Unsteady Computational Fluid Dynamics in Aeronautics


Book Description

The field of Large Eddy Simulation (LES) and hybrids is a vibrant research area. This book runs through all the potential unsteady modelling fidelity ranges, from low-order to LES. The latter is probably the highest fidelity for practical aerospace systems modelling. Cutting edge new frontiers are defined. One example of a pressing environmental concern is noise. For the accurate prediction of this, unsteady modelling is needed. Hence computational aeroacoustics is explored. It is also emerging that there is a critical need for coupled simulations. Hence, this area is also considered and the tensions of utilizing such simulations with the already expensive LES. This work has relevance to the general field of CFD and LES and to a wide variety of non-aerospace aerodynamic systems (e.g. cars, submarines, ships, electronics, buildings). Topics treated include unsteady flow techniques; LES and hybrids; general numerical methods; computational aeroacoustics; computational aeroelasticity; coupled simulations and turbulence and its modelling (LES, RANS, transition, VLES, URANS). The volume concludes by pointing forward to future horizons and in particular the industrial use of LES. The writing style is accessible and useful to both academics and industrial practitioners. From the reviews: "Tucker's volume provides a very welcome, concise discussion of current capabilities for simulating and modellng unsteady aerodynamic flows. It covers the various pos sible numerical techniques in good, clear detail and presents a very wide range of practical applications; beautifully illustrated in many cases. This book thus provides a valuable text for practicing engineers, a rich source of background information for students and those new to this area of Research & Development, and an excellent state-of-the-art review for others. A great achievement." Mark Savill FHEA, FRAeS, C.Eng, Professor of Computational Aerodynamics Design & Head of Power & Propulsion Sciences, Department of Power & Propulsion, School of Engineering, Cranfield University, Bedfordshire, U.K. "This is a very useful book with a wide coverage of many aspects in unsteady aerodynamics method development and applications for internal and external flows." L. He, Rolls-Royce/RAEng Chair of Computational Aerothermal Engineering, Oxford University, U.K. "This comprehensive book ranges from classical concepts in both numerical methods and turbulence modelling approaches for the beginner to latest state-of-the-art for the advanced practitioner and constitutes an extremely valuable contribution to the specific Computational Fluid Dynamics literature in Aeronautics. Student and expert alike will benefit greatly by reading it from cover to cover." Sébastien Deck, Onera, Meudon, France




Computational Aeroacoustics


Book Description

Computational aeroacoustics is rapidly emerging as an essential element in the study of aerodynamic sound. As with all emerging technologies, it is paramount that we assess the various opportuni ties and establish achievable goals for this new technology. Essential to this process is the identification and prioritization of fundamental aeroacoustics problems which are amenable to direct numerical siIn ulation. Questions, ranging from the role numerical methods play in the classical theoretical approaches to aeroacoustics, to the correct specification of well-posed numerical problems, need to be answered. These issues provided the impetus for the Workshop on Computa tional Aeroacoustics sponsored by ICASE and the Acoustics Division of NASA LaRC on April 6-9, 1992. The participants of the Work shop were leading aeroacousticians, computational fluid dynamicists and applied mathematicians. The Workshop started with the open ing remarks by M. Y. Hussaini and the welcome address by Kristin Hessenius who introduced the keynote speaker, Sir James Lighthill. The keynote address set the stage for the Workshop. It was both an authoritative and up-to-date discussion of the state-of-the-art in aeroacoustics. The presentations at the Workshop were divided into five sessions - i) Classical Theoretical Approaches (William Zorumski, Chairman), ii) Mathematical Aspects of Acoustics (Rodolfo Rosales, Chairman), iii) Validation Methodology (Allan Pierce, Chairman), iv) Direct Numerical Simulation (Michael Myers, Chairman), and v) Unsteady Compressible Flow Computa tional Methods (Douglas Dwoyer, Chairman).
















Improved Unsteady Aerodynamic Influence Coefficients for Dynamic Aeroelastic Response


Book Description

"Flutter, or the dynamic instability of an aircraft wing due to aerodynamic loads, must be considered when designing an aircraft. For this reason work has been done to improve a method developed at Bombardier Aerospace to analyze the dynamic aeroelastic response of aircraft. This method replaces original Doublet Lattice Method (DLM) aerodynamic data with that from high-fidelity Computational Fluid Dynamics (CFD) codes. The new aerodynamic loads are transmitted to the NASTRAN aeroelastic module through improved Aerodynamic Influence Coefficients (AIC). Previously this high-fidelity data was solely steady, and weighting factors were needed to obtain unsteady data. This gave good results for flutter calculations in the subsonic and transonic regime, however, for improved results in the transonic and supersonic regime, unsteady aerodynamic data was needed. This research incorporates unsteady high-fidelity CFD data into this analysis method.The unsteady CFD data was obtained by means of the Transpiration Method. This allowed for the unsteady movement of the model to be accounted for, while saving compu- tational time needed to deform and remesh the aerodynamic mesh at each time step. The transpiration method was validated with two standard test cases, for both static deflections and unsteady cyclic movement. Once this method was validated, high-fidelity CFD results could then be used in the AIC method.The AIC method begins with a set of baseline modes being obtained for the wing model. From these modes an aerodynamic base is calculated. Using the AIC method this aerodynamic base is transferred to NASTRAN. The natural mode shapes of a new configuration, along with the modal-based AIC method are used to approximate aerodynamic loads for the new configuration. These loads are used in NASTRAN to compute the flutter analysis of the new configuration." --







Monthly Catalog of United States Government Publications


Book Description

February issue includes Appendix entitled Directory of United States Government periodicals and subscription publications; September issue includes List of depository libraries; June and December issues include semiannual index