Papers by Cristea Lucian Laurentiu
Aerospace, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Engineering, Technology & Applied Science Research, 2024
The purpose of this work is to reduce the noise generated by a compressor that conveys methane ga... more The purpose of this work is to reduce the noise generated by a compressor that conveys methane gas. After certain measurements were conducted a high level of noise was observed in the 2000-3000 Hz range, therefore a solution for noise reduction at the source is addressed and presented in this paper. The research method is based on designing resonators to be applied on the stator of a centrifugal compressor used in a natural gas distribution station. First, the calculations are made on resonators with air as the working fluid and then are validated through real measurements in a Kundt tube. After validation, the working fluid is changed with gas, calculations are made once again, and acoustic simulations are performed. To facilitate acoustic simulations and reduce computational time, a simplified stator geometry was employed. This simplified model encompassed the region starting from the rotor's gas exit, where the resonators were deployed. The purpose of the acoustic simulation was to validate the frequency range influenced by the resonators and to estimate the overall noise reduction. Depending on the operating regime of the compressor, the rotor fundamental can vary within the frequency domain of 2000-3000 Hz. This broadband domain requires the usage of several resonators with different resonant frequencies. The proposed solution obtained an average value of attenuation, excluding the peaks of the attenuation, in the frequency domain of 2000-3000 Hz, of 9 dBA. If the fundamental frequency coincides with a resonance of the resonator, higher attenuation can occur. Also, fundamental attenuation can lead to attenuation of the harmonics.
Applied Science, 2024
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
An active noise control system is designed with the scope of minimization of sound pressure level... more An active noise control system is designed with the scope of minimization of sound pressure level in a certain point or domain, or to control or modify different acoustic parameters in the case of psychoacoustic active control. In enclosed spaces, like cars or aircrafts cabins, the noise could be controlled by reducing the vibration of thin plates which are the main elements of the exterior structural domain of an acoustic cavity. Thin plates are widely used in industry and building construction and the vibration of these thin plates constitute the main way of transmission of noise to or from a cavity. There are situation where the radiated level could be reduced or in other situations the level is increased by plate own resonance. By controlling the vibrations of plates, which constitute a cavity, it is aimed to control the acoustic response of the acoustic space inside the cavity. Better results could be obtained by optimization of structure response of these plates during the simulation of an acoustic event. Size, shape and topological optimization are used for improving the physical properties of structures or to reduce the manufacturing costs. Acoustic or psycho-acoustic response of structure vibrations could be parameters to control the optimization algorithms in designing the plates or adopting the concepts used in active noise control.
An active acoustic control in the case of closed spaces is generally projected to minimize the ac... more An active acoustic control in the case of closed spaces is generally projected to minimize the acoustic energy inside the enclosed space. This article discusses the principles of changing acoustic response of excited enclosures with a psychoacoustic approach, in an interactive manner (IANC). In general the system uses two criteria to reduce energy, active noise reducing of acoustic energy inside the enclosure or reducing psychoacoustic loudness.
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Papers by Cristea Lucian Laurentiu