Giuseppe Dinardo

Fluid flow measurements by means of vibration monitoring

The achievement of accurate fluid flow measurements is fundamental whenever the control and the monitoring of certain physical quantities governing an industrial process are required. In that case, non-intrusive devices are preferable, but these are often more sophisticated and expensive than those which are more common (such as nozzles, diaphrams, Coriolis flowmeters and so on). In this paper, a novel, non-intrusive, simple and inexpensive methodology is presented to measure the fluid flow rate (in a turbulent regime) whose physical principle is based on the acquisition of transversal vibrational signals induced by the fluid itself onto the pipe walls it is flowing through. Such a principle of operation would permit the use of micro-accelerometers capable of acquiring and transmitting the signals, even by means of wireless technology, to a control room for the monitoring of the process under control. A possible application (whose feasibility will be investigated by the authors in a further study) of this introduced technology is related to the employment of a net of micro-accelerometers to be installed on pipeline networks of aqueducts. This apparatus could lead to the faster and easier detection and location of possible leaks of fluid affecting the pipeline network with more affordable costs. The authors, who have previously proven the linear dependency of the acceleration harmonics amplitude on the flow rate, here discuss an experimental analysis of this functional relation with the variation in the physical properties of the pipe in terms of its diameter and constituent material, to find the eventual limits to the practical application of the measurement methodology.

Energy-based indexes for analysis of vibrations from rotating machinery based on the Hilbert-Huang transform

The aim of the paper is to introduce a parameter indicating a possible progressive deterioration of rotating machinery affected by any dynamic misalignment (due to increasing eccentricities, uneven mass distribution, propagating cracks, etc.). Such parameter, which has to be considered as a damage index, is based on a series of post-processing algorithms to be implemented on the vibration signals acquired on static supporting elements. The vibrations acquired from rotating machinery could be influenced by non-stationary and non-linear features, especially when the rotating elements are affected by dynamical unbalances due to misalignments or uneven mass distribution. The authors use the Hibert-Huang Transform tool, that is able to decompose the original signal into Intrinsic Mode Functions (IMFs), each of them holding quite significant information about the instantaneous frequencies and the energy content of the original signal.

Fiber Bragg grating demodulation through innovative numerical procedures

ABSTRACT The aim of this article is to introduce an innovative algorithm for the calculation of the shift of the maximum reflectivity wavelength of a Fiber Bragg Grating experiencing an applied strain. An accurate and precise evaluation of the FBG spectrum displacement is crucial for determining the amount of the physical quantity inducing such perturbations. The proposed method is based on the Fast Fourier Transform based Cross Correlation function. Such method is compared to Least Squares Fitting (LSF) and the centroid algorithms, pointing out remarkable improvements in accuracy, precision, and time consumption performance. In addition, a further improvement of the proposed algorithm is introduced. It consists in an iteratively performed Cross Correlation algorithm. It has been proved that such improvement leads to estimations characterized by better accuracy and precision, thanks also to a considerable reduction of the peak-locking effect due to the FBG spectral resolution.