Download or read book A New Approach to Complete Aircraft Landing Gear Noise Prediction written by Leonard Vincent Lopes and published by . This book was released on 2009 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes a new landing gear noise prediction system developed at The Pennsylvania State University, called Landing Gear Model and Acoustic Prediction code (LGMAP). LGMAP is used to predict the noise of an isolated or installed landing gear geometry. The predictions include several techniques to approximate the aeroacoustic and aerodynamic interactions of landing gear noise generation. These include 1) a method for approximating the shielding of noise caused by the landing gear geometry, 2) accounting for local flow variations due to the wing geometry, 3) the interaction of the landing gear wake with high-lift devices, and 4) a method for estimating the effect of gross landing gear design changes on local flow and acoustic radiation. The LGMAP aeroacoustic prediction system has been created to predict the noise generated by a given landing gear. The landing gear is modeled as a set of simple components that represent individual parts of the structure. Each component, ranging from large to small, is represented by a simple geometric shape and the unsteady flow on the component is modeled based on an individual characteristic length, local flow velocity, and the turbulent flow environment. A small set of universal models is developed and applied to a large range of similar components. These universal models, combined with the actual component geometry and local environment, give a unique loading spectrum and acoustic field for each component. Then, the sum of all the individual components in the complete configuration is used to model the high level of geometric complexity typical of current aircraft undercarriage designs. A line of sight shielding algorithm based on scattering by a two-dimensional cylinder approximates the effect of acoustic shielding caused by the landing gear. Using the scattering from a cylinder in two-dimensions at an observer position directly behind the cylinder, LGMAP is able to estimate the reduction in noise due to shielding by the landing gear geometry. This thesis compares predictions with data from a recent wind tunnel experiment conducted at NASA Langley Research Center, and demonstrates that including the acoustic scattering can improve the predictions by LGMAP at all observer positions. In this way, LGMAP provides more information about the actual noise propagation than simple empirical schemes. Two-dimensional FLUENT calculations of approximate wing cross-sections are used by LGMAP to compute the change in noise due to the change in local flow velocity in the vicinity of the landing gear due to circulation around the wing. By varying angle of attack and flap deflection angle in the CFD calculations, LGMAP is able to predict the noise level change due to the change in local flow velocity in the landing gear vicinity. A brief trade study is performed on the angle of attack of the wing and flap deflection angle of the flap system. It is shown that increasing the angle of attack or flap deflection angle reduces the flow velocity in the vicinity of the landing gear, and therefore the predicted noise. Predictions demonstrate the ability of the prediction system to quickly estimate the change in landing gear noise caused by a change in wing configuration. A three-dimensional immersed boundary CFD calculation of simplified landing gear geometries provides relatively quick estimates of the mean flow around the landing gear. The mean flow calculation provides the landing gear wake geometry for the prediction of trailing edge noise associated with the interaction of the landing gear wake with the high lift devices. Using wind tunnel experiments that relate turbulent intensity to wake size and the Ffowcs Williams and Hall trailing edge noise equation for the acoustic calculation, LGMAP is able to predict the landing gear wake generated trailing edge noise. In this manner, LGMAP includes the effect of the interaction of the landing gear's wake with the wing/flap system on the radiated noise. The final prediction technique implemented includes local flow calculations of a landing gear with various truck angles using the immersed boundary scheme. Using the mean flow calculation, LGMAP is able to predict noise changes caused by gross changes in landing gear design. Calculations of the mean flow around the landing gear show that the rear wheels of a six-wheel bogie experience significantly reduced mean flow velocity when the truck is placed in a toe-down configuration. This reduction in the mean flow results is a lower noise signature from the rear wheel. Since the noise from a six-wheel bogie at flyover observer positions is primarily composed of wheel noise, the reduced local flow velocity results in a reduced noise signature from the entire landing gear geometry. Comparisons with measurements show the accuracy of the predictions of landing gear noise levels and directivity. Airframe noise predictions for the landing gear of a complete aircraft are described including all of the above mentioned developments and prediction techniques. These show that the nose gear noise and the landing gear wake/flap interaction noise, while not significantly changing the overall shape of the radiated noise, do contribute to the overall noise from the installed landing gear.
Download or read book Empirical Prediction of Aircraft Landing Gear Noise written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-31 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report documents a semi-empirical/semi-analytical method for landing gear noise prediction. The method is based on scaling laws of the theory of aerodynamic noise generation and correlation of these scaling laws with current available test data. The former gives the method a sound theoretical foundation and the latter quantitatively determines the relations between the parameters of the landing gear assembly and the far field noise, enabling practical predictions of aircraft landing gear noise, both for parametric trends and for absolute noise levels. The prediction model is validated by wind tunnel test data for an isolated Boeing 737 landing gear and by flight data for the Boeing 777 airplane. In both cases, the predictions agree well with data, both in parametric trends and in absolute noise levels.Golub, Robert A. (Technical Monitor) and Guo, Yue-PingLangley Research CenterMATHEMATICAL MODELS; ANALYSIS (MATHEMATICS); LANDING GEAR; NOISE PREDICTION; AERODYNAMIC NOISE; WIND TUNNEL TESTS; NOISE INTENSITY; NOISE GENERATORS; BOEING 777 AIRCRAFT; BOEING 737 AIRCRAFT
Download or read book Advanced Multifunctional Lightweight Aerostructures written by Kamran Behdinan and published by John Wiley & Sons. This book was released on 2021-01-29 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Offers a review of the newest methodologies for the characterization and modelling of lightweight materials and structures Advances in Multifunctional Lightweight Structures offers a text that provides and in-depth analyses of the thermal, electrical and mechanical responses of multi-functional lightweight structures. The authors, noted experts on the topic, address the most recent and innovative methodologies for the characterization and modelling of lightweight materials and discuss various shell and plate theories. They present multifunctional materials and structures and offer detailed descriptions of the complex modelling of these structures. The text is divided into three sections that demonstrate a keen understanding and awareness for multi-functional lightweight structures by taking a unique approach. The authors explore multi-disciplinary modelling and characterization alongside benchmark problems and applications, topics that are rarely approached in this field. This important book: • Offers an analyses of the thermal, electrical and mechanical responses of multi-functional lightweight structures • Covers innovative methodologies for the characterization and modelling of lightweight materials and structures • Presents a characterization of a wide variety of novel materials • Considers multifunctional novel structures with potential applications in different high-tech industries • Includes efficient and highly accurate methodologies Written for professionals, engineers and researchers in industrial and other specialized research institutions, Advances in Multifunctional Lightweight Structures offers a much needed text to the design practices of existing engineering building services and how these methods combine with recent developments.
Download or read book Airframe noise prediction method written by Martin R. Fink and published by . This book was released on 1977 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aircraft Noise written by Oleksandr Zaporozhets and published by CRC Press. This book was released on 2011-05-13 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aircraft noise has adverse impacts on passengers, airport staff and people living near airports, it thus limits the capacity of regional and international airports throughout the world. Reducing perceived noise of aircraft involves reduction of noise at source, along the propagation path and at the receiver. Effective noise control demands highly s
Download or read book Towards the Design of Low noise Aircraft Landing Gears Using the Lattice Boltzmann Method written by Daniel Armstrong and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Landing Gear and Cavity Noise Prediction written by Donald B. Bliss and published by . This book was released on 1976 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aircraft Noise Prediction Program written by W. E. Zorumski and published by . This book was released on 1982 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hybrid Wing body Aircraft Noise and Performance Assessment written by Philip Andrew Weed and published by . This book was released on 2010 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hybrid wing-body aircraft noise generation and boundary layer ingestion (BLI) performance trends with increased fan face Mach number inlet designs are investigated. The presented topics are in support of the NASA subsonic fixed wing project, which seeks to lower noise and increase performance by improving prediction methods and technologies. The aircraft configurations used for study are the N2A, using conventional podded engines, and the N2B, using an embedded propulsion system. Preliminary FAR Part 36 noise certification assessments are completed using the NASA Aircraft Noise Prediction Program (ANOPP). The limitations of applying current ANOPP noise prediction methods to hybrid wing-body aircraft are investigated. Improvements are made to the landing gear and airfoil self-noise modules, while a diffraction integral method is implemented in a companion thesis to enhance noise shielding estimates. The N2A overall takeoff and landing noise estimate is found to be 5.3 EPNdB higher than the N+2 goal. The dominant noise sources are the fan rearward and jet on takeoff and the main landing gear and elevons on approach. A lower fan pressure ratio and advanced landing gear fairings are recommended to decrease N2A overall noise levels. The available engine noise estimation tools were inadequate to model the N2B distributed propulsion system and rectangular exhaust nozzle; therefore, overall N2B aircraft noise results are presented for reference only. A simplified embedded propulsion system integration study is carried out to explore the N2B fan design space. A 2-D computational domain with contoured slip boundaries around the centerbody is used to replicate the effects of 3-D relief on the airframe and inlet aerodynamics. The domain includes the S-shaped inlet duct and is extended far downstream for a Trefftz plane power balance analysis to determine the propulsive power required for steady level flight. A fan actuator volume is included to couple the airframe external and the engine internal flows. Aircraft power savings, fan efficiency, and boundary layer thickness trends are examined to determine if increasing fan face Mach number improves system performance while mitigating the total pressure distortion risk of boundary layer ingestion. A fan face Mach number near 0.7 is found to increase aircraft power savings 12% relative to the baseline design and to reduce centerbody boundary layer kinetic energy thickness by 4.7%. In addition, power balances at lower fan pressure ratios as fan face Mach number increases suggesting that high-flow low pressure ratio fans are desirable for BLI.
Download or read book Validation of Aircraft Noise Prediction Program written by and published by . This book was released on 1979 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Subsonic Transport Approach Noise The Relative Contribution of Airframe Noise written by and published by . This book was released on 1992 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Landing Approach Airframe Noise Measurements and Analysis written by and published by . This book was released on 1980 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Semiempirical Airframe Noise Prediction Model and Evaluation with Flight Data written by and published by . This book was released on 1976 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AGARD Conference Proceedings written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development and published by . This book was released on 1992 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA Technical Note written by and published by . This book was released on 1974 with total page 780 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research Needs in Aircraft Noise Prediction written by John P. Raney and published by . This book was released on 1975 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flow and Noise Control Review and Assessment of Future Directions written by Russell H. Thomas and published by . This book was released on 2002 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:
