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冷却塔实验室模型英文文献和中文翻译(5)

时间:2017-05-12 21:13来源:毕业论文
investigated, and, on the other hand, it is close to the initial temperature of the water in industrial cooling towers. Figure 2 presents in dimensionless form the changes in the temperature AT/T a of


investigated, and,  on  the other hand,  it  is close to  the  initial  temperature of the water  in  industrial cooling towers.
Figure  2  presents  in  dimensionless  form  the  changes  in  the  temperature  AT/T  a  of  the  vapor-air mixture
with  the  height  z/H.  The  experimental data  relate  to  the axis  of the model  in  the  absence  (Fig.  2a)  and  presence
(Fig.  2b)  of wind  at  S  =  2  for  three  cases:  the  standard mode  of operation  of  the  cooling  tower,  with  one-sided
swirling  of  the  flow  (the  angle  of  rotation  of  the  plates  is  45~  and with  two-sided  circulation  (symmetric with
respect  to  the wind direction).
As  follows  from  the  experimental  data  presented  in  Fig.  2,  for  the  conventional mode of  tower  operation
and  for the mode with swirling the mixing of the flows terminates approximately at  the height z/H  = 0.3.  It should
be noted  that in  the presence of flow circulation at  the bottom of the model the  temperature of the vapor-air mixture
is much higher  (curve  2)  than  in  the usual mode  (curve  1).
As  seen  from  Fig.  2b,  a  strong wind  (S  =  2)  has  a  large  influence on  the  temperature  distribution  inside
the  tower:  a  general  decrease  in  the  temperature  of  the  vapor-air  mixture  along  the  tower  axis  above  the water
distributor  is observed. As noted above,  in  this case  the behavior of curve  1 can be  explained by  the  appearance of
large  stagnant zones having a  vertical dimension of the order  of 0.6H.
One-sided  swirling of the  incoming flow completely eliminates the effect of the formation of stagnant zones
(curves  2).  In  the  case of symmetric swirling  (curves 3)  with and without wind one observes  a  general  lowering in
the  temperature  of  the  ascending vapor-air  flow along  the  tower axis.  The  data  on  the  velocity field  inside of  the
model obtained by  the  authors  are  given  in  [3 ].
Figure  3  shows  profiles  of rms  temperature  oscillations along  the model axis,  nondimensionalized by  the
mean  temperature  of  the  vapor-air mixture'at a  given point  and  obtained  under  the  same  conditions as  in  Fig.  2. It  can  be  noted  that  a  lower  level of  temperature oscillations  is  observed  in  the  case  of  symmetric swirling  of  the
flow  (curves 3).  From  the  figures  it  is  seen  that  the distribution of the amplitude of the oscillations along  the height
of  the model  has  a  rather  complex character and  depends  on  the  conditions  of  the  entry of  the  external  air  flow
into  the  tower.  Using  the  analogy  between  the  processes  of heat  and  momentum  transfer  it  can  be  assumed  that 冷却塔实验室模型英文文献和中文翻译(5):http://www.751com.cn/fanyi/lunwen_6883.html
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