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.

scholarly journals Aerothermal Investigations of Mixing Flow Phenomena in Case of Radially Inclined Ejection Holes at the Leading Edge

1999 ◽  
Author(s):  
Dieter E. Bohn ◽  
Karsten A. Kusterer
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Gas Turbines ◽  
Leading Edge ◽  
Suction Side ◽  
Pressure Side ◽  
Blade Surface ◽  
Cooling Fluid ◽  
Flow Phenomena ◽  
Vortex Systems

A leading edge cooling configuration is investigated numerically by application of a 3-D conjugate fluid flow and heat transfer solver, CHT-Flow. The code has been developed at the Institute of Steam and Gas Turbines, Aachen University of Technology. It works on the basis of an implicit finite volume method combined with a multi-block technique. The cooling configuration is an axial turbine blade cascade with leading edge ejection through two rows of cooling holes. The rows are located in the vicinity of the stagnation line, one row is on the suction side, the other row is on the pressure side. The cooling holes have a radial ejection angle of 45°. This configuration has been investigated experimentally by other authors and the results have been documented as a test case for numerical calculations of ejection flow phenomena. The numerical domain includes the internal cooling fluid supply, the radially inclined holes and the complete external flow field of the turbine vane in a high resolution grid. Periodic boundary conditions have been used in the radial direction. Thus, end wall effects have been excluded. The numerical investigations focus on the aerothermal mixing process in the cooling jets and the impact on the temperature distribution on the blade surface. The radial ejection angles lead to a fully three dimensional and asymmetric jet flow field. Within a secondary flow analysis it can be shown that complex vortex systems are formed in the ejection holes and in the cooling fluid jets. The secondary flow fields include asymmetric kidney vortex systems with one dominating vortex on the back side of the jets. The numerical and experimental data show a good agreement concerning the vortex development. The phenomena on the suction side and the pressure side are principally the same. It can be found that the jets are barely touching the blade surface as the dominating vortex transports hot gas under the jets. Thus, the cooling efficiency is reduced.

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

Longitudinal Blade-Frequency Force Induced by a Propeller on a Prolate Spheroid

1965 ◽  
Vol 9 (01) ◽  
pp. 13-22
Author(s):  
S. Tsakonas ◽  
J. P. Breslin
Keyword(s):  
Slenderness Ratio ◽  
Prolate Spheroid ◽  
Longitudinal Component ◽  
The Other ◽  
Marine Propeller ◽  
Propeller Blade ◽  
Blade Number ◽  
Analytic Expression ◽  
Blade Frequency ◽  
Source Sink

An expression has been developed for the longitudinal component of the vibratory force exerted on a prolate spheroid by the operation of a marine propeller in a space-varying field (wake). Two evaluation schemes have been considered: One by integration of the pressure signal over the surface of the ellipsoid and the other by means of Lagally's theorem with the ellipsoid represented by a known source-sink distribution. The former, considered exact, leads to a complicated analytic expression, whereas the latter, less accurate, yields simple and physically meaningful results. Numerical calculations indicate the important role played by propeller clearance and slenderness ratio in the magnitude of the vibratory force. Also considered is the vibratory force exerted on a fin tail under the same condition of propeller action in a wake. Conclusions are drawn as to the optimum propeller blade number for a given fin-tail configuration.

Cooling of Turbine Blades With Expanded Exit Holes: Computational Analyses of Leading Edge and Pressure-Side of a Turbine Blade

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Fariborz Forghan ◽  
Omid Askari ◽  
Uichiro Narusawa ◽  
Hameed Metghalchi
Keyword(s):  
High Speed ◽  
Turbine Blades ◽  
Leading Edge ◽  
Weak Shock ◽  
Suction Side ◽  
Pressure Side ◽  
Blade Surface ◽  
Cooling Effectiveness ◽  
Hot Gas ◽  
Computational Analyses

Turbine blades are cooled by a jet flow from expanded exit holes (EEH) forming a low-temperature film over the blade surface. Subsequent to our report on the suction-side (low-pressure, high-speed region), computational analyses are performed to examine the cooling effectiveness of the flow from EEH located at the leading edge as well as at the pressure-side (high-pressure, low-speed region). Unlike the case of the suction-side, the flow through EEH on the pressure-side is either subsonic or transonic with a weak shock front. The cooling effectiveness, η (defined as the temperature difference between the hot gas and the blade surface as a fraction of that between the hot gas and the cooling jet), is higher than the suction-side along the surface near the exit of EEH. However, its magnitude declines sharply with an increase in the distance from EEH. Significant effects on the magnitude of η are observed and discussed in detail of (1) the coolant mass flow rate (0.001, 0.002, and 0.004 (kg/s)), (2) EEH configurations at the leading edge (vertical EEH at the stagnation point, 50 deg into the leading-edge suction-side, and 50 deg into the leading-edge pressure-side), (3) EEH configurations in the midregion of the pressure-side (90 deg (perpendicular to the mainstream flow), 30 deg EEH tilt toward upstream, and 30 deg tilt toward downstream), and (4) the inclination angle of EEH.

Numerical Simulation of Cavitating Flow in Mixed Flow Pump With Closed Type Impeller

2009 ◽  
Author(s):  
Katsutoshi Kobayashi ◽  
Yoshimasa Chiba
Keyword(s):  
Leading Edge ◽  
Suction Side ◽  
Experimental Results ◽  
Absolute Pressure ◽  
Pressure Side ◽  
Blade Surface ◽  
Mixed Flow ◽  
Closed Type ◽  
The Absolute ◽  
Flow Pump

LES (Large Eddy Simulation) with a cavitation model was performed to calculate an unsteady flow for a mixed flow pump with a closed type impeller. First, the comparison between the numerical and experimental results was done to evaluate a computational accuracy. Second, the torque acting on the blade was calculated by simulation to investigate how the cavitation caused the fluctuation of torque. The absolute pressure around the leading edge on the suction side of blade surface had positive impulsive peaks in both the numerical and experimental results. The simulation showed that those peaks were caused by the cavitaion which contracted and vanished around the leading edge. The absolute pressure was predicted by simulation with −10% error. The absolute pressure around the trailing edge on the suction side of blade surface had no impulsive peaks in both the numerical and experimental results, because the absolute pressure was 100 times higher than the saturated vapor pressure. The simulation results showed that the cavitation was generated around the throat, then contracted and finally vanished. The simulated pump had five throats and cavitation behaviors such as contraction and vanishing around five throats were different from each other. For instance, the cavitations around those five throats were not vanished at the same time. When the cavitation was contracted and finally vanished, the absolute pressure on the blade surface was increased. When the cavitation was contracted around the throat located on the pressure side of blade surface, the pressure became high on the pressure side of blade surface. It caused the 1.4 times higher impulsive peak in the torque than the averaged value. On the other hand, when the cavitation was contracted around the throat located on the suction side of blade surface, the pressure became high on the suction side of blade surface. It caused the 0.4 times lower impulsive peak in the torque than the averaged value. The cavitation around the throat caused the large fluctuation in torque acting on the blade.

The Analysis of Four-Axis Belt Grinding for Marine Propeller Blade

2010 ◽  
Vol 154-155 ◽  
pp. 647-653
Author(s):  
Jian Qiang Wu ◽  
Yun Huang ◽  
Zhi Huang
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Structural Features ◽  
Free Form ◽  
Marine Propeller ◽  
Propeller Blade ◽  
Belt Grinding ◽  
Abrasive Belt ◽  
Grinding Machine

Marine propeller blade is composite of the free form surface, its machining method has been a difficult thing. The blade is processed by 4-axis belt grinding machine in this experiment, this paper analyze that the wear of the abrasive belt and the processing precision and the material removal rate of the blade according to the grinding performance of the blade material, the structural features of the vane, and the theory of 4-aixs belt grinding machine. Draw formulas with time for the belt wear height and the actual grinding depth. The life expectancy of the ceramic abrasive belt is the longest, and its the material removal rate is maximum in Three kinds of belt，and when the belt line speed is 30m/s or so, the material removal rate is maximum.

Computational Fluid Dynamics (CFD) Mesh Independency Technique for a Propeller Characteristics in Open Water Condition

2015 ◽  
Vol 74 (5) ◽  
Author(s):  
M. Nakisa ◽  
A. Maimun ◽  
Yasser M. Ahmed ◽  
F. Behrouzi ◽  
Jaswar Jaswar ◽  
...  
Keyword(s):  
Independent Solution ◽  
Open Water ◽  
Hydrodynamic Performance ◽  
Marine Propeller ◽  
Propeller Blade ◽  
Laboratory Facilities ◽  
Refinement Method ◽  
Mesh Density ◽  
Computational Fluid Dynamics Cfd ◽  
Marine Laboratory

This paper numerically investigated mesh refinement method in order to obtain a mesh independent solution for a marine propeller working in open water condition.Marine propeller blade geometries, especially of LNG carriers, are very complicated and determining the hydrodynamic performance of these propellers using experimental work is very expensive, time consuming and has many difficulties in calibration of marine laboratory facilities. The present research workhas focused on the hydrodynamic propeller coefficients of a LNG carrier Tanaga class such as Kt, Kq and η, with respect to the different advance coefficient (j). Finally, the results of numerical simulation in different mesh density that have been calculated based on RANS (Reynolds Averaged Navier Stocks) equations, were compared with existing experimental results, followed by analysis and discussion sections. As a result the maximum hydrodynamic propeller efficiency occurred when j=0.84.

Sign in / Sign up

Export Citation Format

Share Document