• Journal of computational fluids engineering
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• v.21 no.2
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• pp.62-69
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• 2016

It has been highly demanded to improve the accuracy of CFD(Computational Fluid Dynamics) methods for the assessment of the hydrodynamic performance of marine propellers in cavitating and non-cavitating flows. This paper presents a validation study on the numerical simulation of the tip vortex flow of a non-cavitating marine propeller SVA VP1304. The calculations are carried out by using the Reynolds averaged Navier-Stokes(RANS) approach, where the Reynolds Stress Model(RSM) is used for turbulence closure. The present paper contains a grid dependence test for the propeller open water simulations and a special emphasis is placed on conducting a local grid adaptation on the blade tip and in the tip vortex to reasonably reproduce the velocity and the pressure in the tip vortex flow field. The numerical results are compared with the experimental validation data, which are published in the second International Symposium on Marine Propulsors 2011(SMP'11). The present numerical results show a reasonable agreement with the experiments.

• Journal of computational fluids engineering
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• v.20 no.1
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• pp.10-15
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• 2015

In this study, the characteristics of water treatment mixer with various propeller profiles are numerically invesitgated. The computation was conducted by solving the incompressible Navier-Stokes equations on unstructured tetrahedral elements with k-${\varepsilon}$ turbulence model. It was found that the spreading angle and swirl magnitude of the jet are important factors for the mixer efficiency, since they clearly characterize the propeller and the frontal surface area of the propeller but not so much affected by the skew angle if it exceeds 30 degrees. The case1 and case2 models are found to show the best propeller efficiency. The case2 with low blade angle, however, requires the lowest power input for the same discharge capacity as the case1.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.10
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• pp.112-119
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• 2003

Design analysis and grow1d test on propellers for 50 m-long airship propulsion were conducted. The design analysis code developed by adopting the vortex-blade-element theory was applied to the design of optimum propeller at the condition of maximum flight speed at sea level. In order to validate the performance of the propeller, ground test of the propeller was performed, and thrust and torque were measured for several different pitch angles at static condition. The power coefficients and thrust coefficients obtained by the test compared well with the analysis results.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.2
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• pp.162-170
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• 2014

A CFD(Computational Fluid Dynamics) analysis is presented to predict hydrodynamic characteristics of a marine propeller. A commercial RANS(Reynolds Averaged Navier-Stokes equation) solver, namely FLUENT, is utilized in conjunction with fully unstructured meshes around rotating propeller. Mesh generation process is greatly accelerated by using fully unstructured meshes composed of both isotropic and anisotropic tetrahedral elements. The anisotropic tetrahedral elements were used in the flow domain near the blade and shaft, where the viscous effect is important, having complex shape yet resolving the thin boundary layers. For other regions, isotropic tetrahedral elements are utilized. Two different approaches simulating rotational effect of the propeller are employed, namely Moving reference frame technique for steady simulation, and Sliding mesh technique for unsteady simulation. Both approaches are applied to the propeller open water (POW) test simulation. The current results, which are thrust and torque coefficients, are compared with available experimental data.

• Journal of Institute of Convergence Technology
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• v.11 no.1
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• pp.33-37
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• 2021

The application of multicopters using a battery is limited by the short endurance due to the low energy density. A propeller is one of crucial components that determine the performance of the multicopter. In the present study, a systematic method for predicting the endurance of multicopters is described. Propeller performance database are constructed using the data from UIUC Propeller Data Site. Using the 'trendline' function of MS Excel software, the performance of the commercial propellers are represented as a function of polynomials. The multicopter's endurance is computed iteratively using Peukert's Law and considering the voltage drop effect. We evaluated the endurance of multicopters that use commercial propellers. The endurance of the multicopter was within the range of 28 min. to 36 min. It is expected that the present method can be utilized for optimal propeller selection for the given multicopters.

• The Journal of the Acoustical Society of Korea
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• v.37 no.2
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• pp.92-98
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• 2018

This paper is a study on the generation mechanism of propeller singing based on the cavitation tunnel test, underwater impact test, finite element analysis and computational flow analysis for the model propeller. A wire screen mesh, a propeller and a rudder were installed to simulate ship stern flow, and occurrence and disappearance of propeller singing phenomenon were measured by hydrophone and accelerometer. The natural frequencies of propeller blades were predicted through finite element analysis and verified by contact and non-contact impact tests. The flow velocity and effective angle of attack for each section of the propeller blades were calculated using RANS (Reynolds Averaged Navier-Stokes) equation-based computational fluid analysis. Using the high resolution analysis based on detached eddy simulation, the vortex shedding frequency calculation was performed. The numerical predicted vortex shedding frequency was confirmed to be consistent with the singing frequency and blade natural frequency measured by the model test.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.2
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• pp.146-158
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• 1996

This paper develops a robot arm for propeller blade grinding. The grinding work requires a high stiffness robot arm to reduce deformation and vibration which are generated during machining operation. Conventional articulated robots have serial connecting links from the base to the gripper. Thus, they have very weak structure to the stiffness for grinding operation. Stewart Platform is a typical parallel robotic mechanism with very high stiffness but it has small work space and large installation space. This research proposes a new grinding robot arm by combining parallel mechanism with serial mechanism. Therefore, the robot has large range of work space as well as high stiffness. This paper introduces the automatic system for propeller grinding utilizing the robot and the design of proposed robot arm.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.379-382
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• 2008

The propeller type hydro turbine model with vertical axis has been tested and analized. The blade angle of runner of turbine model were designed to be varied according to the condition of head and flowrate. When the changes in head and output were comparatively large, the efficiency drop were small, so the efficiency characteristics and stability of the entire operating condition were maintained in good condition. These results showed that the developed model in this study will be suitable for small hydro power stations with large changes in head and load such as sewage treatment plants and agricultural reservoirs.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.2
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• pp.171-176
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• 2003

The propeller type hydro turbine model with vertical axis has been tested and analyzed. The blade angle of turbine model were designed to be varied according to the condition of head and flowrate. When the changes in head and output were comparatively large, the efficiency drop were small, so the efficiency characteristics and stability of the entire operating condition were maintained in good condition. These results showed that the developed model in this study will be suitable for small hydro power stations with large changes in head and load such as sewage treatment plants and agricultural reservoirs.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.3
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• pp.13-21
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• 2004

This paper deals with a theoretical and experimental method for the design of a biased asymmetric pre-swirl stator propulsion system which is an energy saving device by recovering a propeller rotational energy. In the case of slow-speed ships, the upward flow is generated along the afterbody hull form at the propeller plane. The generated upward flow cancels the rotating flow of the propeller at the starboard part while it increases at port part. The present biased asymmetric pre-swirl stator propulsion system consists of three blades at the port and one blade at the starboard which can recover the biased rotating flow effectively. This paper provides the design concept which gives more simple and a high degree of efficiency and the experimental results for the compound propulsion system.