Influence of Air Dissolved in Hydraulic Oil on Cavitation Erosion




Cavitation erosion, vapour cavitation, gas cavitation, air-free oil, cavitation in hydraulic pumps and valves


This article gives experimentally evidence that cavitation erosion in hydraulic components like valves and pumps is caused by vapour cavitation not gas or pseudo cavitation. In fact, the free air content which is released by vapour and gas cavitation reduces the erosion significantly.

In order to clearly separate the different cavitation types, a test rig with a specially designed reservoir with integrated degassing capability is presented. As flow geometry a valve model with realistic dimensions and under realistic operating conditions was used, which ensures very high transferability of the results to the reality of hydraulic components in practical applications and typical operating conditions.

A total of 4 five-hour long tests are performed and analysed. The quantification of the cavitation erosion is determined by the mass loss of the copper samples. The experimental results show a 4.4–5.1 times higher mass loss in tests with air-free oil compared to tests with air-saturated or oversaturated hydraulic oil.

The experimental fact that air-free hydraulic oil causes significantly more cavitation erosion than normal (saturated) hydraulic oil, and its implications are discussed. The conclusion can be drawn, that further developments of hydraulic components and systems towards the use of air-free oil or increasing power densities will be disproportionately challenged by cavitation erosion.


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Author Biographies

Sven Osterland, Chair of Fluid-Mechatronic Systems (Fluidtronics) – Technische Universität Dresden, Germany

Sven Osterland received his diploma in Diploma in Mechanical Engineering in the fields of structural durability from TU Dresden in 2014. Since 2014 he is working as Research Associate at the Chair of Fluid-Mechatronic Systems (Fluidtronics), Institute of Mechatronic Engineering, Technische Universität Dresden. His research areas include numerical multiphase flow simulations (CFD), experimental flow visualisation of cavitating hydraulic flows and cavitation erosion in hydraulic components.

Lutz Müller, Chair of Fluid-Mechatronic Systems (Fluidtronics) – Technische Universität Dresden, Germany

Lutz Müller received his diploma in Aerospace Engineering from TU Dresden in 2002 and did his doctoral thesis on unsteady compressor aerodynamics in 2013. Since 2011 he is working as Research Associate at the Chair of Fluid-Mechatronic Systems (Fluidtronics), Institute of Mechatronic Engineering, Technische Universität Dresden. His research areas are mostly of experimental nature concerning many aspects of mechanics and hydromechanics of hydraulic components and systems.

Jürgen Weber, Chair of Fluid-Mechatronic Systems (Fluidtronics) – Technische Universität Dresden, Germany

Jürgen Weber has been appointed in 1st March 2010 as a University Professor and the Chair of Fluid-Mechatronic Systems as well as the Director of the Institute of Fluid Power at the Technische Universität Dresden, and took on the leadership of Institute of Mechatronic Engineering in 2018. He finished his doctorate in 1991 and was an active Senior Engineer at the former Chair of Hydraulics and Pneumatics until 1997. This was followed by a 13-year industrial phase. Besides his occupation as the Head of the Department Hydraulics and Design Manager for Mobile and Tracked Excavators, starting in 2002, he took on responsibility for the hydraulics in construction machinery at CNH Worldwide. From 2006 onwards, he was the Global Head of Architecture for hydraulic drive and control systems, system integration and advance development CNH construction machinery.


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Original Article