It took years, but finally DeepCool managed to modernize its fans in the 140mm format as well. The DeepCool FT14s present themselves with very attractive specs – both the airflow and static pressure are above standard, but the key is how these fans will fare in practice compared to competing models. What makes the FT14 visually different from those at first glance is that you can see inside the motor.
Basis of the methodology, the wind tunnel
Before you start reading the methodology with all the details, take a look at the test tunnel as a whole. This is the heart of the whole system, to which other arteries are connected (manometer, vibrometer, powermeter, …). The only solid part of the tunnel from the measuring instruments is the anemometer.
The shape of the wind tunnel is inspired by the Venturi tube, which has long been used to measure the flow of liquids and gasses. The Venturi effect for wind speed measuring is also known from the aerospace industry. However, the design for measuring computer fans has its own specificities, which this proposal of ours reflects.
The individual parameters of the HWC wind tunnel for fan tests are the result of physical simulations and practical debugging. All the details (folds, material or finish used) have a rationale behind them and are designed this way for a specific reason. We will discuss the individual design details in turn in the description of the sub-variable measurements.
Now we will briefly elaborate on some things that do not fit thematically into the text of the following chapters. Namely, for example, that the skeleton of the wind tunnel is the work of a 3D printer (PLA). The rough print was, of course, then thoroughly machined by grinding, fusing, polishing and varnishing. Especially important is the smooth finish of the interior walls.
When joining the individual parts, the emphasis was on making sure that they fit together flawlessly, that they were sealed flawlessly (we will come back to this when we describe the test procedures for pressure measurement), but also that the joints were not loosened by use. Everything is disassemblable for servicing purposes, but it is ensured that the properties are maintained during use and, for example, even under the stress of vibration. The threads are secured with either lock nuts or thread-locking fluid. It depends on which is more suitable in which place.
When the wind tunnel is not in use, it is enclosed in a dust-tight chamber. In addition to the technical equipment and its correct storage, it is also important for objective outputs that all measuring instruments are calibrated according to the standard. Without this, it would be impossible to stand behind your results and rely on the manufacturers’ specifications. Calibration protocols are therefore an important part of the methodology. Testing is carried out at an ambient air temperature of 21–21.3 °C, humidity is approximately 45 % (± 2 %).
Fans come to us for testing in at least two pieces of the same model. If the deviations of any of the measured values are greater than 5 %, we also work with a third or fourth sample and the average value is formed by the results of the fans that came out the most similar and the differences between them fit under 5 %.
That’s unexpected results. I would have guessed it performs better on radiators than vs no obstacles, but it’s the opposite!
Is the buzzing noise only present under ~750 RPM, or is it there across the whole speed range? On higher dBA settings, I can still see some of the peaks at 1-2 Khz.
There will probably be some buzzing at higher speeds, but because of the diminishing contribution to the total, in contrast with the aerodynamic noise (which drowns out these sounds) it fades out alongside other, significantly noisier frequencies. The buzzing is, of course, more pronounced at lower speeds (like ~750 rpm), at the limit of minimum rpm. But we don’t have a spectrogram for those. 🙂
Noticeable buzzing noise is present till the 20% of PWM or ~660RPM, have three of those on a 45mm rad :/
I mean buzzing is starting from 20% of PWM and 660RPM, and after 800-900RPM buzzing noise doesn’t bother because airflow noise is louder.
Little correction 🙂
Thank you for sharing your user experience. Yes, the buzzing noise also occurs at higher speeds, and the question is to what extent it is disruptive at which speed compared to the aerodynamic noise. This can be evaluated differently by everyone, as it is subjective.