Due to the lack of high dynamic flow measurement methods,it is difficult to directly measure the flow of pilot stage.A dynamic flowmeter with flow-displacement conversion function was designed,and the flowmeter was applied to the pilot stage of the dis-placement-flow feedback type proportional direction valve to measure and control the flow of the pilot valve,and form a proportional di-rection flow valve with pilot flow amplification.The simulation model of the proportional directional flow valve with pilot flow amplifica-tion was built in SimulationX,and the dynamic and static characteristics of the valve were studied.The results show that the valve has good static control precision and can accurately control the output flow;the larger the pressure difference between the inlet and outlet of the main valve is,the faster the dynamic response of the spool is;the load change will cause the flow overshoot,but the adjustment time is short.
At present, for the study of the dynamic characteristics of the hydro-pneumatic suspension of vehicles, the elastic force is mainly modeled by the variable gas equation of state, and the damping force is modeled by thin-walled orifice theory, which only considers the turbulent flow. Here, based on expressing the whole flow field including laminar flow, transition flow, and turbulence with piecewise function, the turbulence region is modeled by the Brasius formula and thin-walled orifice theory respectively. By applying vibration signals collected from real roads, the responses of two piecewise function damping force models and traditional thin-walled orifice model of 1/4 suspension system in the time domain and frequency domain respectively are calculated. The average absolute error MAE and root mean square error RSME are used to compare them with the real upper fulcrum data of the suspension cylinder. The results show that different models can simulate suspension vibration well in the low-frequency range, but there are obvious deficiencies in the middle and high-frequency range, while the short-hole flow theoretical model in the form of a piecewise function is closer to the real value in the frequency domain.
Aiming at the integration, transmission and sharing of multi-source heterogeneous data in the production process of textile machinery manufacturing enterprises, and combining with the actual production of enterprises, an enterprise-oriented business process model is built, a workshop manufacturing process data management model is established, and the production data is preprocessed such as anomaly correction, time registration, timing data complement, etc., and the ontology-based heterogeneous data integration method is adopted, realized the data integration and sharing of intelligent production in textile machinery manufacturing workshop, and provided data support for digital twin platform and simulation optimization decision; the digital workshop data integration management system is designed and developed. Through the integration of SAP, SCADA and other system data, the production progress tracking, equipment operation monitoring and production-related data statistical analysis are realized, and three-dimensional visualization is carried out in combination with three-dimensional models to meet the data management requirements of the workshop.
In order to improve the energy capture performance of vertical axis lift wind turbines in a low wind speed environment, the drag wind turbine is employed to couple with the design of existing vertical axis lift wind turbines. In contrast to the existing literature, in this work, a computational model is proposed that can simulate the interaction between the turbine and the fluid. The effects of pitch angle (β), installation angle (θ), overlap ratio (ε) and diameter ratio (DL) on the energy capture performance of hybrid vertical axis wind turbines are systematically analyzed based on Taguchi and CFD methods. The results show that under the optimized parameter combination, the peak energy capture coefficient of the lift-drag hybrid wind turbine can be increased to 0.2328, compared with 0.0309 and 0.0287 of the pure lift and drag turbine, respectively. In addition, the result of the prototype test show that the optimized hybrid wind turbine not only has a better-starting performance but also has 2.0 times the output power of that of the lift wind turbine.
Aiming at the problem that the flow rate of the two cavities of the differential cylinder does not match and it is not easy to achieve pump control, the team proposed the asymmetrical distribution principle of the axial piston pump with three ports, which can compensate for the flow difference between the two cavities of the differential cylinder without auxiliary components. Based on this principle, a new type of valve plate structure is designed by using the residual compression method. The pump performance is analyzed by PumpLinx simulation and experiment; the influence of the transition zone structure on the pressure and flow characteristics of the piston pump is researched. The basic characteristics of the pump such as pressure, flow, and noise under different working conditions were tested on the experimental platform, and the rationality of the new structure was verified. The new flow distribution scheme can not only compensate the flow difference of the differential cylinder, but also output two different pressures, which realizes the ideal effect of the hydraulic pump directly controlling the differential cylinder. The research work lays a theoretical foundation for the realization of the pump-controlled volumetric direct drive system.
