RO126058A2 - Non-conventional process for identifying the oscillation frequencies of an inaccessible segment of pipe - Google Patents

Abstract

The invention relates to a process for identifying the oscillation frequencies of an inaccessible segment of a pipe performing vibratory motions induced and maintained by the turbulent flow of a fluid. According to the invention, the process uses an electronic computing equipment (3) for acquiring, computing and comparing the power spectral densities of some electrical signals picked up simultaneously by means of some connection cables (4 and 5) from the output terminals of two absolute pressure transducers (6 and 7) connected by means of some isolating valves (8 and 9) to some pulse lines (10 and 11) and to some pressure intake ports (12 and 13) mounted in some accessible zones (14 and 15) of a conduit, as close as possible to the upstream and downstream ends of the inaccessible pipe segment (1).

Description

NON-CONVENTIONAL METHOD OF IDENTIFICATION 'A * FREQUENCYSr ™

The oscillations of an inaccessible segment of conduct

The invention relates to an unconventional process for identifying the frequencies of oscillations of an inaccessible segment of pipeline that executes vibrational movements induced and maintained by the turbulent flow of a fluid, an alternative method applicable in the case of the impossibility of installing classical measurement chains using conventional vibration transducers such as conventional vibration transducers. , tensometric marks, etc.

Applied exclusively to nuclear reactors, another well-known unconventional method for identifying the vibration frequencies of mechanical structures in the active area consists of processing and interpreting electrical signals collected from a number of neutron flux detectors.

The technical problem solved by the invention consists in identifying the frequencies of the oscillations of an inaccessible segment of pipe that executes the vibrational movements induced and maintained by the turbulent flow of a fluid, by processing and interpreting the electrical signals collected from two absolute pressure transducers.

The problem is solved by a process whereby, with the help of electronic computing equipment, the spectral power densities of the electrical signals simultaneously collected from two absolute pressure transducers mounted as close to the upstream ends are calculated and compared. and downstream of the inaccessible segment of pipe through which a fluid is circulated in a turbulent flow regime.

The method, according to the invention, has the advantage that it does not involve radiative phenomena, and can be applied in any conjuncture that requires the identification of the frequencies of oscillations of a pipe segment that executes vibrational movements induced and maintained by the turbulent flow of a fluid, as an alternative method in situations of impossibility of the use of specialized conventional transducers such as accelerometers, tensometric marks, etc.

in Figure no. 1 presents the scheme of principle and the minimum instrumentation necessary to identify the frequencies through the unconventional process that is the object of the invention.

The invention is further described in detail.

The turbulent flow of a fluid is characterized, at any point of the trajectory, by the existence around the average value of the absolute p-session of some variations having both a periodic component generated by the circulation pump and especially a random component presenting, in the absence of other constraints. preferential, a frequency structure of "white noise" type.

2-2 0 0 9 - 0 0 3 7 5 - 1 3 -05- 2009

The turbulent flow of a fluid through a pipe induces and maintains its vibrating movements by mechanical energy transfer, the fluid power transfer -> pipe being able to take place, for certain flow rates of the flow, even at the limit of the resonance phenomenon.

The qualitative and quantitative differences between the power spectral densities, calculated for absolute pressure values measured simultaneously at two points along the pipeline, reflect the change, upstream and downstream, of the content of the turbulence structure, first of all at the frequencies involved in the mechanical energy transfer. , highlighting them.

In view of the principle diagram shown in Figure no. 1, the object of the invention is the unconventional method of identifying the frequencies of oscillations of the inaccessible pipe segment 1, which executes the vibrational movements induced and maintained by the turbulent flow of the fluid 2, using electronic computing equipment. 3 for the acquisition and then calculation and comparison of the power spectral densities for the electrical signals collected simultaneously through the connecting cables 4 and 5 from the output terminals of two absolute pressure transducers 6 and 7 connected through the isolating valves 8 and 9 to the lines of impulse 10 and 11 and pressure sockets 12 and 13 mounted in accessible areas of the pipe 14 and 15, as close to the upstream and downstream ends of the inaccessible pipeline segment 1.

Claims (1)

An unconventional method for identifying the frequencies of oscillations of an inaccessible segment of conduit that executes the vibrational movements induced and maintained by the turbulent flow of a fluid, characterized by the use of electronic computing equipment for the acquisition and then for the calculation and comparison of the power spectral densities for the signals. electrically collected simultaneously from the output terminals of two absolute pressure transducers connected as close as possible to the upstream and downstream ends of the inaccessible pipeline segment.