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이충연(C.Y. Lee),사정환(J.H. Sa),박수형(S.H. Park),이은석(E.S. Lee),이진익(J.I. Lee),이광섭(K.S. Lee) 한국전산유체공학회 2012 한국전산유체공학회지 Vol.17 No.4
Effects of the subgrid length-scale in the Delayed-Detached Eddy Simulation(DDES) are investigated based on the Spalart-Allmaras(S-A) and the k-ω Shear Stress Transport(SST) turbulence models. Driver & Seegmillers experimental results are used to validate numerical results. Grid convergence with grid resolution and subgrid length-scale is investigated. The simulation results show that the volume method for the subgrid length-scale is more resistant to unfavorable effects of the grid size in the periodic direction than the maximum method. Using a sufficient grid resolution and an appropriate subgrid length-scale, both S-A based DDES and SST based DDES methods can provide a good correlation with the experimental data.
고범용(B.Y. GO),백연식(Y.S. Baik),이은석(E.S. Lee),이재은(J.E. Lee),허기훈(K.H. Hur) 한국전산유체공학회 2013 한국전산유체공학회 학술대회논문집 Vol.2013 No.5
A control fin is necessary for the flying object in order to satisfy its stability and maneuverability. In general, a tail is selected as a control fin and the control effectiveness of the tail is very important. Therefore, it is required to study the variables which have influence on tail performance. When side jets are located ahead of tails, the flow field around tails has interferences with side jets. So the aerodynamic characteristics of a missile with side jet is different from that of a missile without side jet. In this study, the influences of side jet on the missile aerodynamics are investigated by use of the computational fluid dynamics. The aerodynamic characteristics are found be affected by not only the free stream conditions, e.g. free stream velocity, angle of attack and bank angle but also the jet conditions, e.g. the temperature and gas property of jet.
이은석(E.S. Lee),이진익(J.I. Lee),이광섭(K.S. Lee),전병을(B.E. Jun) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5
Modeling studies are conducted to numerically reproduce the flow field generated by the plasma actuator flat plate in a quiescent environment by implementing the body force, moving wall, and specified into the in-house code named KFLOW. The resulting steady flow fields are compared with the PIV Time-accurate computations are also carried out to investigate the dynamic characteristics of the models.
고받음각 동체에 발생하는 측력의 실험적 재현 및 수치적 분석
이은석(E.S. Lee),이진익(J.I. Lee),이광섭(K.S. Lee) 한국전산유체공학회 2013 한국전산유체공학회지 Vol.18 No.1
Behavior of the side force generated at high angles of attack by two ogive-cylinder bodies of revolution with nose fineness ratio of 2.3 (B1) and 3.5 (B2) and the effect of a strip placed close the nose tip of each body (B1S and B2S) are analyzed through the wind tunnel test at ReD=200,000 and a=42~60 deg. The side force generated by B1 is increased by placing a strip. The side force generated by B2 is in the starboard direction and its magnitude is higher than that of the B1S. The effect of the strips with various dimensions placed on B2 is investigated. It is found that the 4-layer strip placed on the starboard reversed the direction of the side force into port direction. It is confirmed by numerical simulations that the strip promotes the flow separation and increases the average pressure on the side where it is placed and consequently produces the side force in the corresponding direction.
비대칭와류 제어기의 Open-Loop 거동 전산해석 및 풍동시험과의 비교
이은석(E. Lee),이광섭(K.S Lee),이진익(J.I. Lee) 한국전산유체공학회 2013 한국전산유체공학회 학술대회논문집 Vol.2013 No.5
The open-loop behavior of the flow actuator for the control of the asymmetric vortex at high angle of attack are simulated using the Cobalt code. Response of the side force to various levels of step inputs and various durations of duty cycle inputs are simulated and compared with wind tunnel measurements, which showed that the simulation well reproduced the measured open-loop dynamic behavior.
이은석(E.S. Lee),이광섭(K.S. Lee),이진규(J.G. Lee) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.11
Aerodynamic characteristics of a missile with strake-tail configuration is numerically simulated by using an inviscid CFD solver within angles of attack of 20 degrees. The results showed a good agreement with the wind-tunnel tests. A significant difference is oberserved in side force and pitching moment between roll attitudes of 0 and 45 degrees. It is found by component-breakdown analysis that the difference is attributed to the influence of the strake-tip vortex on the body and the tail fins.