report, turbulent region)[J]. International Journal of Heat and Mass Transfer, 1967, 10(1): 37-59. doi: 10.1016/0017-9310(67)90182-2