• Title/Summary/Keyword: aerodynamic characteristics

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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.

PREDICTION OF AERODYNAMIC CHARACTERISTICS AND BODY VORTICES OVER SUPERSONIC MISSILES (초음속 유도탄의 동체 와류 예측 및 공력 특성 분석)

  • Yoon, S.H.;Kim, Chang-Am;Hur, K.H.
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.308-314
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    • 2010
  • In this study, NASA test model with four cruciform fins is utilized to validate the in-house code. Sur face pressure distribution and aerodynamic coefficients are compared with experimental data. Through extensive validation work, it is verified that the code has capability to predict aerodynamic characteristics of missile configuration. In inviscid analysis through a relatively low computational time, analysis result close to experimental data can be confirmed. However, at high angle of attack more than 20 degree, the accuracy of analysis is gradually decreased due to massive separation. In addition, it has been seen that Reynolds number, turbulence model and numerical method have effects on body vortices and aerodynamic characteristics.

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Aerodynamic Characteristics of Delta Wing According to Leading Edge Geometries (앞전 형상에 따른 삼각 날개의 공력 특성)

  • Jin, Hak-Su;Kim, Sung-Cho;Kim, Jeong-Soo;Choi, Jong-Wook
    • Journal of the Korean Society of Visualization
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    • v.5 no.2
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    • pp.56-63
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    • 2007
  • Flow visualization and aerodynamic characteristics of delta wings with two different leading edge geometries are investigated by PIV system and wind tunnel balance when the Reynolds number is about based on the freestream velocity and the root chord length. Delta wing models have 65-deg swept angle, and the leading edge shapes are divided into round- and sharp- type. The experimental results indicated that the leading-edge vortex strength and aerodynamic coefficient in the round leading edge are stronger and more, respectively than those in the sharp one. Therefore the flow interactions between vortices and the boundary layer are more desirable or more rapidly swirled in the round-type leading edge.

A Study of Aerodynamic Characteristics of a Car's Side-view Mirror using CFD (CFD를 이용한 자동차 사이드 미러의 공력특성 연구)

  • Min, Sun-sik;Han, Jun-Kyu;Kwon, Ki Hyun;Choi, Eun-Dong;Kim, Moon-Sang
    • Journal of Aerospace System Engineering
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    • v.2 no.2
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    • pp.46-50
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    • 2008
  • Aerodynamic characteristics, such as drag and lift, play an important role in automobile design under certain speed conditions. Such characteristics are essential to design an automobile since they are directly related to automobile's performance such as passenger safety and fuel consumption. There is a huge demand for the automobile to have safe performance at high speed. Reduction in drag is also important and it could lead to the solution of air flow induced noise and dust problems. The objective of this research is to find out the aerodynamic differences between conventional side mirror and a modified one using CFD. Although drag generated around a side mirror is only about 7% of the total drag when a car runs, it is very closely related to driver's field of vision and noise generation. CFD simulation of the flowfield around a car side-view mirror was performed using a commercial code; Gambit and FLUENT.

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Pressure measurements on inclined square prisms

  • Hu, Gang;Tse, K.T.;Kwok, K.C.S.;Chen, Z.S.
    • Wind and Structures
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    • v.21 no.4
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    • pp.383-405
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    • 2015
  • This study investigated aerodynamic characteristics of an inclined square prism experimentally. Pressure measurements were performed on a static square prism with a series of inclinations including forward inclinations (inclined to the upwind direction) and backward inclinations (inclined to the downwind direction). The prism with a vertical attitude was also tested for comparisons. Based on the pressure data, influences of the inclinations on aerodynamic characteristics (e.g., force coefficients, pressure distributions on the surfaces, and vortex shedding features) of the square prism were evaluated in detail. The results show that the inclinations have significant effects on these aerodynamic characteristics. Furthermore, the influences of the forward and backward inclinations are quite different.

Experimental Study on Aerodynamic Characteristics for Missile Configuration With Grid Fins in Subsonic Flow (아음속 유동에서 그리드핀 유도무기의 공력특성 분석을 위한 실험적연구)

  • Lee, Yeongbin;Lee, Changgu;Lee, Jonggeon;Kim, Sungcheol;Kim, Namgyun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.9
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    • pp.721-727
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    • 2021
  • In this paper, aerodynamic characteristics of missile configuration with various grid fins in subsonic flow. To investigate the effects of grid fin shape, four types of experimental models were used. In addition, to examine aerodynamic characteristics of missile configurations with various grid fins according to effects of Reynolds numbers and configurations of grid fins, 6-components aerodynamic forces and moments were measured by internal balance in wind tunnel test.

Dynamic analysis of long-span cable-stayed bridges under wind and traffic using aerodynamic coefficients considering aerodynamic interference

  • Han, Wanshui;Liu, Huanju;Wu, Jun;Yuan, Yangguang;Chen, Airong
    • Wind and Structures
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    • v.24 no.5
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    • pp.405-430
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    • 2017
  • The aerodynamic characteristics of vehicles are critical to assess vehicle safety and passenger comfort for vehicles running on long span bridges in a windy environment. However, in previous wind-vehicle-bridge (WVB) system analysis, the aerodynamic interference between the vehicle and the bridge was seldom considered, which will result in changing aerodynamic coefficients. In this study, the aerodynamic coefficients of a high-sided truck on the ground (ground case) and a typical bridge deck (bridge deck case) are determined in a wind tunnel. The effects of existent structures including the bridge deck and bridge accessories on the high-sided vehicle's aerodynamic characteristics are investigated. A three-dimensional analytical framework of a fully coupled WVB system is then established based on the finite element method. By inputting the aerodynamic coefficients of both cases into the WVB system separately, the vehicle safety and passenger comfort are assessed, and the critical accidental wind speed for the truck on the bridge in a windy environment is derived. The differences in the bridge response between the windward case and the leeward case are also compared. The results show that the bridge deck and the accessories play a positive role in ensuring vehicle safety and improving passenger comfort, and the influence of aerodynamic interference on the response of the bridge is weak.

Aerodynamic Characteristics for various front shapes of High Speed Train (고속열차의 선두부 형상에 따른 공력특성 변화)

  • Lee S. C.;Kim S. L.;Hur N.
    • 한국전산유체공학회:학술대회논문집
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    • 1995.10a
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    • pp.49-54
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    • 1995
  • A numerical analysis on the effect of the front shape on the aerodynamic characteristics of HST model is made, using FVM based general purpose 3D Navier-Stokes eq. solver, TURBO-3D program. Numerical solutions are compared with each case of different front shape for HST model. The result shows a good quantitative aerodynamic characteristic tendencies for variation of front shape of HST. Thus it may be used as a basis in the design of the shape of real HST.

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Experimental Analysis on Aerodynamic Drag of HEMU-400X as Variations of Pantograph Cover Configurations (팬터그래프 커버형상에 따른 HEMU-400X 항력의 실험적 분석)

  • Lee, Yeong-Bin;Kwak, Min-Ho;Kim, Kyu-Hong;Lee, Dong-Ho
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.88-93
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    • 2011
  • The aerodynamic drag characteristics of HEMU-400X which has been being developed for the maximum speed of 430km/h were analyzed experimentally as the variations of the pantograph cover configurations to reduce the acoustic noise and the aerodynamic drag of the pantograph system. The wind tunnel tests were performed with three pantograph cover models upon 1/20 scaled 5-car model of HEMU-400X. Two kinds of wedge shapes which induce up-flow in the vicinity of the pantograph and one cone shape which reduces the whole train drag were used in order to compare the aerodynamic characteristics as the pantograph cover shape changes. The each axial force of 5 each car was measured at a time with the test velocities, 30, 40, 50, 60m/s. Through the wind tunnel test the base drag forces of HEMU-400x model and the forces by the pantograph cover on the train model were investigated and the aerodynamic drag characteristics of the train model by the pantograph cover configurations were analyzed.

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Effect of Geometric Variation on Aerodynamic Characteristics of a Shrouded Tail Rotor (덮개꼬리로부터의 형상변화에 따른 공력 특성에 관한 연구)

  • Lee, H.-D.;Kang, H.-J.;Kwon, O.-J.
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.5
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    • pp.9-17
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    • 2005
  • In the early stage of helicopter design, an optimal configuration is usually determined after a numerous parametric study about the aerodynamic performance due to geometric variation. In order to improve the aerodynamic performance of a shrouded tail rotor, optimization of the tip clearance gap between blade and shroud, the blade planform shape, and the arrangement of blade spacing is required. In the present study, the aerodynamic performance characteristics of a shrouded tail rotor due to geometric variation was investigated by using an inviscid compressible unstructured mesh flow solver for rotary wings.