Download or read book Helicopter Model Rotor blade Vortex Interaction Impulsive Noise Scalability and Parametric Variations written by and published by . This book was released on 1984 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acoustic data taken in the anechoic Deutsch-NIederlaendischer Windkanal (DNW) have documented the blade-vortex interaction (BVI) impulsive noise radiated from 1/7-scale model main rotor of the AH-1 series helicopter. Average model-scale data were compared with averaged full-scale, in-flight acoustic data under similar nondimensional test conditions. At low advance ratios (mu = 0.164-0.194), the data scale remarkably well in level and waveform shape, and also duplicate the directivity pattern of BVI impulsive noise. At moderate advance ratios (mu = 0.224-0.270), the scaling deteriorates, suggesting that the model-scale rotor is not adequately simulating the full-scale BVI noise; presently, no proved explanation of this discrepancy exists. Carefully performed parametric variations over a complete matrix of testing conditions have shown that all of the four governing nondimensional parameters -- tip Mach number at hover, advance ratio, local inflow ratio, and thrust coefficient -- are highly sensitive to BVI noise radiation. Keywords: Helicopter noise; Blade vortex interaction; Measured acoustics.

Download or read book NASA Technical Paper written by and published by . This book was released on 1990 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Preliminary Study of a Model Rotor in Descent written by and published by . This book was released on 2000 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Within a program designed to develop experimental techniques for measuring the trajectory and structure of vortices trailing from the tips of rotor blades, the present preliminary study focuses on a method for quantifying the trajectory of the trailing vortex during descent flight conditions. This study also presents rotor loads and blade surface pressures for a range of tip-path plane angles and Mach numbers. Blade pressures near the leading edge and along the outer radius are compared with data obtained on the same model rotor, but in open jet facilities. A triangulation procedure based on two directable laser-light sheets, each containing an embedded reference, proved effective in defining the spatial coordinates of the trailing vortex. When interrogating a cross section of the flow that contains several trailing vortices, the greatest clarity was found to result when the flow is uniformly seeded. Surface pressure responses during blade-vortex interactions appeared equally sensitive near the leading edge and along the outer portion of the blade, but diminished rapidly as the distance along the blade chord increased. The pressure response was virtually independent of whether the tip-path plane angle was obtained through shaft tilt or cyclic pitch. Although the shape and frequency of the pressure perturbations on the advancing blade during blade-vortex interaction are similar to those obtained in open-jet facilities, the angle of the tip-path plane may need to be lower than the range covered in this study.

Download or read book Rotorcraft Blade vortex Interaction Noise Reduction Through Attitude and Flight Parameter Variations written by Juan Abelló and published by . This book was released on 2004 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NASA Technical Paper written by United States. National Aeronautics and Space Administration and published by . This book was released on 1990 with total page 656 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Wake Geometry Effects on Rotor Blade vortex Interaction Noise Directivity written by Ruth McVoy Martin and published by . This book was released on 1990 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Helicopter Blade Vortex Interaction Noise with Comparisons to CFD Calculations written by and published by . This book was released on 1996 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Blade vortex Interaction Noise Generation and Directionality written by Wel-Chong Sim and published by . This book was released on 1996 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Acoustic Measurements from a Rotor Blade vortex Interaction Noise Experiment in the German Dutch Wind Tunnel DNW written by Ruth McVoy Martin and published by . This book was released on 1988 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acoustic data are presented from a 40-percent-scale model of the four-bladed BO-105 helicopter main rotor, tested in a large aeroacoustic wind tunnel. Rotor blade-vortex interaction (BVI) noise data in the low-speed flight range were acquired using a traversing in-flow microphone array. The experimental apparatus, testing procedures, calibration results, and experimental objectives are fully described. A large representative set of averaged acoustic signals are presented.

Download or read book Acoustic Measurements from a Rotor Blade vortex Interaction Noise Experiment in the German Dutch Wind Tunnel DNW written by and published by . This book was released on 1988 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transonic Blade vortex Interactions written by Anastasios Sotirios Lyrintzis and published by . This book was released on 1988 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Machines Mechanism and Robotics written by Rajeev Kumar and published by Springer Nature. This book was released on 2021-07-21 with total page 1830 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume includes select papers presented during the 4th International and 19th National Conference on Machines and Mechanism (iNaCoMM 2019), held in Indian Institute of Technology, Mandi. It presents research on various aspects of design and analysis of machines and mechanisms by academic and industry researchers.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1985 with total page 1076 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reduction of Blade Vortex Interaction BVI Noise Through X force Control written by Fredric H. Schmitz and published by . This book was released on 1995 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Effect of Signal Jitter on the Spectrum of Rotor Impulsive Noise written by and published by . This book was released on 1987 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Recent Asian Research on Thermal and Fluid Sciences written by Abhilash Suryan and published by Springer Nature. This book was released on 2020-02-18 with total page 693 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a collection of the best papers from the Seventh Asian Joint Workshop on Thermophysics and Fluid Science (AJWTF7 2018), which was held in Trivandrum, India, in November 2018. The papers highlight research outputs from India, China, Japan, Korea and Bangladesh, and many of them report on collaborative efforts by researchers from these countries. The topics covered include Aero-Acoustics, Aerodynamics, Aerospace Engineering, Bio-Fluidics, Combustion, Flow Measurement, Control and Instrumentation, Fluid Dynamics, Heat and Mass Transfer, Thermodynamics, Mixing and Chemically Reacting Flows, Multiphase Flows, Micro/Nano Flows, Noise/NOx/SOx Reduction, Propulsion, Transonic and Supersonic Flows, and Turbomachinery. The book is one of the first on the topic to gather contributions from some of the leading countries in Asia. Given its scope, it will benefit researchers and students working on research problems in the thermal and fluid sciences.