Buffet problem

The present paper may be considered an extension of other efforts of the writer [6-9, 12] to state the bridge flutter-buffeting problem analytically with linearly defined deterministic parameters. In particular, the work outlined below constitutes the extension to three dimensions of the theory given in Ref.[9], as was promised in that paper. The final result offers what may be a useful theoretical format for examining the roles of both structural and aerodynamic parameters in specific practical cases. 

The three-dimensional flutter and buffeting problems of flexible bridges have been treated here together in an analytical fashion from a specifically adopted viewpoint the aeroelastic portion is based... 

Impeller Problems The high-speed rotation of the impeller of a centrifngal compressor imparts the vital aerodynamic velocity to the flow within the gas path. The buffeting effects of the gas flow can canse fatigue failures in the conventional fabricated shrouded impeller due to vibration-induced alternating stresses. These may be of the following types ... 

Tube Bundle Natural Frequency. Elastic structures vibrate at different natural frequencies. The lowest (fundamental) natural frequency is the most important. If the vortex shedding or turbulent buffeting frequency is lower than the tube fundamental natural frequency, it will not create the resonant condition and the tube vibration problem. Hence, the knowledge of the fundamental natural frequency is sufficient in most situations if / is found to be higher than / or fb. Higher than the third harmonic is generally not important for flow-... 

Is gas buffeting seen to be a problem, and has any experimental work or calcualations been carried out indicating a gas flow limit ... 

The atmosphere on Mars is mostly missing, too. Its problem may have been location the asteroid belt is next door. Mars didn t have a big moon to protect it, and strayed too close to the freeway of speeding rocks. A constant rain of meteors buffeted the Martian surface with cosmic shotgun blasts that blew away its atmosphere. Scientists are struggling to explain how Mars stayed wet for even a few hundred thousand years, while Earth has stayed wet for many times that long. 

There had been no Mayday call. There had been no communications with the passengers, most of whom will have been asleep, at least at the onset of the problems. Some passengers will have been woken up by the pitching-up, the buffeting and the changes in air pressure, just in time to wonder what on earth was happening to then-plane. 

The problems of wind-induced buffeting and aerodynamic instability of long flexible bridges have, over some half century, received considerable empirical treatment, notably via wind tunnel experiments on models. Such treatment has, overall, been quite... 

The present paper, an extension of Ref.[9] to the full three-dimensional problem, espouses the same unified treatment of flut.ter and buffeting, particularly in recognizing the common dependence, of both structural motion and buffeting action, upon the frequency parameter K. A further aim has been to make evident the particular roles of structural mode shape and flutter derivatives in the overall action. 

This problem is based on the work by Buffet MF, Dixon DJ, Edwards GL, Ley SV, Tate EW (2000)7. Chem. Soc., Perkin Trans 1, 1815-1827. 

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