https://www.win.tue.nl/~atijssel/pdf_files/Bergant-Simpson-Tijsseling_2006.pdf

Water hammer with column separation: A historical review

This paper presents a hierarchical classification of linear, distributed parameter models which have been used in the study of rigid, uniform fluid transmission lines. The development of the models from the fundamental equations of fluid dynamics is discussed, and the assumptions necessary in obtaining each model are shown. The solutions to the models are presented in general Laplace forms, and the terms that appear in the solutions are discussed with reference to the initial and subsequent assumptions. The existence of seven distinct forms of models was identified and verified by comparison with a vast number of apparently different models quoted in over three hundred research papers covering various engineering, medical, and biological applications. Significant contributions by various researchers over the last eighty years to the development of distributed parameter models of fluid transmission lines are reviewed. The application of the various models based upon comparisons made in the literature is de...

Fluid Transmission Lines—Distributed Parameter Models Part 1: A Review of the State of the Art:

Characteristics of flow through small sharp-edged cylindrical orifices

A mass-conservative algorithm that implements the Jakobsson-Floberg-Olsson cavitation theory is used to predict the performances of seal-like structures and thrust bearings with a dimpled surface texture. The results of a series of simulations for load-carrying capacity, film thickness, dimple depth, dimple density cavitation pressure, leakage, and friction force are presented, and the relationship between these performance parameters is studied. It is shown that, under the conditions simulated, surface roughness can improve the load-carrying capacity, but its effect is limited.

Performance Analysis of Full-Film Textured Surfaces With Consideration of Roughness Effects

This exciting new reference text is concerned with fluid power control. It is an ideal reference for the practicing engineer and a textbook for advanced courses in fluid power control. In applications in which large forces and/or torques are required, often with a fast response time, oil-hydraulic control systems are essential. They excel in environmentally difficult applications because the drive part can be designed with no electrical components and they almost always have a more competitive power/weight ratio compared to electrically actuated systems. Fluid power systems have the capability to control several parameters, such as pressure, speed, position, and so on, to a high degree of accuracy at high power levels. In practice there are many exciting challenges facing the fluid power engineer, who now must preferably have a broad skill set.

/pdf/fundamentals-of-fluid-power-control-23c5jqv8a0.pdf

Fundamentals of Fluid Power Control

If bubble nuclei are the cause of cavitation, how are they initially produced? According to what Washio et al. have found out so far, there are two possible ways for cavitation nuclei to be...

Nucleation and subsequent cavitation in a hydraulic oil poppet valve

/pdf/assessment-of-the-mechanical-properties-of-the-nucleus-175769suqd.pdf

Assessment of the mechanical properties of the nucleus inside a spherical endothelial cell based on microtensile testing

A technique to measure fluctuating differential pressures with high fidelity has been developed first. When applied to detecting differential pressures generated by an accelerated or decelerated liquid column, the technique turned out to be effective in finding unsteady flow rates. An experimental study has been carried out on periodically changing hydraulic oil flows through an orifice. The results support the validity of the traditional standpoint that characteristics of an unsteady orifice flow can be approximately represented by those of a steady-state one. When inspected in detail, however, a net pressure loss across an orifice in a periodical flow is delayed against a change of the flow rate. The resulting relation between the pressure loss and the flow rate describes a loop with a counter-clockwise hysteresis and a nonlinear twist along the steady-state one. Pressure recovery in a pulsating orifice flow varies with the flow rate almost along the steady-state relation, which is confirmed when the change is not fast.

Study of Unsteady Orifice Flow Characteristics in Hydraulic Oil Lines

It is known that the traditional ‘nucleus’ theory for cavitation is incompatible with certain facts physically and experimentally recognizable in oil hydraulic flows. In order to re-examine this issue, cavitation of hydraulic oil flow through a long two-dimensional acrylic constriction was observed by various techniques: stroboscopic photography with a microscope, laser beam transmission, pressure and noise measurements, and luminescence and electrical charge detection. It was revealed that, at the incipient stage of cavitation, one stationary microscopic cavity always emerges suddenly on the inlet edge. Light emission was also observed in the cavitation together with electrostatic charge. All the findings taken together, which cannot be consistently explained by nucleus theory, lead to the following hypothesis: at the separation point a tensile force rips a liquid particle from the wall, leaving behind a vacuum space, which forms the incipient stationary cavity on the edge.

Study on cavitation inception in hydraulic oil flow through a long two-dimensional constriction

An oil hydraulic pilot relief valve was empirically investigated to fully understand its static performance Constriction components which dominate the flow in the valve were individually e

Seiichi Washio

Papers

Nucleation and subsequent cavitation in a hydraulic oil poppet valve

Assessment of the mechanical properties of the nucleus inside a spherical endothelial cell based on microtensile testing

Study of Unsteady Orifice Flow Characteristics in Hydraulic Oil Lines

Study on cavitation inception in hydraulic oil flow through a long two-dimensional constriction

Static characteristics of a piston-type pilot relief valve