Choosing Low Noise Solutions
Final Thermal Design Concepts
Custom fans and value added assemblies are available from YS TECH. Full fabrication abilities off shore and domestically. From fully modified fans to connectors and fan trays we can help simplify your fan assemblies
Choosing a solution with Low Noise
The flow rate, static pressure and acoustic noise are always trade-off. It is very difficult to think over these factors at the same time. Further complications are caused by improper applications as well.
For example, fan mounted to chassis improperly may cause vibration and flow disturbance which leads to higher acoustic noise.
A proper system air impedance design Higher system air impedance needs a higher static pressure fan, but It accompanies with higher noise. Give an enough space to your critical parts and place them at flow path as possible. But It is at a tough work to get space for thermal solutions In a slim and light. However, we recommend you to measure you system air impedance and collect enough parameters to know your (triangle symbol) Pi. Normally, most specialized fan manufactures will support you to measure it by Air Chamber.
Choose a proper fan that is based on Qeff We have illustrated you a method to figure out a right fan for Qeff, and then you should consider about power consumption and acoustic noise. Which one is the first priority? To evaluate these two parameters under the same O base is Y.S. TECH’s recommendations.
Check the fit between proposed fan design and the application area. Vibration and Flow Disturbance always cause resonance and get higher acoustic noise. A proper fan mounting and flow field design may decrease acoustic noise. For example, mounting with a rubber cap on high-speed fan model will decrease vibration resonance. Review your design to make sure there is enough margin space (over 1.5mm) at flow in let /outlet side and no any stuff to disturb flow filed.
Advance fan speed control by your thermal profile. Thermal profile is similar to fan performance profile. Normally, different function will need to dissipate different power consumption. Then we can modulate fan rpm and ask fan working on a proper rpm by different system function. The most popular advanced fan speed controls are PWM control (Pulse Width Modulation), Thermostat control (NTC) and both of them.
Sound Quality Analysis In cooling fan industry, we are always focused on Sound Pressure only in the past but there is no longer sufficient to us because even though legal regulations have lead to a reduction of noise limits, the tendency of people to feel disturbed by noise is increasing. A sole reduction of noise levels is thus not sufficient to reduce the annoyance due to noise to a degree noticeable by human beings. This is due to the fact that the subjective human aural perception is often disregarded. However, the judgment of a sound event involves a wide range of different parameters forming into the total hearing impression. So we are not only concern about sound pressure but also [Sound Quality].
The examination methods are based on the idea of correct recording and describing the noise exposure from the acoustic environment in a way that reflects what humans subjectively perceive. In order to record this entire perception, physical aspects as well as psycho acoustic characteristics of hearing and cognitive aspects must be considered. The main focus of psycho acoustics is the subjective aural perception by human beings. The goal is objectively describing this subjective perception. Psycho acoustic measuring methods account for the actual hearing impression. as opposed to conventional measuring methods that only record the sound level in the form of the equivalent continuous sound level. Y.S.TECH introduced the [Sound Quality Analysis System] of HEAD ACOUSTIC in German. Those include an Artificial Head and analysis tool and also the most popular measuring and analysis system in automotive industry. Its parameters are include [SPL, sound pressure level], [Tonality], [Sone] and [Modulation]. The measuring method and standards are as below:
- ANECHOIC Room Noise Measurement System.
- Digital Head Measurement System, 16-bits version.
- SQ lab Ill, Mobile Multi-channel Analysis System.
- Specifications: ISO 3744, ISO 3745, ISO 7779, CNS 6753, JIS 8346
- Background Noise: < 17 dB(A)