Design of Hydraulic Control System for Press Machine and Analysis on Its Fluid Transmission Features

The stability and reliability of hydraulic control system have a direct bearing on the overall dynamic performance of the press machine. Hydromechanical analysis on the hydraulic control system is of theoretical and practical significance to improving the transmission performance and structural design of the entire press machine. From a quantitative perspective, this paper firstly analyzes the fluid transmission features of the hydraulic control system for the press machine, and presents the fluid transmission route and design drawings of the hydraulic control system. The next step is the design of the hydraulic control system. The authors specified the steps of design and calculation for the hydraulic control cylinder, and the principles for determining the power of the diesel engine. After that, experiments were carried out to verify the dynamic and static features of the designed system, and prove that our system is scientific and rational.

Fluid dynamics around three cylinders in presence of small control cylinders

A numerical study is performed to analyze the effect of small control cylinders on fluid force reduction and vortex shedding suppression on the flow past three inline square cylinders using the lattice Boltzmann method. The Reynolds number Re = 160 is fixed while the spacing between the cylinders is taken in the range of 1.0D ≤ g* ≤ 5.0D (where D is the size of the main cylinder) and the control cylinder size is varied from 0.1D to 0.5D. To systematically understand the effect of control cylinders on the forces, a detailed analysis of Strouhal number (St), mean drag coefficient (CDmean), and root mean square values of the drag and lift coefficients is presented in this paper. In this study, it is observed that the average mean drag coefficient (CDmeanaverage) and Strouhal number reached either maximum or minimum values at different values of separation ratio (g*) and small control cylinder size (d). It is found that at (g*, d) = (5.0, 0.0) and (1.0, 0.5), the average CDmean attains its maximum (CDmeanaverage = 0.7813) and minimum (CDmean = 0.0988) values. Furthermore, at (g*, d) = (5.0, 0.3) and (2.0, 0.0) the average St attains its maximum (St = 0.1780) and minimum (St = 0.041) values. It is found that the flow regimes completely change in the presence of control cylinders. In particular, at g* = 4.0 there is a critical flow regime when the size of the control cylinder changes from 0.1 to 0.5. The sudden jump in the mean drag coefficient and Strouhal number for the middle cylinder with their maximum and minimum values also confirms the critical flow regime. The effect of control cylinders within tandem square cylinders has not been studied before.

Suppression of Vortex Shedding With Rotating Wake-Control Cylinders: Numerical Investigation at a Moderate Reynolds Number

This paper presents an investigation of the suppression of vortex shedding of a larger circular cylinder by the interference of smaller rotating wake-control cylinders positioned around its center. Three-dimensional numerical simulations have been conducted at a moderate Reynolds number of 10,000, thus complementing the previous experimental results by offering a better understanding of the physical mechanisms behind the suppression. Visualization of the vortex wakes revealed a complex disruption of the vortex tubes for the higher rotation speeds, with consequent reduction in the mean drag of almost 52% when compared with that of a bare cylinder. Fluctuating lift has also been drastically reduced in 90%. Configurations of control cylinder that can suppress vortex shedding may produce more efficient suppressors for flow-induced vibrations.