FlowGrid for Axial and Centrifugal Fans Less noise better quality of life. The engineers choiceNoise disturbances Cause and solution Situation Excess noise is the result of the inflow of air to a fan being disturbed. Asymmetrical inlet conditions, such as the walls of a device being at different distances from the fan, create powerful vortices. In the narrowest areas, these combine to form vortex strings. These Innovating for people turbulences then hit the rotating blades of the fan, generating noise specifically a broadband noise and additional narrowband, tonal frequency components, known as propeller noise or tonal noise. FlowGrid stands for ... Formation of air vortices due to an asymmetrical intake area. efficient noise reduction features in cooling, ventilation and air -conditioning technology. Noise spectrum Blade-passing noise ebm-papst offers a future-oriented solution for The tonal noise consists of the blade-passing noise and its the problem of high-performance technology harmonics. The frequency of the blade-passing noise can be generating disturbing noise: FlowGrid for axial Harmonic calculated based on the fan speed and the number of blades. The and centrifugal fans. The grill on the air inlet side harmonics of the blade-passing noise are integer multiples of it. An drastically reduces the noise emissions and minimizes Harmonic axial fan with five blades and 1,200 rpm, for example, would result Harmonic disturbing low frequency tones. in a blade-passing noise with a frequency of 100 Hz. The respective Harmonic Harmonic frequency of the blade-passing noise and its harmonics result in high elevations in the sound pressure level, especially in the low- There are often problems wherever people and technology share space. frequency range. It is exactly this level where it is particularly difficult The movement of air, for example, often goes hand in hand with noise. With to reduce noise. Passive noise-reduction measures often mean large FlowGrid, noise-generating disturbances in the fan inflow are a thing of the past 100 200 300 400 500 600 space requirements and high costs. Frequency f Hz The noise spectrum is characterized by narrowband, tonal frequency components tonal noise. Solution FlowGrid, the grill on the air intake side, drastically reduces the noise-generating disturbances. The vortex strings are split when hitting the grille and considerably weakened as they flow through it. This reduces the sound pressure in the entire frequency range, but particularly the disturbing low frequency tonal range. The result is a considerably lower sound pressure level and a noise which is less disturbing. This means that noise regulations can be complied with more easily and the well-being of people in the direct vicinity is not affected. A clear improvement: FlowGrid reduces the sound pressure level and considerably Whether its heat pumps in the garden, supermarket condensers or ventilation systems on an industrial property: FlowGrid, the innovative air inlet weakens tonal noise. grill from ebm-papst, uses technical expertise to provide drastic noise reduction. 3 2 Sound pressure level L dB p