Technological innovation continues to grow, drones are taking an increasingly important place in our world. The global market will grow tenfold in 10 years, from $28 billion in 2021 to $260 billion in 2030. All industrial sectors are involved, from oversight missions to delivery logistics, from area mapping to military missions. Modern drones offer efficient and versatile solutions. However, the design and development of these devices must be carefully tailored to their specific missions. The performance expected of current drones and the available optimization techniques must meet the varied needs of users. Thus, different types of drones can be considered, depending on capacity needs and different operating environments, with the objective of maximizing their efficiency. And for this, CFD (Computational Fluid Dynamics) simulation becomes a must in the development and optimization of drone performance, whether they are aerial or underwater.
Types of Drones and their Performances
2.1 Types of Drones
Multi-rotor drones are the most common, offering great stability and ease of manoeuvring. They are ideal for short-term missions requiring high precision. However, their autonomy is limited due to poor energy efficiency.
Fixed-wing drones are designed for long-distance flights and have better efficiency when travelling. One of their main drawbacks is the need for a take-off and landing runway, or launch device, which limits their deployment in restricted environments.
To overcome this disadvantage, hybrid drones, with fixed wings but with a vertical take-off and landing capacity, are a very interesting alternative allowing the deployment of efficient aircraft on any field.
2.2 Performance depending on the type of drone
The distance travelled varies considerably between different types of drones. Fixed-wing drones can cover hundreds of kilometres, while multi-rotor drones are limited to a few tens of kilometres.
Fixed-wing drones are the fastest in terms of speed, reaching speeds above 100 km/h. Multi-rotor drones, on the other hand, will have a maximum speed of around 50 km/h.
The carrying capacity is also a crucial factor. Multi-rotor drones can carry various shaped loads. Fixed-wing drones will have a more efficient carrying capacity but the load will need to be adapted in shape in order to not penalize the efficiency of the whole.
Operating Environments : Aerial and Underwater
Aerial Drones (UAV)
Aerial drones, or UAVs (Unmanned Aerial Vehicles), have the constraint of turbulent air, wind and wind gusts, thermal updrafts, and their design must take into account the robustness to these phenomena. Thus, the stability and autonomy of the drone are two essential components in optimizing performance, especially aerodynamics. The reduction of drag and the improvement of the efficiency will contribute to increase its flight range and to improve its operation by minimizing the need for reloading.
Marine and Submarine Drones (AUV)
Underwater drones, or AUV (Autonomous Underwater Vehicles), operate in a more stable environment and at much lower speeds. However, due to the viscosity of water, the Reynolds number will be quite similar to the multi-rotors aerial drones, and thus hydrodynamic phenomena can be approached in a similar way by simulation. The reduction of interaction turbulence and the control of cavitation risk are for example topics that will lead to hydrodynamic optimization. Here too, increasing the range of missions in terms of distance and time is a major objective.
Optimization of the performance of modern drones by CFD simulation
Introduction to CFD (Computational Fluid Dynamics)
CFD (Computational Fluid Dynamics) is a numerical simulation technique that allows to model and analyze the flows of fluids around objects. In the drone context, CFD plays a crucial role in performance design and optimization. It allows for accurate prediction of aerodynamic and hydrodynamic behaviour, reducing development costs and time.
Application of CFD in Drone Design
The application of CFD in drone design leads to the optimization of the shape and the technical characteristics of the drones. For example, adjusting the shape of the wings or the propellers can reduce drag and improve lift. However, it is the analysis of the need and especially the understanding of the objectives of the mission of the drones that will frame the development.
Steps of a CFD Digital Experience Plan
A CFD digital experience plan includes several key steps:
- Scope: Objectives to be achieved and constraints to be taken into account.
- Modelling: Creation of the parameterizable digital model of the drone.
- Simulation: Cloud-based multiprocessor computing, analysis and optimization.
- Validation: Projection of results in the context of the mission and comparative assesment.
These steps provide an overall value to development, focusing on performance but also on the economic aspect.
Tailor-made solutions
This highly segmented market, both by the purpose of the missions and by the variety of the types of drones, sees also the growing importance of flying in swarms as well as the need for each participant to increase the effectiveness of its mission. This is an idyllic terrain for multiplying the optimizations of forms and design in the years to come. In this context, CFD (Computational Fluid Dynamics), combined with creativity and aeronautical skills, will be an essential asset to develop the necessary competitive advantage, whether for the underwater or aerial drones, and for the multi-rotors, fixed-wing or hybrid drones.
