… and airflow
The first and still the only Asus fan that is on sale individually may be a good choice. But you can also get burnt. It depends on what you want to use it for. In the right context, it gives attractive results, and the impression of a very decent fan is spoiled mainly by pointless design details or sugar-coating the specs. Anyway, you can see that compared to the more ordinary fans from the last test, the Strix is a bit of a different class.
… and airflow
PWith 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 rotor 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 connection with the anemometer, we will return a little more to the noise measurements and to the setting of 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 testing fans. For this reason, we insert a belay pad between the frame and the anemometer fan before each measurement and mode setting according to the fixed noise level. This, by the way, holds the anemometer fan also during static pressure measurements.
- Contents
- Analysis of the SilverStone aerodynamic grille
- The basis of the methodology, the wind tunnel
- Static pressure measurement…
- … and airflow
- Results: Airflow w/o obstacles
- Results: Static pressure w/o obstacles
- Results: Frequency response of sound w/o obstacles
- Conclusion
