Co-Flow Jet Airfoil Trade Study Part II: Moment and Drag

Lefebvre, Alexis; Zha, Gecheng

doi:10.2514/6.2014-2683

Cited by 21 publications

(10 citation statements)

References 25 publications

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“…Their study indicates that the CFJ airfoil gains drastic performance enhancement at high AoA for a low energy expenditure. Additional numerical studies performed by Lefebvre et al [23,24] confirm the trends. However, no study has been conducted to investigate CFJ airfoil performance enhancement and energy expenditure with Mach number effect.…”

Section: A the Coflow Jet Airfoilmentioning

confidence: 58%

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Performance and Energy Expenditure of Coflow Jet Airfoil with Variation of Mach Number

Lefebvre

Dano

Bartow

et al. 2016

Journal of Aircraft

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This paper conducts a numerical and experimental investigation of a coflow jet airfoil to quantify lift enhancement, drag reduction, and energy expenditure at a Mach number range from 0.03 to 0.4. The jet momentum coefficient is held constant at 0.08, and the angle of attack varies from 0 to 30 deg. The two-dimensional flow is simulated using a Reynolds-averaged Navier-Stokes solver with a fifth-order-weighted essentially non-oscillatory scheme for the inviscid flux and a fourth-order central differencing for the viscous terms. Turbulence is simulated with the one equation Spalart-Allmaras model. The predicted coflow jet pumping power has an excellent agreement with the experiment. At a constant Mach number, the power coefficient is decreased when the angle of attack is increased from 0 to 15 deg. When the Mach number is increased from 0.03 to 0.3, the suction effect behind the airfoil leading edge is further augmented due to the compressibility effect. This results in an increased maximum lift coefficient and reduced power coefficient at the higher Mach number because of the lower jet-injection pumping pressure required. At Mach 0.4, the lift coefficient is further improved. However as the angle of attack is increased, a λ shock wave interrupts the jet and triggers the boundary layer separation with increased drag and power coefficient. A corrected aerodynamic efficiency that includes the coflow-jet pumping power is introduced. Because of the high lift coefficient and low coflowjet power required, the coflow-jet airfoil in this study achieves a comparable peak aerodynamic efficiency to the baseline airfoil, but the lift coefficient at peak efficiency is substantially increased by 120%. This study indicates that the coflow-jet airfoil is not only able to achieve very high maximum lift coefficient, but also able to improve cruise performance at low angle of attack when the flow is benign.

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Section: A the Coflow Jet Airfoilmentioning

confidence: 58%

“…At AoA 20 deg, there is a mild separation near the TE for Mach 0.03 and 0.3. The separation can be easily removed by increasing C μ slightly, such as to 0.12 [23,24]. In general, the flowfield structures of Mach 0.03 and 0.3 are very much the same.…”

Section: Resultsmentioning

confidence: 99%

Performance and Energy Expenditure of Coflow Jet Airfoil with Variation of Mach Number

Lefebvre

Dano

Bartow

et al. 2016

Journal of Aircraft

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“…The amount of energy expenditure from the larger slot jet was 3.9 times that of the smaller slot jet which would directly correlate to fuel consumption. American Insitute of Aeronautics and Astromautics Conceptual research has been conducted looking into creating "engineless" Co-Flow Jets and applying this technology to UAVs [30][31][32][33][34]. Figure 1 displays a SOILDWORKS 3D CAD Design Software [35]the rendering of the completed experimental setup for one of the configurations.…”

Section: Slot Jetmentioning

confidence: 99%

Performance Characteristics of Fluidic-Based Thrust Augmentation Using a Slot Jet for Unmanned Aerial Vehicle Propulsion

Wiedow¹,

Ahmed²

2015

51st AIAA/SAE/ASEE Joint Propulsion Conference

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Currently most small vertical takeoff and landing Unmanned Aerial Vehicles (UAV's) use a quadcopter design by utilizing four exposed blades rotating at high RPMs around a central array of components. The research performed in this thesis is focused on understanding the underlying fluid dynamics of a slot jet through the use of flow entrainment for thrust augmentation with the application to be integrated into a novel UAV system with no external moving parts. Current publicly available quadcopter rotor design type aircraft were used as a basis for the design target weight and power to estimate the amount of thrust needed to provide lift. The inclusion of the slot jet causes flow entrainment, thereby creating a turbulent jet downstream. The entrainment effects were studied to define how the flow field interacts within the airfoils. The airfoils were constructed utilizing 3-D printing and placed in multiple configurations varying spacing and angle of attack while laboratory shop air was used to control the slot jet exit velocity. In order to determine the effects of this turbulent flow on thrust, a large experimental envelope was created and tested with a Pitot probe experiment. The velocity profiles were recorded and thrust values were calculated. The experimental envelope was narrowed for the most prominent configurations and Particle Image Velocimetry (PIV) with a high speed laser camera setup was used to capture the flow upstream, midstream, and downstream along the airfoils cord length to examine the turbulent mixing and thrust characteristics within the flow field. The effects of slot jet velocity, confinement spacing, and aerodynamic effects were each singularly inspected for the effects on the flow field and thrust characteristics. The results illustrate that higher slot jet velocity along with inward angle and small confinement produce the greatest thrust although efficiency is maximized with a larger spacing. The thrust values produced indicate the feasibility of producing enough force to lift a UAV vertically off the ground.

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“…Recently, the Co-Flow Jet (CFJ) flow control airfoil developed by Zha et al [1,2,3,4,5,6,7,8,9,10,11,12] provides a promising concept to improve the cruise efficiency. In a CFJ airfoil, an injection slot near the leading edge (LE) and a suction slot near the trailing edge (TE) on the airfoil suction surface are created.…”

Section: Introductionmentioning

confidence: 99%

Study of Mach Number Effect for 2D Co-flow Jet Airfoil at Cruise Conditions

Wang

Zha

2019

AIAA Aviation 2019 Forum

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This paper studies the Mach number effect on cruise performance for a 2D Co-Flow Jet (CFJ) airfoil at freestream Mach number of 0.15, 0.30, 0.46 and 0.5. The optimized 2D CFJ airfoil, CFJ6421-SST150-SUC247-INJ117 is redesigned by enlarging the size of the injection and suction slot from the CFJ airfoil previously designed by Lefebvre and Zha. The results show that the best CFJ airfoil corrected aerodynamic efficiency ((C L /C D) c) occurs at M ∞ of 0.30, which produces a (C L /C D) c of 81.04 at C µ of 0.03 and AoA of 6 •. The case at M ∞ of 0.30 has higher compressibility than that at M ∞ of 0.15, but is still far from the sonic speed. The favorable conditions hence provide the optimum aerodynamic efficiency. At the same C µ and AoA, the maximum Mach number on the CFJ airfoil suction surface at M ∞ of 0.15, 0.30, 0.46, 0.50 is 0.264, 0.558, 1.025 and 1.289 respectively. For the case of M ∞ of 0.50, the flow becomes transonic. As the M ∞ increases, the C L is also increased due to the stronger compressibility effect that creates a greater suction effect. At M ∞ of 0.46, which is the critical Mach number for the airfoil at AoA of 6 • , the corrected aerodynamic efficiency is still very good. But when the M ∞ is increased to 0.5, the optimum aerodynamic efficiency occurs at a lower AoA and C µ with AoA = 2 • and C µ = 0.01. Under this condition, the flow remain subsonic without shock wave. For the optimum cruise condition with the Mach number varying from 0.15 to 0.5, the ratio of the injection jet velocity to the freestream velocity is varied from 1.24 to 0.68, and the total pressure ratio between the injection and suction slot is from 1.02 to 1.20. The low CFJ jet velocity is beneficial to reduce the noise and the low total pressure ratio is beneficial to achieve the low power requirement at cruise. Comparing the optimum efficiency point of the baseline NACA 6421 airfoil and CFJ airfoil, the CFJ airfoil improves the lift coefficient by 30%. The aerodynamic efficiency is improved by 60% or more (under 100% pump efficiency) and 40% or more (under 70% pump efficiency). This paper also studies two control laws for cruise control of the CFJ airfoil when the AoA varies: One is to achieve constant injection momentum coefficient, the other is to achieve constant injection total pressure. The latter is preferred for its easier sensor measurement, higher airfoil efficiency, and higher stall AoA. The numerical simulations employ the intensively validated in house FASIP CFD code, which utilizes a 3D RANS solver with Spalart-Allmaras (S-A) turbulence model, 3rd order WENO scheme for the inviscid fluxes, and 2nd order central differencing for the viscous terms. Nomenclature CF J Co-flow jet AoA Angle of attack LE Leading Edge

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Co-Flow Jet Airfoil Trade Study Part II: Moment and Drag

Cited by 21 publications

References 25 publications

Performance and Energy Expenditure of Coflow Jet Airfoil with Variation of Mach Number

Performance and Energy Expenditure of Coflow Jet Airfoil with Variation of Mach Number

Performance Characteristics of Fluidic-Based Thrust Augmentation Using a Slot Jet for Unmanned Aerial Vehicle Propulsion

Study of Mach Number Effect for 2D Co-flow Jet Airfoil at Cruise Conditions

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