Cavitation Erosion Damage in Engine Bearings: Theory and Practice

Cavitation erosion damage in engine bearings has assumed increasing importance during the past 5–10 years, probably as a result of the design trends towards higher rotational speeds, and, in some cases, higher rates of change of cylinder pressure rise. In many instances the damage is merely cosmetically undesirable, and of only minor functional significance; this is particularly so when the bearing is overlay plated. In more extreme cases extensive loss of lining material will result, and the consequential adverse effects on oil film conditions will reduce reliability and life of the bearings and associated parts. This paper presents a general background to cavitation erosion damage and examples of specific forms of this type of damage in plain bearings are given. A number of commonly applied palliatives and their effectiveness, based on engine experience, are discussed. A description of computer-based methods for predicting crankshaft journal locus, oil film pressure profile, and film extent is provided. An attempt has been made to rationalize several typical forms of cavitation damage on the basis of the theoretical model. An ultrasonic vibratory test facility used by the authors to determine the relative erosion resistance of the more commonly used bearing materials is described, and results presented.

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A discussion on deformation of solids by the impact of liquids, and its relation to rain damage in aircraft and missiles, to blade erosion in steam turbines, and to cavitation erosion - Damage to solids caused by cavitation

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1966.0048 ◽

1966 ◽

Vol 260 (1110) ◽

pp. 245-255 ◽

Cited By ~ 15

Keyword(s):

Mechanical Properties ◽

Cavitation Erosion ◽

Cavitation Resistance ◽

Steam Turbines ◽

Single Event ◽

Cavitation Damage ◽

Erosion Damage ◽

Highly Sensitive ◽

Wide Range ◽

The Impact

This paper describes the early stages of cavitation damage observed in cavitating venturi tunnels. The cavitating fluids were water and mercury, and a wide range of specimen materials were used. The damage was found to consist of single-event symmetical craters and irregular fatigue-type failures. The degree of damage was highly sensitive to minor flow perturbations, and this is discussed. The effect of stress level in the specimen before testing, and relations between cavitation resistance and the mechanical properties of the materials are considered.

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State of the art in cavitation erosion studies

TRANSACTIONS OF THE KRYLOV STATE RESEARCH CENTRE ◽

10.24937/2542-2324-2021-1-395-13-34 ◽

2021 ◽

Vol 1 (395) ◽

pp. 13-34

Author(s):

A. Pustoshny ◽

Keyword(s):

Cavitation Erosion ◽

Experimental Studies ◽

Full Scale ◽

Blade Surface ◽

Shot Blasting ◽

Cavitation Damage ◽

Cavitation Bubbles ◽

Cumulative Jets ◽

Computer Based ◽

Propeller Blades

Object and purpose of research. This paper discusses cavitation erosion on propeller blades. The purpose of this work is to review and analyse modern studies on cavitation erosion, as well as to apply these research results for better under-standing of cavitation damage risk on full-scale propellers. Materials and methods. The paper reviews recent studies on cavitation erosion, as well as the author’s own findings in cavitation erosion on full-scale steel propellers, analyzing the energy needed to create cavitation damage of recorded size. This energy was calculated as per the model based on the results of metallurgical studies discussing the effect of shot blasting upon steel properties. Comparison of these results with those obtained as per classic formulae for the collapse energy of cavita-tion bubble made it possible to estimate the conditions of cavitation erosion on propeller blades. Main results. The review of recent studies on cavitation erosion has shown that current progress in the technologies of experimental studies and computer-based simulations made it possible to considerably improve the knowledge about cavitation erosion process as compared to the level of the 20th century. This review shows that cavitation erosion studies followed three practically independent paths: experimental studies and computer-based simulation of flow around propeller blades with locali-zation of peaks for one or several criteria reflecting the intensity of cavitation energy fluctuations; the studies intended to esti-mate the pressure exerted by collapsing cavitation bubbles and emerging cumulative jets; and finally, the studies on the proper-ties of materials affected by cumulative jets and collapsing bubbles. At this point, it would be practicable to merge these three paths using the results of full-scale cavitation erosion analysis for propellers. KSRC findings in cavitation damage of full-scale steel propeller has shown that cavitation damage recorded in these studies might occur due to a certain combination between the required energy, bubble-blade interaction pressure and the size of affect-ed area on steel blade surface, and this combination, in its turn, might take place when cavitation bubbles consisting of vapour fraction with partial air content hit the blade surface and collapse. Conclusion. This paper shows the capabilities of modern research methods in obtaining new data on the inception mecha-nism of cavitation erosion. Still, to develop the methods for prediction of cavitation erosion (in particular, on propellers), it is necessary to merge the results obtained in different branches of cavitation studies. The basis for this merging could become a power-based analysis of cavitation processes, with help of the cavitation erosion model suggested in this paper and based on the similarity between cavitation erosion and shot-blasting.

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Preliminary Evaluation of the 24 Ft. Diameter Fan Performance In the MinWaterCSP Large Cooling Systems Test Facility

10.1115/gt2021-59130 ◽

2021 ◽

Author(s):

S. J. van der Spuy ◽

D. N. J. Els ◽

L. Tieghi ◽

G. Delibra ◽

A. Corsini ◽

...

Keyword(s):

Scaling Laws ◽

Static Pressure ◽

Cooling System ◽

Pressure Rise ◽

Full Scale ◽

Test Facility ◽

Small Scale ◽

Preliminary Evaluation ◽

Cfd Analysis ◽

Setting Angle

Abstract The MinWaterCSP project was defined with the aim of reducing the cooling system water consumption and auxiliary power consumption of concentrating solar power (CSP) plants. A full-scale, 24 ft (7.315 m) diameter model of the M-fan was subsequently installed in the Min WaterCSP cooling system test facility, located at Stellenbosch University. The test facility was equipped with an in-line torque arm and speed transducer to measure the power transferred to the fan rotor, as well as a set of rotating vane anemometers upstream of the fan rotor to measure the air volume flow rate passing through the fan. The measured results were compared to those obtained on the 1.542 m diameter ISO 5801 test facility using the fan scaling laws. The comparison showed that the fan power values correlated within +/− 7% to those of the small-scale fan, but at a 1° higher blade setting angle for the full-scale fan. To correlate the expected fan static pressure rise, a CFD analysis of the 24 ft (7.315 m) diameter fan installation was performed. The predicted fan static pressure rise values from the CFD analysis were compared to those measured on the 1.542 m ISO test facility, for the same fan. The simulation made use of an actuator disc model to represent the effect of the fan. The results showed that the predicted results for fan static pressure rise of the installed 24 ft (7.315 m) diameter fan correlated closely (smaller than 1% difference) to those of the 1.542 m diameter fan at its design flowrate but, once again, at approximately 1° higher blade setting angle.

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An Optimal Method for Lubricating Oil Compounds Properties Estimation - the Computer - Based Approach

Revista de Chimie ◽

10.37358/rc.19.11.7677 ◽

2019 ◽

Vol 70 (11) ◽

pp. 3942-3946

Author(s):

Gabriel Radulescu ◽

Diana Cursaru

Keyword(s):

Process Improvement ◽

Production Cost ◽

Software Tool ◽

Experimental Tests ◽

Theory And Practice ◽

Lubricating Oil ◽

Optimal Method ◽

Lubricating Oils ◽

Computer Based ◽

Optimal Mixing

Obtaining the commercial lubricating oils through an industrial method is a process which has an extensive complexity, requiring a very special attention paid to the final products quality. In this field, any new mixing compound, any new additive and any process improvement is more than welcome. Using the so called optimal mixing recipes � in order to get commercial lubricating oils by the base oils and corresponding additives � is a common way to lower the production cost and increase its quality. This paper proposes an original software tool, developed by the authors, which offers these recipes based on the final mixture properties (explicitly given). The application is built-up around the nonlinear programming and runs under MATLAB� environment. It is a remarkably robust application, with good functionality and accuracy. Its performance is proved both in theory and practice, after laboratory experimental tests.

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Assessment of Cavitation Erosion Damage of Laser Remelted the Superston Alloy

Advances in Materials Science ◽

10.2478/v10077-008-0047-9 ◽

2008 ◽

Vol 8 (4) ◽

Cited By ~ 1

Author(s):

B. Majkowska ◽

W. Serbiński ◽

I. Skalski

Keyword(s):

Cavitation Erosion ◽

Erosion Damage

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Correlation Between Mechanical Properties and Cavitation Erosion Damage of Carbide and Nitride Thick Coatings for Turbomachinery Applications

Lecture Notes in Civil Engineering - Proceedings of 1st International Conference on Structural Damage Modelling and Assessment ◽

10.1007/978-981-15-9121-1_30 ◽

2020 ◽

pp. 439-455

Author(s):

Vladimir Safonov ◽

Anna Zykova ◽

Janusz Steller ◽

Tomasz Seramak

Keyword(s):

Mechanical Properties ◽

Cavitation Erosion ◽

Erosion Damage ◽

Thick Coatings

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Cavitation Erosion Damage Mechanism of a Duplex Stainless Steel Having a Ferrite-Austenite-Sigma-Phase Triplex Microstructure

Journal of Materials Engineering and Performance ◽

10.1007/s11665-020-04807-9 ◽

2020 ◽

Vol 29 (5) ◽

pp. 2806-2815

Author(s):

Wenji Ai ◽

K. H. Lo ◽

Xiang Li ◽

C. T. Kwok ◽

Hui Pan

Keyword(s):

Stainless Steel ◽

Duplex Stainless Steel ◽

Sigma Phase ◽

Cavitation Erosion ◽

Damage Mechanism ◽

Erosion Damage

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A discussion on deformation of solids by the impact of liquids, and its relation to rain damage in aircraft and missiles, to blade erosion in steam turbines, and to cavitation erosion - The collapse of cavitation bubbles and the pressures thereby produced against solid boundaries

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1966.0046 ◽

1966 ◽

Vol 260 (1110) ◽

pp. 221-240 ◽

Cited By ~ 380

Keyword(s):

Cavitation Erosion ◽

Experimental Information ◽

Liquid Jets ◽

Steam Turbines ◽

Jet Formation ◽

Cavitation Damage ◽

Cavity Collapse ◽

New Ideas ◽

The Impact ◽

Shape Changes

Our object is to present a broad review of this subject as a branch of hydrodynamics, referring both to the well known ‘implosion’ mechanism first analysed by Lord Rayleigh and, more particularly, to the recently perceived possibility that effects of equally great violence, such as to damage solid boundaries, may arise through the impact of liquid jets formed by collapsing cavities. In §2 a few practical facts about cavitation damage are recalled by way of background, and then in §3 the significance of available theoretical and experimental information about cavity collapse is discussed. The main exposition of new ideas is in §4, which is a review of the factors contributing to shape changes and eventual jet formation by collapsing cavities. Finally, in §5, some new experimental observations on the unsymmetrical collapse of vapour-filled cavities are presented.

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The Influence of Fan Root Flow on the Aerodynamics of a Low-Pressure Compressor Transition Duct

Volume 2B: Turbomachinery ◽

10.1115/gt2019-92048 ◽

2019 ◽

Author(s):

A. D. Walker ◽

I. Mariah ◽

D. Tsakmakidou ◽

H. Vadhvana ◽

C. Hall

Keyword(s):

Gas Turbines ◽

Pressure Ratio ◽

Axial Compressor ◽

Pressure Profile ◽

Low Pressure ◽

Secondary Flows ◽

Test Facility ◽

Inlet Flow ◽

Flat Profile ◽

Bypass Ratio

Abstract To reduce fuel-burn and CO2 emissions from aero gas turbines there is a drive towards very-high bypass ratio and smaller ultra-high-pressure ratio core engine technologies. However, this makes the design of the ducts connecting various compressor spools more challenging as the higher required radius change increases their aerodynamic loading. This is exacerbated for the duct which feeds the engine core as it must accept the relatively low-quality flow produced by the fan root. This is characterised by a hub-low pressure profile and large secondary flow structures which will inevitably increase loss and the likelihood of flow separation. Additionally, the desire for shorter, lighter nacelles means that the engine intake may be unable provide a uniform inlet flow to the fan when the aircraft is at an angle of attack or subject to cross winds. Any inlet distortion this generates can also further degrade the quality of the flow entering the core of the engine. This paper uses a combination of experiments and CFD to examine the effects of the inlet flow on the aerodynamics of an engine section splitter and transition duct designed to feed the low-pressure spool of a high bypass ratio turbofan. A fully annular test facility incorporating a 1½ stage axial compressor was used to compare the system performance of a rotor that produced a nominally flat profile with one that had a notably hub deficient flow. A RANS CFD model, employing a mixing plane between the rotor and Engine Section Stator (ESS) and a Reynolds Stress turbulence model, was then validated and used to further investigate the effects of increased inlet boundary layer thickness and bulk swirl distortion at rotor inlet. Overall, changes to the inlet condition were seen to have a surprisingly small effect on the flow at duct exit — i.e. the flow presented to the downstream compressor. Changes to the inlet did, however, generate increased secondary flows and degrade the performance of the ESS. This resulted in notably increased total pressure loss; in excess of 12% for the hub-low inlet and in excess of 30% at high inlet swirl where the flow in the ESS separated. However, the increased ESS wake structures, and the enhanced mixing, delayed separation in the duct suggesting that, overall the design was reasonably robust, albeit with a significant penalty in system loss.

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