Experiments and computations of a loosely supported tube in a rigid bundle subjected to single-phase flow
TL;DR: In this paper, the problem of computing the nonlinear vibro-impact responses of loosely supported heat-exchanger tubes subjected to fluidelastic coupling forces, as well as to the turbulence excitation from transverse flows, is addressed.
About: This article is published in Journal of Fluids and Structures.The article was published on 2012-01-01. It has received 27 citations till now.
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TL;DR: In this article, the authors examined the concept of using a single flexible tube in a rigid array for predicting fluidelastic instability and concluded that the tube instability is caused by a combination of damping and stiffness mechanisms.
36 citations
01 Nov 1997
TL;DR: In this article, a mathematical model for fluid damping controlled instability of tubes is presented based on the unsteady flow theory, where motion dependent fluid forces are measured in a water channel.
Abstract: A mathematical model for fluid damping controlled instability of tubes presented in this paper is based on the unsteady flow theory. Motion dependent fluid forces are measured in a water channel. From the measured fluid forces, fluid stiffness and fluid damping coefficients, are calculated as a function of reduced flow velocity, oscillation amplitude, and Reynolds number. Once these coefficients are known, the mathematical model can be applied to predict structural instability due to fluid damping. Many cases are considered: single tube, twin tubes, tube row, triangular array, and square arrays. The results show the instability regions based on the fluid damping coefficients and provide the answers to a series of questions on fluid elastic instability of tube arrays in crossflow.
19 citations
TL;DR: In this article, the surface pressure on a cylinder in the sixth row of a rotated triangular tube array (P / d = 1.375) with air cross-flow has been conducted.
18 citations
TL;DR: In this article, the analysis of the grid generated turbulence on flow induced vibration response of the parallel triangular tube bundle with pitch ratio of 1.54 was conducted in the wind tunnel with the free stream velocity ranging from 0 to 8.9m/s.
17 citations
TL;DR: In this paper, numerical simulations of the turbulent wind flow are performed to clarify the occurrence of the observed ovalling vibrations near the lee side corner of the group by studying the dynamic wind pressures on the silo surfaces and linking to the dynamic properties of the silos structures.
11 citations
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TL;DR: In this paper, the authors used the representations of the noise currents given in Section 2.8 to derive some statistical properties of I(t) and its zeros and maxima.
Abstract: In this section we use the representations of the noise currents given in section 2.8 to derive some statistical properties of I(t). The first six sections are concerned with the probability distribution of I(t) and of its zeros and maxima. Sections 3.7 and 3.8 are concerned with the statistical properties of the envelope of I(t). Fluctuations of integrals involving I2(t) are discussed in section 3.9. The probability distribution of a sine wave plus a noise current is given in 3.10 and in 3.11 an alternative method of deriving the results of Part III is mentioned. Prof. Uhlenbeck has pointed out that much of the material in this Part is closely connected with the theory of Markoff processes. Also S. Chandrasekhar has written a review of a class of physical problems which is related, in a general way, to the present subject.22
5,806 citations
01 Apr 1992
TL;DR: The concept of instantaneous frequency (IF), its definitions, and the correspondence between the various mathematical models formulated for representation of IF are discussed in this paper, and the extent to which the IF corresponds to the intuitive expectation of reality is also considered.
Abstract: The concept of instantaneous frequency (IF), its definitions, and the correspondence between the various mathematical models formulated for representation of IF are discussed. The extent to which the IF corresponds to the intuitive expectation of reality is also considered. A historical review of the successive attempts to define the IF is presented. The relationships between the IF and the group-delay, analytic signal, and bandwidth-time (BT) product are explored, as well as the relationship with time-frequency distributions. The notions of monocomponent and multicomponent signals and instantaneous bandwidth are discussed. It is shown that these notions are well described in the context of the theory presented. >
1,952 citations
01 Jan 1992
TL;DR: In this paper, the concept of instantaneous frequency (IF) is extended to discrete-time signals, and the specific problem of estimating the IF of frequency-modulated (FM) discrete time signals embedded in Gaussian noise is explored.
Abstract: For pt.I see ibid., vol.80, no.4, p.520-38 (1992). The concept of instantaneous frequency (IF) is extended to discrete-time signals. The specific problem explored is that of estimating the IF of frequency-modulated (FM) discrete-time signals embedded in Gaussian noise. Well-established methods for estimating the IF include differentiation of the phase and smoothing thereof, adaptive frequency estimation techniques such as the phase locked loop (PLL), and extraction of the peak from time-varying spectral representations. More recently, methods based on a modeling of the signal phase as a polynomial have been introduced. These methods are reviewed, and their performance compared on both simulated and real data. Guidelines are given as to which estimation method should be used for a given signal class and signal-to-noise ratio (SNR). >
1,260 citations
Journal Article•
807 citations
TL;DR: In this article, the critical velocities of cylinders supported by elastic spars were calculated by using the measured unsteady fluid dynamic forces, which are induced by the vibrating cylinders.
166 citations
"Experiments and computations of a l..." refers background or result in this paper
...It should be noted that the ranges of Reynolds number and response frequencies explored in the present tests are quite different from those in the experiments by Tanaka and Takahara (1981) and Chen et al. (1998)....
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...Reliable modeling of such coupling forces is very difficult, therefore several authors since the pioneering work of Tanaka and Takahara (1981) have attempted to measure the fluidelastic linearized stiffness and damping coefficients as a function of the flow reduced velocity (or reduced frequency),…...
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...It is convenient to define dimensionless coupling coefficients, which may be presented in the following form (Tanaka and Takahara, 1981; Granger et al., 1993): Cm ¼ MF ð1=2ÞrD2L ; CdðVRÞ ¼ DF ðVRÞ ð1=2ÞrDVL ; CkðVRÞ ¼ KF ðVRÞ ð1=2ÞrV2L : ð8Þ Then, after modal projections, the fluidelastic force…...
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