• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.6
• /
• pp.547-556
• /
• 2014

This paper discusses a one-way fluid structural interaction (FSI) analysis and shape optimization of the impeller blades for a 15,000 HP centrifugal compressor using the response surface method (RSM). Because both the aerodynamic performance and the structural safety of the impeller are affected by the shape of its blades, shape optimization is necessary using the FSI analysis, which includes a structural analysis for the induced fluid pressure and centrifugal force. The FSI analysis is performed in ANSYS Workbench: ANSYS CFX is used for the flow field and ANSYS Mechanical is used for the structural field. The response surfaces for the FSI results (efficiency, pressure ratio, maximum stress, etc.) generated based on the design of experiments (DOE) are used to find an optimal shape for the impeller blades, which provides the maximum aerodynamic performance subject to the structural safety constraints.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.17 no.1
• /
• pp.75-82
• /
• 2011

Marine current energy is one of the most interesting renewable and clean energy resources that have been less exploited. Especially, Korea has worldwide outstanding tidal current energy resources and it is highly required to develop tidal in-stream energy conversion system in coastal area. The objective of study is to investigate harnessing techniques of tidal current energy and to design the a 100 kW horizontal axis tidal turbine using blade element momentum theory with Prandtl's tip loss factor for optimal design procedures. In addition, Influence of Prandtl's tip loss factor at local blade positions as a function of tip speed ratio was studied, and the analysed results showed that power coefficient of designed rotor blade using NACA 63812 was 0.49 at rated tip speed ratio.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.5
• /
• pp.442-450
• /
• 2011

A measurement system using stereo pattern recognition (SPR) method was configured to measure the rotor blade deformations and motions. An SPR-based measurement system was prepared using six stereo cameras. Through a series of experiments to evaluate the system measurement uncertainty, it was verified that the SPR system had less than 0.2mm standard uncertainty. The combined standard uncertainties for the lead-lag, flapping, and pitching motions were estimated as 0.296mm, 0.209mm, and $0.238^{\circ}$, respectively. The SPR system was installed at a general small-scaled rotor test system at Korea Aerospace Research Institute. The blade motions and elastic deformation were successfully measured under the conditions with rotating speeds of 360rpm or 589rpm, and collective pitch angles of $0^{\circ}$, $4^{\circ}$, or $6^{\circ}$. The advantages of the SPR system was analyzed in comparison with the measurement system used in Higher Harmonic Control Aeroacoustic Rotor Test -II.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.11
• /
• pp.1049-1059
• /
• 2010

This paper treats the aerodynamic optimization of the blade planform for helicopters. The blade shapes, which should be determined during the threedimensional aerodynamic configuration design step, are defined and are parameterized using the B$\acute{e}$zier curves. This research focuses on the design approaches generally adopted by industries and or research institutes using their own experiences and know-hows for the parameterization and for the definition of design constraints. The hover figure of merit and the equivalent lift-to-drag ratio for the forward flight are used to define the objective function. The resultant nonlinear programming (NLP) problem is solved using the sequential quadratic programming (SQP) method. The applications show the present method can design the important planform shapes such as the airfoil distribution, twist and chord variations in the efficient manner.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.37 no.2
• /
• pp.201-208
• /
• 2009

Recently, the wind energy has been widely used as a renewable energy resource due to lack and environmental issues of the mostly used fossil fuel. This work is to develop a 500W class small wind turbine blade which will be applicable to relatively low speed region like Korea and for the domestic use. For this blade a high efficiency wind turbine blade was designed with the proposing aerodynamic design procedure, and a light and low cost composite structure blade was designed considering fatigue life. Structural analyses including load case study, stress, deformation, buckling and vibration analysis were performed using the Finite Element Method. The fatigue life was estimated using the load spectrum analysis and the Miner rule. In order to evaluate the designed blade, the structural and aerodynamic performance tests were carried out, and the test results were compared with the analysis results.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.2
• /
• pp.593-601
• /
• 2021

The axial fan is an element of a blower used for ventilation in various industrial fields. Many studies on aerodynamic performance have been conducted to assess axial fans using fluid dynamics. The subject was a large axial fan size, 1800 mm in diameter with 100 horsepower. The blower's axial fan consisted of blades, hubs, hub caps, and bosses are important components. The blade design has a great influence on the aerodynamic performance. 3D point data is extracted using an aerodynamic performance prediction program, and a 3D modeling shape is generated. The blades and hubs, which are important components, can be easily modified if processed by cutting owing to the environment in which blades and hubs are manufactured through die casting or gravity casting. In this study, the structural safety of components and the analysis results of weak areas at the rated operating speed of the axial fan were verified using the maximum stress and safety factor. The tip clearance reflected in the design was the rotation of the blade. To check whether there is interference with other components, the displacement result was derived to verify the structural safety of the axial fan.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.39 no.5
• /
• pp.435-441
• /
• 2015

In this study, a method for optimal design of impeller and diffuser blades in the centrifugal compressor using response surface method (RSM) and multi-objective genetic algorithm (MOGA) was evaluated. A numerical simulation was conducted using ANSYS CFX with various values of impeller and diffuser parameters, which consist of leading edge (LE) angle, trailing edge (TE) angle, and blade thickness. Each of the parameters was divided into three levels. A total of 45 design points were planned using central composite design (CCD), which is one of the design of experiment (DOE) techniques. Response surfaces that were generated on the basis of the results of DOE were used to determine the optimal shape of impeller and diffuser blade. The entire process of optimization was conducted using ANSYS Design Xplorer (DX). Through the optimization, isentropic efficiency and pressure recovery coefficient, which are the main performance parameters of the centrifugal compressor, were increased by 0.3 and 5, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.4
• /
• pp.423-428
• /
• 2016

The last stage blades of a low pressure (LP) turbine get frequently fractured because of stress corrosion cracking. This is because they operate in a severe corrosive environment that is caused by the impurities dissolved in condensed steam and high stress due to high speed rotation. To improve the reliability of the blades under severe conditions, 12% Cr martensitic stainless steel, having excellent corrosion resistance and higher strength, is widely used as the blade material. This paper shows the result of root cause analysis on a blade which got fractured suddenly during normal operation. Testing of mechanical properties and microstructure examination were performed on the fractured blade and on a blade in sound condition. The results of testing of mechanical properties of the fractured blade showed that the hardness were higher but impact energy were lower, and were not meeting the criteria as per the material certificate specification. This result showed that the fractured blade became embrittled. The branch-type crack was found to have propagated through the grain boundary and components of chloride and sulfur were detected on the fractured surface. Based on these results, the root cause of fracture was confirmed to be stress corrosion cracking.

• KEPCO Journal on Electric Power and Energy
• /
• v.6 no.2
• /
• pp.137-143
• /
• 2020

The CM247LC, a Ni-based superalloy material used for gas turbine hot gas path parts, is casted using directionally solidified technology to analyze the mechanical properties and microstructures through HIP (Hot Isostatic Pressing) and post-heat treatment, and to derive optimal HIP treatment conditions. The CM247LC material is being researched in various ways as an alternative material for prototyping gas turbine blades. In particular, the blade rotating part is exposed and operated in a high temperature and high-pressure environment, and when damaged, it may cause huge economic losses. Therefore, in order to use the CM247LC material as prototyping materials for gas turbine blades, the reliability of the microstructure and mechanical properties must be verified. In this study, after casting rod test specimens using CM247LC material by directionally solidified technology, after that the specimens were performed by HIP treatment and post-heat treatment to test two HIP conditions designed by KEPCO to derive the possibility of prototyping of CM247LC material and optimization of HIP treatment conditions. Additionally, the properties of CM247LC material were compared to the GTD111DS material using for 1,300℃ class gas turbine blades.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.8 no.1
• /
• pp.70-80
• /
• 2004

This study proposes a development result for the 1-kW class small wind turbine system, which is applicable to relatively low wind speed regions like Korea and has the variable pitch control mechanism. In the aerodynamic design of the wind turbine blade, parametric studies were carried out to determine an optimum aerodynamic configuration which is not only more efficient at low wind speed but whose diameter is not much larger than similar class other blades. A light composite structure, which can endure effectively various loads, was newly designed. In order to evaluate the structural design of the composite blade, the structural analysis was peformed by the finite element method. Moreover both structural safety and stability were verified through the full- scale structural test.