• Title/Summary/Keyword: 공력성능특성

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Flow Separation Control Effects of Blowing Jet on an Airfoil (블로잉 제트에 의한 에어포일에서의 유동박리 제어효과)

  • Lee, Ki-Young;Chung, Heong-Seok;Cho, Dong-Hyun;Sohn, Myong-Hwan
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.12
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    • pp.1059-1066
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    • 2007
  • An experimental study has been conducted to investigate the flow separation control effects of a blowing jet on an elliptic airfoil at a Reynolds number of 7.84×105 based on the chord length. A blowing jet was obtained by pressing a plenum inside the airfoil and ejecting flow out of a thin jet slot that located in leading edge or trailing edge. The experimental results have shown that the blowing jet had an effect of suppressing the flow separation, resulting in the higher suction pressure distribution and higher normal force. The increase in Cn was more pronounced at higher incidence, whereas the effectiveness of the blowing jet reduced at lower incidences. The leading edge pulsating blowing with 90° was the most effective in controlling the flow separation than other types of blowing jet configuration tested in this research. Moreover, when the pulsating blowing was applied, the stall angle was postponed about 2°-3°. The continuous and pulsating blowing jet is a direct and effective flow separation control for improving the aerodynamic characteristics and performances of airfoil.

Numerical Evaluation of Hovering Performance of Next Generation Rotor Blade(Nrsb-1) (차세대 로터 블레이드(NRSB-1)의 제자리 비행 성능 해석)

  • Lee,Gwan-Jung;Hwang,Chang-Jeon;Kim,Jae-Mu;Ju,Jin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.7
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    • pp.69-74
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    • 2003
  • By employing vane tip concept, a new rotor blade (NRSB-I) has been designed to enhance the noise characteristics of BERP blade. Numerical analyses have been performed for hovering rotor and the results are compared with respect to those of original BERP blade. Although the thrust of designed rotor decreases by 6-7% due to cutout at the tip region, the results indicate that the actual performance loss is negligible because power reduction is greater than thrust loss. It is also found that aerodynamic fence is required at the outboard kink to obtain clearly separated twin-vortices because the vortex generated at kink is diffused during the convection over the blade surface.

Aerodynamic Characteristics Analysis of Small Two-Stage Turbo Blower Using CFD (CFD를 이용한 소형 2단 터보블로워의 공력해석)

  • Seo, Seungjae;Ryu, Minhyoung;Cho, Leesang;Cho, Jinsoo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.4
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    • pp.326-335
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    • 2014
  • Aerodynamic characteristics of the small two-stage turbo blower were investigated using commercial CFD tool(ANSYS CFX Ver. 14.5) in this paper. Turbo blower, which is a centrifugal type of turbomachinery, is used in various industries. It is used for application that required high static pressure rising at relatively small volumetric flow rate. In order to understand the mechanism of static pressure rising, the aerodynamic characteristics of the small two-stage turbo blower are analyzed at high rotating speed in this study. The k-${\omega}$ SST turbulence model, which is good at prediction of adverse pressure gradient flows, was applied. The CFD results of the turbo blower are validated by performance test. The static pressure rising of the turbo blower is nonlinearly increased over the first stage and the second stage. The secondary flow occurred at guide vanes, between the casing and the first impeller shroud, and the bottom of the impeller disk. As a result, It is required that whole fluid area is analyzed to predict aerodynamic characteristics of small two-stage turbo blower. and the result should be selected with considering for error from experiment and CFD.

Development of Modeling and Simulation Tool for the Performance Analysis of Pods Mounted on Highly Maneuverable Aircraft (고기동 항공기 탑재 파드 성능 분석을 위한 모델링 및 시뮬레이션 도구 개발)

  • Lee, Sanghyun;Shin, Jinyoung;Lee, Jaein;Kim, Jongbum;Kim, Songhyon;Kim, Sitae;Cho, Donghyurn
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.7
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    • pp.507-514
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    • 2022
  • The EO/IR targeting pod mounted on a fighter to acquire information about tactical targets is typically mounted and operated at the bottom of the aircraft fuselage. Since the aircraft equipped with such an external attachment has complexed aerodynamic and inertial characteristics compared to the aircraft flying without an external attachment, a method of system performance analyses is required to identify development risk factors in the early stages of development and reflect them in the design. In this study, a development plan was presented to provide the necessary modeling and simulation tools to develop a pod that can acquire measurement data stably in a highly maneuverable environment. The limiting operating conditions of the pods mounted on the highly maneuverable aircraft were derived, the aerodynamics and inertial loads of the mounted pods were analyzed according to the limiting operating conditions, and a flight data generation and transmission system were developed by simulating the mission of the aircraft equipped with the mounted pods.

Starting Characteristics Study of Scramjet Engine Test Facility(SETF) (스크램제트 엔진 시험설비의 시동특성 연구)

  • Lee, Yang-Ji;Kang, Sang-Hun;Oh, Joong-Hwan;Yang, Soo-Seok
    • Journal of the Korean Society of Propulsion Engineers
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    • v.15 no.2
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    • pp.15-22
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    • 2011
  • Unlike most aerodynamic wind-tunnel, Scramjet Engine Test Facility(SETF) of Korea Aerospace Research Institute should simulate enthalpy condition at a flight condition. SETF is a blow-down type, high-enthalpy wind tunnel. To attain a flight condition, a highly stagnated air comes into the test cell through a supersonic nozzle. Also, an air ejector of the SETF is used for simulating altitude conditions of the engine, and facility starting. SETF has a free-jet type test cell and this free-jet type test cell can simulate a boundary layer effect between an airplane and engine using facility nozzle, but it is too difficult to predict the nature of the facility. Therefore it is required to understand the starting characteristics of the facility by experiments. In this paper, the starting characteristics of the SETF and modifications of the ejector are described.

Starting Characteristics Study of Scramjet Engine Test Facility(SETF) (스크램제트 엔진 시험설비의 시동특성 연구)

  • Lee, Yang-Ji;Kang, Sang-Hun;Oh, Joong-Hwan;Yang, Soo-Seok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.11a
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    • pp.451-458
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    • 2010
  • Unlike most aerodynamic wind-tunnel, Scramjet Engine Test Facility(SETF) of Korea Aerospace Research Institute should simulate enthalpy condition at a flight condition. SETF is a blow-down type, high-enthalpy wind tunnel. To attain a flight condition, a highly stagnated air comes into the test cell through a supersonic nozzle. Also, an air ejector of the SETF is used for simulating altitude conditions of the engine, and facility starting. SETF has a free-jet type test cell and this free-jet type test cell can simulate a boundary layer effect between an airplane and engine using facility nozzle, but it is too difficult to predict the nature of the facility. Therefore it is required to understand the starting characteristics of the facility by experiments. In this paper, the starting characteristics of the SETF and modifications of the ejector are described.

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Rotor-Blade Shape Design and Power-Performance Analysis for Horizontal-Axis Tidal Turbine Using CFD (수평축 조류발전용 로터 블레이드 형상설계 및 CFD에 의한 출력성능해석)

  • Jung, Ji Hyun;Kim, Bum Suk
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.39 no.8
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    • pp.661-668
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    • 2015
  • We present a design methodology for horizontal-axis tidal turbine blades based on blade element momentum theory, which has been used for aerodynamic design and power-performance analysis in the wind-energy industry. We design a 2-blade-type 1 MW HATT blade, which consists of a single airfoil (S814), and we present the detailed design parameters in this paper. Tidal turbine blades can experience cavitation problems at the blade-tip region, and this should be seriously considered during the early design stage. We perform computational fluid dynamics (CFD) simulations considering the cavitation model to predict the power performance and to investigate the flow characteristics of the blade. The maximum power coefficient is shown to be about 47 under the condition where TSR = 7, and we observed cavitation on the suction and pressure sides of the blade.

Neural Network Based Adaptive Control for a Flying-Wing Type UAV with Wing Damage (주익이 손상된 전익형 무인기를 위한 신경회로망 적응제어기법에 관한 연구)

  • Kim, DaeHyuk;Kim, Nakwan;Suk, Jinyoung;Kim, Byungsoo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.5
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    • pp.342-349
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    • 2013
  • A damage imposed on an unmanned aerial vehicle changes the flight dynamic characteristics, and makes difficult for a conventional controller based on undamaged dynamics to stabilize the vehicle with damage. This paper presents a neural network based adaptive control method that guarantees stable control performance for an unmanned aerial vehicle even with damage on the main wing. Additionally, Pseudo Control Hedging (PCH) is combined to prevent control performance degradation by actuator characteristics. Asymmetric dynamic equations for an aircraft are chosen to describe motions of a vehicle with damage. Aerodynamic data from wind tunnel test for an undamaged model and a damaged model are used for numerical validation of the proposed control method. The numerical simulation has shown that the proposed control method has robust control performance in the presence of wing damage.

A Study on Aircraft Sensitivity Analysis for C.G Variation of Longitudinal Axis (항공기 세로축 무게중심의 변화에 따른 민감도 해석에 관한 연구)

  • 김종섭
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.6
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    • pp.83-91
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    • 2006
  • An advanced method of Relaxed Static Stability (RSS) is utilized for improving the aerodynamic performance of modern version supersonic jet fighter aircraft. The flight control system utilizes RSS criteria in longitudinal axis to achieve performance enhancements and improve stability. The flight control law of T-50 advanced trainer employs RSS concept in order to improve the aerodynamic performance and guarantee aircraft stability. The longitudinal center of gravity(X-c.g) varies as a function of external stores, fuel state and gear position. Shifts in X-c.g relate directly to longitudinal static margin in aircraft stability. This paper deals the maximum aft X-c.g for critical aircraft loadings and checks static margin limits using sensitivity such as damping, natural frequency, gain and phase margin. And nonlinear analysis was conducted for such as short period input. And also, this paper shows the T-50 aircraft stability based on the result of high angle of attack flight such as upright and inverted departure.

A Numerical Study on Aerodynamic Performance by the Blade Mach Number of the Centrifugal Compressor (원심 압축기의 임펠러 마하수에 따른 공력성능 특성에 관한 수치해석적 연구)

  • Heo, Won-Seok;Kang, Shin-Hyoung
    • The KSFM Journal of Fluid Machinery
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    • v.18 no.4
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    • pp.56-61
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    • 2015
  • It is important requirement to properly evaluate the aerodynamic performance and characteristics during preliminary design of a centrifugal compressor. In this study the centrifugal compressor was calculated for variations of mass flow and blade Mach number by means of single passage steady state. A lot of quantitative performance values were obtained and through the obtained values the aerodynamic performance characteristics of designed impeller and vaned diffuser were investigated. The results were classified by blade Mach number to analyze characteristics and the aerodynamic performance was examined at choke of impeller, diffuser and separation of diffuser.