Aerodynamic and Aero-acoustic Analysis of Helicopter Rotor Blades in Hover

Doerffer, Piotr; Szulc, Oskar; Tejero, Fernando; Suarez, Javier Martinez

doi:10.1007/978-3-319-10894-0_31

Cited by 4 publications

(2 citation statements)

References 7 publications

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“…The authors of the present paper have been dealing with this severe test case using different physical models (steady and unsteady), numerical grids (block-structured and chimera), flow solvers (SPARC, FLOWer and NUMECA) and turbulence models (i.e. Spalart-Allmaras) with success [24,25] in the past. One of the most important aspects of hover computations is a proper prediction of the rotor wake.…”

Section: Caradonna-tung Model Helicopter Rotor In High-speed Hovermentioning

confidence: 99%

Application of a Passive Flow Control Device on Helicopter Rotor Blades

Tejero¹,

Doerffer²,

Szulc³

2016

J Am Helicopter Soc

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Application of an efficient flow control system on helicopter rotor blades may lead to improved aerodynamic performance. Recently, the own invention of a passive vortex generator (Rod Vortex Generator-RVG) has been analysed for channel and wing flows proving its capability to reduce flow separation. The application of this passive flow control device on helicopter rotor blades is described in the present paper. The basic flow mechanism is based on the intensification of exchange of momentum in the direction normal to the wall by a streamwise vortex. High momentum air is transferred to the low momentum region close to the surface and therefore the separation bubble is reduced. The present CFD investigation was carried out with the FLOWer code from DLR which solves the Favre-averaged Navier-Stokes equations using the chimera overlapping grids technique and LEA (Linear Explicit Algebraic Stress) k-ω turbulence model. The validation of the numerical setup for high-speed transonic hover conditions is based on a comparison with experimental data obtained by Caradonna and Tung (1981). For forward flight regime, the validation is based on a comparison with flight test data gathered by Cross and Watts for the AH-1G helicopter (1988). It has been proven that the application of the proposed flow control system reduces the size of the separation bubble increasing the aerodynamic performance in both states of flight. Nomenclature Symbols c blade chord (m) d rod diameter (m) h rod height (m) L spacing between vortex generators (m) M Mach number (-) M T tip Mach number (-) M ∞ forward flight Mach number (-) Re T tip Reynolds number (-) r rod radius (m) V ∞ forward flight velocity (km/h) C f skin friction coefficient (-) C P blade pressure coefficient (-) C Po rotor power coefficient (-) C Q rotor torque coefficient (-) C T rotor thrust coefficient (-) α rod skew angle (˚) β c backward disk tilt (˚) β s sideways disk tilt (˚) δ boundary layer thickness (m) µ rotor advance ratio (-) θ 0 blade collective angle (˚) θ c lateral cyclic coefficient (˚) θ s longitudinal cyclic coefficient (˚) ϴ rod pitch angle (˚) ψ blade azimuthal position (˚) Abbreviations C-T Caradonna and Tung FC Flow Control RVGs Rod Vortex Generators VGs Vortex Generators 40th European Rotorcraft Forum 2014, Proceedings of a meeting held 2

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Section: Caradonna-tung Model Helicopter Rotor In High-speed Hovermentioning

confidence: 99%

Application of a Passive Flow Control Device on Helicopter Rotor Blades

Tejero¹,

Doerffer²,

Szulc³

2016

J Am Helicopter Soc

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“…The fluid was modeled as incompressible, and a time-step of one degree was employed, corresponding to the rotational speed of the innermost domain. The solver employed the SIMPLE algorithm, and the inlet velocity was set to 0.01 m/s for the hover flight condition [26]. It is noted that the inlet velocity is set to a very small number equal 0.01 m/s to prevent computational divergence.…”

Section: Methodsmentioning

confidence: 99%

Investigating and Analyzing the Potential for Regenerating Excess Energy in a Helicopter UAV

Kodchaniphaphong,

Pukrushpan,

Klumpol

2023

Drones

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Energy consumption is a critical parameter in the development of helicopter Unmanned Aerial Vehicles (UAVs). Today, helicopter UAVs are playing an increasingly pivotal role in various applications, from surveillance and reconnaissance to package delivery and search and rescue missions. However, their energy efficiency remains a pressing issue, as it directly impacts their operational duration and payload capacity. One of the key challenges in optimizing energy consumption is the existence of excess power during flight, arising from the intricate interplay between helicopter aerodynamic behavior and safety design. Typically, this excess energy is dissipated, resulting in a suboptimal performance and efficiency. This study investigated the behavior of excess power in a helicopter Unmanned Aerial Vehicle (UAV). Typically, this excess energy is wasted in conventional helicopters and helicopter UAVs. A dual-method approach, encompassing numerical and experimental methodologies, was employed to provide comprehensive insights into the helicopter UAV’s performance under various conditions. Computational fluid dynamics (CFD) simulations were performed to analyze the UAV’s aerodynamics. The simulations were validated by comparing the lift force with wind tunnel experimental data, resulting in acceptable deviations. The experimental analysis was conducted using a wind tunnel and a small-sized helicopter UAV. The experiments were designed to examine the excess power behavior of the UAV under two distinct flight conditions: hover and forward flight. The power output from the generator and power input from the battery were measured under various angular velocities and pitch angles. The results revealed a maximum excess power of 6.84% for hover conditions and 9.83% for forward flight conditions. This indicates that the maximum excess power percentage attributable to the helicopter UAV’s safety measure is 6.84% and that resulting from aerodynamics is 2.99%. The findings of this study contribute valuable knowledge to the optimization of helicopter UAV performance and the potential for harnessing excess power during flight operations. When this excess energy is harnessed, it can contribute significantly to the overall performance and efficiency of the UAV, potentially extending its flight duration or accommodating additional payload capacity that could potentially pave the way for the development of hybrid helicopter UAV models in the future.

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