Diary of Properly Vibration (1995) 184(2), 343–368
HIGH EXTRAVAGANCE VORTEX-INDUCED PULSATIONS IN A GAS TRANSPORT SYSTEM P. C. K, Meters. C. A. M. P, A. H A. P. T. W Eindhoven University of Technology, T & S 1 . 53, P. To. Box 513, Eindhoven, The Netherlands
A. I, G. R Ur. P University or college ‘La Sapienza', Via Eudossiana 18, 00184 Rome, Italy
J. C. B
TPD/TNO, P. O. Field 155, 2600 AD Delft, The Netherlands (Received 17 January 1994, and in ﬁnal type 7 06 1994) Excessive Reynolds quantity, low Mach number gas ﬂows in pipe systems with shut down side divisions exhibit amazing low regularity self-sustained pulsations driven by periodic vortex shedding for speciﬁc principles of the Strouhal number. A detailed study is usually presented from the behaviour of the ﬂow within a system with two opposite closed part branches of equal size in a mix conﬁguration. For junctions with sharp and rounded corners the traditional acoustic ﬂow velocity amplitude is just like the main ﬂow velocity. A two-dimensional potential ﬂow model based on the vortex blob method, used to simulate the ﬂow inside the junction, explains accurately the ﬂow visualization and laser beam Doppler info obtained in pipes with square cross-sections and with sharp edged junctions. The numerical ruse is used to calculate the acoustical electricity generated by vortical ﬂow at specific amplitude of the acoustic speed ﬁeld and Strouhal number. In reality, to get a pulsation with constant amplitude, this power is well balanced by the viscothermal losses and acoustic light, which is the foundation for the indirect measurement of the supply power. It is shown that, for the traditional acoustic amplitude noticed, radiation deficits due to the generation of non-resonating harmonics by wavesteepening must be taken into account in the energy stability. This ﬁnding is conﬁrmed by the physical appearance of impact waves in the geometry with rounded sides. 7 1995 Academic Press Limited
1 . INTRODUCTION
The modern day research project was initiated by occurrence of severe ﬂow-induced pulsations in one of the compressor stations of the In. V. Nederlandse Gasunie, which will operates the gas travel system of holland. Measurements simply by Gasunie indicated that pulsations took place in the presence of sealed side branches. In a previous study, Bruggerman et al. [1–4] identiﬁed the tandem-branch conﬁguration demonstrated in Figure 1, two closed side-branches of duration L located at a distance 2mL apart, with m an integer quantity, as a critical conﬁguration by which acoustics velocity amplitudes uac could reach ˆ beliefs comparable to the primary ﬂow speed U0�. The specific case m = zero, which will � In practice uac is determined in the acoustic pressure amplitude pac measured at the end of a closed side ˆ ˆ part by using the estimation uac = pac /r0 c0, where r0 is the mean denseness and c0 is the acceleration of sound. ˆ ˆ
0022–460X/95/270343 + 26 $12. 00/0 7 95 Academic Press Limited
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Determine 1 . The best excited traditional modes for cross and tandem area branch angles.
be called the cross-junction geometry, continues to be studied experimentally by Chen  and Ziada and Buhlmann . ¨ It has been demonstrated by Bruggeman  which a simpliﬁed (single vortex) style for the ﬂow in the junction attaching the main tube and the aspect branch can be used to predict the Strouhal circumstances for traditional acoustic resonance as well as the order of magnitude from the pulsation level. Furthermore, the theory was used to explain qualitatively the dramatic inﬂuence of the angles of the junction's edges for the pulsation level. This ended in the design of extremely eﬃcient termes conseilles which can be placed at the upstream edges with the junctions to lower or stop pulsations. Alternative geometries of spoilers possess later recently been proposed by simply Jungowski ou al. [7, 8]. In the present daily news we focus on a more quantitative description of the ﬂow in the junction making use of the two-dimensional...
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