摘要
分别在直径为114mm 和244mm 的流化床中,采用压力探头和光导纤维探头考察了湍动流态化的上、下限及实验判别准则。发现床内局部点处的床空隙率随气速的变化符合于修正的 Richardson-Zaki 关系,并以此可以揭示出局部区域进入湍动流态化的流型过渡(上限)。压力脉动法的测量结果(U_c)还表明:此时,床内湍动流态化区域实际上已经占有相当的份额。另一方面,分析床内压力及床密度的脉动信号随气速的变化,可以判定脱离湍动流态化时的流型转变(下限)。本文还应用 Kolmogoroff 的湍流理论定性地分析了湍动流态化的湍流结构。
By using pressure probes and optical fiber probes,the upper and lower limit of gas velocity and the criteria of discrimination of the turbulent flow regime have been investigated in fluidized beds of 114 mm and 244 mm i.d.respectively.It was found that the variation of local bed voidage with gas velocity agrees with the modified Richardson-Zaki equation and,by which,the transition into the tur- bulent regime(the upper limit)of the local region can be revealed.From the result of pressure fluc- tuation measurements(U_c),it is known that a certain portion of the bed has already been entered into turbulent regime at that moment.Furthermore,by analyzing the variation of signals of pressure and density fluctuations in the bed,the transition out of the turbulent regime(the lower limit)can be de- termined.Besides,in this paper,the turbulent structure of turbulent fluidization has also been qualita- tively analyzed by using Kolmogoroff's turbulent theory.
出处
《化学反应工程与工艺》
CAS
CSCD
北大核心
1990年第2期8-16,共9页
Chemical Reaction Engineering and Technology
关键词
湍动流化床
流化床
流型
过渡
Flow regime
Transition
Turbulent fluidized bed.
