• Title/Summary/Keyword: Body blade

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A Study on the Low Vibration Design of Paddle Type Composite Rotor Blade for Helicopter (Paddle형 복합재료 헬리콥터 로터 블레이드 저진동 설계 기술 연구)

  • Kim, Deok Gwan;Ju, Jin;Lee, Myeong Gyu;Hong, Dan Bi
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.4
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    • pp.99-104
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    • 2003
  • This paper described the general dynamic point for rotor design and the design procedure of low vibration blade. Generally, rotor rotating natural frequencies are determined to minimize hub loads, blade vibration and to suppress ground resonance at rotor design stage. First, through rotor frequency diagram, natural frequencies must be far away from resonance point and rotating loads generated from blade can be transformed to non-rotating load to predict fuselage vibration. Vibration level was predicted at each forward flight condition by calculating cockpit's vertical acceleration transferred from non-rotating hub load assuming a fuselage as a rigid body. This design method is applied to design current Next-generation Rotor System Blade(NRSB) and will be applied to New Rotor which will be developed Further.

Structural Safety Evaluation of Basic Design Model of Linear Actuator for Blade Pitch Control of eVTOL Aircraft (eVTOL 항공기 블레이드 피치 제어용 선형 구동기 기본설계 모델의 구조 안전성 평가)

  • Young-Cheol, Kim;Dong-Hyeop, Kim;Sang-Woo, Kim;Jeong-Hyun, Kang;Dohyung, Kim
    • Journal of Aerospace System Engineering
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    • v.16 no.6
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    • pp.106-113
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    • 2022
  • The structural safety of the basic design model of the linear actuator for the individual blade pitch control of eVTOL personal aircraft was investigated. Stress analysis based on the finite element method was conducted, and the margin of safety was calculated to examine the structural safety under stall load conditions. Additionally, fatigue analysis was conducted to evaluate the fatigue life of the linear actuators under operating conditions. The load history with the blade pitch angle was calculated using multi-body dynamics analysis, and the static load analysis was used to obtain the stress distribution for the rated load. As a result, it was confirmed that the safety margins exceeded zero, and the fatigue lives of all linear actuator components exceeded 107 cycles, indicating a safe structural range.

Structural and Vibration Analyses of 3MW Class Wind-Turbine Blade Using CAE Technique (CAE 기법을 활용한 3MW급 풍력발전기 로터의 구조 및 진동해석)

  • Kim, Yo-Han;Park, Hyo-Geun;Kim, Dong-Hyun;Kim, Dong-Man;Hwang, Byoung-Sun;Park, Ji-Sang;Jung, Sung-Hoon
    • The KSFM Journal of Fluid Machinery
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    • v.11 no.4
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    • pp.22-31
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    • 2008
  • In this study, computer applied engineering (CAE) techniques are fully used to conduct structural and dynamic analyses of a huge composite rotor blade. Computational fluid dynamics is used to predict aerodynamic load of the rotating wind-turbine blade model. Static and dynamic structural analyses are conducted based on finite element method for composite laminates and multi-body dynamic simulation tools. Various numerical results for aerodynamic load, static stress, buckling and dynamic analyses are presented and characteristics of structural behaviors are investigated herein.

Classification of Upper Body Somatotypes according to the Age Group : Using 3D-Body Scan Data

  • Na, Hyun-Shin
    • International Journal of Costume and Fashion
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    • v.5 no.1
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    • pp.1-13
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    • 2005
  • Two hundreds of female aged 19 years old and up were recruited to evaluate the postural changes and bilateral variation of asymmetry over age. To find out the differences among the age group, subjects were classified into 5 groups, early young age(19-29), late young age(30-39), early middle age(40-49), late middle age(50-59), and old age(60-). 35 body measurements were taken by the 3-D body scanner which allowed us to take measurements which cannot be measured using traditional methods, including the shape of a cross section, slice area surface are, and volume. Bilateral variations were observed as a function of age; Depth of scapular point level, scapular point to center back, and blade angle. Postural change of anterior cervical angle, upper anterior thoracic angle, upper posterior thoracic angle, posterior cervical angle, and center back/center front ratio were also exhibited. In each measurements, subjects were classified into normal, and abnormal group. Percentiles of abnormal in shoulder line angle, blade angle, neck point $\∼$ acromial point $\∼$ scapular point, posterior cervical angle, and upper posterior thoracic angle were increased over age group. The upper body of lateral view was classified into 3 types of posture based on the previous research; straight, erect(leaning back), and stooped(bent forward). The percentiles of subjects who have straight postures were decreased as a function of age, but those of stooped postures were increased. Subjects who have erect postures did not so. The stooped posture group shows the big cervical fossa angle, anterior cervical angle, posterior cervical angle, upper posterior thoracic angle, and the small upper anterior thoracic angle comparing to the straight and erect posture group. These results could be apply for clothing construction reflecting the changes in back, shoulder, neck, and the bilateral asymmetry according to the target age group.

Neural Tract Injuries by Penetration of Foreign Body: a Diffusion Tensor Tractography Study

  • Kwon, Hyeok-Gyu;Hong, Ji-Heon;Kwon, Yong-Hyun;Lee, Mi-Young;Kim, Seong-Ho;Jang, Sung-Ho
    • The Journal of Korean Physical Therapy
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    • v.25 no.3
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    • pp.132-135
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    • 2013
  • We presented with a patient who showed injury of the cingulum and fornix by penetration of a foreign body into the brain on diffusion tensor tractography (DTT). A 63-year-old man suffered a brain injury by a part of a power saw blade that was suddenly detached from a power saw during work. A part of the power saw blade penetrated his right frontal skull and advanced to the right posterior horn of the lateral ventricle. This penetration caused traumatic intracerebral hemorrhage in the right frontal lobe and intraventricular hemorrhage in the lateral ventricle. He underwent craniotomy and removal of intracranial foreign bodies (bony pieces and saw blade). The patient's Memory Assessment Scale scores were 74 (4%ile) for global memory, 78 (7%ile) for verbal memory, and 80 (9%ile) for visual memory. DTTs showed disruptions in the anterior portion of the fornical body, right fornical crus, the anterior portion of the right cingulum, and the middle portion of the left cingulum, compared to the control. It seems that the sustained memory impairment of this patient might be related to injury of the cingulum and fornix.

Signal Processing Algorithm to Reduce RWR Electro-Magnetic Interference with Tail Rotor Blade of Helicopter

  • Im, Hyo-Bin;Go, Eun-Kyoung;Jeong, Un-Seob;Lyu, Si-Chan
    • International Journal of Aeronautical and Space Sciences
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    • v.10 no.2
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    • pp.117-124
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    • 2009
  • In the environment where various and complicated threat signals exist, RWR (Radar Warning Receiver), which can warn pilot of the existence of threats, has long been a necessary electronic warfare (EW) system to improve survivability of aircraft. The angle of arrival (AOA) information, the most reliable sorting parameter in the RWR, is measured by means of four-quadrant amplitude comparison direction finding (DF) technique. Each of four antennas (usually spiral antenna) of DF unit covers one of four quadrant zones, with 90 degrees apart with nearby antenna. According to the location of antenna installed in helicopter, RWR is subject to signal loss and interference by helicopter body and structures including tail bumper, rotor blade, and so on, causing a difficulty of detecting hostile emitters. In this paper, the performance degradation caused by signal interference by tail rotor blades has been estimated by measuring amplitude video signals into which RWR converts RF signals in case a part of antenna is screened by real tail rotor blade in anechoic chamber. The results show that corruption of pulse amplitude (PA) is main cause of DF error. We have proposed two algorithms for resolving the interference by tail rotor blades as below: First, expand the AOA group range for pulse grouping at the first signal analysis phase. Second, merge each of pulse trains with the other, that signal parameter except PRI and AOA is similar, after the first signal analysis phase. The presented method makes it possible to use RWR by reducing interference caused by blade screening in case antenna is screened by tail rotor blades.

Wind Turbine Simulation Program Development using an Aerodynamics Code and a Multi-Body Dynamics Code (풍력발전시스템의 유연체 다물체 동역학 시뮬레이션 프로그램 개발)

  • Song, Jin-Seop;Rim, Chae-Whan;Nam, Yong-Yun;Bae, Dae-Sung
    • New & Renewable Energy
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    • v.7 no.4
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    • pp.50-57
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    • 2011
  • A wind turbine simulation program for the coupled dynamics of aerodynamics, elasticity, multi-body dynamics and controls of turbine is newly developed by combining an aero-elastic code and a multi-body dynamics code. The aero-elastic code, based on the blade momentum theory and generalized dynamic wake theory, is developed by NREL(National Renewable Energy Laboratory, USA). The multi-body dynamics code is commercial one which is capable of accounting for geometric nonlinearity and twist deflection. A turbulent wind load case is simulated for the NREL 5-MW baseline wind turbine model by the developed program and FAST. As a result, the two results agree well enough to verify the reliability of the developed program.

Effects of Various Injection Hole Shapes and Injection Angles on the Characteristics of Turbine Blade Leading Edge Film Cooling (분사홀 형상과 분사각 변화가 터빈블레이드 선단 막냉각 특성에 미치는 영향)

  • Kim, Yun-Je;Gwon, Dong-Gu
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.7
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    • pp.933-943
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    • 2001
  • Using a semi-circled blunt body model, the geometrical effects of injection hole on the turbine blade leading edge film cooling are investigated. The film cooling characteristics of two shaped holes (laterally- and streamwise-diffused holes) and three cylindrical holes with different lateral injection angles, 30°, 45°, 60°, respectively, are compared with those of cylindrical hole with no lateral injection angle experimentally and numerically. Kidney vortices, which decrease the adiabatic film cooling effectiveness, appear on downstream of the cylindrical hole with no lateral injection angle. At downstream of the two shaped holes have better film cooling characteristics than the cylindrical one. Instead of kidney vortices, single vortex appears on downstream of injection holes with lateral injection angle. The adiabatic film cooling effectiveness is symmetrically distributed along the lateral direction downstream of the cylindrical hole with no lateral injection angle. But, at downstream of the cylindrical holes with lateral injection angle, the distribution of adiabatic film cooling effectiveness in the lateral direction shows asymmetric nature and high adiabatic film cooling effectiveness regions are more widely distributed than those of the cylindrical hole with no lateral injection angle. As the blowing ratio increases, also, the effects of hole shapes and injection angles increase.

On the Fixing of the Shoulder Blade Level during Tight Fitting by the Draping Design (입체 재단법에 의한 Tight Fitting시 등폭 기준선의 설정에 관한여)

  • 이순섭
    • The Research Journal of the Costume Culture
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    • v.4 no.3
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    • pp.373-381
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    • 1996
  • Draping design system organized by European about 13C has been developed greatly for a long while, but for the purpose of the practical use the Dress form similar to human body has been needed. In order to make three-dimensional effect as fitting Muslin ot the Dress form. the Basic lien has to be established in Muslin and Dress form each. At this time, Shoulder-blade level is indicated from various angles : measure down 10cm from the back neck point, a quarter of the back neck point to the waist lie, the half-way point between neckline and bust line, measure down 41 inches from the back neck line, measure down 3 inches from the top edge of the muslin at center back and cross mark for neck line, and so forth. This study established the Basic line through the two ways of them (B.N.P∼B.L/2, B.N.P∼W.L/4), did tight fitting to the 5 kinds of Dress forms which ar normal type in the drop value(the difference between hip circumference and bust circumference), and acquired Basic Pattern. After the experiment, fitness are throughly investigate by statistical analysis of measurements. As a result, this study finds out that fit is proper when shoulder blade level is situated on a fourth of the back neck point to the waist line and a quarter point between back neck point and waist line, and waist dart is situated on the back center line and princess line.

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