• Journal of Mechanical Science and Technology
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• v.16 no.8
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• pp.1154-1164
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• 2002

Losses on the turbine consist of the mechanical loss, tip clearance loss, secondary flow loss and blade profile loss etc.,. More than 60 % of total losses on the turbine is generated by the two latter loss mechanisms. These losses are directly related with the reduction of turbine efficiency. In order to provide a new design methodology for reducing losses and increasing turbine efficiency, a two-dimensional axial-type turbine blade shape is modified by the optimization process with two-dimensional compressible flow analysis codes, which are validated by the experimental results on the VKI turbine blade. A turbine blade profile is selected at the mean radius of turbine rotor using on a heavy duty gas turbine, and optimized at the operating condition. Shape parameters, which are employed to change the blade shape, are applied as design variables in the optimization process. Aerodynamic, mechanical and geometric constraints are imposed to ensure that the optimized profile meets all engineering restrict conditions. The objective function is the pitchwise area averaged total pressure at the 30% axial chord downstream from the trailing edge. 13 design variables are chosen for blade shape modification. A 10.8 % reduction of total pressure loss on the turbine rotor is achieved by this process, which is same as a more than 1% total-to-total efficiency increase. The computed results are compared with those using 11 design variables, and show that optimized results depend heavily on the accuracy of blade design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.622-627
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• 2012

During helicopter rotor system development process, whirl tower test is conducted basically. For conducting whirl tower test during bearingless hub development process, design new blade or using existing blade with repair or remodeling. Because simple shape and efficient aerodynamic characteristic, BO-105 blade is used for hub system development widely. Originally BO-105 blade is used for hingeless hub, ho flap stiffness and lag stiffness on blade root area is relatively low. So applying BO-105 blade to bearingless hub whirl tower test, root area have to be reinforce. In this process, blade root area's section property will be changed. In this paper, suggest reinforcement method of BO-105 blade root area and study dynamic characteristic of bearingless rotor system with reinforcement BO-105 blade.

• Journal of Biosystems Engineering
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• v.37 no.1
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• pp.1-10
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• 2012

Purpose: The most important element of an agricultural helicopter is the rotor blade realizing lift force. In order to improve the performance of the rotor blades, two types (KA152313 and KB203611) of airfoils were designed and compared. Methods: The nose shape of the KB203611 airfoil was 'drooped' and 'sharp' compared to the leading edge of the KA152313 airfoil. The performance of the experimental airfoils was simulated using CFD-ACE program, and lifts were measured in situ using the 'AgroHeli-4G', a prototype helicopter. Results: Simulated lifts of the blade with the KA152313 airfoil showed proper values for a wide range of angles of attack between $14^{\circ}{\sim}18^{\circ}$, while the simulated lift of the KB203611 blade exhibited maximum values near $13^{\circ}{\sim}14^{\circ}$. In the lift measurements, the range of operable angles of attack was a collective pitch angle at the grip (GP) of $12^{\circ}{\sim}18^{\circ}$ for the KA152313 blade. On the other hand, the range of angles of attack for the KB203611 blade was a GP of $12^{\circ}{\sim}14^{\circ}$. Conclusions: The blade of KA152313 performed well over a wide range of AoAs and the blade of KB203611 performed better at low AoAs. In this study, a variative airfoil blade, gradually emerging from grip to tip using the two different airfoils, was suggested.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.6-15
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• 2008

This paper deals with the aeroelastic instability of vibrating multiple blade rows under aerodynamic coupling with each other. A model composed of three blade rows, e.g., rotor-stator-rotor, where blades of the two rotor cascades are simultaneously vibrating, is considered. The displacement of a blade vibrating under aerodynamic force is expanded in a modal series with the natural mode shape functions, and the modal amplitudes are treated as the generalized coordinates. The generalized mass matrix and the generalized stiffness matrix are formulated on the basis of the finite element concept. The generalized aerodynamic force on a vibrating blade consists of the component induced by the motion of the blade itself and those induced not only by vibrations of other blades of the same cascade but also vibrations of blades in another cascade. To evaluate the aerodynamic forces, the unsteady lifting surface theory for the model of three blade rows is applied. The so-called k method is applied to determine the critical flutter conditions. A numerical study has been conducted. The flutter boundaries are compared with those for a single blade row. It is shown that the effect of the aerodynamic blade row coupling substantially modifies the critical flutter conditions.

• The KSFM Journal of Fluid Machinery
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• v.19 no.2
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• pp.16-20
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• 2016

Design optimization of a transonic compressor rotor(NASA rotor 37) was carried out using response surface method(RSM) which is one of the optimization methods. A numerical simulation was conducted using ANSYS CFX by solving three-dimensional Reynolds-averaged Navier Stokes(RANS) equations. Response surfaces that were based on the results of the design of experiment(DOE) techniques were used to find an optimal shape of blade which has the maximum aerodynamic performance. Two objective functions, viz., the adiabatic efficiency and the loss coefficient were selected with three design configurations to optimize the blade shape. As a result, the efficiency of the optimized blade is found to be increased.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.5 s.236
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• pp.625-632
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• 2005

This paper describes the shape optimization of a stator blade in a single-stage transonic axial compressor. The blade optimization has been performed using response surface method and three-dimensional Navier-Stokes analysis. Two shape variables of the stator blade, which are used to define a stacking line, are introduced to increase an adiabatic efficiency. Data points for response evaluations have been selected by D-optimal design, and linear programming method has been used for an optimization on a response surface. Throughout the shape optimization of a stator blade, the adiabatic efficiency is increased to 5.8 percent compared to that of the reference shape of the stator. The increase of the efficiency is mainly caused by the pressure enhancement in the stator blade. Flow separation on the blade suction surface of the stator is also improved by optimizing the stator blade. It is noted that the optimization of the stator blade is also useful method to increase the adiabatic efficiency in the axial compressor as well as the optimization of a rotor blade, which is widely used now.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1038-1044
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• 2017

We are working on improving the performance by applying the three-dimensional design element to the rotor blades of high pressure supersonic impulse turbine that drives turbo pump of liquid rocket engine. In this paper, based on the shape of a rotor blade of a turbopump turbine designed in the past, a three-dimensional shape is applied to a rotor blade through a stacking line change such as sweep and dihedral. After performing the flow analysis, the changes in the turbine performance characteristics for each design element were carefully examined and the results were summarized.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.5
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• pp.442-450
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• 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
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• v.41 no.9
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• pp.726-733
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• 2013

The rotor blade of helicopter is the core component determining helicopter performance and requiring low noise and low vibration because the blade becomes the major source of noise during flight. The performance analysis of candidates rotor blades is very critical because LCH(Light Civil Helicopter) will be developed parallel with LAH(Light Armed Helicopter) as an international upgrade program based on the existing platform of foreign civil helicopter. This research was aimed to recognize the performance of the candidates rotor blades compared with the newly developed foreign rotor blades and to investigate the feasibility about developing korea unique shape rotor blades by analysis the rotor performance and noise. The result of this research can be used for the target performance index during negotiation with foreign helicopter company and developing korea unique shape rotor blades.

• Journal of Aerospace System Engineering
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• v.11 no.4
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• pp.36-43
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• 2017

Blade design optimization of QTP-UAV prop-rotor was conducted using ModelCenter(R). Performance efficiency of the blade in hover and forward flight were adopted as the multi-objective function. Required power and pitch link force applied to constraint in each flight mode and limited lower than the value of the baseline blade. Design variables of root chord length of the blade, taper ratio, twist slope, twist angle at 0.5R of the blade, anhedral angle, parabolic coefficient of a tip shape and location of airfoil were used to generate the blade planform. CAMRAD-II, the comprehensive analysis program of rotorcraft, was used for performance analysis of prop-rotor blade in design process. Performance of the optimized blade improved 1.6% of figure of merit in hover and 13.6% of propulsive efficiency in forward flight. Pitch link force also reduced approximately 30% less than that of the baseline blade.