• Title/Summary/Keyword: aerodynamic test

Search Result 652, Processing Time 0.021 seconds

Investigation on Design and Impact Damage for a 500W Wind Turbine Composite Blade (500W급 풍력발전기 복합계 블레이드의 설계 및 충격손상 안전성 연구)

  • Kong, Chang-Duk;Choi, Su-Hyun;Park, Hyun-Bum;Kim, Sang-Hoon
    • Composites Research
    • /
    • v.22 no.1
    • /
    • pp.22-31
    • /
    • 2009
  • Recently the wind energy has been alternatively used as a renewable energy resource instead of the mostly used fossil fuel due to its lack and environmental issues. This work is to propose a structural design and analysis procedure for development of the 500W class small wind turbine system which will be applicable to relatively low speed region like Korea and for the domestic use. The wind turbine blade was performed structural analysis including stress, deformation, buckling, vibration and fatigue. In addition, the blade should be safe from the impact damage due to FOD(Foreign Object Damage) including the bird strike. MSC.Dytran was used in order to analyze the bird strike penomena on the blade, and the applied method Arbitrary Lagrangian-Eulerian was evaluated by comparison with the previous study results. Finally, the structural test was carried out and its test results were compared with the estimated results for evaluation of the designed structure.

On-site Application of a Vehicle Tunnel Ventilation Simulator (도로터널 환기시뮬레이션 모델 현장적용 연구)

  • 이창우;김효규
    • Tunnel and Underground Space
    • /
    • v.11 no.4
    • /
    • pp.319-327
    • /
    • 2001
  • Introduction of new design tools has been required to optimally design and operate the ventilation system of long vehicle tunnels.. The demand has led to wide spread use of the simulation technique throughout the would to analysis the dynamic relationship among the variables associated with vehicle tunnel ventilation. This paper aims at performing on-site study at local tunnels to test the applicability of NETVEN, a simulation model vehicle tunnel ventilation. The study was carried out at four urban as well as highway tunnels model of vehicle tunnel ventilation. The study was carried out at four urban as well as highway tunnels employing different ventilation systems as well as traffic methods. There were some discrepancies sound between the simulation output and measurements and the following four factors are considered to mainly cause those disagreement. (1) The real situation shows distinctive transient and retarding characteristics with respect to air flow and contaminant dispersion, while ventilation forces are not steady-state and in particular those traffic and climatic variables show significant instantaneous variation. (3) Near the exit portal, the CO levels show bigger differences. The general trend is that data with higher CO concentrations carry bigger discrepancies. Turbulent diffusion is though to be the main reason for it and also contribute to the fact hat the highest CO concentrations are found at the locations somewhat inward, not at the exit portals. (4) Higher traffic rate results in higher discrepancies of ventilation velocity. Along with the exhaust characteristics, the vehicle aerodynamic characteristics need to be studied continuously in order to reduce the velocity disagreement.

  • PDF

The Vibration Effect by Induced Pulsation Pressure to the Fatigue Crack of the Dampener Fitting Welding Zone (항공기용 유압 펌프의 맥동 압력에 의한 감쇄기 용접부위 균열 개선 연구)

  • Shin, Jae Hyuk;Kim, Tae Hwan;Kang, Gu Heon;Ha, Do Jun
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.18 no.7
    • /
    • pp.677-687
    • /
    • 2017
  • Aircraft can often be exposed to a variety of environments and vibrations such as engine, hydraulic pump, aerodynamic force. These may cause cracking and destruction of the mechanical structure and sub-components by high-cycle fatigue. The axial piston type pump which is usually applied to the aircraft hydraulic pump can be necessarily accompanied by the fluid pulsation by continuous rotation of the axial piston. The fatigue crack was identified at the dampener fitting welding zone to prevent vibration damping during the running of aircraft equipped with this type of pulsation hydraulic pump. In order to understand the root cause of this matter, fracture and component analyses were carried out and also integral type dampener fitting was applied to prevent recurrence of the crack as a subject of design improvements. Structural integrity stress analysis, fatigue analysis, qualification test and aircraft system equipped test was conducted to verify the design validity in application to integral type dampener fitting. The test results were sufficiently satisfactory with the demand lifetime of the material from the various types of test as conducted and the subject of design improvement in this study could be objectively evaluated that shall be applied to the operational aircraft.

The Phonetic Characteristics and Voice Handicap Index in Allergic Rhinitis Patients (알레르기성 비염 환자들의 음향음성학적 특성 및 음성장애지수)

  • Kim, Seong-Tae;Choi, Seung-Ho;Roh, Jong-Lyel;Lee, Bong-Jae;Shim, Mi-Ran;Kim, Sang-Yoon;Nam, Soon-Yuhl
    • Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
    • /
    • v.18 no.1
    • /
    • pp.39-43
    • /
    • 2007
  • Background and Objectives: There are few studies reported that specifically examine the phonetic characteristics and voice handicap index (VHI) in patients with Allergic Rhinitis. This study was designed to examine phonetic characteristics and VHI in adult patients with allergic rhinitis. Materials and Methods: Forty-two male patients diagnosed as allergic rhinitis were given skin-prick test and others, aged from 20 to 56 years, and were compared with a 16 male control group with no pathology and in the same age group. The VHI was used to measure the changes of patient's perception. Acoustic and aerodynamic analysis test were done, and a nasalance test performed to measure rabbit, baby, and mother passage. Acoustic rhionometry (AR) was performed to evaluate nasal volume and nasal crosssectional area. Statistical analysis was done using independent sample t-test. Results: VHI showed significantly different score in the studied group, higher than that of control group. AR graph showed that there was no significant differences of nasal volume and nasal cross-sectional area. The Shimmer and SFF value in the group of allergic patients were higher than in the control group. MPT value in the group of allergic patients was lower than in the control group. Nasalance in allergic patients showed hypernasality all passage. Conclusion: We suggest that patients with allergic rhinitis have considerable voice problems. Most of them have hypernasality, which may be a compensatory mechanism by nasal obstruction.

  • PDF

Measurement of Dynamic Stability Derivatives of Tailless Lamda-shape UAV using Forced Oscillation Method (강제진동 기법을 이용한 무미익 비행체의 동안정 미계수 측정)

  • Yang, Kwangjin;Chung, Hyoungseog;Cho, Donghyun;An, Eunhye;Ko, Joonsoo;Hong, JinSung;Kim, Yongduk;Lee, MyungSup;Hur, Gi-Bong
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.44 no.7
    • /
    • pp.552-561
    • /
    • 2016
  • In this experimental study, the dynamic stability derivatives of a tailless lambda-shape UAV are estimated from time history data of aerodynamic moments measured from the internal balance while the test model is forced to oscillate at given frequencies and amplitudes. A 3-axis forced oscillation apparatus is designed to induce decoupled roll, yaw, pitch oscillations respectively. The results show that the roll damping derivatives remain stable at the entire range of angle of attack tested, whereas the pitch damping derivatives become unstable beyond $15^{\circ}$ angle of attack. The amplitude and frequency have little impact on roll damping derivatives while the smaller amplitude and frequency of oscillation improves the pitch stability. The yaw damping derivative values are fairly small as expected for a tailless configuration. The results indicate that the proposed methodology and test apparatus area valid for estimating the dynamic stability derivatives of a tailless UAV.

Analysis of Rocket Booster Separation from Air-Breathing Engine with Kane's Method (Kane 다물체 동력학을 이용한 공기흡입식 추진기관 부스터 분리에 관한 연구)

  • Choi, Jong-Ho;Lim, Jin-Shik
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.13 no.3
    • /
    • pp.41-49
    • /
    • 2009
  • The present paper describes a mathematical modeling and simulation of the separation of a solid rocket booster from an air breathing engine vehicle. The vehicle and booster are considered as a multi-connected body and the booster is assumed to move only along the axial direction of the vehicle. The dynamic motion of the vehicle and the booster were modeled by using Kane's method. The aerodynamic forces on the whole system along various positions of booster were calculated by using DATCOM software and the internal pressure force acting on the effective surface during separation was simply calculated with gas dynamics and Taylor MacColl equation. Numerical simulation was done by using Mathworks-Matlab. From the result, the variation of Mach number and angle of attack are not large during the separation, so the variation of pitch angle and the characteristics of inlet flow for varying the Mach number and angle of attack during the separation test can be identified as neglectable values.

Study on the Characteristics of an Annular Combustor for a 500 W Class Micro Gas Turbine Generator (500 W 급 마이크로 가스터빈 제너레이터용 환형 연소기의 특성에 관한 연구)

  • Do, Kyu Hyung;Kim, Taehoon;Han, Yong-Shik;Kim, Myung-Bae;Choi, Byung-Il
    • Journal of the Korean Society of Combustion
    • /
    • v.19 no.4
    • /
    • pp.14-20
    • /
    • 2014
  • In the present study, an annular combustor for a 500 W class micro gas turbine generator was designed and its characteristics were investigated by using both numerical and experimental methods. For this purpose, geometrical configurations of the annular combustor were determined in the aspect of the aerodynamic and chemical consideration. Also, fluid flow and pressure drop characteristics in the combustor were numerically studied by using commercial tool, FLUENT. Based on the numerical results, the diameter and the angle of air admission holes in the primary zone were chosen to be 2.5 mm and $30^{\circ}$, respectively. Finally, an integrated test unit, which consisted of a compressor, combustor, turbine, and motor/generator, was developed in order to measure the combustor efficiency. As the temperature difference between the combustor inlet and the turbine inlet or the air mass flow rate increased, the combustor efficiency increased and it was over 90% when the air mass flow rate was larger than 7.30 g/s. It was shown that the annular combustor developed in this study met the design requirement for a 500 W class micro gas turbine generator.

A wing-tail interference for a tail-controlled missile (꼬리날개 조종 유도무기의 주날개-꼬리날개 간섭 현상)

  • Kim, Duk-Hyun;Lee, Dae-Yeon;Kang, Dong-gi;Lee, Hyoung Jin
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.45 no.10
    • /
    • pp.817-824
    • /
    • 2017
  • This paper presents the characteristics of wing-tail interference for a tail-controlled missile. The magnitude of wing-tail interference was calculated with wind tunnel test results and its effects on aerodynamic coefficients were investigated. The downwash angle of tail wing was calculated with experimental data and the effect of wing-tail interference was expressed as a ratio of angle of attack. Numerical simulations were made to examine flow characteristics of wing-tail interference and the vorticity contour of missile were compared with respect to angle of attack. Experimental and numerical analysis results show that the wing-tail interference has significant effects on static stability of tail-controlled missile.

Performance Evaluation of Propeller for High Altitude by using Experiment and Computational Analysis (시험과 전산해석을 이용한 고고도용 프로펠러 성능 분석)

  • Park, Donghun;Cho, Taehwan;Kim, Cheolwan;Kim, Yangwon;Lee, Yunggyo
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.43 no.12
    • /
    • pp.1035-1047
    • /
    • 2015
  • Wind tunnel experiment and computational analysis have been carried out to evaluate the performance of propeller for scale electric-powered HALE UAV, named EAV-2H+. Performance curves are measured for three propellers and their adequacy for EAV-2H+ installation is examined through consideration of operating conditions. Decline in performance coefficients is observed in low rpm region. Also, the effect of transition tape on propeller performance is measured and analyzed. The computational performance analyses are carried out by using commercial CFD program. The thrust and power coefficient from computations show good agreement with experimental results. Performance coefficients are compared and the influence of measurement device which contributes to discrepancy of the results is examined. Transition SST model is confirmed to yield the tendency of performance decline in low rpm range, similar to experimental observation. The decrease in aerodynamic performance of blade element due to low Reynolds number is identified to cause the decline in propeller performance. Analyses for high altitude conditions confirms degradation in propeller performance.

Effect of Particle Clogging in Orifices on the Particle Collection Efficiency of a Micro-Orifice Impactor (노즐 막힘이 미세 오리피스형 다단 임팩터의 입자 채취 성능에 미치는 영향)

  • Ji, Jun-Ho;Bae, Gwi-Nam;Hwang, Jung-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.27 no.2
    • /
    • pp.197-205
    • /
    • 2003
  • A cascade impactor is a multistage impaction device used to separate airborne particles into aerodynamic size classes. A micro-orifice impactor uses micro-orifice nozzles to extend the cut sizes of the lower stages to as small as 0.05 ${\mu}{\textrm}{m}$ in diameter without resorting to low pressures or creating excessive pressure drops across the impactor stages. In this work, the phenomenon of particle clogging in micro-orifice nozzles was experimentally investigated for a commercial micro-orifice uniform deposit impactor (MOUDI). It was observed, using an optical microscope, that the micro-orifice nozzles of the final stages were partially clogged due to particle deposition during the aerosol sampling. Therefore the pressure drops across the nozzles were higher than the nominal values given by the manufacturer. To examine the effect of particle clogging in micro-orifice nozzles, the particle collection efficiency of the MOUDI was evaluated using an electrical method for fine particles with diameters in the range of 0.1-0.6 ${\mu}{\textrm}{m}$. The monodisperse liquid dioctyl sebacate (DOS) particles were used as test aerosols. A faraday cage was employed to measure the low-level current of the charged particles upstream and downstream of each stage. It was found that the collection efficiency curves shifted to correspond to smaller orifice sizes, and the 50-% cutoff sizes were much smaller than those given by the manufacturer for the three stages with nozzles less than 400 ${\mu}{\textrm}{m}$ in diameter.