Xie Haibo

Effects of structural parameters and rigidity of driving diaphragm on flow characteristics of micro valveless pump.

The structure and operating principle of micro valveless pump were investigated theoretically and experimentally. The mathematical model of pressure and flow rate within the micro nozzle/diffuser was established to analyze the effects of nozzle/diffuser parameters on the output flow rate of the micro valveless pump. The experiments were carried out with different structural parameters, driving frequencies, vibration amplitudes and stiffness of the driving diaphragms. Effects of the structural parameters and driving conditions on the operation performance of the pump are discussed in detail. The work provides useful reference for structure optimization selection of the driving diaphragm of micro valveless pump.

Stability research of the compression process of two-cylinder four-stroke single-piston hydraulic free piston engine

An invariable compression ratio in certain conditions must be achieved to ensure a steady and efficient performance of the single-piston hydraulic free piston engine. The compression ratio is determined by the characteristics of the compression stroke. The mathematical models of the key components during the compression process are established. The kinematic characteristics of the free piston assembly are analyzed under two conditions. One condition is that free piston assembly is driven by the compression accumulator only and the other one is that free piston assembly is driven by the compression accumulator and the pump station. Pressures in compression accumulator and compression chamber are analyzed and compared in both conditions. According to the experimental results, pressures in the compression chamber and compression accumulator are not constant in both conditions during the compression process. The compression stroke and compression time vary with the changing of the pressure in the compression accumulator, which adds the complexity and changeability to the compression ratio control. An improved configuration is put forward to solve the pressure variation. The results show that the improved configuration can make the pressure invariable at the inlet of the compression chamber and the compression process keeps almost the same regardless of the pressure changing in the compression accumulator. With this new structure, there is about 2.5% energy loss, which is acceptable considering the stable compression stroke.

Study on Characteristics of Interface Between Multiple Laminar Streams and Application for Secondary Etching Inside Microchannels

Typical microfluidc devices basically operate at low Reynolds numbers. The flowage in microchannels is entirely laminar. This letter quantifies both experimentally and numerically the diffusion across the interface between two aqueous solutions in pressure-driven laminar flow in microchannels. The relationship between the flow parameters at the inlets and the interfaces location and diffusion extent is verified at high Peclet number (about 800~8000). The experimental results accord with the CFD results very well. A quantitative conclusion of the interface location and the diffusion extent between two streams near the walls, such as described in this letter, are required for the further development of the technology of microfabrication inside microchannels using fluid flow. The features of the micro structures, which are patterned with this fabrication method, are determined by interface location and the diffusion across the interface in a great degree. In the last part of this letter we give some the experiment results about the relationship of the flow parameters and the topography of the secondary patterned micro structures.

Design and testing of micro fluidic chemical analysis chip integrated with micro valveless pump

A new structure and working principle of the chip integrated with micro valveless pump for capillary electrophoresis was proposed in this paper. The micro valveless pump with plane structure has advantages of simple structure, and the process technology is compatible with existing micro chips for capillary electrophoresis. Based upon the mathematical model, simulation study of micro pump was carried out to investigate the influence of structural parameters on flow characteristics, and the performance of the integrated micro pump was also tested with different control parameters. The simulation results agree with the experimental results. Three samples, which are amino acid, fluorescein and buffer solution, have been examined with this chip. The results of the primary experiments showed that the micro valveless pump was promising in the integration and automatization of miniature integrated fluidic systems.A new structure and working principle of the chip integrated with micro valveless pump for capillary electrophoresis was proposed in this paper. The micro valveless pump with plane structure has advantages of simple structure, and the process technology is compatible with existing micro chips for capillary electrophoresis. Based upon the mathematical model, simulation study of micro pump was carried out to investigate the influence of structural parameters on flow characteristics, and the performance of the integrated micro pump was also tested with different control parameters. The simulation results agree with the experimental results. Three samples, which are amino acid, fluorescein and buffer solution, have been examined with this chip. The results of the primary experiments showed that the micro valveless pump was promising in the integration and automatization of miniature integrated fluidic systems.