The plasma polymerization method and dynamic ion-beam mixed implantation method were employed to coat ultra-thin polymer films on copper plates. Experiments indicated that steady dropwise condensation of steam at atmo...The plasma polymerization method and dynamic ion-beam mixed implantation method were employed to coat ultra-thin polymer films on copper plates. Experiments indicated that steady dropwise condensation of steam at atmospheric pressure occurred. The condensation heat transfer coefficients increased by approximately 3 and 5－7 times for the polytrimethylvinylsilane film and polytetrafluoroethylene film respectively, compared with the value for film condensation under the same experimental conditions. The temperatures on the condensing surface and inside the test block were found to be rapidly and randomly fluctuated. The properties of the coated films and advantages of the methods used in this investigation were discussed briefly.展开更多
When condensation occurs in supersonic flow fields, the flow is thected by the latent heat released. In the present study, Navier-Stokes equations were solved numerically using a 3rd-order MUSCL type TVD finitediffere...When condensation occurs in supersonic flow fields, the flow is thected by the latent heat released. In the present study, Navier-Stokes equations were solved numerically using a 3rd-order MUSCL type TVD finitedifference scheme with a second-order fractionabetep for time integration. Baldwin-Lomax model, that is the algebraic model, called the zero equation model was used in the computations. The effects of initial conditions (initial degree of supersaturation and total temperature in the reservoir) on condensing fiow of moist air in a supersonic circular half nozzle were investigated. In this case, the effect of condensation on the boundary layer was also discussed in detail. As a result, the simulated flow fields were compared with experimental data in good agreement, and the velocity and temperature profiles were largely changed by condensation.展开更多
基金the National Natural Science Foundation of China (No. 59906002) and the Foundation for Young Teachers of Dalian University of Technology.
文摘The plasma polymerization method and dynamic ion-beam mixed implantation method were employed to coat ultra-thin polymer films on copper plates. Experiments indicated that steady dropwise condensation of steam at atmospheric pressure occurred. The condensation heat transfer coefficients increased by approximately 3 and 5－7 times for the polytrimethylvinylsilane film and polytetrafluoroethylene film respectively, compared with the value for film condensation under the same experimental conditions. The temperatures on the condensing surface and inside the test block were found to be rapidly and randomly fluctuated. The properties of the coated films and advantages of the methods used in this investigation were discussed briefly.
文摘When condensation occurs in supersonic flow fields, the flow is thected by the latent heat released. In the present study, Navier-Stokes equations were solved numerically using a 3rd-order MUSCL type TVD finitedifference scheme with a second-order fractionabetep for time integration. Baldwin-Lomax model, that is the algebraic model, called the zero equation model was used in the computations. The effects of initial conditions (initial degree of supersaturation and total temperature in the reservoir) on condensing fiow of moist air in a supersonic circular half nozzle were investigated. In this case, the effect of condensation on the boundary layer was also discussed in detail. As a result, the simulated flow fields were compared with experimental data in good agreement, and the velocity and temperature profiles were largely changed by condensation.
