Low Reynolds number flows are central to the performance of airfoils used in small unmanned aerial vehicles (UAVs), micro air vehicles (MAVs), and aerodynamic platforms operating in rarefied atmospheres. Consequently, a deep understanding of airfoil behavior and accurate prediction of aerodynamic performance are essential for the optimal design of such systems. The present study employs Computational Fluid Dynamics (CFD) simulations to analyze the aerodynamic performance of a cambered plate at a Reynolds number of 10,000. Two Reynolds-Averaged Navier–Stokes (RANS) turbulence models, 𝛾–𝑅𝑒𝜃 and 𝑘-𝑘𝐿-𝜔, are utilized, along with the Unsteady Navier–Stokes (UNS) equations. The simulation results are compared against experimental data, with a focus on lift, drag, and pressure coefficients. The models studied perform moderately well at small angles of attack. The 𝛾–𝑅𝑒𝜃 model yields the lowest lift and drag errors (below 0.17 and 0.04, respectively), while the other models show significantly higher discrepancies, particularly in lift prediction. The 𝛾–𝑅𝑒𝜃 model demonstrates good overall accuracy, with notable deviation only in the prediction of the stall angle. In contrast, the 𝑘-𝑘𝐿-𝜔 model and the UNS equations capture the general flow trend up to stall but fail to provide reliable predictions beyond that point. These findings indicate that the 𝛾–𝑅𝑒𝜃 model is the most suitable among those tested for low Reynolds number transitional flow simulations.

Throughout history, human curiosity and the desire to explore have driven advancements in engineering capabilities and technologies. These efforts have extended our reach beyond Earth, with Mars emerging as one of the most important targets for planetary exploration. While rovers and landers have traditionally been used to study planetary surfaces, rotorcraft and other aerial vehicles have recently shown great promise for exploring the Red Planet. Such vehicles can access diverse terrains that are difficult or impossible for conventional landers and rovers to reach. However, the unique characteristics of the Martian atmosphere present significant aerodynamic challenges that must be overcome to enable sustained and efficient flight. Successful operation under these conditions requires a deep understanding of low Reynolds number aerodynamics, due to the rarefied atmosphere, and the influence of environmental factors such as pervasive Martian dust.

The combination of low Reynolds number flows and suspended dust particles creates unique challenges for rotorcraft aerodynamics on Mars. This thesis investigates these challenges through Computational Fluid Dynamics (CFD) simulations, focusing on the performance of a cambered plate airfoil with 6% camber and 1% thickness, which is well suited to the Martian environment. The research addresses both fundamental aerodynamic phenomena and environmental effects, providing insights into model selection for accurate flow prediction, sensitivity of performance to Reynolds number variations, and the long-term impact of dust accumulation on airfoil behavior.

This work presents a comprehensive overview of the evolution of drone designs for planetary exploration, emphasizing the main aerodynamic and control challenges involved. Operating in planetary atmospheres introduces unique difficulties, particularly due to the low chord-based Reynolds numbers and the presence of floating dust particles that can affect both aerodynamics and system reliability. The aerodynamic behavior at Reynolds numbers on the order of 10⁴ is investigated, focusing on the effect of increasing the rotor or chord dimension. Results show that increasing the Reynolds number from 20,000 to 50,000 does not significantly improve performance, as the formation of Laminar Separation Bubbles (LSBs) on the surface still occurs. The transition model used, γ–Re_θ, is able to accurately capture bubble formation. However, its limitations are also identified through comparison with other models, among which  γ–Re_θ is found to be the most reliable transition RANS model for these flows, since k-k_L-ω fails to reproduce the correct post-stall behavior. Unsteady Navier–Stokes (UNS) simulations exhibit the same inability due to the absence of turbulence modeling; however, their lower computational cost makes them suitable for preliminary studies and acceptable for low angles of attack.

The accumulation of dust particles on the airfoil surface is also examined, showing that particle deposition alters the airfoil geometry and leads to measurable changes in aerodynamic performance. While the effect is modest in the short term, it could become significant over long exposure times. The results are obtained under simplifying assumptions, such as a smooth surface and no detachment of particles. Further refinement is achieved by simulating particle deposition on an airfoil exposed solely to wind, where the wind velocity is modeled using a simple stochastic approach. The simulations account for both particle accumulation and instantaneous detachment during the run, and additional detachment is evaluated in a post-processing step. The resulting surface modification is then used to study its effect on the aerodynamic performance, providing a more complete understanding of how dust environments influence drone operation in planetary exploration.

Overall, the findings contribute to a deeper understanding of low Reynolds number aerodynamics and environmental degradation mechanisms relevant to Martian rotorcraft. The results offer guidance for aerodynamic model selection, design optimization, and long-term operational strategies for future aerial exploration missions on Mars.

Unmanned aerial vehicles (UAVs) have emerged as practical and potentially advantageous tools for scientific investigation and reconnaissance of planetary surfaces, such as Mars. Their ability to traverse difficult terrain and provide high-resolution imagery has revolutionized the concept of exploration. However, operating drones in the Martian environment presents fundamental challenges due to the harsh conditions and the different atmosphere. Aerodynamic challenges include low chord-based Reynolds number flows and the presence of dust particles, which can accumulate on the airfoil surface. This paper investigates the accumulation of dust on cambered plates with 6% and 1% camber, suitable for the type of flow studied. The analysis is conducted for Reynolds numbers of around 20,000 as a result of dimension restrictions, assuming a wind speed ranging from 12 to 14 m/s. Computational simulations are performed using a 2D C-type mesh in ANSYS Fluent, employing the 𝛾γ-Re SST turbulence model. Dust particle modeling is achieved through the Discrete Phase Model (DPM), with one-way coupling between phases. The accumulation of particles is monitored over a 6-month period with monthly intervals, and the airfoil is set at a 0° angle of attack. A deposition model, developed using user-defined functions in Fluent, considers particle–airfoil interaction and forces acting on particles. Results indicate a decrease in airfoil performance for negative angles of attack due to geometric changes, particularly due to accumulation on the bottom side near the tip. The discussion includes potential model enhancements and future research directions arising from the assumptions made in this study.

Over the past decade, there has been a considerable increase in space exploration efforts, driving the need for new methods to examine planets and other celestial bodies. The current trend involves designing spacecraft capable of surveying surfaces from elevated positions, with drones proving to be more suited for the task. . The focus of space missions has primarily been on exploring Mars, as evidenced by the pioneering flight of the Ingenuity helicopter in 2021. The Martian environment poses significant aerodynamic challenges due to its thin atmosphere and low pressure, complicating drone flight. The generation of lift is problematic owing to the scant atmosphere and the restricted dimensions required for space missions, resulting in low-chord Reynolds number flows. Despite the reduction in skin friction drag due to lower viscosity, the decrease in airfoil efficiency is significantly compromised, with only a partial counterbalance by the reduced gravitational pull. Two main challenges must be addressed: low chord-based Reynolds number flows and Martian dust. The former results in the formation of Laminar Separation Bubbles (LSB), severely impairing the aerodynamic efficiency of the airfoil. Concurrently, the accumulation of dust particles on the airfoil’s surface significantly affects its performance, altering its geometry and surface roughness. Thus, it is crucial to accurately determine the presence and location of both separation bubbles and particle deposition to predict performance degradation. \\This thesis presents a comprehensive survey on drones for planetary exploration and an analysis conducted on a cambered plate with 6$\%$ camber and 1$\%$ thickness, ideal for the types of flows considered. The studies are carried out for Reynolds number flows, namely 20,000 and 50,000, to observe the effects of rotor and airfoil dimensions. The computational study is performed using ANSYS Fluent, utilising a two-dimensional CFD model with a C-type mesh and the gamma-Re ($\gamma-Re_{\theta}$) transition model, which aids in capturing the behaviour of these flow regimes. Additionally, for the dust study, two phases are created: a primary phase, the atmosphere, and a secondary phase, the dust particles. The volume fraction of particles is assumed to be small enough to imply that the primary phase influences the secondary, but not vice versa (one-way coupling). To assess particle adhesion, a deposition model has been developed to check for the deposition of dust particles, working in conjunction with the Discrete Phase Modelling (DPM), which simulates the trajectory of particles within the control volume. The deposition model comprises a particle transport model, which accounts for the forces acting on the particles, and a particle-wall interaction model, which determines the particles' rebound or adhesion. The results are presented and discussed at the end of the thesis, along with a brief discussion of future studies focusing on alternative assumptions for dust modelling.

In 2021, the Ingenuity helicopter performed the inaugural flight on Mars, heralding a new epoch of exploration. However, the aerodynamics on Mars present unique challenges not found on Earth, such as low chord-based Reynolds number flows, which pose significant hurdles for future missions. The Ingenuity’s design incorporated a Reynolds number of approximately 20,000, dictated by the rotor’s dimensions. This paper investigates the implications of flows at a Reynolds number of 50,000, conducting a comparative analysis with those at 20,000 Re. The objective is to evaluate the feasibility of using larger rotor dimensions or extended airfoil chord lengths. An increase in the Reynolds number alters the size and position of Laminar Separation Bubbles (LSBs) on the airfoil, significantly impacting performance. This study leverages previous research on the structure and dynamics of LSBs to examine the flow around a cambered plate with 6% camber and 1% thickness in Martian conditions. This paper details the methods and mesh used for analysis, assesses airfoil performance, and provides a thorough explanation of the results obtained.

During the last decade, the efforts in space exploration have increased massively and led to a need for new ways to examine planets and other celestial bodies. The modern tendency is to create spacecraft able to scout the surface from a higher point of view, where drones have shown to be most helpful. Even if the benefits brought by this type of technology are considerable, the challenges are still difficult to overcome. This article presents a comprehensive literature review on drone technologies for planetary exploration, focusing mainly on the difficulties encountered. Considerable complications derive from the unknown environment, affecting most of the design, the mathematical model of the body, its controllability, and overall levels of autonomy. Various solutions to these challenges are proposed based on past and future missions. Furthermore, a look into the future gives an idea of possible technological developments and ways to provide the most efficient aerial exploration of other planets.