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 initial stages of deformation in metals subjected to repeated liquid impact

1966 ◽  
Vol 260 (1110) ◽  
pp. 140-143 ◽  
Keyword(s):  
Shock Waves ◽  
Cavitation Erosion ◽  
Loading Conditions ◽  
Steam Turbines ◽  
Hydrodynamic Loading ◽  
Liquid Impact ◽  
Rapid Flow ◽  
The Impact

Experiments have been carried out to investigate the initial stages in the deformation of metals due to repeated liquid impacts. The initiation of damage is discussed and a comparison made with the initial stages of deformation in metals subjected to similar hydrodynamic loading conditions due to the action of shock waves in a liquid. The destructive role played by the rapid flow of liquid across the surface of a specimen after impact is also described.

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 erosion of solids by the repeated impact of liquid drops

1966 ◽  
Vol 260 (1110) ◽  
pp. 121-139 ◽  
Keyword(s):  
Cavitation Erosion ◽  
Impact Load ◽  
Steam Turbines ◽  
Repeated Impact ◽  
Ductile Metals ◽  
Liquid Drops ◽  
Liquid Impact ◽  
Erosion Behaviour ◽  
Brittle Polymers ◽  
The Impact

An investigation of the erosion of solids by repeated liquid impact at relatively low velocities has been carried out. The work has shown that even at low velocities compressible behaviour of the liquid is important in determining the impact pressure. An attempt has also been made to determine the distribution of the impact load. The mechanism of erosion in brittle polymers and in ductile metals has been studied. The effect of altering the conditions of impact on the erosion behaviour is described.

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 - High speed liquid impact

1966 ◽  
Vol 260 (1110) ◽  
pp. 79-85 ◽  
Keyword(s):  
High Speed ◽  
Cavitation Erosion ◽  
High Strain ◽  
Strain Rates ◽  
Steam Turbines ◽  
High Speeds ◽  
Liquid Impact ◽  
Deformation Patterns ◽  
The Impact ◽  
Very High

A study has been made of the deformation at high strain rates of solids under the impact of liquids. A method is described for projecting a short liquid jet against a solid surface at speeds up to 1200 m/s. The flow of the liquid and the deformation of the solid during impact have been examined by high speed photographic methods. An attempt has been made to measure the magnitude and duration of the load by means of a piezoelectric pressure transducer. There is evidence that the liquid behaves initially on impact in a compressible manner. Part of the deformation of the solid is due to this compressible behaviour and part to the erosive shearing action of the liquid flowing at very high speeds out across the surface. The mode of deformation in brittle and in plastically deforming materials has been investigated. The deformation patterns produced are shown to be characteristic of liquid impact. The predominating mechanism of deformation depends on the mechanical properties of the solid and on the velocity of impact.

scholarly journals 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 - Introduction

1966 ◽  
Vol 260 (1110) ◽  
pp. 76-77 ◽  
Keyword(s):  
Cavitation Erosion ◽  
Water Drop ◽  
Short Interval ◽  
Dynamic Strength ◽  
Strength Properties ◽  
Steam Turbines ◽  
Small Water ◽  
Liquid Impact ◽  
The Impact ◽  
Very High

The meeting will begin by considering the physics of liquid impact and the nature, magnitude and duration of the stresses which are produced when a solid is struck by a jet or by a drop of liquid. Even with moderate impacts the pressures developed in the solid are considerable and at high velocities the pressures are very great indeed, and are sufficient to produce deformation of the strongest solids. As we shall see a small water drop, the size of a raindrop, striking a solid moving at a speed of about 500 m/s (Mach 1.5) will exert a pressure of ca. 130 Kg/mm 2 (1.9 x 10 5 Lb./ in. 2 ) on the surface of the solid. The effect resembles that of a small explosion and at this stress level most solids and structural materials are permanently damaged either by plastic flow or by fracture. Since the pressure is applied for a very short interval of time (a few microseconds), it is the dynamic strength properties of the solid at very high rates of strain which are important. Both the nature and duration of the stresses and the mechanism by which deformation occurs will be considered. Apart from the shock pressure the rapid tangential flow of the liquid across the surface will produce deformation and these two effects interact. If the solid is subjected to multiple liquid impact, deformation will occur at much lower impact velocities and pressures. We shall consider the physics of both these processes.

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 formation of microjets in liquids under the influence of impact or shock

1966 ◽  
Vol 260 (1110) ◽  
pp. 94-95 ◽  
Keyword(s):  
Cavitation Erosion ◽  
Concave Surface ◽  
Short Film ◽  
Steam Turbines ◽  
Small Cavity ◽  
The Impact

If a small cavity or bubble in a liquid is subject to impact or to shock, tiny Munroe jets may be formed on its concave surface. The velocity of these microjets may be high. A short film illustrating the formation of these small jets in cavities and in coalescing drops was shown.

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

1966 ◽  
Vol 260 (1110) ◽  
pp. 221-240 ◽  
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.

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

1966 ◽  
Vol 260 (1110) ◽  
pp. 245-255 ◽  
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.

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 resistance of materials to impact erosion damage

1966 ◽  
Vol 260 (1110) ◽  
pp. 193-203 ◽  
Keyword(s):  
Mechanical Properties ◽  
Mass Loss ◽  
Incubation Period ◽  
Turbine Blade ◽  
Cavitation Erosion ◽  
Steam Turbines ◽  
Microstructural Characteristics ◽  
Erosion Damage ◽  
The Impact ◽  
Impact Erosion

The behaviour of established and potential turbine blade and erosion shield materials subject to impact erosion by water droplets of controlled size has been investigated over a range of impact velocities up to 1040 ft./s. Both the topographical form and the microstructural characteristics of damage have been studied, and correlated with the conditions of the test and the mechanical properties and phase constitution of the materials. It has been found that the rate of erosion, as measured by mass loss, changes during the course of a test. An initial incubation period is generally followed, successively, by periods of increasing, constant, and then decreasing rates of erosion, possibly culminating in a second steady, but lower, rate of erosion.

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 - Description of the damage in steam turbine blading due to erosion by water droplets

1966 ◽  
Vol 260 (1110) ◽  
pp. 204-208 ◽  
Keyword(s):  
Steam Turbine ◽  
Cavitation Erosion ◽  
Drop Formation ◽  
Steam Turbines ◽  
Erosion Damage ◽  
Practical Design ◽  
Subsequent Motion ◽  
Efficient Expansion ◽  
The Impact ◽  
Turbine Blading

Efficient expansion of steam in turbines cools the vapour to the point where it becomes wet. As turbines become larger the higher blading speeds employed lead to erosion damage of the blading as a result of impact with accumulated water in the form of drops. The distribution of this damage in the turbine is discussed. The processes of drop formation, release and subsequent motion before impact with the moving blades are described and the application of this knowledge to practical design is illustrated by particular examples.

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