Analysis of the Geometry of Dents on a Propeller Blade Surface during Cavitation Wear

2021 ◽  
Vol 42 (1) ◽  
pp. 17-22
Author(s):  
Y. N. Tsvetkov ◽  
E. O. Gorbachenko ◽  
Ya. O. Fiaktistov
Keyword(s):  
Blade Surface ◽  
Propeller Blade ◽  
Cavitation Wear

scholarly journals Measuring diameter of water jets affecting propeller blade surface under cavitation wear

2021 ◽  
Vol 2021 (1) ◽  
pp. 54-64
Author(s):  
Yuriy Nickolayevich Tsvetkov ◽  
Yaroslav Olegovich Fiaktistov ◽  
Evgeniy Olegovich Gorbachenko
Keyword(s):  
Hydrodynamic Cavitation ◽  
Cold Hardening ◽  
Mean Deviation ◽  
Blade Surface ◽  
Propeller Blade ◽  
Water Jets ◽  
Proportional Relationship ◽  
Cavitation Wear ◽  
Propeller Blades ◽  
Ship Propeller

The article analyses the structure of cavitated areas of the ship propeller blades made from aluminum bronzes with different composition. The most informative zones of cavitation wear are the cold-hardening zone and the peripheral one that help estimate the mechanical parameters causing the cavities to collapse. The dents formed on the metal surface in the process of hydrodynamic cavitation wear have spherical parts on their bottoms, in which it is possible to inscribe a circle of a definite diameter. There were conducted the experiments on forcing the ball indentors into the surface of different metal alloys. The first run of the experiments includes forcing of a steel ball with a diameter of 1.588 mm into the surface of 33 alloys with different hardness under the loads of 1 470, 980 and 588 N. The impression diameters were measured using Brinell magnifying glass. There has been found the power dependence between deformation of dents on the metals tested under hydrodynamic cavitation and hardness of the materials, which is similar to the dependence of deformation after forcing the ball indentors into the alloys of different hardness. The second run of the experiments included modeling the cold-hardening zone of the cavitation wear area by repeated forcing the ball indentors with the diameters of 1.588, 2.5, 3.175 and 5.0 mm into the bronze BrAZhNMts9-4-4-1 plates with area of 100 × 50 × 20 mm. Forcing was made into the side 100 × 50 mm previously ground and polished. The equal strain rate in impressions of different diameters was observed during forcing. A direct proportional relationship was obtained between the arithmetic mean deviation of the surface profile and the indenter diameter. The arithmetical mean deviation of the assessed profile of the side plotted against the ball indentor yields a direct proportional relationship. Using the dependence for the case of cavitation attack on the propeller blades helps to infer that the diameter of water jets striking against the propeller blade surface with diameter of 3 700 mm makes about 10 mm. The obtained value allows to choose reasonably the experimental equipment and the parameters of testing the ship propeller materials for cavitation wear.

scholarly journals Roughness of propeller blade surface and its implications for propulsion performance

2019 ◽  
Vol 4 (390) ◽  
pp. 11-26
Author(s):  
A. Pustoshny ◽  
◽  
A. Sverchkov ◽  
S. Shevtsov ◽  
◽  
...  
Keyword(s):  
Blade Surface ◽  
Propeller Blade ◽  
Propulsion Performance

Specification of Acceptable Blade Porosity for Cavitation Performance of Marine Propellers

2003 ◽  
Author(s):  
David R. Stinebring ◽  
William A. Straka ◽  
W. R. Hall
Keyword(s):  
Blade Surface ◽  
Propeller Blade ◽  
Cavitation Inception ◽  
Local Boundary ◽  
Marine Propellers ◽  
Surface Pressure Distribution ◽  
Cavitation Performance ◽  
Penn State ◽  
Propeller Blades ◽  
Made In

The issues of cavitation inception for porosity for cast propeller blades are addressed. Desinent cavitation measurements were made in the ARL Penn State 48-inch diameter water tunnel for a series of holes machined into inserts mounted in the tunnel test section. The data were compared to previous measurements with slots and isolated roughnesses. A design exercise is presented for a generic propeller blade to specify “acceptable” blade porosity for a given cavitation inception goal. The application to the blade accounts for the spanwise velocity distribution, local blade surface pressure distribution, local boundary layer thickness, and porosity size. The final result is a mapping of ranges in acceptable porosity for locations on the blade.

Marine Propeller Geometric Models for NC Machining Efficiency and Accuracy

2001 ◽  
Vol 17 (02) ◽  
pp. 97-102
Author(s):  
Hsing-Chia Kuo ◽  
Wei-Yuan Dzan
Keyword(s):  
Differential Geometry ◽  
Numerical Analysis ◽  
Geometric Model ◽  
Nc Machining ◽  
Machining Efficiency ◽  
Pressure Side ◽  
Marine Propeller ◽  
Blade Surface ◽  
Propeller Blade ◽  
Constant Pitch

Via the theories of computational geometry and differential geometry, the equation of the pressure side of a propeller blade with a constant pitch is presented. The model for defining maximal admissible ball-end cutter radius used in the NC machining of propeller blade surface is deduced. The odels for numerical analysis and for calculation of step lengths and path intervals are also provided. Besides, the related geometric model for calculating the actual maximal error by using the envelope surface of the cutter is presented. Finally, the feasibility and reliability of the proposed models and methods are verified by an example. It is also verified that the proposed method provides improved machining efficiency and accuracy relative to many other common contemporary methods.

Flow Around the Revolving Propeller Blades in Low Reynolds Number Field

2007 ◽  
Author(s):  
Nobuyuki Arai ◽  
Hironori Yoshida ◽  
Katsumi Hiraoka
Keyword(s):  
Reynolds Number ◽  
Wind Tunnel ◽  
Number Field ◽  
Wind Tunnel Testing ◽  
Edge Region ◽  
Blade Surface ◽  
Propeller Blade ◽  
Trailing Edge ◽  
Propulsion Efficiency ◽  
Propeller Blades

By studying the flow around the revolving propeller blades, an improvement of the propulsion efficiency can be found. We made the propeller blade optimized to get good propulsion efficiency by the Adkins & Liebeck’s propeller theory in low Reynolds number field. We call this blade “Prop00”. In order to investigate the flow around the propeller blades, distributions of pressure on the surface of the revolving propeller blade in some pitch angles were measured by wind tunnel testing. For Prop00, it was observed that the contour lines of Cp are dense near the trailing edge of blade’s tip. And it is thought that the separation may exist around the tip of blade. In order to compare the flow characteristics and to get the hint of improvement of the shape of the propeller blades, three different shape types of propeller blades, rectangle, trapezoid, and inverted trapezoid, were made. We call these blades “Prop01”, “Prop02”, and “Prop03”, respectively. According to the pressure distribution, it’s necessary to improve the shape of the propeller which suppresses the effect by a separation to improve the propulsion efficiency more. We took some photographs of tufts on the revolving blades with stroboscope to investigate vectors of the flow on the blade surface. These photographs are taken under identical conditions of the direct pressure measurement. It was observed that tufts tend to bent to the outer side direction by centrifugal force. However, differences on tufts bending were observed in the regions of the leading and the trailing edges at same radius. The tufts at the trailing edge region more bent to the tip of blade than that at leading edge region. Then, it is thought that separation and crossflow on the blade surface exist. We thought that the stability of the flow around the trailing edge is lost by the separation and the boundary layer transition. Furthermore, universal CFD software is used to study the improvement of the propeller performance. By using FLUENT 6 as universal CFD software, the result of CFD was compared with the result of wind tunnel testing.

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