In order to evaluate the influence of ultrasonic cavitation on mixing, based on the method of UFD (User Defined Function), the flow field in the mixer（KSM）was numerical simulated by using FLUENT software and verified by experiment. The results showed that the fluid in the KSM mixed faster and more uniform due to the ultrasonic cavitation. The pressure drop of the mixer increased slightly. The flow rate of the fluid increased from 0.50 m/s to 0.55 m/s at the inlet of the mixer and it increased by 10%. The turbulence intensity of the fluid was enhanced, and the strengthening effect was most significant at the first mixing element. And more important, the strengthening effect was most significant for the first element which is basically stable after second mixing elements. The result of experiment also is basically consistent with the simulation results. The fluid mixed more uniform and the mixing was better. With the addition of ultrasonic cavitation, the mixing of the fluid in the static mixer was more uniform and the mixing effect was better.

According to the theory of the spiral groove of the Muijderman,the MATLAB software is used to calculate the spring pressure of the dry gas seal.In this process,the gas film pressure equation is solved and a two-dimensional array about the radius and pressure is obtained. MATLAB curve fitting tool was used to fit the equation of radius and pressure.Combined with the classic example, the root pressure and the opening force of the spiral groove are calculated, and the relative error is compared with the literature, which verifies the reliability of inference calculation.The spring pressure of the working condition is obtained, which provides the basis for the design of the spring pressure and the maintenance of the spring.

The impeller and volute are important parts of centrifugal pump.Their degree of precision and coupling production directly affect the performance of centrifugal pump water conservancy.In order to improve the flow loss generated atthe impeller and volute coupling, Pro/E is taken as the design platform. the analysis and mapping method of impeller and volute Wooden patterns 2D projection are put forward. Combined with Pro/E in the "offset coordinate datum point command" commands, the twisted blade and volute impeller entity modeling precision are realized through Fluent numerical simulation. The pressure and velocity distribution of impeller and volute coupling shows that pressure and velocity are uniform regularity, and head of delivery calculation shows that the design requirements meet design requirement.The analysis results show that this method is not only drawing accurate, but also is fast and flexible, and it can improve the flow loss of the coupling of the impeller and the volute, which lays the foundation for further numerical analysis.

In order to improve the heat transfer efficiency of the twophase closed thermosyphon, different working conditions of the twophase closed thermosyphon under different working condition were simulated by the FLUENT software. Including,the twophase closed thermosyphon under the working condition of different influence of wall temperature of the evaporation zone, and the different filling factor of the evaporation zone on heat transfer efficiency was studied. The results showed that when the wall temperature of the evaporation was 570 K and the filling factor of the evaporation was 50%, the best heat transfer efficiency of the twophase closed thermosyphon was best.

In petrochemical industry, most of the centrifugal pumps work in nondesign conditions. A method of changing the impeller diameter and wrap angle was proposed in order to improve the efficiency of centrifugal pumps. Then impeller flow field was analyzed using Fluent. It was found that the distribution of impeller field speed and pressure was gradually increased and no mutations occurred from the suction port to the outlet.

The fluid flow and heat transfer process of circular finned tube with longitudinal vortex generators（LVGs） were numerically simulated with the CFD calculation software FLUENT, then compared with the normal circular finned tube. The simulation results show that the performance of circular finned tube with longitudinal vortex generators is far better than that of the normal circular finned tube. It can be explained from the view point of field synergy principle, which says that the longitudinal vortex generators can enhance effect of heat transfer because it reduces the angle between velocity and fluid temperature gradient.

The structure design method of the guide plate distributor was put forward and the design method wasmathematically described ，then deduced the formula of pressure reduction ，flow pattern in the distributor was simulated by CFX ．The inlet fluid field show a uniform distribution． These have some importance to fundamental thought of distributer optimum design and formular reduction of pressure on the distributor design ．