• Proceedings of the KSME Conference
• /
• 2001.06c
• /
• pp.380-385
• /
• 2001

The paper presents a new multidisciplinary design optimization architecture using optimal sensitivity and coordination of interdisciplinary design variables. Original design problem is decomposed into a number of sub-problems that represent individual engineering analysis. The coupled effects between sub-problems are computed by interdisciplinary design variables. System level coordination is determined by optimal parameter sensitivity calculated by finite difference method. The proposed. MDO strategy is applied to a simplified model of rotorcraft blade design associated with structures and aerodynamic disciplines.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.05a
• /
• pp.335-338
• /
• 2010

A recent study for tracing the profiles of supersonic axisymmetric Minimum Length Nozzle with uniform and parallel flow at the exit section, the stagnation temperature is taken into account. The aim of this work is to add optimization algorithm to the supersonic nozzle design in order to get the optimum nozzle shape. The comparisons of the nozzle contours based on the method of characteristics are presented. The specific heats and their ratio vary with the stagnation temperature when this temperature of a perfect gas increases. An application is made for air in a supersonic nozzle.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.9
• /
• pp.16-26
• /
• 2005

The aerodynamic design of a proprotor for the Smart UAV adopting tiltrotor aircraft concept is conducted in this study. Since proprotor of tiltrotor aircraft is operated at both rotary and fixed wing mode with single configuration rotor, the proprotor has to be designed to meet performance requirements for both flight modes. The aerodynamic design of proprotor is accomplished by combining three sources of data - the proprotor performance data, the aerodynamic data of vehicle, and the performance data of engine. The performance analysis code for proprotor is based on the combined momentum and blade element theory and validated by comparison with the TRAM data. In order to design configuration for a proprotor satisfying requirements for both rotary and fixed wing mode, various kind of performance maps are constructed for many performance and configuration parameters. From the analysis the twist angle of 38 degrees and the solidity of 0.118 are decided to be the optimal geometric parameters for both operating conditions.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.11
• /
• pp.1060-1066
• /
• 2010

This paper focuses on the application of the proposed aerodynamic optimization techniques to design the blade planform of helicopter rotors. The design problems are formulated to maximize the hover figure of merit and the equivalent lift-to-drag ratio for high forward speed by optimally distributing airfoils, twist, and chord along the blade span. The numerical characters are investigated by solving various design problems. The advantages and limitations with the present design approach and the present modeling features for performance prediction are discussed. The recommendations for the required model refinements to get more accurate optimal configurations are addressed as future research areas.

• 유체기계공업학회:학술대회논문집
• /
• 2001.11a
• /
• pp.135-142
• /
• 2001

Design optimization of a transonic compressor rotor (NASA rotor 37) using response surface method and three-dimensional Navier-Stokes analysis has been carried out in this work. Baldwin-Lomax turbulence model was used in the flow analysis. Three design variables were selected to optimize the stacking line of the blade. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, adiabatic efficiency was successfully improved. Ana, it is found that the design process provides reliable design of a turbomachinery blade with reasonable computing time.

• Archives of design research
• /
• v.17 no.3
• /
• pp.123-132
• /
• 2004

This paper shows a study on the "Korean High Speed Train Design" method, its design process and the result in the form of aerodynamic optimal exterior design development of a prototype test train(HSR 350${\times}$). It was developed from 1996 until 2002, six years long in R '||'&'||' D project titled "Development of High Speed Railway Technology" The end result of the project is a prototype test train, which has two power cars, two motorized trailers and three trailers, had been tested successfully in the year 2003 to the highest speed limit 380km/h on high speed line. The improved conceptual design work of a new commercial train and next generation's train is also performed for future needs.uture needs.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.15 no.6
• /
• pp.625-635
• /
• 2013

Although the TBM method is mainly adopted in overseas market including the Europe, etc, the method scarcely adopted in domestic market. For highly enhancing applications of the TBM method for railway, It is needed to select the optimal cross-section considering design elements of civil engineering and aerodynamic effects. Also, it is needed to establish plan of proper section as well as reviewing aerodynamic effects and consideration about civil engineering elements such as length of tunnel, speed of railway, height of whole lines and size of utility tunnel, etc. Even though it should be recently considered high-speed railway tunnels and required to be standard establishments in aerodynamic reviews, it is being applied to be criteria of inconsistent pneumatic analysis owing to be not related with domestic standards. In this study, therefore, we are willing to establishment of domestic and foreign aerodynamic standards and investigate correlation between optimal cross-section and aerodynamic effects of TBM railway tunnels.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.1
• /
• pp.11-19
• /
• 2005

In order to improve dynamic stall characteristics of an oscillating airfoil, optimal design has been performed for fixed nose droop and Gurney flap. Fixed nose droop is known to be very effective to improve pitching moment characteristics but may cause degeneration of aerodynamic lift at the same time. On the other hand, Gurney flap has the opposite characteristics. For fixed nose droop, location and angle are chosen as design variables, while length is defined as design variable for Gurney flap. Higher order response surface methodology and sensitivity based optimal design method are employed to handle highly nonlinear problem such as dynamic stall. Optimal design has been performed so that lift and pitching moment are simultaneously improved. The design results show that aerodynamic characteristics can be remarkably improved through present design approach and the present passive control method is as good as active control method which combines variable nose droop and Gurney flap.

• Journal of computational fluids engineering
• /
• v.18 no.4
• /
• pp.41-46
• /
• 2013

The selection of the optimal position of the flap was performed in order to improve the aerodynamic performance during the take-off and landing processes of aircraft. For this, the existing airfoils of the main wing and flap are selected as the baseline model and the lift coefficients (cl) according to angle of attacks (AOA) were calculated with the change of the position of flap airfoil. The objective function was defined as the consideration of the maximum cl, lift to drag ratio and cl at certain AOA. Then, at 121 experimental points within $20mm{\times}20mm$ domain, two dimensional flow simulations with Spalart-Allmaras turbulence model were performed concerning the AOA from 0 to 15 degree. If the optimal position was located at the domain boundary, the domain moved to the optimal position. These processes were iterated until the position was included in the inside of the domain. From these processes, the flow separation at low AOA was removed and cl increased linearly comparing with that of the baseline model.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.377-380
• /
• 2008

In this study, an aerodynamic shape optimization system was developed to study the optimal shape of airfoil. The system consists of GA (Genetic Algorithm) and CFD code based on the Navier-Stokes equation. Lift-drag ratio is chosen as the object function and optimization is conducted for PARSEC airfoil with nine design variables, which is very efficient in representing the surface geometry of airfoil.