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Environmental Analysis
Published in Connie Kelly Tang, Lei Zhang, Principles and Practices of Transportation Planning and Engineering, 2021
Sound power is the amount of energy per unit of time that is emitted from a source in the form of sound waves. Linking sound power and sound pressure is critical in building modeling tools to predict noise levels under various conditions.
Sound Levels
Published in Fang Zhu, Baitun Yang, Power Transformer Design Practices, 2021
Sound power is the rate at which energy is radiated (energy per unit time). Sound intensity is the rate of energy at a point, that is, through a unit area. Sound intensity is a vector quantity. Sound pressure is a scalar equivalent quantity having only magnitude. Normal microphones are capable only of measuring sound pressure, this is sufficient for majority of transformer sound measurement situations.
Combustion Turbine Acoustics and Noise Control
Published in Tony Giampaolo, Gas Turbine Handbook: Principles and Practice, 2020
Sound power can only be calculated from a set of sound pressure level measurements where a microphone measures the sound pressure over a given area that completely envelops the equipment being measured. For instance, a piece of equipment setting on the ground, measures 1m × 1m × 1m (5 square meters exposed surface area) but measuring the sound pressure level on a rectangular grid one meter away results in an area of 33 square meters. If the area averaged adjusted sound pressure level is 85 dB, then the sound power is: () Lω=Lp+10LOG(Area)=85+10LOG(33)=100dB
Assessment of cavitation noise in a centrifugal pump using acoustic finite element method and spherical cavity radiation theory
Published in Engineering Applications of Computational Fluid Mechanics, 2023
Qiaorui Si, Asad Ali, Minquan Liao, Jianping Yuan, Yuanyuan Gu, Shouqi Yuan, Gerard Bois
Sound power is the total energy of sound radiated by a sound source into space per unit of time, in units of W. In 1952, (Proudman & Taylor, 1952) proposed a formula for calculating sound power based on theoretical analysis. However, there was a problem with the delay time difference in the derivation process. Therefore, (Lilley, 1994) solved the issue of the delay time difference in 1993 and derived a new equation for sound power with the following expressions: where α is a constant, generally takes the value of 0.1, while c denotes the speed of sound in water, valued about 1500 m/s; l denotes the turbulence scale; and u indicates the turbulence velocity, and the expression is as follows: where k denotes the turbulence energy of the fluid. Thereby, Equation (15) can be expressed as: where , and the formula for calculating the sound power level is: where Wref represents the reference sound power, taking the value of 10−12 W/m3.
Tapboost - the design for manufacture of a low voltage water pump to boost the poor domestic water flow rate
Published in Australian Journal of Mechanical Engineering, 2023
Determination of sound power levels and sound energy levels of noise sources using sound pressure. Engineering methods for an essentially free field over a reflecting plane. Testing was carried out in a semi-anechoic chamber. This is a room where sound reflections only come from the floor because the walls and ceiling are absorbent (University of Salford 2022). The pump was set up in a semi-anechoic chamber with 10 microphones in fixed positions over a hemispherical surface to meet the requirements of BS EN ISO3744: 2010. The acoustic laboratory provides two types of sound measurement over a 30-s testing period. Over the 10 microphones, the average A-weighted sound power level is recorded and the sound pressure level from a 1 m distance is recorded. The difference between the two values is that the sound power level picks up the noise generated from the pump at its centre. The measurement, which is useful to the end consumer, is the sound pressure level which looks at the sound generated by the pump from a 1 m distance. This also considers any background noise in the chamber. Measurements were taken over a range of boosted flow rates to observe how the sound pressure level, measured in dBA, changes as the pump is boosting more water (Table 1).
Acoustic behaviour of textile structures
Published in Textile Progress, 2021
Parikshit Paul, Rajesh Mishra, B. K. Behera
Sound power is the sound energy being emitted by a source each cycle. The energy, which is the mechanical work done by a wave, is the force moving through a distance: where root-mean-square acoustic pressure, area, power rate of energy flow