• 한국항공운항학회:학술대회논문집
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• 2015.11a
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• pp.102-106
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• 2015

항공 운송량의 증가로 운항 중 예상치 못한 난류(Turbulence)에 직면하는 경우도 증가하고 있다. 이로 인한, 손님/승무원의 부상, 화물 손상, 항공기 효율성 하락 등으로 많은 Cost가 발생하고 있으며, 항공 안전에도 치명적인 위협이 되고 있다. 하지만, 이에 대한 정보는 운항 중인 항공기의 조종사기상보고(Pilot Weather Reports, PIREP)에 의존하여 발생 지역을 예측하고 있으나, 보고시간 지체에 따른 부정확한 위치, 주관적인 강도 예측으로 실제 유사 지역을 운항하는 항공기에 도움을 주는데 한계가 있다. 금번 논문에서 TAPS(Turbulence Auto PIREP System)의 원리와 실제 운영하는 항공사의 활용 방안을 고찰하여, 정보의 자동 송/수신을 통한 실시간 난류 정보 제공으로 위험 요인을 사전 인지하여 제거할 수 있는 방안을 살펴보고자 한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.4
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• pp.92-98
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• 2003

The optimum design of Hanyang low speed wind tunnel has been performed to augment flow uniformity and to reduce turbulence intensity of wind tunnel test section have to be known for reliability of wind tunnel test. The non-uniformity and turbulence intensity of Hanyang low speed wind tunnel were measured with Pilot tube and X-type hot-wire probe at various wind speeds. As the results, the non-uniformity decreases as the wind speed increases. The non-uniformity is relatively high in the proximity of the diffuser. The turbulence intensity is a little higher than design requirement in the middle of the test section.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.6
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• pp.1-8
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• 2004

The objective of this study is convergence acceleration of multigrid Navier-Stokes solvers. This study has been performed to enhance the performance of preconditioned multi-stage time stepping method which is a popular smoother for the multigrid Navier-Stokes solvers. Comparative study on the convergence characteristics of the ADI and DDADI preconditioners has been conducted. It is shown that the DDADI preconditioner has better performance than the ADI by numerical tests on the 2-D compressible turbulent flows past airfoils. The Spalart-Allmaras turbulent model and the Baldwin-Lomax turbulent model have been compared with the multigrid calculations.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.1
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• pp.89-99
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• 2010

The purpose of this study is analysis of Korean peninsula aircraft turbulence using the numerical weather prediction model, KWRF with the various turbulence index and pilot weather report data. Compared with the pilot weather report data and Calculated the turbulence index using the KWRF model result, many turbulence index show the similar horizontal distribution, except for the TUB2 and VWS. The analysis of vertical structure of turbulence, there are some difference each turbulence index respectively, but severe turbulence turn up in 15,000ft almost turbulence index. above 20,000ft height, intensity of turbulence vary each turbulence index. Through this turbulence study, It is founded on the research and development of the Korean peninsula aircraft turbulence

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.1-8
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• 2005

Flows in segmented arc-heaters have been calculated for prediction of experimental operating condition or for analysis and design of arc-heater itself. Some researchers succeeded in calculating accurately inner flows of a arc-heater, but could not made mathematical models which satisfy various operating conditions for many arc-heaters. this study is forced on turbulence for the generality of mathematical model. Instead of algebraic turbulence models which are frequently used for calculating inner flow of arc-heater, two equation turbulent models are used. Prediction results agree well with experiment data and it was confirmed that $k-\varepsilon$ two equation turbulence model is appropriate for a flow in an arc heater throughout extensive numerical testing.

• Journal of Aerospace System Engineering
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• v.12 no.5
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• pp.40-47
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• 2018

The objective of this study is to investigate the turbulence models with compressibility correction for large separation-flow in a supersonic convergent-divergent rectangular nozzle. As turbulence models, Yang and Shih's Low-Re $k-{\varepsilon}$ model, Mener's $k-{\omega}$ SST model and Wilcox's $k-{\omega}$model were evaluated. In order to get a significant compressible effects, Sarkar and Wilcox compressibility correction models were applied to the turbulence models respectively. Also, the simulation results were compared with experimental data. The turbulence model with compressibility correction model improves both of shock position and pressure recovery, but deteriorates the length of Mach disk.

• Journal of Aerospace System Engineering
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• v.13 no.6
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• pp.1-8
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• 2019

The synthetic turbulence generation model for inlet boundary conditions of subsonic Backward Facing Step (BFS) was investigated. The average u-velocity and Reynolds stress at inlet boundary follows experimental data. Synthetic Eddy Method (SEM), random noise, and uniform flow conditions were implemented relative to the synthetic turbulence generation method. A three dimensional Large Eddy Simulation (LES) was applied for turbulent flow simulation. Turbulent and mean flow characteristics such as flow reattachment length, velocity profiles, and Reynolds stress profiles of BFS were compared with respect to the turbulent effects.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.4
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• pp.36-42
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• 2018

Although continuous passenger injuries and physical damages are repeated due to the unexpected aviation turbulence encountered during operations, there is still exist the limitation for preventing recurrence of similar events because the lack of real-time information and delay in technological developments regarding various operating conditions and variable weather phenomena. The purpose of this study is to compare and analyze the meteorological data of the aviation turbulence occurred and actual flight data extracted from the Quick Access Recorder(QAR) to provide some precursors that the pilot can identify aviation turbulence early by referring thru the flight instrumentation indications. The case applied for this study was recent event, a scheduled flight from Incheon Airport, Korea to Narita Airport, Japan that suddenly encountered turbulence at an altitude of approximately 14,000 feet during approach. According to the Korea Meteorological Administration(KMA)'s Regional Data Assessment and Prediction System(RDAPS) data, it was observed that the strong amount of vorticity in the rear area of jet stream, which existed near Mount Fuji at that time. The QAR data analysis shows significant changes in the aircraft's parameters such as Pitch and Roll angle, Static Air Temperature(SAT), and wind speed and direction in tens of seconds to minutes before encounter the turbulence. If the accumulate reliability of the data in addition and verification of various parameters with continuous analysis of additional cases, it can be the precursors for the pilot's effective and pre-emptive action and conservative prevention measures against aviation turbulence to reduce subsequent passenger injuries in the aviation operations.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.1-7
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• 2003

The numerical simulation of flow-filed around a square cylinder near a wall with $\varepsilon$-SST turbulence model is carried out in this study. The newly suggested $\varepsilon$-SST turbulence model that modifies the original SST turbulence model is proved to yield more accurate results than the other 2-equation turbulence models in large separation region around a bluff body. Therefore, $\varepsilon$-SST turbulence model can be effectively applied for predicting the flow-fields with large separation. And it is found that vortex shedding is suppressed below the critical gap height, the Strouhal number is affected by the gap height and the wall boundary layer thickness.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.8
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• pp.20-28
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• 2004

For the prediction on the onset of oblique shock wave-induced vortex breakdown, computational studies on the Oblique Shock wave/Vortex Interaction (OSVI) are conducted and compared with both experimental results and analytic mode1. A Shock-stable numerical scheme, the Roe scheme with Mach number-based function (RoeM), and a two-equation eddy viscosity-transport approach arc used for three-dimensional turbulent flow computations. The computational configuration is identical to available experiment, and we attempt to ascertain the effect of parameters such as a vortex strength, streamwise velocity deficit, and shock strength at a freestream Mach number of 2.49. Numerical simulations using the k-w SST turbulence model and suitably modeled vortex profiles are able to accurately reproduce many fine features through a direct comparison with experimental observations. The present computational approach to determine the criterion on the onset of oblique shock wave-induced vortex breakdown is found to be in good agreement with both the experimental result and the analytic prediction.