Acoustic Analysis of an Automobile Horn
Objective: D65 is a type of horn of Diameter 65mm and mainly consists of a resonator and a
diaphragm which are separated by an air column which is responsible for the
functioning of the horn. The resonator of the horn is 0.6mm in thickness and
attached to the diaphragm with the help of a washer. The resonator consists of
three humps in its design. The functioning will be best when the frequency of
the air gap and resonator match or are almost equal and this is analyzed by
various FEM methods.
Methodology and Analysis: By using FEM we can easily find out the frequency of the
resonator but the frequency of the air column is a fluid-solid interaction(FSI)
problem. Advanced FEM algorithm was used for the air column frequency and then
by iterative method the frequency of both were matched . From the analysis
done, some factors which can improve the design are modifying the
dimension of the washer between
resonator and diaphragm, like 0.5, 0.8, 1.0 etc and modification in the
thickness of the resonator. Analysis is done
by using different thickness of the resonator for different dimension of
the washer. Few of the results are shown in the image.
Result and Conclusion: From various analysis done it can be concluded that the dB and quality
of sound depends on the natural frequency of the air column and natural
frequency of the resonator. Smaller the gap the better will be the quality of sound in the
particular range. Since 0.6mm is the actual thickness of the resonator which
upon analysis was modified to 0.4mm so that the air column volume was increased
and hence the quality of sound improved. After
changing the thickness and the profile the output is found to be good
i.e. 0.4mm thickness and base is up from second hump and outer side by
0.8mm. Hence the resonator design was
optimized to produce maximum sound with
high quality.
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