System-Level Trade Studies for Transonic Transports with Active Flow Control (AFC) Enhanced High-Lift Systems

Hartwich, Peter; Camacho, Peter; El-Gohary, Kareem; Gonzales, Antonio B.; Lawson, Edward L.; Shmilovich, Arvin

doi:10.2514/6.2017-0321

Cited by 20 publications

(7 citation statements)

References 6 publications

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“…Moreover, the fuel burn may be reduced by 2.25% with an AFC system applied to a simplified high-lift configuration (Hartwich et al 2017), accompanied by an expected noise and drag reduction, once the slat and flap tracks, and the slots between high lift devices and the main element from conventional systems are eliminated (Delfs et al 2017;Lin et al 2019). Assuming that a wing equipped with an AFC system substitutes a single slotted flap for a hinged plain one, the negative effect of weight additions due to the redundancies of the AFC system is compensated by the benefits of the simplification of the flap system (Hartwich et al 2017). Therefore, a configuration with an AFC system is comparable in weight to a single slotted multi-element one.…”

Section: Overviewmentioning

confidence: 99%

Numerical Study of Flow Control on Simplified High-Lift Configurations

2023

JAFM

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Enhancement in the aerodynamic performance of wings and airfoils is very notable when Active Flow Control (AFC) is applied to Short Take-off and Landing aircraft (STOL). The present numerical study shows the application of steady, pulsed and synthetic tangential jets applied to the plain flap shoulder of a modified NASA Trapezoidal Wing. Pulsed jets are modeled by sinusoidal and square waveforms while synthetic jets are modeled only by pure sine waveform. The freestream airflow conditions are Mach number equal to 0.2 and Reynolds number equal to 4.3 million based on the mean aerodynamic chord. The presented simulations are two-dimensional and based on RANS for steady jet cases and URANS for pulsed and synthetic cases, compiled with the open-source suite SU2 and adapted for time varying boundary conditions. Numerical results for modified configurations based on the same baseline wing profile considering different leading edges, jet slot height, flap position, blowing mass flow, type and frequency of the jets are presented. Curves of pressure coefficient distribution revealed a substantial influence upstream of the AFC, around the slat and main element. The jet slot height analysis showed that the lift gain is also influenced by the slot size due to the change of the local flow velocity considering the same blowing momentum coefficient. Regarding the jet frequency, no significant differences on the lift coefficients were found between the reduced frequencies F+ equal to 1 and 2. Results of aerodynamic loads showed an improved lift coefficient in relation to the baseline airfoil when pulsed and steady jets are employed. Pulsed jets under square waveform were effective even at high deflected flap condition at 50°, with a significant gain in the lift coefficient of 36%, in relation to the uncontrolled case, combined with a drag reduction of 20%, and a decrease in mass flow up to 49% in relation to the steady jet for the same lift gain. Although sine and square waveform results presented similar improvements for lift, the drag is around 15% higher for the former. When compared with the steady jet case, the mass flow reduction is 36% for the sinewave. Synthetic jets with zero-net-mass-flux proved superior to the baseline conventional multi-element airfoil only with deployed flap at 50°, where a modest lift improvement of 5% was observed.

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Section: Overviewmentioning

confidence: 99%

Numerical Study of Flow Control on Simplified High-Lift Configurations

2023

JAFM

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“…(1) The massive flow separation on the flap at large deflections limits the lift performance (Aley et al, 2020;Chu et al, 2012), and the Fowler flap has no effective technical measures to eliminate separation; (2) Positions of the flap side edge and external fairing, as well as flow phenomena such as separation vortexes and boundary layer mixing of the main element and flap, are sources of airframe noise (Ma et al, 2020;Zhang, 2010); (3) Retraction/extension mechanisms of the Fowler flap increase both the operating empty weight and cruise excrescence drag. Studies have shown that removing external fairings can reduce the overall cruise drag by up to 3.3 counts (1 count = 0.0001), resulting in fuel savings of 2.25% (Hartwich et al, 2014(Hartwich et al, , 2017.…”

Section: Introductionmentioning

confidence: 99%

Numerical study on technical and conceptual improvements to a civil aircraft trailing-edge flap using passive/active flow control

Wang

Zhang

2021

Engineering Applications of Computational Fluid Mechanics

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Future civil aircrafts require simple, low-noise, and highly efficient trailing-edge flaps. In this study, a detailed numerical study for flap improvements using steady and unsteady Reynolds-averaged Navier-Stokes computations was conducted. A movable trailing edge (MTE) was applied to the main element as a passive flow control method to improve the traditional Fowler flap. A new concept of a backward seamless flap (BSLF) based on the MTE configuration is proposed, which can eliminate external fairings, simplify the mechanisms, and reduce the cruise drag. Then, a wall jet active flow control method was used to improve the BSLF. The improvement effect, flow mechanism, and parameter influences were investigated in detail. The results indicated that the MTE can increase the lift coefficient in the linear segment by 1.2-1.4 for an aerofoil and 0.79 for a wing by controlling the slot flow, energy distribution, and circulation. Moreover, the BSLF provided an improvement in performance higher than 27% over the plain flap, and the wall jet controlled BSLF configuration could reach or even exceed the MTE configuration in terms of performance. The zero-mass jet had a higher control effect and efficiency than the continuous jet. This study highlighted the significance and engineering value for technical improvement and concept exploration of new-generation high-lift devices.

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“…The NASA Advanced Air Transport Technology (AATT) Project is seeking to demonstrate the potential benefits of reducing the cruise drag (and therefore fuel burn) associated with modern high-lift systems without sacrificing aerodynamic and acoustic performance during takeoff and landing operations. One possible approach is to use active flow control (AFC) [2,3] to provide the required low-speed lift performance while reducing the cruise drag associated with the external mechanisms used to deploy a conventional slotted flap (Fowler flap) during high-lift operations [4,5].…”

Section: Introductionmentioning

confidence: 99%

“…A recent system integration study by Hartwich et al [5,6] indicated that up to a 2.25% fuel burn reduction is possible if an AFC-enabled simplified high-lift system (i.e., simple hinged flaps inboard and outboard) could provide the necessary lift at the approach angle of attack. The AFC-related performance gains are primarily due to the 3.3-count excrescence drag reduction from the removal of the external fairings for the Fowler flap mechanism [7] (see Fig.…”

Section: Introductionmentioning

confidence: 99%