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Projects / Programmes source: ARIS

Evaluation and characterization of noise sources

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Research activity

Code Science Field Subfield
2.03.03  Engineering sciences and technologies  Energy engineering  Renewable resources and technologies 

Code Science Field
T210  Technological sciences  Mechanical engineering, hydraulics, vacuum technology, vibration and acoustic engineering 
T200  Technological sciences  Thermal engineering, applied thermodynamics 
Keywords
NOISE, MACHINERY, FANS, PUMPS, NOISE SOURCES, NOISE GENERATING MECHANISMS, SPECTRAL ANALYZES, EVALUATION, CHARACTERIZATION, NOISE REDUCTION
Evaluation (rules)
source: COBISS
Evaluation of bibliographic research performance indicators according to ARIS methodology
Citations Citations for bibliographic records in COBIB.SI that are linked to records in citation databases
source: WoS source: Scopus source: COBISS
Researchers (3)
no. Code Name and surname Research area Role Period No. of publications
1.  03569  PhD Mirko Čudina  Energy engineering  Head  1998 - 1999  764 
2.  18228  Milan Steržaj    Researcher  1998 - 1999  73 
3.  07682  MSc Erika Želežič  Energy engineering  Researcher  1998 - 1999  42 
Organisations (1)
no. Code Research organisation City Registration number No. of publications
1.  0782  University of Ljubljana, Faculty of Mechanical Engineering  Ljubljana  1627031  29,205 
Abstract
In fans, pumps and compressors (forward fans) there are two mechanisms that generate the overall noise: the rotational and non-rotational one. Rotational noise is mainly a consequence of the fluctuating forces on the rotor blades and is provoked by the interaction of the rotor blades with the inflow distortion, unsteady flow, turbulence, and nearby stationary objects (guide vanes, protecting grid, struts or fan drive belt). On the other hands non-rotational noise is caused by: a) laminar boundary layer vortex shedding, b) blade interaction with the tip clearance vortex and c) blade stall. A great number of investigations that have been made, led to a wide variety of algorithms. But none of the models do satisfy the entire spectra of the fan types or operating conditions. The well-known analytical or numerical models neglected one or more physical effects affecting the noise generating mechanism so that the calculated results agree with the measured results poorly or well in only a narrow range of operating conditions (mostly in the vicinity of the best efficiency point). In practice the operation point of the fan is often not stable and at the best efficiency point, it depends on many factors and can move within a wide range of flow rate - extremely from zero flow rate to free delivery. Within the entire flow rate, the fan can operate at the critical point, called surge point, and also left from the surge point where the unstable pressure-flowrate characteristic occurs. In unstable operating region, there appears also a steep increase of the sound power level. Therefore, the analytical model describing the sound power level of the fan must contain all the noise generating mechanism within the whole range operating conditions.
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