Maxim Tyan

인증규정을 고려한 KLA-100항공기 고양력장치 최적화 설계

고양력장치는 항공기의 이착륙 및 실속성능에 큰 영향을 미친다. 그러므로, 이 논문에서는 주어진 2차원 플랩 형상에 대하여 가장 최적화된 플랩 위치와 변위각을 얻는 슬롯티드플랩 설계 최적화 프로세스을 제안하였다. 플랩 변위각 및 Gap, Overlap을 양력을 증가시키는 주요 변수로 생각하였고, 정확한 해석결과를 위해 공력해석 소프트웨어로 ANSYS Fluent 13.0.0®을 사용하였다. 최적화된 형상은 SQP(Sequential Quadratic Programming) 알고리즘을 통해 도출됐으며, 최적화된 플랩과 함께 ADSP(Aircraft Design Synthesis Program) in-house 성능해석 코드를 사용하여 항공기의 성능을 시험하였고, 이착륙 거리, 실속속도 등의 성능변수들이 KAS-VLA 인증규정을 만족하는 결과를 얻었다.

Adaptive Multifidelity Constraints Method for Efficient Multidisciplinary Missile Design Framework

The adaptive multifidelity constraints method is developed and proposed to ensure the convergence of significant constraints to high-fidelity results for increasing the reliability and robustness of an optimal configuration at the conceptual design stage without any noticeable turnaround time. The adaptive multifidelity constraints algorithm is demonstrated for two numerical examples, with savings of 58.6 and 64% in high-fidelity evaluations, to obtain the convergence of adaptive constraints to high-fidelity results. The implementation of the adaptive multifidelity constraints algorithm is integrated into the multidisciplinary air-to-ground missile design optimization framework. The lift, drag, and longitudinal control effectiveness coefficient constraints are considered as multifidelity constraints due to their importance in the sizing of air-to-ground missile control surfaces for diving and attacking missions. The optimal air-to-ground missile configuration using adaptive multifidelity constraints yield...

Possibility-Based Multidisciplinary Optimisation For Electric-Powered Unmanned Aerial Vehicle Design

This paper describes a possibility-based multidisciplinary optimisation for electric-powered unmanned aerial vehicles (UAVs) design. An in-house integrated UAV (iUAV) analysis program that uses an electric-powered motor was developed and validated by a Predator A configuration for aerodynamics, weight, and performance parameters. An electric-powered propulsion system was proposed to replace a piston engine and fuel with an electric motor, power controllers, and battery from an eco-system point of view. Moreover, an in-house Possibility-Based Design Optimisation (iPBDO) solver was researched and developed to effectively handle uncertainty variables and parameters and to further shift constraints into a feasible design space. A sensitivity analysis was performed to reduce the dimensions of design variables and the computational load during the iPBDO process. Maximising the electric-powered UAV endurance while solving the iPBDO yields more conservative, but more reliable, optimal UAV configuration results than the traditional deterministic optimisation approach. A high fidelity analysis was used to demonstrate the effectiveness of the process by verifying the accuracy of the optimal electric-powered UAV configuration at two possibility index values and a baseline.

Investigations on stability and control characteristics of a CS-VLA certified aircraft using wind tunnel test data:

The stability and control characteristics using a wind tunnel test data process are proposed and developed to investigate the stability and control characteristics of a CS-VLA certified aircraft and to comply with the CS-VLA subpart B at the preliminary design review (PDR) and critical design review (CDR) stage. The aerodynamic characteristics of a 20% scale model are provided and investigated with clean, rudder, aileron, elevator, and winglet effects. The Mach and Reynolds correction methods are proposed to correct the aerodynamics of the scale model for stability and control analysis to obtain more reliable and accurate results of the full-scale model. The aerodynamic inputs and moment of inertia (MOI) comparison between the PDR and CDR stage show good agreement in the trends of stability and control derivatives. The CDR analysis results with the corrected wind tunnel test data and accurate MOI are investigated with respect to the longitudinal and lateral stability, control, and handling qualities to comply with the CS-VLA 173, CS-VLA 177, and CS-VLA 181 for finalizing the configuration in the CDR stage.

Subsonic Airfoil and Flap Hybrid Optimization Using Multi-Fidelity Aerodynamic Analysis

A method for airfoil and slotted ap design optimization using hybrid optimization approach and multidelity aerodynamic analysis was developed. The procedure is based on global optimization using medium delity aerodynamic solvers to localize the optimum design search region and local gradient-based optimization using combination of medium delity solver, high delity CFD solver and surrogate models. The geometry parameterization of airfoil is performed using CST method. Flap parameterization method was developed using Piecewise Bezier curves to capture speci c geometry of slotted ap. Designed airfoil and ap show good aerodynamic performance for given ight conditions of VLA category aircraft: low cruise drag and high lift at landing speed using slotted ap and without it. The aerodynamic analysis method shows good agreement with experimental results due to combination of strong points of each solver.

Database Adaptive Fuzzy Membership Function Generation for Possibility-Based Aircraft Design Optimization

Aircraft conceptual design traditionally uses simplified analysis and optimization methods to generate the basic configuration of the aircraft. Analysis methods cannot fully represent the real physical phenomena, and hence the optimum solution may fail to satisfy the constraints when more sophisticated analysis is applied. This research proposes the use of a database to estimate the prediction errors associated with a particular analysis method. Newly proposed adaptive piecewise-linear fuzzy membership functions accurately represent the intervals of prediction errors to compensate for the discrepancies caused by analysis. A possibility-based design optimization framework is developed to solve nonprobabilistic design problems with uncertainties represented by the adaptive piecewise-linear fuzzy membership intervals. A two-seater light aircraft design problem has been solved to demonstrate the proposed method. The adaptive piecewise-linear fuzzy membership fu\nctions for six major analysis modules of in-hou...

Repetitively Enhanced Neural Networks Method for Complex Engineering Design Optimization Problems

Repetitively Enhanced Neural Networks (RENN) method is developed and presented for complex and implicit engineering design problems. Enhance neural networks module constructs an accurate surrogate models and ensures for avoiding over-fitting during neural networks training from supervised learning data. The optimizer is executed by the enhanced neural networks models to seek for a tentative optimum point. It is repetitively added into the supervised learning data set to refine surfaces till the RENN tolerance reaches. The RENN method demonstrates the effectiveness and feasibility for 2D highly non-linear numerical example and the structure design of two-member frame reaching convergent solution at 10 and 14 iterations respectively at the maximum error of 1% when compared with the exact solution. Then, the RENN method is applied for a long endurance unmanned aerial vehicle (UAV) airfoil design optimization. Class/Shape function transformation (CST) geometry parameterization method represents an accurate UAV airfoil with 10 geometry design variables. The high-fidelity analysis solvers with structured mesh for airfoil is used for UAV airfoil design problem. The total 88 experiment points are required to obtain an optimal UAV airfoil configuration after 13 RENN iterations and 75 initial experiments by Latin Hypercube method in reasonable turnaround time. The optimal UAV airfoil shows 10.8% in drag reduction in cruise condition and improvement in the maximum lift coefficient and stall angle of attack.

Enhanced multi-fidelity model for flight simulation using global exploration and the Kriging method

Using the global exploration and Kriging-based multi-fidelity analysis methods, this study developed a multi-fidelity aerodynamic database for use in the performance analysis of flight vehicles and for use in flight simulations. Athena vortex lattice, a program based on vortex lattice method, was used as the low-fidelity analysis tool in the multi-fidelity analysis method. The in-house high-fidelity AADL-3D code was based on the Navier–Stokes equations. The AADL-3D code was validated by comparing the data and the analysis results of the Onera M-6 wing and NACA TN 3649. The design of experiment method and the Kriging method were applied to integrate low- and high-fidelity analysis results. General data tendencies were established from the low-fidelity analysis results. The high-fidelity analysis results and the Kriging method were used to generate a surrogate model, from which the low-fidelity analysis results were interpolated. To reduce repeated calculations, three design points were simultaneously added for each calculation. The convergence of three design points was avoided by considering only the peak points as additional design points. The reliability of the final surrogate model was determined by applying the leave-one-out cross-validation method and by obtaining the cross-validation root mean square error. Using the multi-fidelity model developed in this study, a multi-fidelity aerodynamic database was constructed for use in the three degrees of freedom flight simulation of flight vehicles.

Efficient stall compliance prediction method for trimmed very light aircraft with high-lift devices

An efficient stall compliance prediction method using quick configuration generation, adapted mesh, high fidelity analysis, and wind tunnel test data for trimmed very light aircraft is proposed. The three-dimensional Navier–Stokes equations are used to determine the characteristics of the flow field around the aircraft, and the k - ω shear stress transport model is used to interpret the turbulent flow as a solver in the high fidelity analysis. The calibrated mesh and model are developed by comparing the results with the wind tunnel test and adjusting the adapted mesh to match the wind tunnel data. The calibrated mesh and model are applied to conduct the full-scale very light aircraft analysis for the clean and full flap extended flight conditions to comply with the CS-VLA stall regulations. It is recommended that the flap area be increased in the trimmed full flap extended condition. The proposed method demonstrates the feasibility and effectiveness of very light aircraft VLA stall compliance prediction in reducing the development cost and time with small configuration changes at the preliminary very light aircraft design stage.

Design Optimization of Subsonic Airfoil and Slotted Flap Shape Using Multi-Fidelity Aerodynamic Analysis

A method for efficient design optimization of subsonic airfoil and slotted flap shape using high and medium fidelity aerodynamic solvers and hybrid optimization technique is proposed. The procedure is based on global optimization procedure using medium fidelity aerodynamic solvers to localize the optimum design search region and local gradient-based optimization using combination of medium fidelity solver, high fidelity CFD solver and surrogate models that accelerate convergence while maintaining high-fidelity solver accuracy. High and medium fidelity aerodynamic solvers were selected according to results validation study to obtain best agreement with experimental results at given Reynolds and Mach numbers. Case study of VLA category aircraft airfoil optimization shows good performance of optimized airfoil and flap sections at desired flight conditions. Geometry parameterization of airfoil is performed using CST method. New methodology for geometry modeling of slotted flap was developed and applied.