서지주요정보
박리를 수반하는 익형주위의 점성유동해석 : 격자계 생성 및 난류모델에 관한 연구 = Viscous-flow analysis about the airfoil with separation : a study on grid generation and turbulence model
서명 / 저자 박리를 수반하는 익형주위의 점성유동해석 : 격자계 생성 및 난류모델에 관한 연구 = Viscous-flow analysis about the airfoil with separation : a study on grid generation and turbulence model / 손창현.
저자명 손창현 ; Sohn, Chang-Hyun
발행사항 [대전 : 한국과학기술원, 1991].
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소장정보

등록번호

8001653

소장위치/청구기호

학술문화관(문화관) 보존서고

DME 9108

휴대폰 전송

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반납예정일

초록정보

A new Navier-Stokes procedure for the calculation of the complex turbulent flow about a two-dimensional airfoil has been developed. The solution to the Reynolds-averaged Navier-Stikes equations are sought in the domain that encompasses the entire airfoil using the CELS (Coupled Equation Line Solver) algorithm. Major elements of the calculation have been critically examined and improved whenever possible. Firstly, the grid is made orthogonal. Using conformal mapping, the potential-and stream-lines for an arbitrary airfoil at incidence are generated. The equations written in this coordinate system are expected to be least prone to the error due to numerical diffusion. Secondly, to accurately predict the turbulence quantities and thereby the entire flow field, a modified k-$\varepsilon$ turbulence model has been devised the new model is basically a combination of the model by Hanjalic & Launder, which accounts for the irrotational strain, and improves the performance in the adverse pressure gradients region, and the model by Pope, which takes the vortex stretching (or squeezing) effects into account. The Reynolds normal stresses, which are required for the closure of the model, are obtained by incorporating Yoshizawa's anisotropic model rather than using experimentally observed relations of these stresses to the turbulence kinetic energy as was done by Hanjalic & Launder. The new model gives a markedly improved result over other models when applied to the plane-of-symmetry boundary layer of a body of revolution. Thirdly, the transport equations for the turbulence quantities, k and $\varepsilon$, are solved for the entire domain to ensure the smooth transition to turbulent flow. In the laminar region, however, the eddy viscosity is set equal to zero to suppress the growth of turbulence. By comparing the result with that obtained in the non-streamline coordinates, it has been found that the solution can be obtained more efficiently in the streamline coordinates. The code is then applied to predict the turbulent flows about NACA airfoil sections, 0012 and 4412. The results are in much better agreement with the experiments than those of other methods. The pressure and the lift are well predicted even past the stall angle. The distribution of pressure, turbulent kinetic energy and eddy viscosity indicate that the transition is smooth. Furthermore, as the predicted turbulent kinetic energy in the laminar region is almost nil, the present approach of handling the laminar region appears physically sound. The mean velocities and the turbulence quantities are also compared with experiments and show reasonable agreement. The Reynolds normal stresses are better predicted by the present model than the standard k-$\varepsilon$ model. The discrepancies observed in these quantities may be due to the insufficient grid distribution near the surface; a further investigation is necessary to improve the results.

서지기타정보

서지기타정보
청구기호 {DME 9108
형태사항 xiv, 146 p. : 삽도 ; 26 cm
언어 한국어
일반주기 부록 : A, Laurent 급수에 대한 역사상함수. - B, Yoshizawa의 비등방성 난류모델. - C, Speziale의 비등방성 난류모델. - D, 대수응력모델
저자명의 영문표기 : Chang-Hyun Sohn
지도교수의 한글표기 : 최도형
지도교수의 영문표기 : Do-Hyung Choi
학위논문 학위논문(박사) - 한국과학기술원 : 기계공학과,
서지주기 참고문헌 : p. 129-135
주제 Turbulence
Viscous flow
Numerical grid generation
Reynolds stress
점성 유동 --과학기술용어시소러스
난류 --과학기술용어시소러스
이차원 에어포일 --과학기술용어시소러스
레이놀즈 응력 --과학기술용어시소러스
격자 생성 --과학기술용어시소러스
Aerofoils
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