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Master's Thesis
Author of thesis: Ing. Jan Bernard
Acad. year: 2018/2019
Supervisor: prof. Ing. Jan Jedelský, Ph.D.
Reviewer: doc. RNDr. Miroslav Doložílek, CSc.
This diploma thesis deals with comparing noise levels of three side vents of different constructions, which are used for distribution and directing of ventilation air in a cabin of an automobile. The fundamental knowledge of the physical and physiological acoustics is described in the introduction part of this study. Following the introduction part there is a brief explanation of the car air conditioning system (HVAC system) as well as are explained the acoustic properties of specific elements of this system. The study also deals with dividing ventilation vents and describes the vast traceable types of automobile vents. Prior to the description of the experiment, which was conducted as a part of this study, the procedures and results of the measurements carried out in other theses are explained. Measurement of noise levels of the compared vents was carried out in a semi-anechoic chamber under the ČSN ISO 3475 standardization. To clarify increase of noise generated by the vent in an interior of an automobile, additional measurement of noise was carried out in a cabin of Porsche Cayenne 2018. From the gathered results we can conclude that under the constant flow, (of 60 square meters per hour) louder vents are those with higher pressure loss. This pressure loss is dependant primarily on the speed of the flow in the vent, as well as on the number and the adjustment of the deflectors. In a cabin of an automobile, the noise produced by the vent is negligible in comparison with total noise in an interior of a car. However, in the area surrounding the air flowing out from the vent, (approximately 0,7 meters from it) the level of acoustic pressure increases significantly.
vents, noise, sound power level A, sound pressure level A, loudness, car cabin, Porsche, system HVAC
Date of defence
11.06.2019
Result of the defence
Defended (thesis was successfully defended)
Grading
A
Process of defence
Zodpovězeny dotazy oponenta. Doc. Katolický položil dotaz, proč nebyla použita metoda měření parametrů s umístěním výustek na podlaze? Doc. Katolický se dotázal na vliv akustického tlumiče, umístěného uvnitř komory a zda by nebylo lepší jej umístit vně komory? Doc. Katolický se zeptal, proč nebyla polobezdozvuková komora použita k měření již od počátku? Prof. Pavelek se dotázal jestli diplomant provedl teoretický rozbor nejistot měření před začátkem měření? Doktor Fišer se dotázal jaké by byly výsledky měření hluku v automobilu v případě, že by se nejednalo o automobil se spalovacím motorem, ale elektromotorem. Prof. Jícha se dotázal na význam jednotky "Son". Student odpověděl na všechny dotazy.
Language of thesis
Czech
Faculty
Fakulta strojního inženýrství
Department
Energy Institute
Study programme
Mechanical Engineering (M2I-P)
Field of study
Environmental Engineering (M-TEP)
Composition of Committee
doc. Ing. Jaroslav Katolický, Ph.D. (předseda) prof. Ing. Miroslav Jícha, CSc. (místopředseda) prof. Ing. František Kavička, CSc. (člen) prof. Ing. Milan Pavelek, CSc. (člen) prof. Ing. Jan Jedelský, Ph.D. (člen) Ing. Stanislav Patočka, Ph.D. (člen) doc. Ing. Bc. Jan Fišer, Ph.D. (člen)
Supervisor’s reportprof. Ing. Jan Jedelský, Ph.D.
Grade proposed by supervisor: A
Reviewer’s reportdoc. RNDr. Miroslav Doložílek, CSc.
Grade proposed by reviewer: A