The present work is a visualization study of a typical kerosene （RP-3） flowing through vertical and horizontal quartz-glass tubes under both sub- and supercritical conditions by a high speed camera. The experiments ...The present work is a visualization study of a typical kerosene （RP-3） flowing through vertical and horizontal quartz-glass tubes under both sub- and supercritical conditions by a high speed camera. The experiments are accomplished at temperatures of 300-730 K under pressures from 0.107-5 MPa. Six distinctive two-phase flow patterns are observed in upward flow and the critical point of RP-3 is identified as critical pressure pc=2.33 MPa and critical temperature Tc=645.04 K and it is found that when the fluid pressure exceeds 2.33 MPa the flow can be considered as a single phase flow. The critical opalescence phenomenon of RP-3 is observed when the temperature is between 643.16 K and 648.61 K and the pressure is between 2.308 MPa and 2.366 MPa. The region filled by the critical opalescence in the upward flow is clearly larger than that in the downward flow due to the interaction between the buoyancy force and fluid inertia. Morecover, obvious layered flow phenomenon is observed in horizontal flow under supercritical pressures due to the differences of gravity and density.展开更多
At high rotation numbers,the rotational effects on heat transfer and flow could be diverse among the channels with different blockage ratios.However,most studies are conducted under low rotation number(less than 0.25)...At high rotation numbers,the rotational effects on heat transfer and flow could be diverse among the channels with different blockage ratios.However,most studies are conducted under low rotation number(less than 0.25)and selected blockage ratio.This paper experimentally investigates the effect of rib blockage ratio(ranges from 0 to 0.3)on pressure loss and heat transfer in a rotating square channel under high rotation number(up to 0.81).The ribs staggered on leading and trailing walls were oriented 90°to the mainstream flow.The Reynolds number and the wall-to-fluid temperature ratio varied from 20000 to 40000 and 0.08 to 0.2,respectively.The results showed that a larger blockage ratio resulted in a better heat transfer but a higher pressure drop.The optimum blockage ratio was 0.1 for the best thermal performance.The rotational effects were weakened in the passage with a higher blockage ratio,where the critical rotation number could not be observed.Moreover,the heat transfer enhancement induced by rotation was more significant when the temperature ratio increased.Finally,the correlations were developed for the pressure drop and the convective heat transfer on the leading and trailing edges.展开更多
基金National Natural Science Foundation of China(50676005)
文摘The present work is a visualization study of a typical kerosene （RP-3） flowing through vertical and horizontal quartz-glass tubes under both sub- and supercritical conditions by a high speed camera. The experiments are accomplished at temperatures of 300-730 K under pressures from 0.107-5 MPa. Six distinctive two-phase flow patterns are observed in upward flow and the critical point of RP-3 is identified as critical pressure pc=2.33 MPa and critical temperature Tc=645.04 K and it is found that when the fluid pressure exceeds 2.33 MPa the flow can be considered as a single phase flow. The critical opalescence phenomenon of RP-3 is observed when the temperature is between 643.16 K and 648.61 K and the pressure is between 2.308 MPa and 2.366 MPa. The region filled by the critical opalescence in the upward flow is clearly larger than that in the downward flow due to the interaction between the buoyancy force and fluid inertia. Morecover, obvious layered flow phenomenon is observed in horizontal flow under supercritical pressures due to the differences of gravity and density.
文摘At high rotation numbers,the rotational effects on heat transfer and flow could be diverse among the channels with different blockage ratios.However,most studies are conducted under low rotation number(less than 0.25)and selected blockage ratio.This paper experimentally investigates the effect of rib blockage ratio(ranges from 0 to 0.3)on pressure loss and heat transfer in a rotating square channel under high rotation number(up to 0.81).The ribs staggered on leading and trailing walls were oriented 90°to the mainstream flow.The Reynolds number and the wall-to-fluid temperature ratio varied from 20000 to 40000 and 0.08 to 0.2,respectively.The results showed that a larger blockage ratio resulted in a better heat transfer but a higher pressure drop.The optimum blockage ratio was 0.1 for the best thermal performance.The rotational effects were weakened in the passage with a higher blockage ratio,where the critical rotation number could not be observed.Moreover,the heat transfer enhancement induced by rotation was more significant when the temperature ratio increased.Finally,the correlations were developed for the pressure drop and the convective heat transfer on the leading and trailing edges.
