Calculation and experimental verification of noise attenuation of the noise hood
Authors: RNDr. B. Madejewski,CSc., Ing. V. Kotrba, CSc.
The article describes the design, calculation and test results noise attenuation of the noise hood for large industrial compressors driven by electric motors. Predicted noise attenuation (software UTLUM) has been validated by practical measurements at the customer's place.
Introduction
On the basis of the requirement of the customer there was designed and produced a noise hood for two compressor units being installed in the production shop of the firm LONZA a.s., Kouřim. Initial parameters of the task were basic dimensions of the covered equipment, necessary cross-sections of inlet and outlet of cooling air and total required noise attenuation of the noise hood.
Design of the noise hood
The noise hood was designed on the basis of preceding experience acquired in realization of noise hoods and utilization of the program ÚTLUM that, in the design stage, enables a range of variants to be assessed. The final realization of the noise hood was then made for the structure of its wall consisting of:
- steel sheet
- acoustic barrier
- absorption layer
In the calculation there were taken into consideration inlet and outlet openings of the hood, attenuation in inlet and outlet channels and deflection of cooling air flow in these channels. Under these conditions the calculation determined noise attenuation of the noise hood being designed in compliance with omnidirectional incidence of sonic waves inside the hood in individual octave frequency bands.
…
It means therefore that noise attenuation of the designed and realized noise hood reaches 16,7 dB.
Conclusion
The measurement of sound level LA in the chosen reference measuring points in the production shop of LONZA a.s., Kouřim, where there were installed two designed noise hoods of compressor units, confirmed that they comply with the guaranteed noise attenuation according to the performed design and calculation.
(taken from Center of environmental hygiene of State Health Institute Prague)
Noise is every unwanted sound that is disturbing or troublesome or that affects adversely human health. Negative effects of noise on human health are partly specific ones, presented by disorders of the function of acoustic analyzer, partly non-specific ones (extra hearing), when functions of various systems of the organism are affected. These non-specific system effects appear almost in the whole range of noise intensities, frequently they are accompanied by stress reaction and impact on neurohumoral a neurovegetative regulation, biochemical reactions, sleep, higher nervous functions, such as learning and memory, impact on sensory motoric functions and coordination.
…(more…)Authors:
RNDr. B. Madejewski,CSc., Ing. V. Kotrba, CSc.
The article describes the design, calculation and test results noise attenuation of the noise hood for large industrial compressors driven by electric motors. Predicted noise attenuation (software UTLUM) has been validated by practical measurements at the customer¢s place.
...(more…)