摘要
目的:公路隧道在采用横向式通风系统时,送风道内的空气应通过送风孔均匀地输送至隧道内,以满足整个隧道范围内的新鲜空气补充和污染物稀释的需求。但是,目前的隧道通风设计规范并没有明确的等量送风设计方法,且业界关于该问题的研究也极为缺乏。考虑到多页对开式风阀在风量调整方面的便利性与实用性,本文旨在通过明确风阀风阻特性以及等量送风管道内外静压的分布规律,研究一种通过调整风阀开角来实现风孔风量控制的理论设计方法。创新点:1.结合量纲分析与数值模拟分析方法得出多页对开式风阀的风阻特性;2.通过对等量送风道内外部建立一元伯努利方程,得出等量送风管道内的静压分布规律;3.结合风阀风阻特性以及管道内外静压分布规律,得出一种基于压力平衡的风阀叶片开角理论调节方法,且该方法可以实现各风孔送风风量的理论控制。方法:1.利用量纲分析方法得出多页对开式风阀风阻特性的影响因素;2.利用二维和三维数值分析方法计算得出不同叶片开角和风速比值条件下的风阀阻力系数(表2和图6);3.通过理论分析,在送风道内部和风阀内外侧断面间建立一元伯努利方程,得到风道内的风速与静压分布规律,以及通过调节开角实现风量控制的理论设计方法;4.利用数值分析方法对研究得到的等量送风理论设计方法进行可行性验证(图9和10)。结论:1.影响多页对开式风阀风阻特性的2个因素分别是风阀的叶片开角和风道与风阀内的风速比值;2.结合等量送风管道内静压分布规律以及风阀风阻特性,可以通过调整叶片开角实现风阀送风风量的理论控制;3.数值验证结果表明,通过控制叶片开角来实现风阀出风风量的理论控制方法具备可行性且精度较高。
We focused mainly on a uniform air flow distribution design strategy for a multi-perforated air supply duct with a multi-blade opposed regulation damper. This design is especially required in tunnel transverse ventilation systems, in which a uniform air flow distribution is needed to dilute vehicle exhaust gases or vehicle emissions to acceptable concentrations. First, local resistance coefficients arising when air flows out of the duct through the damper were investigated by means of dimensional analysis and computational fluid dynamics(CFD) simulation, and a mutual authentication was performed with 3 D and 2 D simulation results. This revealed that the ratio of the velocity in the duct and the damper, and the blade opening angle are the two main factors affecting the resistance coefficient. Second, theoretical analysis based on Bernoulli's equation was implemented to establish the relationship between the local resistance coefficient and the pressure drop. Based on the simulation results, a uniform air flow distribution design strategy corresponding to the opening angle adjustment was obtained. Finally, a calculation case study was carried out, and sufficient consistency between the theoretical and numerical calculation results was achieved, verifying the reliability of the design strategy.
引文
Ascough GW,Kiker GA,2002.The effect of irrigation uniformity on irrigation water requirements.Water SA,28(2):235-242.https://doi.org/10.4314/wsa.v28i2.4890
Chen A,Sparrow EM,2009a.Effect of exit-port geometry on the performance of a flow distribution manifold.Applied Thermal Engineering,29(13):2689-2692.https://doi.org/10.1016/j.applthermaleng.2008.12.035
Chen A,Sparrow EM,2009b.Turbulence modeling for flow in a distribution manifold.International Journal of Heat and Mass Transfer,52(5-6):1573-1581.https://doi.org/10.1016/j.ijheatmasstransfer.2008.08.006
El Moueddeb K,Barrington S,Barthakur N,1997.Perforated ventilation ducts:part 1,a model for air flow distribution.Journal of Agricultural Engineering Research,68(1):21-27.https://doi.org/10.1006/jaer.1997.0176
Farajpourlar M,2017.On the prediction of uniformity of air flow out from manifold distribution.Materialwissenschaft und Werkstofftechnik,48(3-4):249-254.https://doi.org/10.1002/mawe.201600765
Foust J,Rockwell D,2007.Flow structure associated with multiple jets from a generic catheter tip.Experiments in Fluids,42(4):513-530.https://doi.org/10.1007/s00348-006-0249-z
Ibukiyama S,1957.The calculation methods of static pressures in the ventilation ducts of uniform area with slots of equal size at equal intervals and opening areas of those slots.Transactions of the Japan Society of Civil Engineers,47:30-37.https://doi.org/10.2208/jscej1949.1957.47_30
Ji CZ,Zhang X,Jiang M,et al.,2010.Numerical simulation of influence of 90°-bend pipeline geometric shape on local loss coefficient.International Conference on Mechanical and Electrical Technology,p.668-672.https://doi.org/10.1109/ICMET.2010.5598446
Jo HJ,Chun KM,Min DK,et al.,2017.A study on the program development for optimizing the supply and exhaust port opening ratio in road tunnels with transverse ventilation system.Journal of Korean Tunnelling and Underground Space Association,19(3):517-532.https://doi.org/10.9711/KTAJ.2017.19.3.517
Kalpakli A,?rlüR,2013.Turbulent pipe flow downstream a90°pipe bend with and without superimposed swirl.International Journal of Heat and Fluid Flow,41:103-111.https://doi.org/10.1016/j.ijheatfluidflow.2013.01.003
Kareeri AA,Zughbi HD,Al-Ali HH,2006.Simulation of flow distribution in radial flow reactors.Industrial&Engineering Chemistry Research,45(8):2862-2874.https://doi.org/10.1021/ie050027x
Kim S,Choi E,Cho YI,1995.The effect of header shapes on the flow distribution in a manifold for electronic packaging applications.International Communications in Heat and Mass Transfer,22(3):329-341.https://doi.org/10.1016/0735-1933(95)00024-S
Lee S,Moon N,Lee J,2012.A study on the exit flow characteristics determined by the orifice configuration of multiperforated tubes.Journal of Mechanical Science and Technology,26(9):2751-2758.https://doi.org/10.1007/s12206-012-0721-z
Lesser N,Horowitz F,King K,1987.Transverse ventilation system of the Holland tunnel evaluated and operated in semi-transverse mode.Transportation Research Record,1150:24-28.
Li JSM,Chow WK,2003.Numerical studies on performance evaluation of tunnel ventilation safety systems.Tunnelling and Underground Space Technology,18(5):435-452.https://doi.org/10.1016/S0886-7798(03)00023-3
Oliveira PJ,Pinho FT,1997.Pressure drop coefficient of laminar Newtonian flow in axisymmetric sudden expansions.International Journal of Heat and Fluid Flow,18(5):518-529.https://doi.org/10.1016/S0142-727X(97)80010-0
Rong GW,Wei WL,Liu YL,2010.3D numerical simulation for hydraulic characteristics of turbulent flow in bifurcated duct.Journal of Hydraulic Engineering,41(4):398-405(in Chinese).https://doi.org/10.13243/j.cnki.slxb.2010.04.011
Singh RK,Rao AR,2009.Simplified theory for flow pattern prediction in perforated tubes.Nuclear Engineering and Design,239(10):1725-1732.https://doi.org/10.1016/j.nucengdes.2009.05.028
VanGilder JW,Schmidt RR,2005.Airflow uniformity through perforated tiles in a raised-floor data center.AMSE Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS,NEMS,and Electronic Systems Collocated with the ASME,p.493-501.https://doi.org/10.1115/IPACK2005-73375
Wang J,Priestman GH,Wu D,2001.A theoretical model of uniform flow distribution for the admission of highenergy fluids to a surface steam condenser.Journal of Engineering for Gas Turbines and Power,123(2):472-475.https://doi.org/10.1115/1.1359237
Ye WB,2017.Design method and modeling verification for the uniform air flow distribution in the duct ventilation.Applied Thermal Engineering,110:573-583.https://doi.org/10.1016/j.applthermaleng.2016.08.177
Yu HQ,2013.Engineering Fluid Mechanics(3rd Edition).Southwest Jiaotong University Press,Chengdu,China,p.122-128(in Chinese).