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 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 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 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 Characterization of Cavity Flow Fields Using Pressure Data Obtained in the Langley 0 3 Meter Transonic Cryogenic Tunnel written by Maureen B. Tracy and published by . This book was released on 1993 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Airframe Noise Prediction Evaluation written by Kingo J. Yamamoto and published by . This book was released on 1995 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Prediction of Airframe Noise written by and published by . This book was released on 1975 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Methods of predicting airframe noise generated by aircraft in flight under nonpowered conditions are discussed. Approaches to predictions relying on flyover data and component theoretical analyses are developed. A nondimensional airframe noise spectrum of various aircraft is presented. The spectrum was obtained by smoothing all the measured spectra to remove any peculiarities due to airframe protrusions, normalizing each spectra by its overall sound pressure level and a characteristics frequency, and averaging the spectra together. A chart of airframe noise sources is included.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1976 with total page 984 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aircraft Noise Prediction Program Theoretical Manual Part 2 written by and published by . This book was released on 1982 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Design of Aircraft Landing Gear written by Robert Kyle Schmidt and published by SAE International. This book was released on 2021-02-18 with total page 1092 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aircraft landing gear and its associated systems represent a compelling design challenge: simultaneously a system, a structure, and a machine, it supports the aircraft on the ground, absorbs landing and braking energy, permits maneuvering, and retracts to minimize aircraft drag. Yet, as it is not required during flight, it also represents dead weight and significant effort must be made to minimize its total mass. The Design of Aircraft Landing Gear, written by R. Kyle Schmidt, PE (B.A.Sc. - Mechanical Engineering, M.Sc. - Safety and Aircraft Accident Investigation, Chairman of the SAE A-5 Committee on Aircraft Landing Gear), is designed to guide the reader through the key principles of landing system design and to provide additional references when available. Many problems which must be confronted have already been addressed by others in the past, but the information is not known or shared, leading to the observation that there are few new problems, but many new people. The Design of Aircraft Landing Gear is intended to share much of the existing information and provide avenues for further exploration. The design of an aircraft and its associated systems, including the landing system, involves iterative loops as the impact of each modification to a system or component is evaluated against the whole. It is rare to find that the lightest possible landing gear represents the best solution for the aircraft: the lightest landing gear may require attachment structures which don't exist and which would require significant weight and compromise on the part of the airframe structure design. With those requirements and compromises in mind,The Design of Aircraft Landing Gear starts with the study of airfield compatibility, aircraft stability on the ground, the correct choice of tires, followed by discussion of brakes, wheels, and brake control systems. Various landing gear architectures are investigated together with the details of shock absorber designs. Retraction, kinematics, and mechanisms are studied as well as possible actuation approaches. Detailed information on the various hydraulic and electric services commonly found on aircraft, and system elements such as dressings, lighting, and steering are also reviewed. Detail design points, the process of analysis, and a review of the relevant requirements and regulations round out the book content. The Design of Aircraft Landing Gear is a landmark work in the industry, and a must-read for any engineer interested in updating specific skills and students preparing for an exciting career.

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 Scientific and Technical Aerospace Reports written by and published by . This book was released on 1974 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NASA Contractor Report written by and published by . This book was released on 1979 with total page 690 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics based Aeroacoustic Modelling of Bluff bodies written by Edward Peers and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work physics-based modelling of bluff-body noise was performed with application to landing gear noise prediction. The landing gear is a primary contributor to airframe noise during approach. Noise is primarily generated from the unsteady pressures result- ing from the turbulent flow around various components. The research was initiated in response to the need for an improved understanding of landing gear component noise characteristics and to assist in the development of landing gear noise prediction tools. A computational approach was adopted so that the noise generating physics of the prob- lem could be captured. Governing laws were solved numerically to predict the noise source characteristics and the resulting acoustic far-field. Three-dimensional compress- ible Navier-Stokes simulations were performed to solve the unsteady turbulent near-field flow and the acoustic analogy was used to predict the resulting far-field acoustic pres- sure. The flow solver included a high-order computational aeroacoustics code adopting large-eddy simulation, whilst a Ffowcs Williams and Hawkings solver was used for the acoustic prediction. Circular cylinders in various configurations were selected to rep- resent basic landing gear struts and results were used to form a modelling database. Initially, cylinders at various Reynolds numbers were investigated in cross-flow to de- termine the noise characteristics of a simple model strut. The work was extended to investigate the effect of strut alignment to the flow by simulating cylinders in yaw. The effect of yaw was shown to modify the peak level and frequency of far-field noise spectra. Component interaction effects were then investigated by simulating cylinders in tandem arrangements. The resulting aerodynamic and far-field noise characteristics were shown to be complex and extremely sensitive to the separation distance between the cylin- ders. Finally, a prediction model was developed and validated by comparing predictions against theory and measurements of the noise radiated by a simple two-wheel landing gear model. The results demonstrated the capability of the model to accurately predict correct spectral and directivity characteristics.

Download or read book Aeroacoustics of Flight Vehicles written by Harvey H. Hubbard and published by . This book was released on 1991 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NASA Reference Publication written by and published by . This book was released on 1977 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt: