Type of research: applied Duration from: 04/01/92. Papers on project (total): 8
Papers on project quoted in Current Contents: 1
Institution name: Brodarski institut, Zagreb (192) Department/Institute: Special Technology Department Address: Av. V. Holjevca 20 City: 10000 - Zagreb, Croatia
Communication
E-mail: bajic@irs.hrbi.hr
Fax: 385 (0)1 6550-947
Phone: 385 (0)1 6551-022
Summary: For a class of rotating sources of airborn or
hydroacoustical noise, important in various applications, the
possibilities of space-time signal processing methods have been
investigated. The final aim to develop measurement methods which will
furnish the estimates of a free-field source signature, extracting it
from input signals corrupted by disturbances and reflections, while
providing selectivity in the analysis of source spatial distribution. The
classification of the methods has been founded by theoretical means,
numerical simulation and experiments. The dependence of the gain in
signal-to-noise ratio and efficiency of the free-field extraction and
spatial resolution on the algorithm's parameters, have been established.
The effects of signal degradation due to random inhomogeneities of a
medium have been investigated, as well as the problems of implementation
of the methods. The procedure for the measurement system optimisation has
been founded. The methods have been applied to the case of screw
propeller cavitation noise and cavitation erosion in hydro-turbines.
Keywords: noise, acoustical source, rotating source, space-time signal processing, correlation methods, signal decorrelation, random inhomogeneities, polarity-coincidence correlation, relay correlation, cavitation, erosion, turbine
Research goals: 1.To evaluate the classification scheme of
space-time signal processing methods which extract the free field of a
rotating acoustical source from reflections and correlated and
uncorrelated disturbances, providing spatial resolution of a contribution
arising from various parts of a source. 2.To establish the methods for
evaluation of a detailed description of the source parameters: total
averaged source strength, source strength as a function of a source
angular position, dependence of the spatial distribution of the averaged
source strength volume density on the source angular position, or the same
function averaged over the angular position of the source. 3.To
investigate the mechanisms of reflection reduction, and for the chosen
methods, develop the ways for their optimisation. 4.To investigate the
problems of implementation of these methods. 5.To investigate the effects
of signal degradation caused by random inhomogeneities in a medium. 6.To
develop a measuring system realizing the chosen methods. 7.Experimental
verification of the measuring system in real conditions. 8.To apply the
results to the propeller cavitation and cavitation in a hydro-turbine.
COOPERATION - PROJECTS
Name of project
: 1 KRO ENG1 Acoustical Diagnosis of Cavitation Name of institution: Oskar-von-Miller-Institut, Technische
Universitaet Muenchen City: D-82432 - Obernach/Walchensee, Njemačka
COOPERATION - INSTITUTIONS
Name of institution
: Oskar-von-Miller-Institut, Technische
Universitaet Muenchen Type of institution: University/Faculty Type of cooperation: Joint project City: D-82432 - Obernach/Walchensee, Njemačka Other information about the project.