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Book Database of Inlet and Exhaust Noise Shielding for Wedge Shaped Airframe

Download or read book Database of Inlet and Exhaust Noise Shielding for Wedge Shaped Airframe written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-16 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experiment to measure the noise shielding of the blended wing body design concept was developed using a simplified wedge-shaped airframe. The experimental study was conducted in the Langley Anechoic Noise Research Facility. A wideband, omnidirective sound source in a simulated engine nacelle was held at locations representative of a range of engine locations above the wing. The sound field around the model was measured with the airframe and source in place and with source alone, using an-array of microphones on a rotating hoop that is also translated along an axis parallel to the airframe axis. The insertion loss was determined from the difference between the two resulting contours. Although no attempt was made to simulate the noise characteristics of a particular engine, the broadband noise source radiated sound over a range of scaled frequencies encompassing 1 and 2 times the blade passage frequency representative of a large, high-bypass-ratio turbofan engine. The measured data show that significant shielding of the inlet-radiated noise is obtained in the area beneath and upstream of the model. The data show the sensitivity of insertion loss to engine location. Gerhold, Carl H. and Clark, Lorenzo R. Langley Research Center NASA/TM-2001-210840, L-18053, NAS 1.15:210840

Book Database of Inlet and Exhaust Noise Shielding for Wedge shaped Airframe

Download or read book Database of Inlet and Exhaust Noise Shielding for Wedge shaped Airframe written by Carl H. Gerhold and published by . This book was released on 2001 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experiment to measure the noise shielding of the blended wing body design concept was developed using a simplified wedge-shaped airframe. The experimental study was conducted in the Langley Anechoic Noise Research facility. A wideband, omnidirective sound source in a simulated engine nacelle was held at locations representative of a range of engine locations above the wing. The sound field around the model was measured, with the airframe and source in place and with source alone, using an array of microphones on a rotating hoop that is also translated along an axis parallel to the airframe axis. The insertion loss was determined from the difference between the two resulting contours. Although no attempt was made to simulate the noise characteristics of a particular engine, the broadband noise source radiated sound over a range of scaled frequencies encompassing 1 and 2 times the blade passage frequency representative of a large, high-bypass-ratio turbofan engine.

Book NASA Langley Scientific and Technical Information Output 2001

Download or read book NASA Langley Scientific and Technical Information Output 2001 written by and published by . This book was released on 2002 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book An Estimate of the Noise Shielding on the Fuselage Resulting from Installing a Short Duct Around an Advanced Propeller

Download or read book An Estimate of the Noise Shielding on the Fuselage Resulting from Installing a Short Duct Around an Advanced Propeller written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-16 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: A simple barrier shielding model was used to estimate the amount of noise shielding on the fuselage that could result from installing a short duct around a wing-mounted advanced propeller. With the propeller located one-third of the duct length from the inlet, estimates for the maximum blade passing tone attenuation varied from 7 dB for a duct 0.25 propeller diameter long to 16.75 dB for a duct 1 diameter long. Attenuations for the higher harmonics would be even larger because of their shorter wavelengths relative to the duct length. These estimates show that the fuselage noise reduction potential of a ducted compared with an unducted propeller is significant. Even more reduction might occur if acoustic attenuation material were installed in the duct. Dittmar, James H. Glenn Research Center NASA-TM-100262, E-3891, NAS 1.15:100262 RTOP 535-03-01...

Book Effect of Blowing on Boundary Layer of Scarf Inlet

Download or read book Effect of Blowing on Boundary Layer of Scarf Inlet written by National Aeronaut Administration (Nasa) and published by . This book was released on 2020-08-05 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: When aircraft operate in stationary or low speed conditions, airflow into the engine accelerates around the inlet lip and pockets of turbulence that cause noise and vibration can be ingested. This problem has been encountered with engines equipped with the scarf inlet, both in full scale and in model tests, where the noise produced during the static test makes it difficult to assess the noise reduction performance of the scarf inlet. NASA Langley researchers have implemented boundary layer control in an attempt to reduce the influence of the flow nonuniformity in a 12-in. diameter model of a high bypass fan engine mounted in an anechoic chamber. Static pressures and boundary layer profiles were measured in the inlet and far field acoustic measurements were made to assess the effectiveness of the blowing treatment. The blowing system was found to lack the authority to overcome the inlet distortions. Methods to improve the implementation of boundary layer control to reduce inlet distortion are discussed. Gerhold, Carl H. and Clark, Lorenzo R. Langley Research Center NASA/TM-2004-213267, L-18369 WU 781-30-14-01 ACOUSTIC MEASUREMENT; AIR FLOW; BOUNDARY LAYER CONTROL; ENGINE INLETS; BLOWERS; BLOWING; BOUNDARY LAYERS; LOW SPEED; NOISE REDUCTION; STATIC PRESSURE; TURBULENCE

Book Noise Benefits of Increased Fan Bypass Nozzle Area

Download or read book Noise Benefits of Increased Fan Bypass Nozzle Area written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-21 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: An advanced model turbofan (typical of current engine technology) was tested in the NASA Glenn 9 by 15 Foot Low Speed Wind Tunnel (9-by 15-Foot 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 for the engine at a high altitude, cruise point condition. However, the wind tunnel testing is conducted near sea level conditions. Therefore, in order to simulate and obtain performance at other aircraft operating conditions, two additional nozzles were designed and tested-one with a +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 conditions, 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 conditions. 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 several percentage points except fro the most open nozzle at takeoff rotor speed where stage performance decreased. These noise reduction benefits were seen to primarily affect broadband noise, and were evident throughout the range of measured sideline angles. Woodward, Richard P. and Hughes, Christopher E. Glenn Research Center NASA/TM-2004-213396, AIAA Paper 2005-1201, E-14899

Book A Parametric Study of the Aerodynamic Characteristics of Nose cylinder flare Bodies at a Mach Number of 6 0

Download or read book A Parametric Study of the Aerodynamic Characteristics of Nose cylinder flare Bodies at a Mach Number of 6 0 written by George C. Ashby and published by . This book was released on 1965 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Summary of Flight test Results of the VZ 2 Tilt wing Aircraft

Download or read book Summary of Flight test Results of the VZ 2 Tilt wing Aircraft written by Robert J. Pegg and published by . This book was released on 1962 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Investigation of Engine exhaust airframe Interference on a Cruise Vehicle at Mach 6

Download or read book Investigation of Engine exhaust airframe Interference on a Cruise Vehicle at Mach 6 written by James M. Cubbage and published by . This book was released on 1971 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results from an investigation of the effects of underexpanded engine exhaust flow on the aerodynamic performance and stability of a cruise airplane at Mach 6 are presented. The influence of wing reflex angle and nozzle geometry on exhaust flow interference effects was investigated on a flat-plate model. The experiments were conducted at a free-stream Reynolds number of 17.05 X 10 (to the 6 power) based on the length of the airplane model over a model angle-of-attack range of 0(degrees) to 10(degrees) and at nozzle static-pressure ratios from 1 to approximately 4.

Book Analysis of Partly Wrinkled Membranes

Download or read book Analysis of Partly Wrinkled Membranes written by Manuel Stein and published by . This book was released on 1961 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book A Theory for Inflated Thin wall Cylindrical Beams

Download or read book A Theory for Inflated Thin wall Cylindrical Beams written by W. B. Fichter and published by . This book was released on 1966 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: