High-Pressure Gear Pumps

1946 ◽  
Vol 155 (1) ◽  
pp. 417-452 ◽  
Author(s):  
T. E. Beacham
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Journal Bearings ◽  
Volumetric Efficiency ◽  
Solid Matter ◽  
Excessive Pressure ◽  
Low Viscosity ◽  
Large Numbers ◽  
Gear Pumps ◽  
The Relationship

Gear pumps have been used in very large numbers for the various hydraulic services of war aircraft. For the higher pressures the main problems have been in connexion with the load on the journal bearings, with wear, and with the reduction in volumetric efficiency caused by internal leakage. The journal loads are affected by the number of teeth and by the ratio of width to diameter of the gears. With high pressures it is difficult to accommodate standard ball or roller races on account of their diameter: designs are illustrated using a combination of standard races and special needle roller bearings. Small amounts of wear cause comparatively large reductions in volumetric efficiency. Major causes of wear are rubbing on the gear end faces and solid matter in suspension in the liquid and methods of dealing with these are discussed. The percentage slip due to internal leakage varies inversely as the factor (r.p.m. × viscosity). At low speeds and with low-viscosity liquids, internal leakage often limits the pressure at which the pump can be used. Multistage pumps reduce the leakage and have been used extensively for undercarriage operation. Internal leakage becomes relatively less as the size of the pump is increased and the paper gives a graph, showing the relationship between the limit of pressure at which 80 per cent volumetric efficiency is possible, the capacity and rotational speed of the pump, and the viscosity of the liquid. Aircraft pumps generally use gears with involute teeth: ports in the end covers of the casing are used to prevent excessive pressure in the liquid trapped between the teeth. Low- and high-leakage conditions call for difficult arrangements of ports, and this involves differing displacements and variations in flow velocity.

Materials Research at University of Nevada, Las Vegas

2016 ◽  
Vol 879 ◽  
pp. 386-389
Author(s):  
Ravhi S. Kumar ◽  
Weldu Gabrimicael ◽  
Andrew L. Cornelius
Keyword(s):  
High Pressure ◽  
Interdisciplinary Research ◽  
High Pressures ◽  
Las Vegas ◽  
Science And Engineering ◽  
High Pressure Studies ◽  
Materials Research ◽  
Potential Applications ◽  
Indirect Band Gap ◽  
The Relationship

High-pressure studies on thermoelectric materials allow the study of the relationship between structural, elastic, and electronic properties. The High Pressure Science and Engineering Center (HiPSEC) at UNLV performs interdisciplinary research on a wide variety of materials at high pressures. One such system, CrSi2 is an indirect band gap semiconductor that has potential applications in solar cells.

Micro Surface Shaping for the High-Pressure Operation of Piston Machines With Water as a Working Fluid

2015 ◽  
Author(s):  
Meike H. Ernst ◽  
Monika Ivantysynova
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Working Fluid ◽  
Hydraulic Systems ◽  
Machinery Construction ◽  
Pressure Buildup ◽  
Piston Cylinder ◽  
Low Viscosity ◽  
Load Carrying ◽  
Surface Shaping

Oil is the main working fluid used in the hydraulics industry today — but water is nonflammable, environmentally friendly and cheap: it is the better choice of working fluid for hydraulic systems. However, there is one caveat. Water’s extremely low viscosity undermines its ability to carry load. In forest machinery, construction machinery, and aircraft systems, today’s hydraulic circuits have high operating pressures, with typical values between 300 and 420 bar. These high pressures create the need for high load-carrying abilities in the fluid films of the tribological interfaces of pumps and motors. The most challenging of these interfaces is the piston-cylinder interface of swashplate type piston machines, because the fluid must balance the entire piston side load created in this design. The low viscosity of the water turns preventing metal-to-metal contact into quite a challenge. Fortunately, an understanding of how pressure builds and shifts about in these piston-cylinder lubrication interfaces, coupled with some clever micro surface shaping, can allow engineers to drastically increase the load-carrying ability of water. As part of this research, numerous different micro surface shaping design ideas have been simulated using a highly advanced non-isothermal multi-physics model developed at the Maha Fluid Power Research Center. The model calculates leakage, power losses, film thickness and pressure buildup in the piston-cylinder interface over the course of one shaft revolution. The results allow for the comparison of different surface shapes, such as axial sine waves along the piston, or a barrel-shaped piston profile. This paper elucidates the effect of those surface profiles on pressure buildup, leakage, and torque loss in the piston-cylinder interface of an axial piston pump running at high pressure with water as the lubricant.

ULTRASONIC PROPAGATION IN SOLENHOFEN LIMESTONE AT HIGH PRESSURES

Geophysics ◽  
1978 ◽  
Vol 43 (5) ◽  
pp. 1014-1017
Author(s):  
I. J. Fritz
Keyword(s):  
High Pressure ◽  
Wave Propagation ◽  
Phase Transitions ◽  
Seismic Waves ◽  
High Pressures ◽  
Sound Propagation ◽  
Wave Measurements ◽  
Ultrasonic Propagation ◽  
Propagation Properties ◽  
The Relationship

The measurement of ultrasonic velocities at high pressure in minerals and rocks provides information pertinent to a variety of geophysical and engineering problems such as those of determining the state of matter in the earth's interior, understanding the propagation of seismic waves, and characterizing mechanical behavior of materials that are important in mining technology. In recent years there have been a number of reported high pressure sound velocity measurements in various kinds of limestone. (A concise review of this work can be found in a recent paper by Singh and Kennedy, 1974.) Such measurements continue to be of interest because of the relationship to shock‐wave propagation properties (Grady et al, 1977). From the previous measurements it has been found that the phase transitions in calcite, which is the main constituent of limestone, strongly influence the sound velocities. The phase transitions in pure calcite occur at 14.5 kbar (calcite I–II) and 17.4 kbar (calcite II–III) (Singh and Kennedy, 1974); however, because the transitions may be shifted in pressure and spread out over a range of pressures in a rock, it is necessary to make measurements to pressures in excess of 20 kbar in order to characterize the effects of the transitions. To date there has been only one experimental study of the effect of the II–III transition on sound propagation, namely the longitudinal wave measurements in Oak Hall limestone made by Wang and Meltzer (1973). In order to further characterize the effect of the II–III transition on sound propagation in limestone, we have made measurements to 25 kbar on Solenhofen limestone. We were able to measure both longitudinal and transverse velocities over the full pressure range; thus, our measurements represent the first study of the effect of the II–III transition on shear wave propagation under conditions of hydro static pressure.

Charge density wave, superconductivity, and non-metallic behaviour under high pressure in ZrTe3

2002 ◽  
Vol 12 (9) ◽  
pp. 97-98
Author(s):  
K. Igarashi ◽  
S. Yasuzuka ◽  
K. Inagaki ◽  
S. Tanda ◽  
Y. Okajima ◽  
...  
Keyword(s):  
High Pressure ◽  
Fermi Surface ◽  
Charge Density ◽  
Charge Density Wave ◽  
High Pressures ◽  
Density Wave ◽  
Metallic State ◽  
Resistivity Measurements ◽  
Low Dimensional ◽  
The Relationship

The charge-density-wave (CDW) order of low-dimensional inorganic conductor ZrTe3 is found to increase with increasing pressure, while the superconductivity with filamentary nature is significantly suppressed. It was evidenced in resistivity measurements under pressure up to 0.8 Cpa. The present results suggest that competition between the superconductivity and the CDW is not simply explained by a nesting effect of the Fermi surface, but other origin is needed. Non-metallic behaviour is also found below 4 K under high pressures above 0.6 Gpa. The relationship between the non-metallic state and the pressure-enhanced CDW is expected, although yet inexplicable.

scholarly journals Jovian seismology

1994 ◽  
Vol 147 ◽  
pp. 481-511
Author(s):  
Benoît Mosser
Keyword(s):  
High Pressure ◽  
Internal Structure ◽  
Low Temperatures ◽  
High Pressures ◽  
Giant Planets ◽  
The Other ◽  
Interior Structure ◽  
Theoretical Approaches ◽  
Thermodynamical Laws ◽  
The Relationship

AbstractThis paper reviews a new astrophysical subject: seismology of the giant planets. Seismology is dedicated to the sounding of the interior structure of any object; on the other hand, the interiors of the Jovian planets need to be constrained, in order to improve our knowledge of their structure and of their evolution, as well as the thermodynamical laws involved at high pressures and low temperatures. The relationship between Jovian seismology and, first, Jovian internal structure, and second, high pressure physics, is examined, in order to determine the task of “dioseismology”† in the next years. We present then the seismological theoretical approaches developped since the pionnering work of Vorontsov et al. (1976), who calculated the frequencies of the Jovian eigenmodes. We report the first observational attempts for the detection of the oscillations of Jupiter. We discuss the observational results and examine what can be done in the future.

Study on the Angle of Stationary Crescent for Radial Compensation of Inner Mesh Gear Pumps

2011 ◽  
Vol 317-319 ◽  
pp. 1438-1443
Author(s):  
Jian Zhuo Zhang ◽  
Kang Kang Li ◽  
Meng Gao ◽  
Tian Zi Zhu
Keyword(s):  
High Pressure ◽  
Pressure Distribution ◽  
Volumetric Efficiency ◽  
Hydraulic Pressure ◽  
Working Mechanism ◽  
Outlet Pressure ◽  
Hydraulic Force ◽  
Pressure Area ◽  
Gear Pumps ◽  
Internal Gear

Abstract：The working mechanism of the stationary crescent for radial compensation in the inner mesh gear pumps was studied in this paper. The force of the top and bottom stationary crescent in one hydraulic pressure changing cycle was analysed. The pressure distribution on the top and bottom stationary cressent in different positions and the hydraulic force at the x，y direction were determined.Under the condition of the force of the top and bottom stationary crescent is least and the two stationary crescents stay close to the tooth crest of internal gear and external gear to form radial seal，the angle of the end of the top stationary crescent in the high pressure area and the fixing angle of the seal stick was optimized. Experiment results show that the volumetric efficiency is 0.94 when the outlet pressure reach to 30Mpa, and the oil temperature is less than 55°C, there is no abrasion on the two sationary crescents and the tooth crest.

Study on Tooth Profile of Involute Conjugated Internal Gear for High-Pressure Internal Gear Pumps

2011 ◽  
Vol 328-330 ◽  
pp. 186-189 ◽  
Author(s):  
Wei Song ◽  
Hua Zhou
Keyword(s):  
High Pressure ◽  
3D Models ◽  
Tooth Profile ◽  
Volumetric Efficiency ◽  
Flow Pulse ◽  
Wear Life ◽  
Gear Pumps ◽  
Gear Geometry ◽  
Internal Gear

Conjugated internal gear is the key component of high-pressure internal gear pumps, which decides the performance of the pumps, such like volumetric efficiency, capacity of fluid discharge, wear life, flow pulse, vibration and noise. In this paper, a method of generating tooth profiles for conjugated internal gear is presented. Based on gear geometry and meshing theory, the parametric equations of involute conjugated internal gear are derived. With the help of MATLAB and SolidWorks, 3D models of the gear couple are built to evaluate the feasibility of the method.

Prolonged Fixation Studies For Spaceflight

1973 ◽  
Vol 31 ◽  
pp. 332-333
Author(s):  
Robert Corbett ◽  
Delbert E. Philpott ◽  
Sam Black
Keyword(s):  
High Pressure ◽  
Living Systems ◽  
Prolonged Storage ◽  
Time Intervals ◽  
Early Signs ◽  
Large Numbers

Observation of subtle or early signs of change in spaceflight induced alterations on living systems require precise methods of sampling. In-flight analysis would be preferable but constraints of time, equipment, personnel and cost dictate the necessity for prolonged storage before retrieval. Because of this, various tissues have been stored in fixatives and combinations of fixatives and observed at various time intervals. High pressure and the effect of buffer alone have also been tried.Of the various tissues embedded, muscle, cartilage and liver, liver has been the most extensively studied because it contains large numbers of organelles common to all tissues (Fig. 1).

Peculiarities of high-pressure hydrogen adsorption on Pt catalyzed Cu-BTC metal–organic framework

2021 ◽  
Vol 23 (7) ◽  
pp. 4277-4286
Author(s):  
S. V. Chuvikov ◽  
E. A. Berdonosova ◽  
A. Krautsou ◽  
J. V. Kostina ◽  
V. V. Minin ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Hydrogen Adsorption ◽  
Metal Organic Framework ◽  
Pt Catalyst ◽  
Metal Organic ◽  
Pt Catalyzed ◽  
Pressure Hydrogen ◽  
Organic Framework

Pt-Catalyst plays a key role in hydrogen adsorption by Cu-BTC at high pressures.

scholarly journals Crystal and electronic structure engineering of tin monoxide by external pressure

2021 ◽  
Author(s):  
Kun Li ◽  
Junjie Wang ◽  
Vladislav A. Blatov ◽  
Yutong Gong ◽  
Naoto Umezawa ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Band Gap ◽  
High Pressures ◽  
Low Pressure ◽  
Widespread Application ◽  
Space Group ◽  
Tin Monoxide ◽  
High Possibility ◽  
Pressure Phase

AbstractAlthough tin monoxide (SnO) is an interesting compound due to its p-type conductivity, a widespread application of SnO has been limited by its narrow band gap of 0.7 eV. In this work, we theoretically investigate the structural and electronic properties of several SnO phases under high pressures through employing van der Waals (vdW) functionals. Our calculations reveal that a metastable SnO (β-SnO), which possesses space group P21/c and a wide band gap of 1.9 eV, is more stable than α-SnO at pressures higher than 80 GPa. Moreover, a stable (space group P2/c) and a metastable (space group Pnma) phases of SnO appear at pressures higher than 120 GPa. Energy and topological analyses show that P2/c-SnO has a high possibility to directly transform to β-SnO at around 120 GPa. Our work also reveals that β-SnO is a necessary intermediate state between high-pressure phase Pnma-SnO and low-pressure phase α-SnO for the phase transition path Pnma-SnO →β-SnO → α-SnO. Two phase transition analyses indicate that there is a high possibility to synthesize β-SnO under high-pressure conditions and have it remain stable under normal pressure. Finally, our study reveals that the conductive property of β-SnO can be engineered in a low-pressure range (0–9 GPa) through a semiconductor-to-metal transition, while maintaining transparency in the visible light range.

Sign in / Sign up

Export Citation Format

Share Document