Vane Tip Research Articles

Optimization and Simulation on Pressure-Reducing Valve in Water Hydraulic Vane Pump

High contact stress between the vane tips and the cam ring is one of the main obstacles to improve the working pressure of a water hydraulic vane pump. A pressure-reducing valve for regulating the bottom pressure of the vanes at the pump suction zone is presented in this paper. Through optimization and simulation, it is found that the throttle structure has great influence on the dynamic performance of the pressure-reducing valve, and the triangular-rectangular groove is proved to be more suitable for the valve among all the investigated grooves. The theoretical analysis results show that the use of the pressure reducing valve can obviously reduce the contact forces between the cam ring and the vanes at the suction zone of the pump. The work in this research provides a feasible solution to improve the working pressure of a water hydraulic vane pump.

Inlet Condition Effects on the Tip Clearance Flow With Zonal Detached Eddy Simulation

In the present study, the influence of the inlet condition on the tip clearance flow of an axial compressor is investigated. Two different zonal detached eddy simulations (ZDES) computations are carried out and compared to Reynolds-averaged Navier–Stokes (RANS) and unsteady RANS (URANS) computations as well as to experimental data. A rotating distortion map of the flow cartography is set as inlet condition for the first ZDES computation. An azimuthally averaged inlet condition is used for the second one and uncouples the rotor tip-leakage vortex flutter phenomenon, which stems from the arrival of the inlet guide vane wake from the behavior inherent to the rotor tip-leakage vortex. In the studied configuration, the inlet guide vane tip vortex reveals to lower the effects from double leakage on the rotor. The topology of the rotor tip-leakage vortex is described, and its development is analyzed.

유압 베인 펌프에서의 탄성유체윤활 해석

Hydraulic vane pumps are widely used in various hydraulic systems because of its compactness and light weight. It is well known that the vanes and cam ring are separated by very thin liquid films which result in the EHL state. Contrary to the case of cylindrical roller bearings, the inlet and side boundary pressures are much higher than the atmospheric pressure. In this paper, a numerical solution of the EHL of finite line contacts between the cam ring and vane tip with profiled ends is presented. Using a finite difference method with non-uniform grids and the Newton-Raphson method, converged solutions are obtained for moderate load and material parameters. The EHL pressure distribution and film shape are considerably affected by pump delivery pressure and the side boundary condition applied. Both the maximum pressure and the minimum film thickness always occurred near the edge regions. The present results can be used in the design of optimum vane profile in hydraulic vane pump.

Friction Analysis on Vane of an Existing and of a Novel Multi Vane Rotary Compressor

This paper presents results of a frictional analysis on a new rotating sleeve multi-vane rotary (RSMVR) compressor. The new five-vane rotary compressor is adapted from the existing concept of a rotating sleeve single-vane rotary (RSSVR) compressor, in which the extended rounded end of one vane is embedded into the inner surface of the sleeve which allows the vane to swing within a certain small angle. As the rotor rotates, this vane drives the sleeve which in turn pushes and pulls the vane into and out of the slot in the rotor, respectively. The other four vanes are similarly pushed into the respective slots in the rotor but slide out only when a sufficient centrifugal force is developed. The driving vane ensures that suction, compression and discharge of the gas occur at all speeds of rotation. Although the sleeve rotates along, due to eccentricity between the rotor and the sleeve, each tip of the four vanes still rubs against the inner surface of the sleeve. The focus of the present study limits its analysis on to only frictions between the vane tip and the inner surface of the sleeve and between the vane sides and the respective slot walls. The frictional analysis is carried out by first determining the instantaneous pressure inside the compression cell and all the associated forces that exist. This involves an analysis on the dynamics of each vane when it reciprocates and at the same time rotates eccentrically with the sleeve. The kinematics of the vane are modelled using cosine and sine rules taking the cell leading vane as a reference to the angle of rotation. In the operation the model estimates a dramatic reduction in friction which is up to 82% lower than that occurs in an existing design of an equivalent conventional multi-vane rotary compressor (MVR). A friction between the rotating sleeve and the two opposite end plates exists in the RSMVR compressor but does not in that of the MVR. This will be included in a later study but on a new integrated brushless DC motor RSMVR compressor concept and on that of the existing shaft driven MVR, to see the overall difference in the frictions exerted.

Energy Efficient Wind Turbine System based on Fuzzy Control Approach

Abstract Both air flow mechanics and control system of a wind turbine play an important role in its energy management system. Energy is considered as the essential part for the national development in the form of mechanical power or any other which has major contribution for improving the quality of life and enhancing the economic growth. Subsequently, power generation by wind velocity is a complex process with many interacting factors such as wind velocity, climate condition, natural disaster, control system, design structure, vane tip speed ratio, centrifugal force, rotor drag, turbulence flow, roughness and wind shear, etc. Various procedures have been reported in literature to achieve an optimal performance and system effectiveness. However, these control methods had depended only on exact mathematical modelling or on expert's knowledge that can’t be relied on solely in modelling such a complex management of air flow mechanics due to its unstable climate condition and so on. In the proposed study, an integrated control model using an adaptive neuro- fuzzy inference system for wind turbine power management strategy has been introduced. In this model, an artificial neural network is employed to develop the fuzzy expert system in order to achieve a more realistic evaluation of wind power extraction. Simulations and experiments have been carried out to investigate the effect of control strategy parameters of the wind turbine and its power extraction.

Hydrodynamic performance enhancement of a mixed-flow pump

This paper presents an optimization procedure based on a radial basis neural network surrogate model for design of a vaned diffuser in a mixed-flow pump. Numerical analysis of fluid flow in a mixed-flow pump has been carried out by solving three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model. The optimization processes have been performed twice to investigate the coupled effects of diverse variables. The first optimization process has been conducted with two design variables defining the straight vane length ratio and the diffusion area ratio, and the second one has been conducted with four design variables, i.e., the angle at the diffuser vane tip, the distance between the impeller blade trailing edge and the diffuser vane leading edge, and the two design variables used in the first optimization. The efficiency as a hydrodynamic performance parameter has been selected as the objective function for optimizations. The objective function values have been assessed through three-dimensional flow analysis at design points sampled by Latin hypercube sampling in the design space. The first and second optimizations with the coupled effects of diverse variables have yielded maximum increases in efficiency of 7.16% and 9.75%, respectively, compared to the reference shape. The off-design performance has been also improved in most of the optimum shapes except in the shut-off flow region.

Development and beam test of a continuous wave radio frequency quadrupole accelerator

The front end of any modern ion accelerator includes a radio frequency quadrupole (RFQ). While many pulsed ion linacs successfully operate RFQs, several ion accelerators worldwide have significant difficulties operating continuous wave (CW) RFQs to design specifications. In this paper we describe the development and results of the beam commissioning of a CW RFQ designed and built for the National User Facility: Argonne Tandem Linac Accelerator System (ATLAS). Several innovative ideas were implemented in this CW RFQ. By selecting a multisegment split-coaxial structure, we reached moderate transverse dimensions for a 60.625-MHz resonator and provided a highly stabilized electromagnetic field distribution. The accelerating section of the RFQ occupies approximately 50% of the total length and is based on a trapezoidal vane tip modulation that increased the resonator shunt impedance by 60% in this section as compared to conventional sinusoidal modulation. To form an axially symmetric beam exiting the RFQ, a very short output radial matcher with a length of $0.75\ensuremath{\beta}\ensuremath{\lambda}$ was developed. The RFQ is designed as a 100% oxygen-free electronic (OFE) copper structure and fabricated with a two-step furnace brazing process. The radio frequency (rf) measurements show excellent rf properties for the resonator, with a measured intrinsic $Q$ equal to 94% of the simulated value for OFE copper. An ${\mathrm{O}}^{5+}$ ion beam extracted from an electron cyclotron resonance ion source was used for the RFQ commissioning. In off-line beam testing, we found excellent coincidence of the measured beam parameters with the results of beam dynamics simulations performed using the beam dynamics code TRACK, which was developed at Argonne. These results demonstrate the great success of the RFQ design and fabrication technology developed here, which can be applied to future CW RFQs.

Investigation of Electromagnetic Field Perturbation With Respect to Mechanical Imperfections in Radio-Frequency Quadrupole (RFQ) Structure

Electromagnetic (EM) fields near the beam axis in a radio frequency quadrupole (RFQ) are very sensitive to dimensional changes especially on vane tip geometries. Due to measurement difficulties, field distribution around the beam axis is generally assumed to be equal to that measured outside of vane gaps in quadrants using a bead-pull technique. If an RFQ structure has any mechanical imperfections in its vanes, local field distributions around the beam axis could be different from the design field profiles. The distorted field may affect beam quality as well as the operational stability and reliability of the RFQ system. In order to understand changes of field distribution in the RFQ against localized mechanical imperfections, a study with systematic 3D simulations has been carried out using a model developed for the RFQ in Spallation Neutron Source (SNS) of Oak Ridge National Laboratory. Field information at various locations such as around the beam-axis, bead-pull positions, and pickup probe positions are investigated with the vane tip perturbations. Design considerations for proper field retuning with perturbation are also presented and discussed to help future RFQ designs.

Analysis and Optimization of a Vaned Diffuser in a Mixed Flow Pump to Improve Hydrodynamic Performance

Hydrodynamic analysis and an optimization of a vaned diffuser in a mixed-flow pump are performed in this work. Numerical analysis is carried out by solving three-dimensional Reynolds-averaged Navier-Stokes equations using the shear stress transport turbulence model. A validation of numerical results is conducted by comparison with experimental data for the head, power, and efficiency. An optimization process based on a radial basis neural network model is performed with four design variables that define the straight vane length ratio, the diffusion area ratio, the angle at the diffuser vane tip, and the distance ratio between the impeller blade trailing edge and the diffuser vane leading edge. Efficiency as a hydrodynamic performance parameter is selected as the objective function for optimization. The objective function is numerically assessed at design points selected by Latin hypercube sampling in the design space. The optimization yielded a maximum increase in efficiency of 9.75% at the design flow coefficient compared to a reference design. The performance curve for efficiency was also enhanced in the high flow rate region. Detailed internal flow fields between the reference and optimum designs are analyzed and discussed.

On-machine non-contact dimension-measurement system with laser displacement sensor for vane-tip machining of RFQs

We have developed a new on-machine non-contact dimension-measurement system using a laser displacement sensor (LDS) for machining the vane tips of RFQs. The LDS was attached to a milling machine, and the dimensions of a test piece (TP) with a modulated vane tip were measured to evaluate the performance of the system. A longitudinal profile was measured with the LDS and it was compared with the profile measured with a coordinate measuring machine (CMM). A transverse profile was also measured. The required accuracy of dimension measurement was achieved using our system.

Studies on several key problems of water hydraulic vane pump

PurposeThe balanced vane pump is a common transmission component in hydraulic systems. Since the physicochemical properties of water and seawater are different from that of mineral oil, some problems can occur, for instance, poor lubrication, more leakage, and more corrosion. The paper aims to demonstrate the technical feasibility for the water hydraulic vane pump.Design/methodology/approachThe material combinations were selected based on related research in literature. The volumetric efficiency and suction performance were measured in the current experiment. The relations between gap clearances and leakage flow, the contact and the friction forces between a vane tip and a cam contour were simulated based on mathematic models.FindingsThe soft‐hard material combinations in the prototype pump show preferable friction characteristics during tests. The axial clearances are the main channels of leakage flow. Pin type vane pump can reduce the contact force of the vane tip.Originality/valueThis paper outlines some key problems of the water hydraulic vane pump, such as the friction pair material,the structure, and the contact force of the vane tip by means of testing the basic performance of pump and mathematic model.

Improved rotary vane expander for trans-critical CO 2 cycle by introducing high-pressure gas into the vane slots

The loss of contact between the vane tip and cylinder wall was proven to cause a serious leakage and inefficient operation of the rotary vane expander, which was developed to replace the throttling valve in the trans-critical CO 2 refrigeration system. An improved structure was suggested by introducing high-pressure gas into the vane slots. This paper presents the experimental investigation of the improved prototype expander. By comparing the improved prototype with the original, focusing on the expander performance and the p– θ diagram as well as the vane movement, the effects of introducing high-pressure gas into the slots on the thermodynamic processes and performance were analyzed. The results showed that, by introducing the high-pressure gas into the vane slots, the volumetric efficiency was increased from 17% to 35%, and the isentropic efficiency improved from 15% to 45%, resulting in a maximum COP improvement of 27.2% compared to the throttling cycle under the same working conditions.

Multistage Compressor and Turbine Modeling for the Prediction of the Maximum Turbine Speed Resulting From Shaft Breakage

A mathematical model for the prediction of the maximum speed of a high pressure turbine following a shaft failure event was developed. The model predicts the high pressure compressor and ducting system pre- and poststall behaviors such as rotating stall and surge after the shaft breakage. The corresponding time-dependent high pressure turbine inlet conditions are used to calculate the turbine maximum speed, taking into account friction and blade and vane tip clearance variations as a result of the rearward movement of the turbine and destruction of the turbine blading. The compressor and ducting system is modeled by a one-dimensional, stage-by-stage approach. The approach uses a finite-difference numerical technique to solve the nonlinear system of equations for continuity, momentum, and energy including source terms for the compressible flow through inlet ducting, compressor, and combustor. The compressor blade forces and shaft work are provided by a set of quasisteady state stage characteristics being valid for prestall and poststall operations. The maximum turbine speed is calculated from a thermodynamic turbine stand-alone model, derived from a performance synthesis program. Friction and blade and vane tip clearance variations are determined iteratively from graphical data depending on the axial rearward movement of the turbine. The compressor and ducting system model was validated in prestall and poststall operation modes with measured high pressure compressor data of a modern two-shaft engine. The turbine model was validated with measured intermediate pressure shaft failure data of a three-shaft engine. The shaft failure model was applied on a modern two-shaft engine. The model was used to carry out a sensitivity study to demonstrate the impact of control system reactions on the resulting maximum high pressure turbine speed following a shaft failure event.

Reduction of Friction Torque in Vane Pumps by Using Physical Vapour Deposition-Coated Vane

This paper presents a method of reducing friction torque in a hydraulic vane pump through a short-period pump operation by using physical vapour deposition (PVD)-coated vanes. It is well known that the friction torque in a vane pump as well as in other hydraulic machines can be reduced by running-in through a long-time pump operation. This paper revealed that the reduction in the friction torque was derived from lowered friction between a cam contour and vane tips owing to the smoothed surface of a cam contour. Commonly, it was difficult to obtain such an effect through a short-period pump operation. The author has attempted to lessen the surface roughness of the cam contour and to decrease the friction torque of a vane in a short period of time by using vanes coated with an extremely hard PVD layer on their tips. In this study, three kinds of coatings of chromium nitride (CrN), titanium carbonitride (TiCN), and diamond-like carbon (DLC) by PVD were examined. It was found that the TiCN-coated vane was excellent in smoothing the surface roughness of the cam contour and in reducing the friction torque of the vane in a short period of time. It was also shown that the reduced friction torque of the vane depended essentially on the smoothness of the cam contour surface. In addition, the difference of the friction at the vane tip between an ordinary vane and coated vanes was indistinct for the same surface roughness of the cam contour below 0.8 μ m Rz.

A study of the vane dynamics in a rotary vane expander for the transcritical CO2 refrigeration cycle

Because of the loss of contact between the vane tip and the cylinder wall, excessive gas leakage existed in the rotary vane expander, which was developed to replace the throttling valve to improve the coefficient of performance of the transcritical CO2 refrigeration cycle. The mathematical model of the vane dynamics was established to analyse the vane movement in two different cases depending on whether the vane contacted the cylinder wall or not. From the recorded pressures, instead of assumed ones in the slots, the forces acting on the vane were analysed and the vane movement in the slot, as well as the contact state between the vane and the cylinder wall, was described quantitatively. The dynamics model was validated with the vane movement data recorded by a high-speed video. The results showed that the two adjacent vanes presented different movement behaviours. Both vanes left the cylinder wall because of the impact of the charging gas, but while one vane could rebound quickly back to and maintain contact with the cylinder wall, the adjacent vane did not contact the cylinder wall throughout most of the angles until the rotation angle reached ∼ 70°. Arranging springs in the slot underneath the vane proved to be beneficial in maintaining a tight contact between the vane and the cylinder wall and thus improve the working processes of the expander. Compared with the gas forces on the vane, the centrifugal force was much smaller and therefore had negligible influence on the vane movement.

Experimental Investigation of Friction Force between Vane Tip and Cam-Ring in Oil Vane Pumps

AbstractAn experimental investigation was conducted to measure the friction forces between a vane tip and cam-ring in oil vane pumps. The incentive of this work is to study the effect of important parameters on the friction coefficient between a vane tip and cam-ring. Such parameters are relative speed between the vane tip and cam-ring, normal vane force, pressure difference between the two sides of the vane, and coating of the vane tip. A comparison was performed between five different (Physical Vapor Deposition) PVD-coated vane tips and the normal vane without coating. To satisfy such requirements a special test rig was designed and constructed in the lab. The results show that the effect of the vane force and the pressure difference between the two sides of the vane are very small compared to the relative speed. The coating material shows no significant effect on the friction force in vane pumps. Therefore the wear properties of the coating materials should be considered in future studies. For friction...

New Curve Vane’s Design Based on Three Circular Arc for Rotary Vane Compressor

The vane tip profile contacted with the inner wall of the stator is the key to design the rotary vane compressor. A new principle and design theory based on the three circular arc(TCA) to design vane profile is creatively presented, it provides a theoretical calculation basis designing the rotary vane compressor with high efficient compression ,and broadens the design theory of the rotary vane compressor. Computer simulation and test demonstrate that the vane based on three circular arc has a better meshing characteristics than the traditional one, it eliminates the scraping between the vane tip and the cylinder and partial abrasion conditions completely, and leads to slide uniformly. The shape of the vane tip profile ensures the reliability of the seal between the vane tip and the inner wall of the stator; the vane tip profile is simple, and easy to machine. When the vane is meshed with inner wall of the stator, the front and back transitional arc smoothly connected with the main vane profile can not only avoid to result the cutting edge shape, but also benefit to form oil membrane, it further improves lubrication conditions and reduces precision requirements of the stator, rotor, vane and rotor slot when machined and assembled.

Reduction of friction torque in vane pump by smoothing cam ring surface

This work deals with the influence of surface roughness of cam contours on friction torque in a hydraulic balanced vane pump and it is verified that smoothing the surface of the cam contour can reduce friction torque. In the vane pump, the friction torque arising from the friction between a cam contour and vane tips is significant. In this article, first, the values of the coefficient of friction between the vane tip and its sliding surfaces were measured by using cylindrical test rings with various kinds of surface roughness. Then the torque characteristics of vane pumps having cam ring contours with various values of surface roughness were measured and their results compared with the results of an analysis of the coefficient of friction investigated using test rings. As a result, the friction torque caused by the friction between the cam contour and the vane tip was reduced by lessening the surface roughness of the cam contour, resulting in an improvement of the mechanical efficiency. The coefficient of friction measured by using the test rings could be applied to the actual vane pumps.

Vane Pump의 유동 특성에 대한 수치 해석

In this study, the characteristic of a vane pump of automotive power steering system is numerically analyzed. The vane pump changes the energy level of operation fluid by converting mechanical input power to hydraulic output. To simulate this mechanism, moving mesh technique is adopted. As a result, the flow rate and pressure are obtained by numerical analysis. The flow rate agrees well with the experimental data. Moreover, the variation and oscillation of the pressure around the rotating vane are observed. As a result of flow characteristics, The difference of pressure between both side of vane tip causes the back flow into the rotor. As the rotational velocity increases, the flow rate at the outlet and the pressure in the vane tip rises with higher amplitude of oscillation. In order to reducing the oscillation, the design of devices for decreasing the cross-area of the outlet part and returning the flow from the outlet to the inlet is required.

The Lubrication characteristics of the vane tip under pressure boundary condition of oil hydraulic vane pump

The Lubrication Mode of line contacts between the vane and the camring in an oil hydraulic vane pump has been investigated. First, the variations of the radial force of a vane were calculated from previous measurements of dynamic internal pressure in four chambers surrounding a vane. Next, the lubrication modes were distinguished with Hooke’s chart, which is an improvement over Johnson’s chart. Finally, the influence of the boundary conditions in the lubrication region on the fluid film lubrication was examined by calculating the film pressure distributions. The results showed that the lubrication mode of the vane tip exists in the rigidvariable-viscosity region, and that discharge pressure higher than 7 MPa greatly affects the oil film pressure in the small and the large arc section because of the Piezo-viscous effect.