| 摘要 |
<p>1464971 Gas turbine engine air intake ducts; ducted fan engines GENERAL ELECTRIC CO 7 Feb 1974 [14 Feb 1973] 05733/74 Headings F1G and F1J The invention relates to a sound attenuating duct such as the inlet duct of a gas turbine engine in which the inlet air-flow is maintained at a velocity less than the speed of sound, i.e. it is unchoked in order to provide-the equivalent sound attenuation of a conventional sound attenuating inlet which accelerates the inlet air-flow to the speed of sound. The inlet duct is formed with throat 32' of length L 1 and diameter D 1 . The inlet duct shown is defined by a casing the internal wall of which defines first a short convergent portion, then a throat portion 32' of length L 1 and diameter D 1 , then a divergent portion, a fan assembly 28 being disposed downstream of the divergent portion. The spinner 36' of the fan rotor reduces the flow area of the duct in that region. The variation in flow area of the duct is indicated in Fig. 3a and the flow velocity in Fig. 3b, the velocity at the throat having a maximum value Mach 0.6. In Fig. 4 the fairing cone or spinner 36" projects into the throat so that the throat of length L 1 and of constant area A 1 is partly circular in form and partly annular.</p> |
