1,235 research outputs found
Aeroacoustics of a porous plug jet noise suppressor
The aeroacoustics of a porous plug jet noise suppressor was investigated. The predicted flow features of isentropic plug nozzles for different pressure ratios or exit flow Mach numbers, throat areas, ratios of the plug to annular nozzle radii, mass flow rates and the available run times possible with the existing compressed air supply system, are compiled. The dimensions and the coordinates of the contour of typical isentropic external expansion plugs with different exit flow Mach numbers are listed. Design details of the experimental facility and the plug nozzle selected for experimental aeroacoustic studies are reported. The analytical flow prediction by method of characteristics of a conical porous plug nozzles is initiated. The role of the shape, size, and porosity of the plug surface in achieving over a perforated conical plug a nearly isentropic shockfree supersonic flow field which is closely similar to the flow field of a contoured isentropic plug nozzle is examined
Noise investigations with impinging jet flows Status report no. 5, 1 Jun. - 30 Nov. 1965
Noise from interacting high speed jet flow
Aeroacoustics of supersonic jet flows from contoured and solid/porous conical plug-nozzles
The results of an experimental study of the acoustic far-field, the shock associated noise, and the nature of the repetitive shock structure of supersonic jet flows issuing from plug-nozzles having externally-expanded plugs with pointed termination operated at a range of supercritical pressure ratios Xi approaching 2 to 4.5 are reported. The plug of one of these plug-nozzles was contoured. The other plug-nozzles had short conical plugs with either a solid surface or a combination of solid/porous surface of different porosities. The contoured and the uncontoured plug-nozzles had the same throat area and the same annulus-radius ratio K = R sub p/R sub N = 0.43. As the result of modifications of the shock structure, the acoustic performance of improperly expanded jet flows of an externally-expanded short uncontoured plug of an appropriate geometry with suitably perforated plug and a pointed termination, is shown to approach the acoustic performance of a shock-free supersonic jet issuing from an equivalent externally-expanded contoured plug-nozzle
Noise Investigations with Impinging Jet Flows Status Report No. 6, 1 Dec. 1965 - 31 May 1966
Far field noise radiation from underexpanded convergent axisymmetric main jet flow in anechoic chambe
Editorial
The last year has been a very busy one for the BMB. We have published 140 articles online, which is over twice the publication rate of the previous year. This reflects the increase in the submission rates and Springer's view that papers should be published online as quickly as possible. In addition, the entire archive of the Bulletin of Mathematical Biology is now available on the Springer website for the journal, digitized back to Vol. 1, No. 1, published in 1939
Supersonic Jet Noise Reduction by Coaxial Jets with Coplanar and Staggered Exits
Far-field noise radiated from coaxial cold underexpanded
jet flows issuing from convergent two-nozzle
configurations with coplanar and staggered-exits
is investigated experimentally. The coaxial
jets are operated in the "inverted" mode, i.e., the
outer (annular) jet flow Mach number is higher than
that of the inner (round) jet. Keeping all other
geometrical and operating conditions the same, the
exit-stagger of the inner (round) and the outer
(annular) nozzles was varied. It is shown that the
extent of the exit-stagger affects both the flows
and the radiated noise from such coaxial underexpanded
jet flows and that comparatively, the lowest
noise levels are achieved when the coaxial nozzle-exits
are coplanar. Moreover, the effectiveness
of the co-flowing inner jet flow in reducing the
noise radiated from either the annular or the coaxial
underexpanded jet flows decreases noticeably
as the exit-stagger is increased
Childhood asthma and anthropogenic CO2 emissions
Amrita DosanjhPediatric Pulmonologist, San Diego, California, USATrends in the incidence of childhood asthma worldwide have paralleled the sharp increase in carbon dioxide (CO2) emissions, over at least the last two decades. The prevalence of asthma in the United States has quadrupled over the last 20 years in part due to climate-related factors. In a report released by Harvard Medical School and the Center for Health and the Global Environment, it was noted that there was an increase in asthma incidence of 160% from 1980–1994 among preschool children. &nbsp
Guru Nanak: Life, Lessons & Relevancy
This senior project is centered on understanding the thought of Nanak the founder of Sikhism. It consist of historiography of Nanak, and understanding the core of Nanak\u27s thought as centered around G-d\u27s Immanenc
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