scholarly journals Numerical continuation and bifurcation analysis in aircraft design: an industrial perspective

2015 ◽  
Vol 373 (2051) ◽  
pp. 20140406 ◽  
Author(s):  
Sanjiv Sharma ◽  
Etienne B. Coetzee ◽  
Mark H. Lowenberg ◽  
Simon A. Neild ◽  
Bernd Krauskopf
Keyword(s):  
Steady State ◽  
Design Process ◽  
Bifurcation Analysis ◽  
Aircraft Design ◽  
Numerical Continuation ◽  
Valuable Insight ◽  
Systems Software ◽  
Control Community ◽  
Passenger Aircraft ◽  
The Military

Bifurcation analysis is a powerful method for studying the steady-state nonlinear dynamics of systems. Software tools exist for the numerical continuation of steady-state solutions as parameters of the system are varied. These tools make it possible to generate ‘maps of solutions’ in an efficient way that provide valuable insight into the overall dynamic behaviour of a system and potentially to influence the design process. While this approach has been employed in the military aircraft control community to understand the effectiveness of controllers, the use of bifurcation analysis in the wider aircraft industry is yet limited. This paper reports progress on how bifurcation analysis can play a role as part of the design process for passenger aircraft.

Design of Circularly Towed Cable-Body Systems

2011 ◽  
Author(s):  
Varma Gottimukkala ◽  
Christopher D. Rahn
Keyword(s):  
Steady State ◽  
Bifurcation Analysis ◽  
Small Diameter ◽  
The Body ◽  
Numerical Continuation ◽  
Stable Steady State ◽  
Dimensional System ◽  
Design Algorithm ◽  
Towed Cable ◽  
Steady State Solutions

Circularly towed cable-body systems can be used to pickup and deliver payloads, provide surveillance, and tow aerial and marine vehicles. To provide a stable operating platform, the body or end mass should have a unique and stable steady state solution with small diameter so that it travels at a much slower speed than the tow vehicle. In this paper, the minimum damping is calculated that ensures the stable single valued steady state solutions as a function of non-dimensional system parameters including cable length and end mass. Steady state solutions are found using the numerical continuation and bifurcation analysis and Galerkin’s method provides the linearized vibration equations that determine stability. Bifurcation analysis is also used to find the minimum achievable end mass radius. A design algorithm is presented and demonstrated using an example.

scholarly journals Konsistensi dan Akurasi Data Hasil Pengukuran pada Pengujian Aerodinamika Model Pesawat Jenis Penumpang Sipil (AirLiner) di Wind Tunnel BBTA3-BPPT

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Novan Risnawan ◽  
F. Andree Yohanes ◽  
Sunarno Sunarno ◽  
Alief Sadlie Kasman
Keyword(s):  
Wind Tunnel ◽  
Design Process ◽  
National Laboratory ◽  
Aircraft Design ◽  
Aerodynamic Characteristics ◽  
Data Consistency ◽  
Aircraft Model ◽  
Measurement Results ◽  
Passenger Aircraft ◽  
Test Result

AbstractAerodynamic testing of an aircraft model in wind tunnel is important step in an aircraft design process. National Laboratory of Aerodynamic, Aeroelastic and Aeroacoustics Technology (BBTA3) have conducted a testing of a type of civilian passenger aircraft model to obtain aerodynamic characteristics data in ILST wind tunnel. The test result will be used in design process to predict performance and stability, so that the data must be consistent and accurate. This paper discusses the process of data consistency and accuracy checking by performing short repeatability and long repeatability testing so that the measurement results can be regarded valid and can be used to represent the validity of whole measurement data.Keywords: Consistency of test result data, wind tunnel, aerodynamics.Abstraks Pengujian aerodinamik sebuah model pesawat di terowongan angin merupakan tahap penting dalam proses desain pesawat. Balai Besar Teknologi Aerodinamika, Aeroelastika dan Aeroakustika (BBTA3) telah melakukan pengujian sebuah model pesawat bertipe penumpang sipil (airliner) untuk mendapatkan data karakteristik aerodinamika di terowongan angin ILST. Data hasil pengujian ini akan digunakan di dalam proses disain untuk memprediksi kinerja dan kestabilan pesawat sehingga data tersebut harus konsisten dan akurat. Tulisan ini mendiskusikan proses pengecekan konsistensi dan akurasi data dengan melakukan pengujian keberulangan dekat dan pengujian keberulangan jauh sehingga hasil pengukuran dapat dinyatakan valid dan dapat digunakan untuk mewakili keabsahan seluruh data pengukuran.Kata Kunci : Konsistensi data hasil pengujian, wind tunnel, aerodinamika.

scholarly journals Numerical continuation applied to internal combustion engine models

2020 ◽  
Vol 234 (14) ◽  
pp. 3458-3475
Author(s):  
Shaun Smith ◽  
James Knowles ◽  
Byron Mason
Keyword(s):  
Steady State ◽  
Internal Combustion Engine ◽  
Parameter Space ◽  
Bifurcation Analysis ◽  
Combustion Engine ◽  
State Parameter ◽  
Internal Combustion ◽  
Numerical Continuation ◽  
Data Driven ◽  
Engine Model

This paper proposes tools from bifurcation theory, specifically numerical continuation, as a complementary method for efficiently mapping the state-parameter space of an internal combustion engine model. Numerical continuation allows a steady-state engine response to be traced directly through the state-parameter space, under the simultaneous variation of one or more model parameters. By applying this approach to two nonlinear engine models (a physics-based model and a data-driven model), this work determines how input parameters ‘throttle position’ and ‘desired load torque’ affect the engine’s dynamics. Performing a bifurcation analysis allows the model’s parameter space to be divided into regions of different qualitative types of the dynamic behaviour, with the identified bifurcations shown to correspond to key physical properties of the system in the physics-based model: minimum throttle angles required for steady-state operation of the engine are indicated by fold bifurcations; regions containing self-sustaining oscillations are bounded by supercritical Hopf bifurcations. The bifurcation analysis of a data-driven engine model shows how numerical continuation could be used to evaluate the efficacy of data-driven models.

scholarly journals Spatiotemporal Patterns Formed by a Discrete Nutrient-Phytoplankton Model with Time Delay

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Feifan Zhang ◽  
Wenjiao Zhou ◽  
Lei Yao ◽  
Xuanwen Wu ◽  
Huayong Zhang
Keyword(s):  
Steady State ◽  
Time Delay ◽  
Numerical Simulations ◽  
Functional Response ◽  
Bifurcation Analysis ◽  
Discrete Model ◽  
Continuous Model ◽  
Spatiotemporal Patterns ◽  
Homogeneous Steady State ◽  
Simulation Results

In this research, a continuous nutrient-phytoplankton model with time delay and Michaelis–Menten functional response is discretized to a spatiotemporal discrete model. Around the homogeneous steady state of the discrete model, Neimark–Sacker bifurcation and Turing bifurcation analysis are investigated. Based on the bifurcation analysis, numerical simulations are carried out on the formation of spatiotemporal patterns. Simulation results show that the diffusion of phytoplankton and nutrients can induce the formation of Turing-like patterns, while time delay can also induce the formation of cloud-like pattern by Neimark–Sacker bifurcation. Compared with the results generated by the continuous model, more types of patterns are obtained and are compared with real observed patterns.

scholarly journals The mathematical stability study for the system of the CoO(OH) – overoxidized polypyrrole composite synthesis in the presence of fluor ions

2016 ◽  
Vol 16 ◽  
pp. 13-17
Author(s):  
V. Tkach ◽  
S.C. De Oliveira ◽  
R. Ojani ◽  
P.I. Yagodynets ◽  
U. Páramo-García
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Bifurcation Analysis ◽  
Stability Theory ◽  
Stability Study ◽  
Linear Stability Theory ◽  
Monotonic Instability ◽  
Overoxidized Polypyrrole ◽  
Polypyrrole Composite ◽  
Steady State Stability

The potentiostatic synthesis of CoO(OH) – Overoxidized polypyrrole composite in the presence of fluor ions has been investigated mathematically. The corresponding mathematical model was described and analyzed by means of linear stability theory and bifurcation analysis. The steady-state stability requirements, like also oscillatory and monotonic instability conditions are derived.Mongolian Journal of Chemistry 16 (42), 2015, 13-17

Advanced aircraft performance analysis

2018 ◽  
Vol 90 (4) ◽  
pp. 627-638 ◽  
Author(s):  
Marc Immer ◽  
Philipp Georg Juretzko
Keyword(s):  
Performance Analysis ◽  
Design Process ◽  
Performance Optimization ◽  
Electric Propulsion ◽  
Vertical Plane ◽  
Aircraft Design ◽  
Efficient Design ◽  
Content Type ◽  
Aircraft Performance ◽  
Hybrid Electric

Purpose The preliminary aircraft design process comprises multiple disciplines. During performance analysis, parameters of the design mission have to be optimized. Mission performance optimization is often challenging, especially for complex mission profiles (e.g. for unmanned aerial vehicles [UAVs]) or hybrid-electric propulsion. Therefore, the purpose of this study is to find a methodology that supports aircraft performance analysis and that is applicable to complex profiles and to novel designs. Design/methodology/approach As its core element, the developed method uses a computationally efficient C++ software “Aircraft Performance Program” (APP), which performs a segment-based mission computation. APP performs a time integration of the equations of motion of a point mass in the vertical plane. APP is called via a command line interface from a flexible scripting language (Python). On top of APP’s internal radius of action optimization, state-of-the-art optimization packages (SciPy) are used. Findings The application of the method to a conventional climb schedule shows that the definition of the top of climb has a significant influence on the resulting optimum. Application of the method to a complex UAV mission optimization, which included maximizing the radius of action, was successful. Low computation time enables to perform large parametric studies. This greatly improves the interpretation of the results. Research limitations/implications The scope of the paper is limited to the methodology that allows for advanced performance analysis at the conceptual and preliminary design stages with an emphasis on novel propulsion concepts. The methodology is developed using existing, validated methods, and therefore, this paper does not contain comprehensive validation. Other disciplines, such as cost analysis, life-cycle assessment or market analysis, are not considered. Practical implications With the proposed method, it is possible to obtain not only the desired optimum mission performance but also off-design performance of the investigated design. A thorough analysis of the mission performance provides insight into the design’s capabilities and shortcomings, ultimately aiding in obtaining a more efficient design. Originality/value Recent developments in the area of hybrid or hybrid-electric propulsion systems have shown the need for performance computation tools aiding the related design process. The presented method is especially valuable when novel design concepts with complex mission profiles are investigated.

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