Chuan Ding

The Tesla valve (TV) is a valvular conduit that allows fluid to flow in one direction while restricting flow in the opposite direction, making it useful for enhancing fluid control in the field of microfluidics. Our previous research has found that the enhancement of multi-stage TVs’ diodicity is mainly due to the interstage non-uniform flow field. In this study, we introduce baffles in different positions to discover the effect of non-uniform flow field on single-stage TV’s diodicity. We employed 3D printing technology to fabricate a TV for experimental purposes. The experimental data revealed that flow distortion can lead to an increase in diodicity of up to 30% for the studied single-stage TV. Concurrently, we conducted simulations, establishing a simulation model, and then compared the results of the simulation model with the experimental outcomes. This comparison demonstrated the reliability of the model. The detailed analysis indicates that the high-performance optimization is attributed to the baffle design, which preferentially directs fluid into the arc channel, enhancing reverse flow resistance while minimally affecting forward flow resistance. These findings provide valuable strategies for the optimization of the design and performance prediction of single-stage Tesla valves.

A new type of two-dimensional piston pump with magnetic motion converters is proposed, which uses a pair of magnetic motion converters capable of generating a periodic axial force to replace the original roller-cam rail two-dimensional converters of the pump. By establishing the analytical model of the magnetic motion converters, the motion law of the two-dimensional piston under the magnetic motion converters is analyzed, and the efficiency model of the pump is established according to the principle of pump. The magnetic field simulation model of the magnetic motion converters is established based on Maxwell, and the simulation model of the piston pump is established based on AMESim. The simulation results verify the validity of the analytical model. The prototype pump and test rig were built, and the volumetric efficiency and mechanical efficiency of the pump under various working conditions were obtained. The deviation between the test results and the simulation results was less than 5%, which verified the correctness of the theoretical analysis.

Pulsating flow signals are widely used in the fields of dynamic calibration of flow meters and reliability testing of fluid transmission pipelines. A high-frequency pulsating flow control valve is proposed, its structure and working principle are introduced, and its mathematical model is also established. Finally, an experimental platform is built to experimentally verify the performance of the high-frequency pulsating flow signal generation of this flow control valve prototype. When applying sinusoidal flow signals of 1–25 Hz, the amplitude of the output flow starts to decay after 2 Hz, and the frequency corresponding to the decay to −3 dB is about 23.5 Hz. The experimental results show that the valve can effectively generate unidirectional sinusoidal flow with a maximum amplitude of 25 L/min and a frequency of 23.5 Hz.

For 2D piston pump the churning torque of its cam guide rails at high speed is one of the main sources of mechanical efficiency loss. To conveniently calculate the churning torque and also provide guidance for future optimization of churning torque reduction, an accurate analytical model of constant acceleration and constant deceleration cam guide rail assembly of the stacked-rollers 2D piston pump is established, where the whole churning torque is divided into the peripheral churning torque, the pushing flow churning torque, and the end face churning torque. Then the analytical model is verified by CFD simulation preliminarily. Analytical modeling shows that at 16,000 rpm, the churning torque reaches about 0.826 N m, where the peripheral churning torque, the pushing flow churning torque, and the end face churning torque account for about 55.4%, 37.3%, and 7.3% of the total torque respectively, indicating that the structural parameters related to the pushing flow torque should be optimized with first priority at high rotational speed. Finally, the churning torque at 1000–16,000 rpm was experimentally measured and the influence of oil temperature was considered. The experimental results are in good agreement with the results of analytical modeling and CFD simulation, thus verifying the correctness of the proposed analytical model.

A 2D piston pump’s mechanical efficiency is limited at high rotational speeds, in particular, its mechanical efficiency decreases as its load pressure rises. In this paper, the conventional 2D piston pump is redesigned by changing its suspension rotation into rail rotation to decrease mechanical loss. The mechanical efficiency of this new 2D piston pump is studied by building a mathematical model for analyzing the relationship between the load and the mechanical loss caused by the rolling of the cone rollers on the guiding rails. Hertz contact theory is used for the first time for such analysis. Test results prove that the mechanical efficiency of the 2D piston pump with rail rotation is better than that of a 2D piston pump with suspension rotation, with the former’s mechanical efficiency increasing with the load. According to theoretical analysis and test results, the material used to manufacture the cone rollers and guiding rails is changed from 45 steel to GCr15 to improve the mechanical efficiency of the developed 2D piston pump further.

Because the axial piston pump is often used in the aerospace and aviation fields, it is necessary to pay attention to its outlet pressure and flow characteristics. The parallel 2D piston pump proposed, based on the axial piston pump, has no structural flow ripple because it has a rail with a uniform acceleration and deceleration. Now, the pump is used in the special working conditions of the aerospace field, and it is required to meet the rated flow of 50 L/min, the rated load of 8 MPa, and an extremely low-pressure ripple. Based on CFD technology, this paper studies the pump’s outlet flow and pressure ripples through numerical simulation. According to the causes of the outlet pressure ripple, an improved geometry is determined to further reduce the outlet pressure ripple. Using a high-frequency pressure sensor to measure the outlet pressure ripple of the optimized pump prototype, it was found that the outlet pressure ripple rate of the prototype was only 6%. The parallel 2D piston pump has been proved by the simulation and test that its outlet pressure ripple is extremely low. However, it is not effective to reduce the outlet flow ripple by increasing the pre-pressure and reducing the backflow. In parallel 2D piston pumps, it is still necessary to find a new method to further reduce outlet pressure and flow ripples.