Rotor Aerodynamics in Ground Effect at Low Advance Ratios

Curtiss, H. C.; Sun, Mao; Putman, W. F.; Hanker, Edward J.

doi:10.4050/jahs.29.48

Cited by 72 publications

(35 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Measuring instruments are installed on the carriage and move with the model, recording various physical quantities such as forces, moments, flow field, etc. Curtiss et al (1983) used this method to study the ground vortex phenomena of a helicopter rotor flying near the ground. understanding and meticulous implementation of ground effect aerodynamics can maximize a vehicle's aerodynamic efficiency and improve the safety of the vehicles in operation.…”

Section: Towing Model Methodsmentioning

confidence: 99%

Ground Effect Aerodynamics

Cui

Zhang

2010

Encyclopedia of Aerospace Engineering

View full text Add to dashboard Cite

The ‘ground effect’ is the aerodynamic phenomenon whereby the flow field around a vehicle, either an aircraft or a car, is constrained and altered by the presence of the ground. For an aircraft operating in ground effect, it is the creation of an effective air cushion between the lower surface of the wing and the ground that modifies the physics of the flow resulting in positive lift enhancement. For a car utilizing ground effect, the dominant feature is a low‐pressure field between the vehicle and the ground caused by significant flow acceleration, similar to the ‘Venturi effect’, leading to downforce (negative lift) enhancement. Components such as wings and diffusers operate within this regime. The impact of ground effect is generally an increase in aerodynamic efficiency, that is, an increase in lift‐to‐drag ratio for aircraft or the equivalent downforce‐to‐drag ratio for cars. When a vehicle operates too close to the ground, the beneficial response diminishes. The ground effect can adversely affect the flight stability of an aircraft during take‐off and landing as well as under cruise conditions in close proximity to the ground. This chapter provides a brief summary concerning the history of ground effect vehicles. Various methods employed to study the phenomenon are introduced; these include empirical approximations, analytical methods, numerical simulations, and wind tunnel tests. Applications of ground effect to aircraft and vehicle design are also discussed. Advantages and risks are further examined with an emphasis on control and stability.

show abstract

Section: Towing Model Methodsmentioning

confidence: 99%

Ground Effect Aerodynamics

Cui

Zhang

2010

Encyclopedia of Aerospace Engineering

View full text Add to dashboard Cite

show abstract

“…Analysis of the wake structure was conducted using the video and sonic anemometer data, focusing on the frontal recirculation zone or ground vortex. Investigators have found that the wake flow regime structure during low-level flight is dependent on the thrustnormalized advance ratio, μ * , of the rotorcraft and the height of the rotor above the ground [21]. Flight greater than 1 rotor-diameter above the surface does not result in ground-effect and therefore the flow regimes do not occur.…”

Section: M-omentioning

confidence: 97%

Development of a rotorcraft dust-emission parameterization using a CFD model

et al. 2010

View full text Add to dashboard Cite

Flights of rotorcraft over the desert floor can result in significant entrainment of particulate matter into the atmospheric boundary layer. Continuous or widespread operation can lead to local and regional impacts on visibility and air quality. To account for this pollutant source in air quality models, a parameterization scheme is needed that addresses the complex vertical distribution of dust ejected from the rotorcraft wake into the atmospheric surface layer. A method to parameterize the wind and turbulence fields and shear stress at the ground is proposed here utilizing computational fluid dynamics and a parameterized rotor model. Measurements taken from a full scale experiment of rotorcraft flight near the surface are compared to the simulation results in a qualitative manner. The simulation is shown to adequately predict the forward detachment length of the induced ground jet compared to the measured detachment lengths. However, the simulated ground vortex widths and vorticity deviate substantially from the measured values under a range of flight speeds. Results show that the method may be applicable for air quality modeling assuming slow airspeeds of the rotorcraft, with advance ratios of 0.005-0.02.

show abstract

“…As mentioned before, the ground effect for single-rotor helicopters has been extensively studied in the literature [11][12][13][14][15][16]. When the rotor is under the ground effect, there is an increment in the thrust generated by the rotor for the same power, which is greater the closer the rotor is to the ground.…”

Section: Ground Effect For Single Rotormentioning

confidence: 99%

“…This alters the velocity of the slipstream and the induced velocity, which then affects the rotor thrust and power. The ground effect in helicopters has been well researched in literature [11,12] and has been studied for take-off, landing, and hovering near the ground [13][14][15]. However, for multirotors, it has not received much attention yet, although these platforms are being increasingly used in multiple applications.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the Aerodynamic Ground Effect and Its Influence in Multirotor Control

Sanchez-Cuevas

Heredia

Ollero

2017

International Journal of Aerospace Engineering

126

View full text Add to dashboard Cite

This paper analyzes the ground effect in multirotors, that is, the change in the thrust generated by the rotors when flying close to the ground due to the interaction of the rotor airflow with the ground surface. This effect is well known in single-rotor helicopters but has been assumed erroneously to be similar for multirotors in many cases in the literature. In this paper, the ground effect for multirotors is characterized with experimental tests in several cases and the partial ground effect, a situation in which one or some of the rotors of the multirotor (but not all) are under the ground effect, is also characterized. The influence of the different cases of ground effect in multirotor control is then studied with several control approaches in simulation and validated with experiments in a test bench and with outdoor flights.

show abstract

Rotor Aerodynamics in Ground Effect at Low Advance Ratios

Cited by 72 publications

References 3 publications

Ground Effect Aerodynamics

Ground Effect Aerodynamics

Development of a rotorcraft dust-emission parameterization using a CFD model

Characterization of the Aerodynamic Ground Effect and Its Influence in Multirotor Control

Contact Info

Product

Resources

About