The video features Jacob Dallinger from Noctua explaining the intricate balance in fan blade angle design, blade count, and heat sink fin density to optimize airflow, static pressure, and noise in computer cooling fans. He highlights the challenges and trade-offs in achieving peak fan performance, sharing insights from Noctua’s recent developments and emphasizing that future breakthroughs will require fundamentally new design innovations.
The video features an in-depth discussion with Jacob Dallinger from Noctua, a company renowned for its high-quality computer fans, focusing on the engineering nuances of fan blade angles and overall fan design. Jacob explains the distinction between blade angle (or stagger angle), which is the mechanical angle between the plane of rotation and the chord line of the blade, and angle of attack, which is the angle between the chord line and the relative airflow. He highlights how the blade angle typically varies along the blade length, being steeper near the hub and flatter towards the tip, to accommodate the differing blade velocities and maintain optimal airflow.
A key point in the discussion is the trade-off involved in selecting blade angles. Steeper blade angles drive more airflow per rotation but increase the risk of stall and flow separation, which causes turbulence, noise, and reduced fan efficiency. Conversely, flatter blade angles improve the fan’s ability to push air through resistance, such as densely packed heat sink fins, making them more suitable for high static pressure applications. Jacob notes that even a one-degree change in blade angle can significantly affect fan performance, emphasizing the precision required in initial fan design stages.
The number of blades also plays a critical role in fan performance and acoustics. Noctua typically uses seven, nine, or eleven blades in their designs, with nine blades often being the sweet spot for balancing static pressure performance and noise. Increasing blade count can lead to mechanical constraints, higher blade passing frequency (which contributes to noise), and blade interaction issues. On the other hand, fewer blades require larger blade surface areas and flatter angles, which can limit performance. Jacob discusses how blade passing frequency directly impacts noise and how engineers strive to minimize it while maintaining performance.
The conversation also touches on heat sink design and its interaction with fans. While fans prefer fewer fins to reduce airflow resistance, heat sinks benefit from densely packed fins to maximize surface area and heat transfer. The challenge lies in balancing fin density and spacing to avoid excessive airflow resistance that could cause fan stall and noise. Jacob explains that turbulence generated by airflow around fins can negatively affect noise and performance, but some turbulence can be beneficial, such as in Noctua’s G2 fans where specific structures on the hub improve airflow attachment and efficiency.
Towards the end, Jacob shares insights from Noctua’s recent G2 fan development, highlighting that many experimental designs did not yield improvements but provided valuable lessons for future projects. He suggests that significant performance breakthroughs will likely require fundamentally new design approaches, possibly years away. The video concludes with an invitation to explore more technical discussions on cooling design, emphasizing the complexity and continuous innovation involved in creating the perfect computer cooling fan.