基于水模拟回风流场的PIV测试粒子跟随性研究
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摘要
根据相似理论,选择某大空间建筑,以1∶15的缩尺比例搭建液态水模型实验台,研究实际大空间下送中回分层空调建筑中部回风汇流流场特性。选取粒径10~100μm聚苯乙烯示踪粒子,以盐水溶液为流体介质,分析计算其示踪模型回风汇流区域速度不均匀流场的准确性。结果表明:当粒子与流体的密度比σ<1.0时,粒子粒径越小,速度幅值比η越小,数值越接近1,示踪粒子跟随性越好;当粒子与流体的密度比σ>1.0时,获得的流场信息越能真实地反映实际流场特性。利用粒子图像测速技术PIV获得模型回风汇流区域流场速度矢量信息及其流线图。实验结果表明:在实验特定条件下,规定的汇流区域内示踪粒子几乎不受沉降速度Ug影响且延迟速度Us较小,说明粒子跟随性较好。
According to similarity theory,the paper chose a large space building and established an experimental table of liquid water model with 1∶ 15 reduced-scale to study flow field characteristics around the return air grille in a large space building air-conditioned with low-side wall air supply and medium-height air return. It took salt water as fluid medium and chose the polystyrene particles whose diameter was from 10 to 100μm as tracer particles to calculate their flowing behaviors and accuracy in tracing non-uniform flow field around the air return grille. Three indexes such as velocity amplitude ratio η,settling velocity Ugand delay velocity Uswere used to judge whether their flowing characteristics were good. The results indicate that when the density ratio σ between the particles and the fluid is less than 1. 0,the smaller the diameter of particles,the smaller the velocity amplitude ratio η is,and η is close to 1. 0,which means that the flowing behaviors is better. While the density ratio σ is larger than1,the smaller the diameter of particles,the larger is its velocity amplitude ratio η,and the closer the value of η is 1,the better are the flowing behaviors. The better flowing behaviors represented that the tested flow field could truly reflex the actual flow field Characteristics. The paper used PIV technique to get the velocity information of air return flow field. The results indicated that under certain experiment conditions,the settling velocity Ughas no influence on particle movement and the delay velocity Usis very little,which demonstated the flowing behaviors of the particles are fairly well in the salt water fluid medium.
According to similarity theory,the paper chose a large space building and established an experimental table of liquid water model with 1∶ 15 reduced-scale to study flow field characteristics around the return air grille in a large space building air-conditioned with low-side wall air supply and medium-height air return. It took salt water as fluid medium and chose the polystyrene particles whose diameter was from 10 to 100μm as tracer particles to calculate their flowing behaviors and accuracy in tracing non-uniform flow field around the air return grille. Three indexes such as velocity amplitude ratio η,settling velocity Ugand delay velocity Uswere used to judge whether their flowing characteristics were good. The results indicate that when the density ratio σ between the particles and the fluid is less than 1. 0,the smaller the diameter of particles,the smaller the velocity amplitude ratio η is,and η is close to 1. 0,which means that the flowing behaviors is better. While the density ratio σ is larger than1,the smaller the diameter of particles,the larger is its velocity amplitude ratio η,and the closer the value of η is 1,the better are the flowing behaviors. The better flowing behaviors represented that the tested flow field could truly reflex the actual flow field Characteristics. The paper used PIV technique to get the velocity information of air return flow field. The results indicated that under certain experiment conditions,the settling velocity Ughas no influence on particle movement and the delay velocity Usis very little,which demonstated the flowing behaviors of the particles are fairly well in the salt water fluid medium.
引文
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[13]胡华,刘书亮,王天友,等.关于测量内燃机缸内流场用示踪粒子的研究[J].小型内燃机与摩托车,2002,31(1):5-8.
[2]王昕.大空间建筑不同上开口形式室内热环境研究[D].上海:上海理工大学,2004:1-10.
[3]刘迎云,王汉青,高建民.盐水溶液模拟非等温室内气流组织的试验研究[J].流体机械,2005,33(11):77-79.
[4]崔恒.流体二维图像测速技术的研究[D].大连:大连理工大学,2006:1-5.
[5]赵宇.PIV测试中示踪粒子性能的研究[D].大连:大连理工大学,2004:7-45.
[6]Ayati A A,Kolaas J,Jensen A,et al.A PIV investigation of stratified gas-liquid flow in a horizontal pipe[J].International Journal of Multiphase Flow,2014,61:129-143.
[7]Hadad T,Gurka R.Effects of particle size,concentration and surface coating on turbulent flow properties obtained using PIV/PTV[J].Experimental Thermal and Fluid Science,2013,45:203-212.
[8]高建民.PIV在室内气流组织模型实验中的应用研究[D].衡阳:南华大学,2004:21-39.
[9]TSI Incorporated.Insight 3G&4G user's guide[M].Shoreview,Minnesota,USA:TSI Incorporated,2011.
[10]陈钊,郭永彩,高潮.三维PIV原理及其实验方法[J].实验流体力学,2006,20(4):77-82.
[11]阮驰,孙传东,白永林,等.水流场PIV测试系统示踪粒子特性研究[J].实验流体力学,2006,20(2):72-77.
[12]李志平.激光粒子图像测量中示踪粒子特性及实验方法研究[D].天津:天津大学,2007:31-51.
[13]胡华,刘书亮,王天友,等.关于测量内燃机缸内流场用示踪粒子的研究[J].小型内燃机与摩托车,2002,31(1):5-8.