How do ducted fans work

Nowadays, plenty of different remote-controlled model aircrafts are propelled using ducted fans. Some of the most popular modern model aircrafts that are being used by different hobbyists nowadays are drones. When you notice how most drones are constructed, one of the things that you will first see right off the bat is that drones make use of propeller blades instead of ducted fans. And at this point, you already know how effective ducted fans are when propelling aircrafts and model planes.

Drones work at a low thrust level, and their engines need to be able to provide low-level static thrust all the time for the drones to maintain their flight. This makes the inefficiency of ducted fans apparent as they do not work very well at low thrust levels. Of course, you should also factor in how difficult it would be for you to make use of ducted fans on drones that are supposed to be light and easy to carry. The ducts themselves add weight to the drones, which would now require the propellers to work harder just to provide the lift and the thrust that the drones need.

This makes it harder for drone manufacturers to design drones that can be light enough when using ducted fans as their propellers. Meanwhile, because more and more mini and light drones are becoming popular because you can basically fold them and their propeller blades in order to place them inside your bag, it would be quite difficult for drones with ducted fans to be portable.

The ducts themselves would have to take up a ton of space, and would not have a readily foldable design. And while traditional propeller blades are usually longer than the blades on a ducted fan, the fact is that the propeller blades on most drones can be folded so that you can carry them easier. This is something you probably cannot do with ducted fans because of the ducts. The thrust that a ducted fan can produce is highly dependent on a lot of different factors such as the design of the ducts and the size of the ducted fan itself.

As such, there really is no specific number when it comes to the thrust that a ducted fan can produce because it can be entirely dependent on how it was made and designed. As an example, we can look at a 15 cm diameter ducted fan so that you can understand how much thrust a larger or a smaller ducted fan can produce.

But you can increase its thrust capacity by increasing the solidity of the rotor. If that is the case, the ducted fan might be able to lift somewhere close to 6 kg. However, you would need more ducted fans that are similar in size if you want to be able to carry 10 or more kilograms.

DARcorporation engineers work with customers to solve their most critical problems and combine extensive engineering experience with computerized simulation tools to provide the services our customers want.

Through the following disciplines, DARcorporation provides professional services for the design and analysis of propellers, ducted fan and open rotor systems.

Based on Blade Element Momentum BEM theory, DARcorporation has developed and customized in-house software for initial aerodynamic design of propeller blades in ducted or unducted configurations. Employing a robust surface vorticity panel code and lifting line axisymmetric ducted fan analysis tool, thrust coefficient and power coefficient versus advance ratio charts are obtained. Using high-fidelity computational fluid dynamics CFD software with rotation simulation, the full power-thrust curve can be constructed.

The deliverables of aerodynamic design include recommendations on the number of blades, airfoil selection, chord and pitch distribution, rotor diameter, RPM, etc. If a motor has not been selected based on the propeller power requirements, DARcorporation engineers have the ability to select the ideal motor for your configuration, either fuel burning or electric. Services include:. Sign up to join this community. The best answers are voted up and rise to the top.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Are ducted fans more efficient? Ask Question. Asked 5 years, 6 months ago. Active 1 year ago. Viewed 33k times. Source Of course I can see how an improperly implemented duct could really kill efficiency creating more interference and turbulence , but what about a well designed one?

Improve this question. Daniel Caoili Daniel Caoili 1 1 gold badge 5 5 silver badges 10 10 bronze badges. That is what happens when the air at the tips of the propeller goes in circles through the blades repeatedly.

The shroud stops that. Add a comment. Active Oldest Votes. Improve this answer. Marius Marius 3, 13 13 silver badges 23 23 bronze badges. It's not clear if it comes from the thesis paper, or somewhere else.

These are lift fans driven by gas from the engine which is not on the wings and using the circumference of the fan as a turbine. The duct is actually the turbine annular duct, I don't know if it is also used as a fan duct. Show 3 more comments. Henrique Moritz Henrique Moritz 1. As for your answer, you definitely have a valid point with your explanation that increasing blade count generally improves many factors of efficiency, but nonducted and ducted fans can have similar to equal blade counts.

The question in specifics is asking about the aerodynamic effects of the duct itself, which iirc offhand, mainly contributes in the area of thrust loss at the tips, which leads to issues that are countered by the ducts. Thrust density does improve with ducted propulsion though, so I see what you're saying here.

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