|
|
Determination of sound power level of transmission
Švanigová, Lenka ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
The field of vibrations and associated noises is a very current topic. Noise can be measured with different equipment and the gained data might be compared using different methods, which are in accordance with defined norms. This bachelor thesis deals with the CSN EN ISO 9614 norm, especially its first part which focuses on the method of measuring in points. To apply this method to measure the transmission, basic terminology and formulas used to determine the individual indicators were described in detail. The whole procedure was applied to two industrial transmission units with different parameters and transmitted power. The total sound power on these sources was determined as well as the sound power levels for the individual measured sides, even without using the A-filter, which is the most commonly used filter in transmissions. Lastly, acoustic maps were created. These maps make it possible to discover locations which dominantly contribute to the total sound power level.
|
|
|
Noise study of heat pump
Gregorovičová, Eva ; Hejčík, Jiří (referee) ; Jedelský, Jan (advisor)
The thesis deals with a noise study of a heat pump, which is important for the assessment of the acoustic comfort of people. The thesis describes the theory of basic terms, quantities, measuring devices and the chosen method of determining sound power. The acoustic properties and technical condition of the measured heat pump, its possible noise sources and the possibilities of reducing their emissions are also described. The total noise level of the device is determined by the intensity probe according to the scanning method according to ČSN ISO 9614-2. Based on the acoustic map and frequency spectrum, the partial noise sources of the heat pump are identified. The resulting values from the measurements are compared with the manufacturer's values. The noise situation is assessed by measuring and comparing the measured values with the hygienic limits. Furthermore, the designs of the noise protection measures are assessed, and the design of the noise protection measures for the specific case is carried out. Finally, possible noise protection measures are implemented and experimentally verified. The results confirm the need for further development of heat pumps to reduce noise emissions.
|
|
|
Acoustic Holography
Vacula, Jan ; Janoušek, Michal (referee) ; Prokop, Aleš (advisor)
This bachelor´s thesis is focused on description and process during contactless identification of sound source for near and far field. Principles of individual methods of acoustic holography are relatively shortly described and for details of this problem (on the level of algorithm of software equipment) you can see the references below thesis, which were the basic theory of my study. The introduction was conceived like description of “acoustics world”. You can find the basic information and principles about sound propagation in space and their mathematical contain at time. For this it was essential to define quantity and their units. Subsequently there is inventory of used sensors and their own construction for this measurement. Next chapter point to some techniques of acoustic holography used in practice. It includes mainly a method NAH (Nearfield Acoustical Holography) and SONAH (Statistically Optimised Nearfield Acoustical Holography) used for near-field. For reconstruction of far-field is shown principle of a method of Beamforming and manual measurement by intensity probe. The ending is focused on a concrete application these methods on combustion engines of cars.
|
|
| |
|
|
Noise study of heat pump
Gregorovičová, Eva ; Hejčík, Jiří (referee) ; Jedelský, Jan (advisor)
The thesis deals with a noise study of a heat pump, which is important for the assessment of the acoustic comfort of people. The thesis describes the theory of basic terms, quantities, measuring devices and the chosen method of determining sound power. The acoustic properties and technical condition of the measured heat pump, its possible noise sources and the possibilities of reducing their emissions are also described. The total noise level of the device is determined by the intensity probe according to the scanning method according to ČSN ISO 9614-2. Based on the acoustic map and frequency spectrum, the partial noise sources of the heat pump are identified. The resulting values from the measurements are compared with the manufacturer's values. The noise situation is assessed by measuring and comparing the measured values with the hygienic limits. Furthermore, the designs of the noise protection measures are assessed, and the design of the noise protection measures for the specific case is carried out. Finally, possible noise protection measures are implemented and experimentally verified. The results confirm the need for further development of heat pumps to reduce noise emissions.
|
|
|
Determination of sound power level of transmission
Švanigová, Lenka ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
The field of vibrations and associated noises is a very current topic. Noise can be measured with different equipment and the gained data might be compared using different methods, which are in accordance with defined norms. This bachelor thesis deals with the CSN EN ISO 9614 norm, especially its first part which focuses on the method of measuring in points. To apply this method to measure the transmission, basic terminology and formulas used to determine the individual indicators were described in detail. The whole procedure was applied to two industrial transmission units with different parameters and transmitted power. The total sound power on these sources was determined as well as the sound power levels for the individual measured sides, even without using the A-filter, which is the most commonly used filter in transmissions. Lastly, acoustic maps were created. These maps make it possible to discover locations which dominantly contribute to the total sound power level.
|
|
|
Determination of sound power levels of heating equipment by measurement of the acoustic intensity
Wagnerová, Klára ; Doložílek, Miroslav (referee) ; Jedelský, Jan (advisor)
This thesis concerns method of determining sound power level of heating devices from acoustic intensity as a primary measured value. Thesis describes the characteristics of acoustic parameters and principles of acoustic measuring. Method of measurement at discret points according to ČSN EN ISO 9614-1 is compared with measurement by scanning according to ČSN ISO 9614-2. Methods are evaluated teoreticly as well as practically by companing results of experimental testing. Thesis also includes description of created model which evaluates acoustic measurement acording to the definitionof point method. The model is designed for measuring chain of Engineering Test Institute, Public Enterprise (SZU).
|
|
| |
|
|
Acoustic Holography
Vacula, Jan ; Janoušek, Michal (referee) ; Prokop, Aleš (advisor)
This bachelor´s thesis is focused on description and process during contactless identification of sound source for near and far field. Principles of individual methods of acoustic holography are relatively shortly described and for details of this problem (on the level of algorithm of software equipment) you can see the references below thesis, which were the basic theory of my study. The introduction was conceived like description of “acoustics world”. You can find the basic information and principles about sound propagation in space and their mathematical contain at time. For this it was essential to define quantity and their units. Subsequently there is inventory of used sensors and their own construction for this measurement. Next chapter point to some techniques of acoustic holography used in practice. It includes mainly a method NAH (Nearfield Acoustical Holography) and SONAH (Statistically Optimised Nearfield Acoustical Holography) used for near-field. For reconstruction of far-field is shown principle of a method of Beamforming and manual measurement by intensity probe. The ending is focused on a concrete application these methods on combustion engines of cars.
|
guest ::
