气液两相流诱发顺列双圆柱升力功率谱特性研究

Power Spectrum Characteristics of Fluctuating Lift for the Tandem Circular Cylinders Subjected to Two Phase Crossflow

两相流诱发管束振动的研究尚处于起步阶段，研究气液两相流中串联双圆柱的诱发振动特性，有助于理解管束中管子之间相互影响机理，对于进一步研究复杂管束中的流体诱发振动现象具有重要意义，为此对受到垂直向上气液两相流横向冲刷的顺列双圆柱所受的升力进行了实验研究．实验中来流雷诺数的范围为１．６×１０４～８×１０４，截面含气率的范围为０～０．３０，管间距比Ｌ／Ｄ等于２．０、３．０、４．０．实验结果表明：在一定的试验范围内，在含气率小于０．１５的情况下，当管间距比等于４．０时，每个圆柱的脉动升力功率谱图都存在峰值，而管间距比等于２．０、３．０时，只有后面的圆柱升力功率谱图上有峰值；当含气率大于０．１５时，两根圆柱脉动升力功率谱图的峰值消失；雷诺数对功率谱特性的影响相对较小．

This work is concerned with two phase flow induced vibration of tube array. Vibration characteristics of two tandem cylinders subjected to gas liquid two phase flow could assist understanding the interaction effects for more complex tube arrangements. Fluctuating lift data are obtained for Reynolds number varying from 1.6×10 4 to 8×10 4, and void fraction in the main flow ranged from 0.0 to 0.30. Pitch ratios of the two tandem cylinders are 2.0, 3.0 and 4.0. Peak values are found in the lift spectrogram for every cylinder when void fraction is less then 15% and pitch ratio of the two cylinders is equal to 4.0. But if the pitch ratio is equal to 2.0 or 3.0 and void fraction is the same, peak value would prevail only in the downstream cylinder. When the void fraction is greater than 15%, peak value disappears for both cylinders. Reynolds number was found to have little influence on the power spectrum characteristics of fluctuating lift.