Last edited by Shalar
Friday, July 31, 2020 | History

3 edition of Active attenuation of propeller blade passage noise found in the catalog.

Active attenuation of propeller blade passage noise

Active attenuation of propeller blade passage noise

  • 54 Want to read
  • 0 Currently reading

Published by National Aeronautics and Space Administration, Langley Research Center in Hampton, Va .
Written in English

    Subjects:
  • Airplanes -- Turbine-propeller engines,
  • Aircraft cabins -- Noise

  • Edition Notes

    StatementJ.M. Zalas and J. Tichy
    SeriesNASA contractor report -- 172386
    ContributionsTichy, J, Langley Research Center, Lord Corporation
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL14928195M

    active noise control (ANC) systems in five different propeller airplanes. Binaural recordings were made of the sounds inside the airplanes at passenger head positions under typical steady flight conditions. Digital filtering and reduction of the propeller tones at blade passage frequency and higher harmonics provided. A method of evaluating the intermittent propeller blade fixed cavitation and shedding of free cavitation bubbles is presented. The number and size of free cavitation bubbles are related to the variation of propeller blade attached cavitation. The.

    Ship Noise Sources: Propellers Dominant Source of Radiated Underwater Noise for Surface Vessels • Cavitation Blade Tonals - Blade Passage Frequency and Harmonics • Propeller Cavitation Noise - Broad Spectal Range Mid-Frequency Active Sonar 0 Time (seconds) 3 . DJI Mavic 2 Low-Noise Propellers for Mavic 2 Zoom, Mavic 2 Pro Drone Quadcopter Accessory Replacement - Part 13 (Bundle: 2 Pairs) out of 5 stars $ DJI Mavic Pro Platinum Low-Noise Quick-Release Propellers - Gold Tips - 2 Pairs out of 5 stars $ Reviews:

    • Fan noise - low frequency • Blade passage tone below 63 Hz level typically 5 dB less than discharge • Noise increases with fan speed. Typical Noise Spectrum Ton Induced-Draft Propeller-Fan Cooling Tower 50’ from Air Inlet 50 55 60 65 70 75 80 63 • 12 dBA reduction possible. Low Noise Fan.   "The other half of the noise is due to the thickness of the blade - the noise of the air being pushed outward by the prop and having to come back together after the prop's passage. The thicker the blade, the greater that effect is, but with advanced materials, you could reduce the propeller noise just by reducing the thickness.".


Share this book
You might also like
Czechs and the Czech-German Declaration

Czechs and the Czech-German Declaration

Channel Islands

Channel Islands

Guide to the stars.

Guide to the stars.

Historical and personal notes upon the village of Littleborough

Historical and personal notes upon the village of Littleborough

365 easy, fast recipes

365 easy, fast recipes

Power of a Promise

Power of a Promise

Top management forum: Redesign of Japanese management systems and practices

Top management forum: Redesign of Japanese management systems and practices

rational illustration of the Book of common prayer of the Church of England

rational illustration of the Book of common prayer of the Church of England

The tomb of Tut·ankh·Amen

The tomb of Tut·ankh·Amen

Pleasant and Delightful History of Dorastus and Fawnia. Pleasant for Age to shun drowsie Thoughts; Profitable for Youth, to avoid other wanton Pastimes, and bringing to Both a desired Content

Pleasant and Delightful History of Dorastus and Fawnia. Pleasant for Age to shun drowsie Thoughts; Profitable for Youth, to avoid other wanton Pastimes, and bringing to Both a desired Content

The vision

The vision

Worship-The Missing Jewel V 02:

Worship-The Missing Jewel V 02:

Active attenuation of propeller blade passage noise Download PDF EPUB FB2

Acoustic measurements are presented to show that active cancellation can be used to achieve significant reduction of blade passage noise in a turboprop cabin.

Simultaneous suppression of all blade passage frequencies was attained. The spatial volume over which cancellation occurred, however, is by: Get this from a library.

Active attenuation of propeller blade passage noise. [J M Zalas; J Tichy; Langley Research Center.; Lord Corporation.]. NASA Contractor Report Active Attenuation of Propeller Blade Passage Noise J. Zalas and J. Tichy Lord Corporation West Grandview Blvd. Erie, PA Contract NASI -I July NASA National Aeronautics and.

The propeller acoustic field on the port side of the aircraft was simulated in a laboratory using a speaker-ring consisting of four loudspeakers. The control system was tested using this acoustic field, producing noise attenuation as high as 28 dB in the interior, and fuselage vibration reduction as high as 16 by:   The noise generated from the propeller of this ship is well within levels one might expect from such a ship as can best be derived from the levels at blade rate harmonics.

Except for the tonal at Hz and the broad band part around 60 Hz it roughly changes with speed as assumed in the simple acoustic by: Active Noise Control in Propeller Aircraft generated anti-noise determine the noise attenuation.

Active noise control systems significantly increase the capacity for attenuating low frequency noise below noise is typically the first three or four harmonics of the Blade Passage Frequency (BPF).

The noise is transmitted through several. Introducing holes in propeller blades to reduce root cavitation, for example, is not in itself new, but achieving high levels of noise reduction by strategically placing relatively few holes.

Available from UMI in association with The British Library. Requires signed TDF. This work considers the use of secondary acoustic sources for the reduction of noise levels in harmonically excited enclosed sound fields.

This possibility is studied initially through the use of an analytical model of a single frequency "two-dimensional" rectangular, enclosed sound field of low modal.

Insufficient blade tip clearance almost always results in excessive generation of noise, often sounding like sand or gravel being blasted against the hull in the area of the propeller. Blade area must also be factored into this calculation, ensuring that the blades do not suffer from overloading, which leads to inefficiency and cavitation.

USA USA USA USA US A US A US A US A US A US A US A US A US A US A US A US A Authority US United States Prior art keywords propeller impeller fluid drive shaft chambered hub Prior art date Legal.

Discrete-frequency axial-flow fan noise reduction using active noise control is described. The unique aspect of the current research is the use of the fan. 1. Introduction.

The recent increase of the number of small unmanned aerial vehicles (UAVs) has renewed the interest in the development of the propellers and puts some serious requirements on the noise produced by the propulsion a small propeller quietness and efficiency are appealing and some times demanding features for the success of.

Common fan noise reduction methods. Several methods can reduce fan noise. However, because of the many different combinations of fan types and installations, consulting the fan manufacturer and an experienced noise attenuation company is often the best practice.

American Institute of Aeronautics and Astronautics Sunrise Valley Drive, Suite Reston, VA Aircraft noise contains the following main components: engine noise, propeller noise, airframe noise and structure borne noise, [1, 4, 5]. Aircraft interior noise is the combination of all.

active-control system require a knowledge of the directional radiation characteristics of the propeller noise source. Thus, it is crucial to characterize the source and the noise radiated. Finally, run-up areas often have blast-fences, providing some noise attenuation, next to them.

Active technology can be used alone, or in combination with. The predicted noise contributions of propeller A and propeller B at the primary BPF, with blade phase differences of (a) 24, (b)(c) 5, and (d) C. Effects of the propeller tilt angle. The cabin noise inside propeller aircraft is essentially dominated by strong tonal components at harmonics of the blade passage frequency of the propellers.

In order to achieve an efficient reduction of such a periodic low frequency noise, it is advisable to use an active noise control system based on adaptive narrowband feedforward techniques.

This paper describes an active noise control experimental implementation in propeller aircraft. It relies on synchronous excitation of acoustic sources in order to minimize the sound field measured at passenger head height by a set of microphones.

System performance predictions coupled with optimization algorithms showed that 32 loudspeakers and 48 monitoring. Fan noise 7/12/ Noise Comparison For lowest noise output, fans should always be operated near their peak efficiency point.

A common mistake is to use a fan that is too small (or too large) for the application, so that it cannot be run at its most efficient point. Variable airflow applications can also cause noise problems.

The prop will make noise by the simple face that it's moving the air. I'm not an engineer so I don't have all the deets but I do beleive that the prop tip dosen't have to be going supersonic to make that noise, due to the blade accelerating the airmass you might have localized supersonic flow near the tips.Low-frequency interior noise in prop-driven aircrafts: Sources and control methodologies 4 August | Noise & Vibration Worldwide, Vol.

48, No. Optimization for rotor blade-tip planform with low high-speed impulsive noise characteristics in forward flight.Together they establish the correct combination of rpm, fuel flow, and propeller blade angle to create the propeller thrust required to provide the requested power.

Turboprop Engine Systems. The turboprop engine consists of three major assemblies. They are the power section assembly, the torquemeter assembly, and the reduction gear assembly (RGA).