β Scribed by Felice E. Corcione; Gerardo Valentino
No coin nor oath required. For personal study only.
The in-cylinder turbulent flow field of a small modern d.i. diesel engine motored over a wide speed range (from 1000 to 3000 rpm) has been studied with LDA. The engine has been modified with an optical access on the head, to allow measurements along horizontal planes. The experiments provide operational conditions similar to those of a real engine. Cycle-resolved LDA measurements were made in a reentrant combustion chamber. Data have been analyzed using the ensemble-averaging, low-pass filtering and spectral analysis techniques. Measurements during the intake and compression strokes highlight the jetlike character of the intake flow that generates large-scale rotating flow. This is characterized by high turbulence and unstable swirling flow, which becomes more stable during the compression stroke. The mean motion, as well as the rms turbulent velocity scale almost linearly with engine speed. The spectral analysis shows the turbulent flow field during the compression to be nonisotropic and nonstationary at all engine speeds.
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The relation between the deposition rate of the films and the velocity distribution in the flow field is investigated in detail. The thin SiN films are deposited on Si substrates by the infrared thermal chemical vapor deposition (CVD) at 600 Β°C, flux ratio (NH3/Si2H6) of 50 and 800 and total pressur
Prediction of the noise transmitted from machinery and Β―ow sources on a submarine to the sonar arrays poses a complex problem. Vibrations in the pressure hull provide the main transmission mechanism. The pressure hull is characterised by a very large number of modes over the frequency range of inter