Sean Wakayama

Bio: Sean Wakayama is an academic researcher from Stanford University. The author has contributed to research in topics: Aerodynamics & Multidisciplinary design optimization. The author has an hindex of 11, co-authored 15 publications receiving 558 citations.

Subsonic wing planform design using multidisciplinary optimization

Abstract: This article presents basic results from wing planform optimization for minimum drag with constraints on structural weight and maximum lift. Analyses in each of these disciplines are developed and integrated to yield successful optimization of wing planform shape. Results demonstrate the importance of weight constraints, compressibility drag, maximum lift, and static aeroelasticity on wing shape, and the necessity of modeling these effects to achieve realistic optimized planforms.

Simultaneous Optimization of a Multiple-Aircraft Family

Abstract: Multidisciplinary design optimization is considered in the context of designing a family of aircraft Aframework is developed in which multiple aircraft, each with different missions but sharing common parts, can be optimized simultaneouslyThenewframeworkisusedtogaininsighttotheeffectofdesignvariablescalingontheoptimization algorithm Results are presented for a two-member family whose individual missions differ signie cantly Both missions can be satise ed with common designs Moreover, optimizing both airplanes simultaneously rather than following the traditional baseline plus derivative approach vastly improves the common solution A cost modeling framework is outlined that allows the value of commonality to be quantie ed for design and manufacturing costs A notional example is presented to show the cost benee t that may be achieved by designing a common family of aircraft

Lifting surface design using multidisciplinary optimization

Abstract: Lifting surface design is affected by many considerations; drag, weight, and high-lift are particularly important. These effects place different and often opposite requirements on wing shape, complicating the selection of a best configuration. To assist this selection, a preliminary design method using nonlinear optimization has been developed. An isolated lifting surface design problem is formulated from aircraft mission parameters, typically to calculate the platform and twist minimizing cruise drag or maximizing range, subject to constraints such as structural weight and maximum section lift. Solving this with optimization requires very fast analyses that are capable of capturing the effects of detailed changes in wing shape. This motivated significant improvements that were made to structural calculations and maximum-lift prediction methods for preliminary design. A method was developed to evaluate wing weight and stiffness considering bending and buckling strength. A critical section method was modified to enable the prediction of flaps-down maximum lift, correcting for induced camber near the flap edge. The lifting surface optimization method performs platform design while accounting for many effects: static aeroelasticity, weight evaluated from multiple structural design conditions, induced drag, profile drag, compressibility drag, maximum lift, static stability, and control power constraints. The method was used to explore the influence of these effects on optimal wings, demonstrating how strongly lifting surface design is influenced by maximum-lift constraints. The method was also applied to studies of wing tip shape and optimal wing-tail configurations. In many cases, the optimizer exploits physical effects, creating design features that are easy to interpret in hindsight but difficult to predict in advance. In creating these designs, the method has demonstrated that optimization can be a valuable tool for lifting surface design.

Environmentally Responsible Aviation (ERA) Project - N+2 Advanced Vehicle Concepts Study and Conceptual Design of Subscale Test Vehicle (STV) Final Report

Abstract: NASA has set demanding goals for technology developments to meet national needs to improve fuel efficiency concurrent with improving the environment to enable air transportation growth. A figure shows NASA's subsonic transport system metrics. The results of Boeing ERA N+2 Advanced Vehicle Concept Study show that the Blended Wing Body (BWB) vehicle, with ultra high bypass propulsion systems have the potential to meet the combined NASA ERA N+2 goals. This study had 3 main activities. 1) The development of an advanced vehicle concepts that can meet the NASA system level metrics. 2) Identification of key enabling technologies and the development of technology roadmaps and maturation plans. 3) The development of a subscale test vehicle that can demonstrate and mature the key enabling technologies needed to meet the NASA system level metrics. Technology maturation plans are presented and include key performance parameters and technical performance measures. The plans describe the risks that will be reduced with technology development and the expected progression of technical maturity.

Multidisciplinary Aerospace Design Optimization: Survey of Recent Developments

Abstract: The increasing complexity of engineering systems has sparked increasing interest in multidisciplinary optimization (MDO). This paper presents a survey of recent publications in the field of aerospace where interest in MDO has been particularly intense. The two main challenges of MDO are computational expense and organizational complexity. Accordingly the survey is focused on various ways different researchers use to deal with these challenges. The survey is organized by a breakdown of MDO into its conceptual components. Accordingly, the survey includes sections on Mathematical Modeling, Design- oriented Analysis, Approximation Concepts, Optimization Procedures, System Sensitivity, and Human Interface. With the authors'' main expertise being in the structures area, the bulk of the references focus on the interaction of the structures discipline with other disciplines. In particular, two sections at the end focus on two such interactions that have recently been pursued with a particular vigor: Simultaneous Optimization of Structures and Aerodynamics, and Simultaneous Optimization of Structures Combined With Active Control.

Multidisciplinary design optimization: A survey of architectures

Abstract: Multidisciplinary design optimization is a field of research that studies the application of numerical optimization techniques to the design of engineering systems involving multiple disciplines or components. Since the inception of multidisciplinary design optimization, various methods (architectures) have been developed and applied to solve multidisciplinary design-optimization problems. This paper provides a survey of all the architectures that have been presented in the literature so far. All architectures are explained in detail using a unified description that includes optimization problem statements, diagrams, and detailed algorithms. The diagrams show both data and process flow through the multidisciplinary system and computational elements, which facilitate the understanding of the various architectures, and how they relate to each other. A classification of the multidisciplinary design-optimization architectures based on their problem formulations and decomposition strategies is also provided, a...

Product family design and platform-based product development: a state-of-the-art review

Abstract: Product family design and platform-based product development has received much attention over the last decade. This paper provides a comprehensive review of the state-of-the-art research in this field. A decision framework is introduced to reveal a holistic view of product family design and platform-based product development, encompassing both front-end and back-end issues. The review is organized according to various topics in relation to product families, including fundamental issues and definitions, product portfolio and product family positioning, platform-based product family design, manufacturing and production, as well as supply chain management. Major challenges and future research directions are also discussed.

Multidisciplinary aerospace design optimization: Survey of recent developments

Abstract: The increasing complexity of engineering systems has sparked increasing interest in multidisciplinary optimization (MDO). This paper presents a survey of recent publications in the field of aerospace where interest in MDO has been particularly intense. The two main challenges of MDO are computational expense and organizational complexity. Accordingly the survey is focussed on various ways different researchers use to deal with these challenges. The survey is organized by a breakdown of MDO into its conceptual components. Accordingly, the survey includes sections on Mathematical Modeling, Design-oriented Analysis, Approximation Concepts, Optimization Procedures, System Sensitivity, and Human Interface. With the authors' main expertise being in the structures area, the bulk of the references focus on the interaction of the structures discipline with other disciplines. In particular, two sections at the end focus on two such interactions that have recently been pursued with a particular vigor: Simultaneous Optimization of Structures and Aerodynamics, and Simultaneous Optimization of Structures Combined With Active Control.

High-Fidelity Aerostructural Design Optimization of a Supersonic Business Jet

Abstract: This paper focuses on the demonstration of an integrated aerostructural method for the design of aerospace vehicles. Both aerodynamics and structures are represented using high-fidelity models such as the Euler equations for the aerodynamics and a detailed finite element model for the primary structure. The aerodynamic outer-mold line and a structure of fixed topology are parameterized using a large number of design variables. The aerostructural sensitivities of aerodynamic and structural cost functions with respect to both outer-mold line shape and structural variables are computed using an accurate and efficient coupled-adjoint procedure. Kreisselmeier‐ Steinhauser functions are used to reduce the number of structural constraints in the problem. Results of the aerodynamic shape and structural optimization of a natural laminar-flow supersonic business jet are presented together with an assessment of the accuracy of the sensitivity information obtained using the coupled-adjoint procedure.