Yu Jiuyang

Development and experimental research of new impact pneumatic cylinder

This paper presents a design scheme of the new model of the impact pneumatic cylinder, and analyzes its key part such as direction-control valves, piston rod and so on. An experimental model-machine is manufactured and used for the tests on the experimental platform. We obtain the pressure variation in the impact pneumatic cylinder from numerous lifespan tests based on simulated practical working environments and find that its impact energy and working lifetime is substantially improved.

Numerical simulation for heat transfer performance of four arc-type slotted fin

To develop heat exchangers with high efficiency and low energy consumption, four kinds of arc-type slotted fins are modeled and simulated in the paper. The four kinds of fins the paper selects are a combined slotted fin, a wide slotted fin, a narrow slotted fin and an improved one, respectively. Before numerical simulation for the slotted fins, physical model, computational domain, governing equations and boundary conditions are determined. After the simulation, an enhanced heat transfer criterion including two major factors that are the heat transfer and the resistance is introduced. The simulation results show that the integrated heat transfer performance of the arc-type combined slotted fin is better when the velocity is lower, and the integrated heat transfer performance of the narrow slotted fin is better when the velocity is higher.

Numerical analysis of heat transfer and flow field of pulsating flow in a transverse tube

In this paper, the flow and heat transfer of pulsating flow under low vibrational Reynolds number in a transverse tube were studied through numerical simulation method. The results showed that: the sine (or cosine) fluctuation of outlet pressure was produced by pulsating flow, furthermore, the fluctuate scope increased with increasing amplitude and frequency of pulsating flow; under low velocity and low vibrational Reynolds number, the vortices were induced to generate, migrate and shed periodically by pulsating flow; due to the growing of vortices, radial and mutual disturbance of flow were aggravated and flow boundary layer was thinner, therefore, the mass and energy transfer were enhanced; with the increasing amplitude of pulsating flow, the maximum enhanced heat transfer coefficient can reach 1.97.