If you’re looking for illuminated fans without compromises that also deliver high cooling efficiency, the FD Momentum 12 RGB may be the right choice. These fans strike an excellent balance between visual appeal and performance. Their efficient geometry and exceptionally rigid blades are complemented by circular lighting. The Momentum 12 RGB fans are so far the only illuminated fans we’ve given the “Top-notch” award.
… and of airflow
With airflow measurements, we can well explain why the test tunnel is shaped the way it is. It doesn’t consist of two parts just so that the “exhaust” can be conveniently clogged for pressure measurements. The anemometer (i.e. the wind speed measuring instrument) is held together by two parts, two formations, through the flanges.
The front part, at the beginning of which the fan is mounted, becomes steadily narrower and from about two thirds of the way through the cross-section is smaller than that of a 120 mm fan. The reason for this is that the cross-section of the anemometer is always smaller than that of the fans tested. The taper towards the anemometer fan is as smooth as could be chosen and the tunnel walls are smooth. This has minimized the occurrence of unnatural turbulence.
The difference between the cross section at the intake (fan under test) and at the constriction point (anemometer) also means a difference in dynamic pressure, the principles of the Venturi effect apply here. In order to avoid distortion at this level and to ensure that the fan airflow is not different from what it actually is, the Bernoulli equation must be applied to the measured values (for maximum accuracy, the calculation also takes into account the internal cross-sectional area of the anemometer, i.e. its inactive part ). After all this, it is again possible to confront our results with the paper parameters.
We use an Extech AN300 anemometer with a large 100 mm fan for the measurements. Its big advantage over other anemometers is that it is made for bidirectional sensing. This allows tests at different fan orientations. However, the “pull” position is more suitable or accurate for measurements, even though it may not seem so at first glance, but we’ll explain.
Here, we get to the second part of the tunnel, the part behind the anemometer. It is part of the whole device, mainly to allow a laminar flow of air to arrive at the impeller of the anemometer. Otherwise, uncontrolled side whirls would be reflected in the results, which are inconsistent with accurate measurements. Therefore, we will test the flow in the pull position. If anyone would like us to elaborate more on this topic, we can elaborate further at any time in the discussion below the article. Ask away. 🙂
In regard to the anemometer, we shall return for a bit to noise measurements and to setting modes according to fixed noise levels. It may have occurred to you as you were reading that the anemometer fan is also a source of sound that needs to be filtered out when measuring fans. For this reason, we insert a securing pad between the frame and the anemometer fan before each measurement and mode setting according to the fixed noise level. This, by the way, also holds the anemometer fan during static pressure measurements.
The RGB variant, despite having a smaller rotor size to work with, outperforms the black variant the vast majority of the time. I suspect the RGB variant was designed first, which is then stretched outwards to form the black variant’s motor… If the 14 cm variants are designed the same way I suspect we’ll see relatively worse results.
Anyway, excellent job from Fractal.
In terms of unobstructed flow, they are similar, but with increasing resistance, the flow of the RGB variant increases. Ľubo and I thought, that the paradoxically shorter blades, which probably lead to higher RPM, probably contribute the most to this behavior. And secondarily, perhaps the less conical inner frame 🙂