Recently, a large number of multi-objective evolutionary algorithms (MOEAs) for many-objective optimization problems have been proposed in the computation community. However, an exhaustive benchmarking study has never performed. As result, performance MOEAs not well understood yet. Moreover, almost all previous studies, was evaluated based on nondominated solutions final population at end search. Such traditional methodology several critical issues. In this paper, we exhaustively investigate...

A high-performance Ishii airfoil was analyzed using both a wind-tunnel and large-eddy simulations at low-Reynolds-number condition . The design guidelines for an shape with high lift-to-drag ratio under the aforementioned are described by analyses of flowfields aerodynamic characteristics airfoil. Compared conventional airfoils, such as NACA 0012 0002, characteristic effects on its flowfield discussed. suction side can cause delays in flow separation low angle attacks. separated reattaches,...

In this study, the flowfields around NACA0012 and NACA0002 airfoils at Reynolds number of 23,000 aerodynamic characteristics these were analyzed using implicit large-eddy simulation laminar-flow simulation. Around number, flow over an airfoil separates, transits, reattaches, resulting in generation a laminar separation bubble angle attack certain degree range. Over airfoil, point moves toward its leading edge with increasing attack, separated may transit to create short bubble. On other...

The development of a high-fidelity aerodynamic design optimization tool based on evolutionary algorithms for turbomachinery is attempted. A three-dimensional Navier-Stokes solver was used analysis, so thatflowfields would be represented accurately and that realistic reliable designs produced. For efficient robust optimization, the real-coded adaptive range genetic algorithm adopted, computation parallelized performed an SGI Origin 2000 cluster to reduce turnaround time. redesign NASA rotor...

A new approach to extract useful design information from Pareto-optimal solutions of optimization problems is proposed and applied an aerodynamic transonic airfoil shape optimization. The enables analysis line, face, or volume data all such as flow field by decomposing the into principal modes corresponding base vectors using proper orthogonal decomposition (POD). Analysis surface pressure problem showed that optimized airfoils can be categorized two families (low drag designs high lift...

Mechanisms behind the pressure distribution and skin friction within a laminar separation bubble (LSB) are investigated by large-eddy simulations around 5% thickness blunt flat plate at chord length based Reynolds number 5.0 × 103, 6.1 1.1 104, 2.0 104. The characteristics inside LSB change with number; steady (LSB_S) 103 steady-fluctuating (LSB_SF) Different of distributions observed increasing number, such that gradual monotonous recovery in LSB_S plateau followed rapid region LSB_SF....

The effectiveness of closed-loop flow control using a deep Q network (DQN), such as reinforcement learning algorithm, was experimentally researched for NACA0015 airfoil. system used dielectric barrier discharge plasma actuator the device, and experiment conducted at chord Reynolds number . selected nondimensional burst frequency by analyzing time series surface pressure data. neural DQN sequentially trained angles attack 12 15 deg. As result, successfully generated higher gain compared with...

A new constraint-handling method based on Pareto-optimality and niching concepts for multi-objective multi-constraint evolutionary optimization is proposed. The proposed does not require any constants to be tuned constraint-handling. In addition, the present use weighted-sum of constraints thus tuning weight coefficients efficient even when all individuals in initial population are infeasible or amount violation each constraint significantly different. approach demonstrated remarkably more...

The parameters of DBD (Dielectric Barrier Discharge) plasma actuator with burst wave (duty cycle) are investigated by the low speed wind tunnel experiment for airfoil. In this paper, influence frequency f, input voltage sine fbase and ratio BR on stall control discussed. experiments conducted conditions Rec=44,000, 63,000. is applied to NACA0015 airfoil then flow-fields around visualized smoke wire method pressure its surface measured multipoint steady measurement. results show that within...

A benchmark problem based on a real-world car structure design optimization1 is proposed. The constructed by using response surface method from the optimization result of problem. Because this bases actual conducted Mazda, it contains features problems. Objectives are minimization total weight different type cars and maximization number common gauge (standard plate thickness) parts among cars. This has 148 discrete parameters 36 constraints for simultaneous two types 222 54 three Thus,...

In this paper, we are proposing a generalized analytical solution to the point reactor kinetics equations for six groups of delayed neutron precursors both conventional and subcritical equations. The methodology presented aims obtain an using similarity transformation technique. This will make it possible evaluate behavior nuclear power as function time, given constant reactivity inserted in core, very simple way without computational effort, compared numerical solutions. results obtained be...

A reliable and efficient aerodynamic design optimization tool using evolutionary algorithm has been developed for transonic compressor blades. real-coded adaptive-range genetic is used to improve efficiency robustness in optimization. To represent flow fields accurately produce designs, three-dimensional Navier- Stokes computation analysis. ensure feasibility of the present method, redesign NASA rotor67 demonstrated. Entropy production considered as objective function be minimized. The...

A large-scale, real-world application of evolutionary multi-objective optimization is reported. The multidisciplinary design among aerodynamics, structures, and aeroelasticity the wing a transonic regional-jet aircraft was performed using high-fidelity evaluation models. Euler Navier-Stokes solvers were employed for aerodynamic evaluation. commercial software NASTRAN coupled with computational fluid dynamics solver structural aeroelastic evaluations. An adaptive range genetic algorithm as an...

We investigate the properties of widely used constrained multi-objective optimization benchmark problems. A number Multi-Objective Evolutionary Algorithms (MOEAs) for Constrained Optimization Problems (CMOPs) have been proposed in past few years. The C-DTLZ functions and Real-World-Like (RWLPs) frequently evaluating performance MOEAs on CMOPs. In this paper, however, we show that widely-used RWLPs some unnatural problem features. experimental results an MOEA without any Constraint Handling...

The Reynolds number effect on the aeroacoustic fields of a supersonic jet was experimentally investigated via particle image velocimetry (PIV), schlieren visualization, and near-field acoustic measurements. Cold jets under ideally expanded conditions at Mach 2.0 were produced with number, based diameter nozzle exit, ranging from 105 to 106. This study focuses laminar-to-turbulent transition jet, including transitional condition (Re ≈ 105). PIV results high-Reynolds-number = 106), which...

Multi-objective genetic algorithm (MOGA) and a data mining technique were applied to the multidisciplinary design optimization (MDO) of hybrid rocket. In this study, swirling-oxidizer-type rocket engine with single cylindrical grain port was designed. MOGA solve multi-objective problem using real-number cording Pareto ranking method. two objective functions considered: one maximized flight altitude other minimized gross weight. Each function empirically estimated. Many non-dominated...

The flowfields around the NACA 0012 airfoil at Reynolds numbers , and are studied, predictability of aerodynamic characteristics derived from various numerical methods is examined. Two-dimensional laminar simulation, two-dimensional Reynolds-averaged Navier–Stokes simulation using Baldwin–Lomax turbulence model, three-dimensional implicit large-eddy employed in this study. simulations accurately predict separation point, capture a bubble for each number angle attack. Nonlinearity lift curve...

A design tool for simultaneous structure optimization of multiple car models is developed and applied to MAZDA CX-5 (SUV car), MAZDA6 wagon (large MAZDA3 hatchback (small car) demonstrate feasibility the tool. This problem a multiobjective where objectives are minimization total weight three maximization number common thickness parts. To find nondominated designs efficiently, an evolutionary algorithm named Cheetah adopted. For analysis obtained dominated designs, interactive data mining...