[PDF] Cavitation Damage Mechanisms Experimental Study Of Cavitation In A Spool Valve eBook

Author : C. S. Martin
Publisher :
Page : 147 pages
File Size : 32,67 MB
Release : 1980
Category :
ISBN :

GET BOOK

Cavitation has been investigated in directional control valves in order to identify damage mechanisms characteristic of components of aircraft hydraulic systems. Extensive tests were conducted in a representative metal spool valve and in a model three times larger. Both valves are well instrumented for the purpose of accurately measuring mean quantities as well as detecting the onset and extent of cavitation once it developed. Non-cavitating data taken with both valves showed that the position of the high-velocity annular jet issuing from the orifice shifted orientation depending upon valve opening and Reynolds number. By means of high-frequency response pressure transducers strategically placed in the valve chamber of each test valve cavitation could be sensed by the correlation of noise with a cavitation index. Cavitation inception could be detected by comparing energy spectra for a fixed valve opening and a constant discharge. Another sensitive indicator of cavitation inception is the ratio of cavitating to non-cavitating spectral densities. The incipient cavitation index as defined in this investigation correlates well with the Reynolds number for both valves. Once cavitation develops, an accelerometer properly located on the cavitating component can be as sensitive to cavitation noise as a pressure transducer. Energy levels under developed cavitation were affected to some extent by temperature differences.

Author : D. C. Wiggert
Publisher :
Page : 58 pages
File Size : 35,30 MB
Release : 1980
Category :
ISBN :

GET BOOK

This report is a companion volume to 'Cavitation Damage Mechanisms: Experimental Study of Cavitation in a Spool Valve.' The state-of-the-art available in the literature is reviewed relative to occurrence of cavitation, the effects of dissolved and free gas, and so-called secondary aspects of combustion/sono-luminescence and electrical/chemical effects. It should be noted that a paucity of literature exists with regard to cavitation in oil hydraulic systems; consequently much of the material discussed deals with water as the working fluid. Throughout the text clear distinctions are made as to the fluid under discussion. The small number of references which do relate to oils are covered as thoroughly as deemed necessary. The last topic to be presented concerns cavitation in hydraulic actuators. This is a markedly different type of cavitation than is dealt with in the present experimental study; it is included for completeness and due to the fact that it can be a potential problem in control system performance, although most often it creates no permanent mechanical damage to actuator components.

Author : Guangjian Zhang
Publisher : Scientific Research Publishing, Inc. USA
Page : 202 pages
File Size : 24,76 MB
Release : 2023-11-06
Category : Antiques & Collectibles
ISBN : 1649977328

GET BOOK

Cavitation refers to a distinctive occurrence within liquid flows where there is a phase change process involving the rapid transformation of liquid into vapour in regions of low pressure, followed by collapsing or implosion when pressure rises again. The study of cavitation dates back to the late 19th century. While the term “cavitation” was originally coined by R. E. Froude and first documented by Barnaby and Thornycroft in 1895, the concept had been speculated upon much earlier by L. Euler in his 1754 theory on water turbines. However, the phenomenon of cavitation was initially observed and examined by Barnaby and Parsons in 1893. They identified that the formation of vapour bubbles on propeller blades had led to the failure of the sea trial of the British high-speed warship HMS Daring in 1885. In 1895, Parsons established the first water tunnel dedicated to cavitation research, revealing the connection between cavitation and propeller damage. The theoretical groundwork for cavitation research was laid by Rayleigh in 1917, as he successfully addressed the collapse of an empty cavity within a substantial liquid mass. Since then, numerous research work has been published on cavitating flow.