Download or read book Fan Noise Reduction An Overview written by Edmane Envia and published by . This book was released on 2001 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book FAN NOISE REDUCTION AN OVERVIEW NASA TM 2001 210699 JUN 20 2001 written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Study Program for Lift Fan Noise Reduction and Suppression written by M. J. Benzakein and published by . This book was released on 1970 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Low Speed Fan Noise Reduction With Trailing Edge Blowing written by and published by . This book was released on 2002 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Controlling Ventilation Noises written by Armour Research Foundation (U.S.) and published by . This book was released on 1957 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Active Control of Fan Noise written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-02 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the Active Noise Cancellation (ANC) System designed by General Electric and tested in the NASA Lewis Research Center's (LERC) 48 inch Active Noise Control Fan (ANCF). The goal of this study is to assess the feasibility of using wall mounted secondary acoustic sources and sensors within the duct of a high bypass turbofan aircraft engine for global active noise cancellation of fan tones. The GE ANC system is based on a modal control approach. A known acoustic mode propagating in the fan duct is canceled using an array of flush-mounted compact sound sources. The canceling modal signal is generated by a modal controller. Inputs to the controller are signals from a shaft encoder and from a microphone array which senses the residual acoustic mode in the duct. The key results are that the (6,0) was completely eliminated at the 920 Hz design frequency and substantially reduced elsewhere. The total tone power was reduced 6.8 dB (out of a possible 9.8 dB). Farfield reductions of 15 dB (SPL) were obtained. The (4,0) and (4,1) modes were reduced simultaneously yielding a 15 dB PWL decrease. The results indicate that global attenuation of PWL at the target frequency was obtained in the aft quadrant using an ANC actuator and sensor system totally contained within the duct. The quality of the results depended on precise mode generation. High spillover into spurious modes generated by the ANC actuator array caused less than optimum levels of PWL reduction. The variation in spillover is believed to be due to calibration procedure, but must be confirmed in subsequent tests. Pla, Frederic G. and Hu, Ziqiang and Sutliff, Daniel L. Glenn Research Center...

Download or read book Axial Fan Noise Reduction written by Vyacheslav M. Ryaboy and published by . This book was released on 1997 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report contains a survey of Russian technical literature concerning design methodologies for low-noise axial flow fans. Recommendations are cited for nominating the main design parameters, such as rotor and stator blades number combinations, blade shape and tilt, and axial clearance. Comparisons are made with corresponding American sources.--Abstract.

Download or read book A Method to Further Reduce the Perceived Noise of Low Tip Speed Fans written by and published by . This book was released on 2000 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Noise and Vibration Control written by Malcolm J. Crocker and published by John Wiley & Sons. This book was released on 2007-10-05 with total page 1594 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two of the most acclaimed reference works in the area of acoustics in recent years have been our Encyclopedia of Acoustics, 4 Volume set and the Handbook of Acoustics spin-off. These works, edited by Malcolm Crocker, positioned Wiley as a major player in the acoustics reference market. With our recently published revision of Beranek & Ver's Noise and Vibration Control Engineering, Wiley is a highly respected name in the acoustics business. Crocker's new handbook covers an area of great importance to engineers and designers. Noise and vibration control is one largest areas of application of the acoustics topics covered in the successful encyclopedia and handbook. It is also an area that has been under-published in recent years. Crocker has positioned this reference to cover the gamut of topics while focusing more on the applications to industrial needs. In this way the book will become the best single source of need-to-know information for the professional markets.

Download or read book Benefits of Swept and Leaned Stators for Fan Noise Reduction written by Richard P. Woodward and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Broadband Noise Reduction of a Low Speed Fan Noise Using Trailing Edge Blowing written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-24 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental proof-of-concept test was conducted to demonstrate reduction of rotor-stator interaction noise through the use of rotor-trailing edge blowing. The velocity deficit from the viscous wake of the rotor blades was reduced by injecting air into the wake from a continuous trailing edge slot. Hollow blades with interior guide vanes create flow channels through which externally supplied air flows from the blade root to the trailing edge. A previous paper documented the substantial tonal reductions of this Trailing Edge Rotor Blowing (TERB) fan. This report documents the broadband characteristics of TERB. The Active Noise Control Fan (ANCF), located at the NASA Glenn Research Center, was used as the proof-of-concept test bed. Two-component hotwire data behind the rotor, unsteady surface pressures on the stator vane, and farfield directivity acoustic data were acquired at blowing rates of 1.1, 1.5, and 1.8 percent of the total fan mass flow. The results indicate a substantial reduction in the rotor wake turbulent velocity and in the stator vane unsteady surface pressures. Based on the physics of the noise generation, these indirect measurements indicate the prospect of broadband noise reduction. However, since the broadband noise generated by the ANCF is rotor-dominated, any change in the rotor-stator interaction broadband noise levels is barely distinguishable in the farfield measurements. Sutliff, Daniel L. Glenn Research Center E-15171, NASA/TM-2005-213814, AIAA Paper 2005-3028

Download or read book Active Control of Fan Noise Feasibility Study written by and published by . This book was released on 1996 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fan Noise Reduction from a Supersonic Inlet written by William E. Nuckolls and published by . This book was released on 1992 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fans written by Thomas Carolus and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fans In a unique approach, this textbook combines the design and construction of centrifugal and axial fans with the problem of their noise generation and its mitigation. Easily applicable methods of fan selection, aerodynamic fan design, and fan noise prediction are compiled, including most of the underlying physical principles. Other features of this book include introductions to numerical and experimental methods, simulation-based optimization techniques for fan design, and psychoacoustic methods for evaluating fan noise. Numerous practical problems illustrate and reinforce the ideas and concepts. Content Fan performance parameters, demand of a plant and fan selection, fan performance characteristics, model laws, flow kinematics, efficiencies - Design methods for centrifugal and axial fans - Mechanisms of fan sound generation, methods for fan sound prediction - Psychoacoustic evaluation of fan noise - Design features of noise reduced fans - Computational fluid dynamics, fan test rigs, simulation-based optimization - Practice problems and solutions. Target group Students of mechanical engineering at colleges and universities Engineers in the industrial fan manufacturing industry, planning engineers for heating, ventilation air conditioning systems and in equipment and plant engineering Author Prof. Dr.-Ing. Thomas Carolus taught fluid mechanics at the Department of Mechanical Engineering at the University of Siegen, Germany, with a focus on fluid machinery. This book is a translation of the original German 4th edition Ventilatoren by Thomas Carolus, published by Springer Fachmedien Wiesbaden GmbH, part of Springer Nature in 2020. The translation was done with the help of artificial intelligence (machine translation by the service DeepL.com), but with a subsequent human revision in terms of content. Springer Nature works continuously to further develop tools for the production of books and on the related technologies to support the authors.

Download or read book Aeroacoustic Analysis of Fan Noise Reduction with Increased Bypass Nozzle Area written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-29 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: An advanced model turbofan was tested in the NASA Glenn 9-by 15-Foot Low Speed Wind Tunnel (9x15 LSWT) to explore far field acoustic effects of increased bypass nozzle area. This fan stage test was part of the NASA Glenn Fan Broadband Source Diagnostic Test, second entry (SDT2) which acquired aeroacoustic results over a range of test conditions. The baseline nozzle was sized to produce maximum stage performance at cruise condition. However, the wind tunnel testing is conducted near sea level condition. Therefore, in order to simulate and obtain performance at other operating conditions, two additional nozzles were designed and tested one with +5 percent increase in weight flow (+5.4 percent increase in nozzle area compared with the baseline nozzle), sized to simulate the performance at the stage design point (takeoff) condition, and the other with a +7.5 percent increase in weight flow (+10.9 percent increase in nozzle area) sized for maximum weight flow with a fixed nozzle at sea level condition. Measured acoustic benefits with increased nozzle area were very encouraging, showing overall sound power level (OAPWL) reductions of 2 or more dB while the stage thrust actually increased by 2 to 3 percent except for the most open nozzle at takeoff rotor speed where stage performance decreased. Effective perceived noise levels for a 1500 ft engine flyover and 3.35 scale factor showed a similar noise reduction of 2 or more EPNdB. Noise reductions, principally in the level of broadband noise, were observed everywhere in the far field. Laser Doppler Velocimetry measurements taken downstream of the rotor showed that the total turbulent velocity decreased with increasing nozzle flow, which may explain the reduced rotor broadband noise levels.Woodward, Richard P. and Hughes, Christopher E. and Podboy, Gary G.Glenn Research CenterAEROACOUSTICS; FAN BLADES; LOW SPEED WIND TUNNELS; NOZZLE FLOW; WIND TUNNEL TESTS; NOISE REDUCTION; AIRCRAFT ENGINES; BYPASSES; NOZZLE DESIGN; EFFECTIVE

Download or read book Acoustic Performance of Novel Fan Noise Reduction Technologies for a High Bypass Model Turbofan at Simulated Flights Conditions written by David M. Elliott and published by BiblioGov. This book was released on 2013-07 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two novel fan noise reduction technologies, over the rotor acoustic treatment and soft stator vane technologies, were tested in an ultra-high bypass ratio turbofan model in the NASA Glenn Research Center s 9- by 15-Foot Low-Speed Wind Tunnel. The performance of these technologies was compared to that of the baseline fan configuration, which did not have these technologies. Sideline acoustic data and hot film flow data were acquired and are used to determine the effectiveness of the various treatments. The material used for the over the rotor treatment was foam metal and two different types were used. The soft stator vanes had several internal cavities tuned to target certain frequencies. In order to accommodate the cavities it was necessary to use a cut-on stator to demonstrate the soft vane concept.

Download or read book A Concept for a Counterrotating Fan with Reduced Tone Noise written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-09 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: As subsonic jet engine designs incorporate higher bypass ratios to reduce jet noise and increase engine cycle efficiency, the fan noise becomes a significant part of the perceived total noise. The conventional method of reducing fan tone noise is to design a low tip-speed device. An alternative approach of using a counterrotating fan with a high number of rotor blades is investigated in this report. The source of noise at the blade passing frequency of this device is the rotor-only mechanism, which is cut off for a subsonic tip speed rotor. The interaction noise occurs at twice the blade passing frequency, which, for this fan, was shifted high enough in frequency to be above the perceived noise rating range. The result was a counterrotating fan which had more potential for tone noise reduction than does the conventional fan. A potential broadband noise reduction was also indicated. Dittmar, James H. Glenn Research Center NASA-TM-105736, E-7138, NAS 1.15:105736 RTOP 535-03-10...