Reverse Jet Flow on Fans: Does it Improve Performance?

Today, any technology that reaches the market does so with great fanfare. Technological marketing is sometimes above the marketing of the product itself, not for nothing have we seen presentations where the news that X includes is given more importance than the product itself and its performance. Reverse Jet Flow technology is little known in theory and more in practice, so is it marketing or does it really work?

It is more than likely that you have no idea what we mean when we talk about Reverse Jet Flow, but do not worry, because we are going to explain it simply and briefly to delve into that world of fans and heatsinks, their performance and With this, we are going to try to explain the reasons for the industry in excluding it in certain models of heatsinks.

Reverse Jet Flow on Fans

Reverse Jet Flow, taking push-pull to the next level

Push-Pull

Let’s start with the basic and brief, but at the same time necessary, what is Reverse Jet Flow technology? It is a system that each brand tends to call differently and that is nothing more than the inclusion of two push-pull fans where the second rotates its blades in the opposite direction to the first.

Actually, the term was born many years ago and it does not necessarily have to have a push-pull under its belt (although it is the most indicated), since this system was taken from jet engines of combat aircraft (it is not exactly extrapolated ), to the fan flow industry and then to GPU heatsinks without having two fans pushing air at the same point, which makes sense on a graphics card.

Reverse-Jet-Flow

In graphics, the system works in a simpler way and needs at least two fans, where each one rotates in the opposite direction to its brother. If there are three, normally the middle one turns in the opposite direction to the two extremes.

With this explained, let’s go back to the Reverse Jet Flow where it is most incident, in the heatsinks.

What is the concept of operation?

Reverse-Jet-Flow-Scythe

Reverse Jet Flow is based on the so-called Reverse Function of industrial fans, and it is nothing more than changing the direction of the blades to move the air, on the contrary. The technique applied to PC fans in the heatsinks goes one step further by including two fans.

Why make them turn the other way? When we have two fans in Push-pull without restriction in the middle, a vortex is generated that cuts off the natural flow of air that is sent from the first fan, generates more noise and vibrations in the motors.

Following the same example, placing the second fan rotating against the first one breaks this vortex and allows the suction of air through the blades to be simpler and more direct, at a higher speed, thereby improving flow and static pressure. This is more than proven and anyone with an axial digital anemometer can measure it at home, or even it is not necessary, because in many highway tunnels you can see those gigantic fans where they achieve this effect despite the great distance in which they are find.

Do you gain pressure or flow or is it marketing?

Scythe-Fuma

What is the problem then about marketing? Doubts come when a restriction is incorporated between fans, in this case the body of the heatsink. In this case we have an air flow that impacts with the fins and causes said air to pass through a laminar space, so that once it exceeds its restriction it finds the next fan turning in the opposite direction.

Is performance gained? The answer is “it depends”. And the key is in the laminar flow that reaches that second fan that turns backwards. How the fins break the air in its inlet and subsequent channeling will be crucial to choose to perform this Reverse Jet Flow and gain performance with it.

Scythe-Fuma-2

The problem is that most manufacturers choose not to optimize the fins to the extreme and prefer to take the simpler route: fins that break sound wavelengths and highly optimized high static pressure fans at high RPM. In fact, most heatsinks today are built with the fans included and optimizing both as a system.

It is not surprising that changing the fans to a heatsink causes a loss of performance to this, especially if the cooler has been designed with a Reverse Jet Flow system. Therefore, this system is not marketing, but requires the heatsink as a whole to be optimized with the fans for best results.