Outlet Port Position Research Articles

Pressure-Drop Coefficients for Cushioning System of Hydraulic Cylinder With Grooved Piston: A Computational Fluid Dynamic Simulation

Cushioning is an important aspect in hydraulic cylinder performance. The piston has to be decelerated before it strikes the end cap in order to avoid stresses in the cylinder components and reduce vibration that can be transmitted to the machine. One of the least-studied methods is internal cushioning by grooves in the piston. In this method, the flow is throttled with adequately designed grooves when the piston reaches the outlet port position. The purpose of the present work is to present a method to estimate the pressure-drop coefficients for a certain design of piston grooves in order to provide a model to develop a dynamic system simulation of the cushion system. The method is based on a computational fluid dynamic simulation of flow through piston grooves to the outlet port for each piston’s static position. The results are compared with experimental measurements, and a correction, based on Reynolds number, is proposed. Good agreement, below 16%, was obtained for all the positions but particularly for the last grooves, for which the numerical result’s deviation to the experimental measurements was less than 10%. In general, the numerical simulation tended to underestimate the pressure drop for the first grooves and overestimate the calculation for the last grooves.

Numerical investigation and optimization of mixed convection in ventilated square cavity filled with nanofluid of different inlet and outlet port

PurposeThe purpose of this paper is to study the optimal conditions of the mixed convection in a ventilated square cavity filled with Cu-water nanofluid using the Taguchi method. The paper aims to discuss diverse issues affecting the said model.Design/methodology/approachThe numerical solutions of nonlinear coupled equations are developed by means of the Taguchi method. The Taguchi method is used as an effective way to optimize the design process engineering tests.FindingsThe governing equations are discretized using a finite volume method and solved with semi-implicit method for pressure linked equations (SIMPLE) algorithm. The effect of Richardson number (0.01-10), the volume fraction of nanofluid (0-5 per cent), distance of inlet port position from bottom wall of the cavity (0-0.9 H) and distance of outlet port position from top wall of the cavity (0-0.9 H) as effective parameters are analyzed across four levels. This analysis is done for fixed Grashof number 104. The results show that the mean Nusselt number almost decreases by an increase in the Richardson number, volume fraction of nanofluid, position of the inlet port and position of the outlet port. It is found that the cavity with distance of inlet port position from bottom wall of the cavity 0 and distance of outlet port position from upper wall of the cavity 0.9 H at the Richardson number 0.01 and the volume fraction 3 per cent is the optimal design for heat transfer.Originality/valueAs far as the authors know, this model has been investigated for the first time.

Mixed magnetohydrodynamic convection in a Cu-water-nanofluid-filled ventilated square cavity using the Taguchi method: A numerical investigation and optimization

In this paper, the optimal condition of mixed magnetohydrodynamic convection in a ventilated square cavity filled with a Cu-water nanofluid with different positions of inlet and outlet port is analyzed. To serve the purpose, the L16 (43) orthogonal Taguchi array is used by means of the Taguchi method. Discretization of the governing equations is obtained through the finite volume method and then solved with the SIMPLE algorithm. A very effective mode, namely the Taguchi method, is used for the L16 (43) orthogonal Taguchi array. The effects of Richardson number (0.01-10), Hartmann number (0-50), and inlet and outlet positions (0-0.9 H) at \(\Phi\) = 1% are investigated. The entire analysis is performed for fixed Grashof number 104. It is found that the mean Nusselt number decreases by increasing the Richardson number, Hartmann number and the position of the inlet port, whereas the position of the outlet port has an increment effect on the mean Nusselt number. The optimal distance of outlet port position from the upper wall of the cavity is 0.9H at Richardson number 0.01, while the Hartmann number of optimal design for heat transfer is noted as 30. Comparison with existing studies is made as a limiting case of the considered problem.

Mixed convection heat transfer in a ventilated cavity with hot obstacle: Effect of nanofluid and outlet port location

In the present study, the lattice Boltzmann method is implemented to investigate the effect of suspension of nanoparticles on mixed convection in a square cavity with inlet and outlet ports and hot obstacle in the center of the cavity. The effect of outlet port location is examined on heat transfer rate then the effect of nanoparticles is inspected for volume fraction of nanoparticles in the range of 0 to 0.03 at the different position of outlet port. The study was carried out for different Richardson numbers ranging from 0.1 to 10. Grashof number is assumed to be constant (104) so that the Richardson number changes with Reynolds number. The isothermal boundary condition is assumed for obstacle walls and the cavity walls are adiabatic. The result is presented by isotherms, streamlines, and local and average Nusselt numbers. The maximum heat transfer rate occurs when the outlet port is located at P2 for Ri=0.1 and P1 for Ri=1, Ri=10, respectively. Results show that by adding the nanoparticles to base fluid and increasing the volume concentration of nanoparticles the heat transfer rate is enhanced at different Richardson numbers and outlet port positions. But this phenomenon is not observed at Ri=10 when the outlet port is located at P1.

Flow Characteristics of a Spool Valve (2nd Report, Modeling Method by Three-Dimensional Numerical Analysis and Evaluation of Flow Characteristics)

A study was conducted to obtain fundamental flow characteristics for a practical spool valve whose inlet and outlet port position was set at 90°angle. Particularly in the present investigation two different geometric configurations of spool were examined. One spool has rectangular notches and another spool has no notch. Experiments were carried out to obtain basic flow and pressure relationship. By examining experimental data with numerical results, it was found that numerical results predicted the flow and pressure relationship very well, modeling approximate edge configuration on the spool and body. Various flow characteristics also were verified based on flow parameters of the spool valves.

Flow Characteristics of a Spool Valve. 1st Report, Evaluation of Flow Behavior by Experimentation with an Aid of Three Dimensional Numerical Analysis.

A study was conducted to obtain fundamental flow characteristics for a spool valve whose inlet and outlet port position was set at 90° angle. Basic experiment was carried out to obtain basic flow and pressure relationship, which was used to the basis of the three dimentional computer simulation. By examining experimental data with the numerical results, the spool configuration was connected in order to give the consistency between the experiment and numerical analysis. Various flow characteristics were verified by the numerical simulation, and detailed flow field and their associated flow parameters of the spool valve were obtained in the present study.

Development of Design Methods for a Centrifugal Blood Pump with a Fluid Dynamic Approach: Results in Hemolysis Tests

The purpose of this study was to examine the relationship between local flow conditions and the hemolysis level by integrating hemolysis tests, flow visualization, and computational fluid dynamics to establish practical design criteria for centrifugal blood pumps with lower levels of hemolysis. The Nikkiso centrifugal blood pump was used as a standard model, and pumps with different values of 3 geometrical parameters were tested. The studied parameters were the radial gap between the outer edge of the impeller vane and the casing wall, the position of the outlet port, and the discharge angle of the impeller vane. The effect of a narrow radial gap on hemolysis was consistent with no evidence that the outlet port position or the vane discharge angle affected blood trauma in so far as the Nikkiso centrifugal blood pump was concerned. The radial gap should be considered as a design parameter of a centrifugal blood pump to reduce blood trauma.