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A high-performance Ishii airfoil was analyzed using both a wind-tunnel and large-eddy simulations at a low-Reynolds-number condition (Re=23,000). The design guidelines for an airfoil shape with a high lift-to-drag ratio under the aforementioned condition are described by analyses of flowfields and aerodynamic characteristics of the Ishii airfoil. C...
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... side not only allows for the enhancement of the lift but also allows a reduction of the pressure drag. On the suction side at Δα 3 deg, the NACA 0012 has more than twice the pressure drag than the Ishii airfoil. The flowfields and the pressure distribution of the Ishii airfoil and the NACA 0012 are markedly similar to each other, as shown in Figs. 10, 11, and 13. However, the flow on the NACA 0012 separates earlier than that on the Ishii airfoil. A subtle difference in the shape on the suction side around the separation points between the NACA 0012 and the Ishii airfoil is due to the flatness. The Ishii airfoil with a smaller curvature in the shape of the upper surface has a lower ...
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Citations
... According to the conservation of momentum, the surface forces and body forces acting on a fluid is equal to the rate of change in linear momentum of a volume flowing with a fluid [12]. ...
A computational study explores the aerodynamic and flow properties of rough-surfaced NACA-0018 airfoils using turbulent K-omega SST methodology and the control volume method. Ansys Fluent 2022 R2 was used to do the simulations, and Reynolds numbers between 5000 and 10000 were used. The analysis of how the rough surface affects the performance of the airfoil was the main goal of the study. The skin friction coefficient, drag force, lift force, pressure contours, and stream functions were among the many variables assessed. To have a thorough understanding of the flow behavior, these parameters were studied at various Reynolds numbers. The findings revealed a clear pattern: along the wall of the airfoil, the average drag force, lift force, and skin friction coefficient all increased linearly as the Reynolds number rose from 5000 to 10000. This discovery sheds important light on how the rough surface affects the overall aerodynamic performance of the airfoil. This study advances knowledge of the aerodynamic behavior of rough airfoils by illuminating the flow characteristics and their relationship to surface roughness. Significant results impact aeronautics, wind turbine design, and other airfoil applications.
... The airfoil configuration of the fixed wing is the Ishii airfoil, which reportedly exhibits a high flight performance at low Reynolds numbers. 24) The Ishii airfoil has the following characteristics: 1) thin profile, 2) flat upper surface, and 3) cambered lower surface. These characteristics match the suggested characteristics for high flight performance at low Reynolds numbers, 25,26) and the Ishii airfoil is one of the candidates for the main-wing airfoil of the Mars airplane. ...
To realize a propeller-driven Mars airplane, the propeller-wing flow interaction characteristics should be clarified. Thus, we conducted numerical simulations of the propeller-wing interaction at low Reynolds number conditions (Re = 3.0 × 10⁴) corresponding to Mars atmosphere, focusing on the propeller slipstream effects on the fixed wing. Solutions for the tractor case (propeller in front of the fixed wing) and the wing only case were compared. The results showed that in the tractor case, the lift coefficient (CL) of the fixed wing increased with the angle of attack (α) more linearly than for the wing only case and showed delayed stall because the propeller slipstream favorably suppressed the expansion of the recirculation region over the fixed wing in the time-averaged flow fields, supporting the experimental result. The flow over the fixed wing separated from near the leading-edge in both low and high thrust conditions even at a moderate angle of attack (α = 5°), whereas previous studies at relatively high Reynolds numbers (Re ∼ O(10⁵)) showed that almost attached flow fields were formed under the propeller slipstream influence. Additionally, it was observed that the CL fluctuation of the fixed wing increased even when the time-averaged CL was lower than that of the wing only case.
... Japanese researchers have made significant contributions to Martian flight research, providing extensive and valuable experimental data gathered from the Martian Wind Tunnel at Tohoku University Munday et al. (2015); Anyoji et al. (2014); Suwa et al. (2012); Anyoji et al. (2009Anyoji et al. ( , 2010. These findings have served to validate various numerical approaches at these Reynolds numbers, spanning from finite volume Navier-Stokes solvers Désert et al. (2019) to high-order DNS (Direct Numerical Simulation) solvers Caros et al. (2022). ...
The recent success of the Ingenuity Mars helicopter developed by the jet propulsion laboratory (JPL) demonstrated the feasibility of the Martian flight. Low pressure (660 Pa) and temperature (210 K) characterize the ground-level Martian atmosphere. Since such conditions are difficult and expensive to mimic on Earth, it is necessary to have reliable simulation tools that can correctly reproduce Martian aerodynamics. In the case of unmanned aerial systems (UAS), the latter is characterized by a high subsonic Mach number at the tip of the blades and an Ultra-low Reynolds number regime (\(1000< \hbox {Re} < 10000\)). To this purpose, the laminar solver embedded in the commercial CFD code STAR CCM+ was validated by reproducing experiments carried out in the Martian Wind Tunnel at Tohoku University using a triangular airfoil wing at Reynolds 3000 and a Mach number of 0.5. Simulations are performed at angles of attack ranging from 0 to 16 degrees showing a satisfactory agreement with experimental results for very different flow conditions.
... Simulation findings related to the rotors of rotary-wing Mars UAVs indicate that the precision of finite element simulations in the context of three-dimensional rotors lag behind that of two-dimensional airfoil simulations. Within Ref. [80], a fusion of simulation outcomes and rotor design theory corroborated the consistency in two-dimensional simulation outcomes, encompassing lift characteristics, power characteristics, and experimental findings. Nevertheless, the lower precision in the simulation of the transition region from laminar to turbulent flow rendered three-dimensional simulation outcomes less consistent with experimental results. ...
The sparse atmosphere on the surface of Mars provides the necessary flight conditions for Mars unmanned aerial vehicles (UAVs) to perform low-altitude flights. This work presents a comprehensive overview of key technologies in the development of Mars UAVs, with a specific focus on rotary-wing Mars UAVs. It summarizes prototypes of rotary-wing Mars UAVs developed by various global research institutions. It reviews essential technologies in rotary-wing Mars UAV research, including the Mars near-surface atmospheric environment, aerodynamic characteristics, and principles of low-pressure flight control. This work also summarizes various experimental setups and ground test results for rotary-wing Mars UAVs. Furthermore, it discusses the future development trends of rotary-wing Mars UAVs.
... Shan, Jiang & Liu 2005;Jones, Sandberg & Sandham 2008). Moreover, to optimize the design of the aircraft-like device operated in the thin Mars atmosphere, a series of LES were conducted by Kojima et al. (2012) and Anyoji et al. (2014) to examine the performance of different types of aerofoil sections in different angles of attack. Taking advantage of modern computational power, these high-fidelity numerical studies revealed spectacular details of flows in transition and turbulent regimes, providing valuable information on the fine-scale flow structures around aerofoils at low-Reynolds-number flows. ...
... Recently, low-Reynolds-number flow operating at Re ∼ O(10 4 ) has drawn much attention due to a variety of engineering and industrial applications. Examples include smallto medium-scale wind turbines (Tangler & Somers 1995), unmanned aerial vehicles (Carmichael 1981;Mueller & DeLaurier 2003), and recently, the Mars explorer (Kojima et al. 2012;Anyoji et al. 2014). A very important feature in this flow regime is laminar separation and the transition to turbulence, leading to various flow patterns that can pose Figure 1. ...
This study examined the impact of coherent structures on the aerodynamic forces exerted on a NACA0012 aerofoil with angles of attack $7.5^{\circ }$ and $10^{\circ }$ , and a chord-based Reynolds number $50\,000$ . The study utilized the spectral proper orthogonal decomposition (SPOD) algorithm to identify the coherent structures, and vorticity force analysis to quantify their impact on lift and drag forces. Results showed that at $10^{\circ }$ , the zeroth frequency of the first SPOD mode had a significant impact on drag and lift forces due to a large vortex structure that caused a strong flow along the suction side of the aerofoil. The first and second frequencies of the first SPOD mode represented asymmetric vortex pairs and a series of vortex pairs that determined the leading-edge separation, respectively. At $7.5^{\circ }$ , the zeroth frequency of the first mode corresponded to an oscillating near-wall stream that followed the reattachment flow pattern, while the first frequency corresponded to a counter-rotating vortex pair that originated where the flow reattaches. Finally, the second frequency of the first mode corresponded to smaller counter-rotating vortex pairs at the shear layer originated near the reattachment point. These findings suggest that coherent structures have a significant impact on aerodynamic forces exerted on aerofoils, and can be identified and quantified using the SPOD algorithm and vorticity force analysis.
... RANS numerical simulations through the CIRA built in-house UZEN code has been conducted on three suitable airfoils, for compressible low Reynolds aerodynamics in Martian atmosphere, that have been selected through a bibliographic study: Triangular, NACA 0012-34 and Ishii airfoils. The experiments in the low-density CO2 facility of the Mars Wind Tunnel of Tohoku University over a NACA0012-34, Triangular and Ishii airfoils (sketched in Fig. 2, considering [2,4,5], respectively) with global forces and local PSP measurements, have been considered to first assess the UZEN code. ...
The space exploration and colonization Roadmap, and the growing interest of the international scientific community toward the Mars colonization, are highlighting the need to develop, or improve to higher TRLs, those technologies enabling human exploration and colonization. In this framework, the CIRA - PRORA research program TEDS has identified some of the most promising technologies and research areas for human/robotic exploration, and human survivability in hostile environments in future space missions. In this contest, Aerodynamics in the Martian low atmosphere, characterized by low Reynolds number and high Mach number, is one of the research areas to investigate. The compressible aerodynamics of low Reynolds number flow (Reynolds number of orders of magnitude 104-105 and Mach number of 0.2-0.7) characterizes the low altitude Martian atmosphere. The need in the exploration of the Martian surface has increased the interest in this “particular" aerodynamic regime, currently, scarcely investigated, and an assessment of the numerical methods is necessary. Three suitable airfoils for compressible low-Reynolds aerodynamics in Martian atmosphere have been selected through a bibliographic study: Triangular, NACA 0012-34 and Ishii airfoils. The experiments in the low-density CO2 facility of the Mars Wind Tunnel, at Tohoku University, over a Triangular, NACA0012-34 and Ishii airfoils with global forces and local PSP measurements, have been considered. The CIRA in-house developed flow solver UZEN (Unsteady Zonal Euler Navier-Stokes) code has been applied by employing several turbulence models. The flow over the Triangular airfoil has been simulated inside the wind tunnel and the free air flow over the NACA 0012-34 and Ishii airfoils have been simulated, and in this paper many results are reported.
... Similarly, Japanese researchers have made significant contributions to Martian flight research, providing extensive and valuable experimental data gathered from the Martian Wind Tunnel at Tohoku University. [2][3][4][5][6] These findings have served to validate various numerical approaches, spanning from commercial finite volume Navier-Stokes (NS) solvers 7,8 to high-order DNS (direct numerical simulation) solvers. 9 However, it is worth noting that the primary focus of the Japanese researchers' efforts has been on analyzing airfoil performance under low Reynolds number conditions, specifically in the context of designing fixed-wing aircraft, as shown in several studies. ...
... 9 However, it is worth noting that the primary focus of the Japanese researchers' efforts has been on analyzing airfoil performance under low Reynolds number conditions, specifically in the context of designing fixed-wing aircraft, as shown in several studies. 3,10,11 Regarding airfoil design for Martian rotors, Koning and coauthors 12,13 have presented detailed aerodynamic and optimization analyses of airfoils specifically for the Mars environment. Their study includes a multi-objective optimization (MOO) aiming to simultaneously maximize lift and minimize drag. ...
... Due to its limited influence, we have neglected the tangential induction factor in Eq. (3). Let us introduce the definition of local solidity, ...
Ultra-low Reynolds number aerodynamics has gained significant attention in recent times, primarily due to the proliferation of micro-aerial vehicles and their utilization in low-density environments such as the Martian atmosphere and high altitudes in Earth's atmosphere. The Martian atmosphere presents a unique combination of low Reynolds numbers and high subsonic Mach numbers, necessitating the use of unconventional airfoil designs in this regime. This study focuses on optimizing airfoils for rotors operating in the compressible ultra-low Reynolds number regime. We demonstrate the capability of XFOIL, a panel method code incorporating an integral boundary layer formulation, to accurately predict airfoil loads when the flow remains attached. We determine the optimal camber and maximum camber positions by analyzing the four digits, two percent thickness, National Advisory Committee for Aeronautics XX02 airfoil family using XFOIL. Subsequently, we employ a multi-objective optimization approach, utilizing a Class Shape Transformation airfoil parameterization to maximize lift and minimize drag. We select several points from the resulting Pareto front and evaluate their performance through unsteady compressible Navier–Stokes simulations. Our findings reveal that incorporating sharp leading-edge variations in these airfoil designs enhances the peak efficiency by over 10%, primarily attributable to the development of laminar separation bubbles on the suction side of the airfoils. Importantly, these modified airfoils maintain favorable performance at low angles of attack.
... There have been many numerical and experimental studies on the aerodynamic performance of different airfoils at high Reynolds number regimes in the range of 10 4 < Re < 10 6 (Selig et al., 1996;Counsil and Boulama, 2013;Anyoji et al., 2014;Winslow et al., 2018). However, in the range of Re = O(10 2 -10 3 ), much fewer studies exist in literature. ...
... We encourage future testing of both currently available technology and/or newly developed, specialized turbines in Mars wind tunnels or environmental chambers, as in refs. [18][19][20][21][62][63][64] , including generating Mars-specific power curves that account for Mars' reduced gravity, low atmospheric density and low Reynolds numbers. For example, additional study is required to understand the changing lift and drag on turbine blades in laminar or transitional airflow regimes associated with low-Reynolds-number atmospheres 21 . ...
Energy sustainability and redundancy for surface habitats, life support systems and scientific instrumentation represent one of the highest-priority issues for future crewed missions to Mars. However, power sources utilized for the current class of robotic missions to Mars may be potentially dangerous near human surface habitats (for example, nuclear) or lack stability on diurnal or seasonal timescales (for example, solar) that cannot be easily compensated for by power storage. Here, we evaluate the power potential for wind turbines as an alternative energy resource on the Mars surface. Using a state-of-the-art Mars global climate model, we analyse the total planetary Martian wind potential and calculate its spatial and temporal variability. We find that wind speeds at some proposed landing sites are sufficiently fast to provide a stand-alone or complementary energy source to solar or nuclear power. While several regions show promising wind energy resource potential, other regions of scientific interest can be discarded based on the natural solar and wind energy potential alone. We demonstrate that wind energy compensates for diurnal and seasonal reductions in solar power particularly in regions of scientific merit in the midlatitudes and during regional dust storms. Critically, proposed turbines stabilize power production when combined with solar arrays, increasing the percent time that power exceeds estimated mission requirements from ~40% for solar arrays alone to greater than 60–90% across a broad fraction of the Mars surface. We encourage additional study aimed at advancing wind turbine technology to operate efficiently under Mars conditions and to extract more power from Mars winds.
... Koning et al. used Blade Element Momentum Theory (BEMT) combined with an iterative algorithm to optimize the Mars rotorcraft airfoil [30][31][32]. Bohorquez [33], Anyoji [34] and Zhao [35] used a combination of two-dimensional simulation and experimental verification to design the optimal Mars rotorcraft airfoil in different flight conditions and blade diameters. Uwatoko [27]. ...
The Mars rotorcraft can help the Mars rover to optimize the driving route and explore more efficiently. However, the thin and cold Martian atmosphere can heavily increase the consumed power of the rotorcraft blades and reduce the generated thrust, leading to the reduction in power loading. The aerodynamic force generated by the Mars rotorcraft blade can be significantly influenced by the blade structure, which has several main structural characteristics and needs to be well designed. A multivariable optimization design method of blade structure is proposed based on neural network, genetic algorithm, and computational fluid dynamics simulations. Experiments conducted in the Martian atmosphere simulator indicate that the Mars rotorcraft blades with the hyperbolic chord length distribution and twist have higher power loading in the constant collective pitch angle.
