The Effect of Incoming Boundary Layer Characteristics On The Performance Of a Distributed Propulsion System

Upadhyay, Puja; Zaman, K. B. M. Q.

doi:10.2514/6.2019-1092

Cited by 4 publications

(5 citation statements)

References 23 publications

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“…Using a simplified distributed propulsion model, the study aims to understand how the incoming flow condition, for example, boundary-layer thickness, influences the overall performance of the system. Preliminary results from this work were presented earlier in a conference paper [31]. With only velocity field data, the effects of ingesting a thicker incoming boundary layer remained inconclusive.…”

Section: Introductionmentioning

confidence: 82%

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Effect of Incoming Boundary-Layer Characteristics on Performance of a Distributed Propulsion System

Upadhyay

Zaman

2021

Journal of Propulsion and Power

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An experimental study is conducted to advance the understanding of flow physics associated with a boundary-layer ingesting, distributed propulsion system. The influence of incoming boundary-layer thickness on the performance of the system is examined. The propulsion model, integrated with electrical fans, is mounted on a flat plate and tested at subsonic speeds. Detailed characterization of the incoming boundary layer and the downstream flowfield is performed using hot-wire anemometry and static pressure measurements. Modification of the boundary layer is achieved by placing trip rods of two different diameters near the leading edge of the flat plate. Overall performance of the system is analyzed by estimating thrust, flow power, and input power to the fans. Ingestion of a thicker boundary layer is found to result in an increase in thrust and net flow power.

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Section: Introductionmentioning

confidence: 82%

“…For the sake of brevity, this paper only focuses on the cases using rods. A curious reader may refer to [31], where the results for the ramps are discussed. The rods are chosen to produce a roughly two-dimensional boundary layer upstream of the inlets and to avoid significant three-dimensional effects.…”

Section: B Measurement Conditions and Techniquesmentioning

confidence: 99%

Effect of Incoming Boundary-Layer Characteristics on Performance of a Distributed Propulsion System

Upadhyay

Zaman

2021

Journal of Propulsion and Power

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“…This layout, known as over-the-wing distributed propulsion [17], can partially mitigate the penalties associated with large OTW propellers [18] and, additionally, enables short takeoff and landing operations when installed on a flap [19]. As a consequence, several studies focusing on the aerodynamic characteristics of an array of small propellers or fans placed over the wing have been performed in recent years [20][21][22].…”

Section: Experimental Investigation Of Over-the-wingmentioning

confidence: 99%

Experimental Investigation of Over-the-Wing Propeller–Boundary-Layer Interaction

et al. 2021

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This experimental study focuses on the aerodynamic interaction between an over-the-wing (OTW) propeller and a wing boundary layer. An OTW propeller is positioned above the hinge line of a wing with a trailing-edge flap. Measurements are carried out with and without axial pressure gradients by deflecting the flap and by extending the flat upper surface of the wing in the streamwise direction, respectively. Surface-pressure taps, microphones, and particle image velocimetry are combined to quantify both the time-averaged and unsteady interaction effects. Results show that the propeller generates an adverse pressure gradient on the wing surface that scales linearly with thrust and decreases with increasing blade-tip clearance. The pressure gradient is partially caused by slipstream contraction, which decelerates the flow near the wall. Additionally, the surface-pressure fluctuations generated beneath the propeller blades and slipstream are stronger than the time-averaged pressure increase due to flow deceleration. Consequently, the propeller triggers flow separation over the hinge line when the flap is deflected. A parametric study of different propeller locations indicates that increasing the tip clearance is not an effective way to mitigate flow separation. However, displacing the propeller half a radius upstream of the hinge line creates a Coandă effect, which allows the flow to remain attached.

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“…Bres et al [22,23] investigated the influence of mesh resolution, inlet conditions, inflow turbulence and wall modeling in LES of supersonic round jets. Some researchers also addressed the effect of incoming turbulence on flow characteristics both experimentally and numerically [24,25]. Hu and Rizzi [26] investigated the transition to turbulence in supersonic and hypersonic nozzles using RANS and highlighted the effect of transition point near throat on the flowfield downstream of the nozzle.…”

Section: Introductionmentioning

confidence: 99%

High-Order Accurate Numerical Simulation of Supersonic Flow Using RANS and LES Guided by Turbulence Anisotropy

Bhide

Abdallah

2022

Fluids

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This paper discusses accuracy improvements to Reynolds-Averaged Navier–Stokes (RANS) modeling of supersonic flow by assessing a wide range of factors for physics capture. Numerical simulations reveal complex flow behavior resulting from shock and expansion waves and so, a supersonic jet emanating from rectangular nozzle is considered. PIV based experimental data for the jet is available from literature and is used for validation purposes. Effect of various boundary conditions and turbulence modeling approaches is assessed qualitatively and quantitatively. Of particular interest are the inlet conditions considering the turbulence intensity and the effect of upstream air supply duct, the effect of nozzle wall surface roughness on nozzle internal flow and downstream, wall y+ sensitivity for boundary layer resolution and laminar to turbulent transition modeling. In addition to mesh sensitivity, domain dependency is conducted to evaluate the appropriate domain size to capture the kinetic energy dissipation downstream of the nozzle. To further improve the flow characteristics, accounting for the anisotropy of Reynolds stresses is also one of the focuses. Therefore, non-linear eddy viscosity-based two-equation model and Reynolds stress transport model are also investigated. Additionally, the results of baseline linear (Boussinesq) RANS are compared. Corresponding comparisons with high-fidelity LES are presented. Jet self-similar behavior resulting from all simulation fidelities is assessed and it appears that turbulent flow in LES becomes self-similar, but not in RANS. Finally, various factors such as the nozzle geometry and numerical modeling choices influencing the anisotropy in jet turbulence are discussed.

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The Effect of Incoming Boundary Layer Characteristics On The Performance Of a Distributed Propulsion System

Cited by 4 publications

References 23 publications

Effect of Incoming Boundary-Layer Characteristics on Performance of a Distributed Propulsion System

Effect of Incoming Boundary-Layer Characteristics on Performance of a Distributed Propulsion System

Experimental Investigation of Over-the-Wing Propeller–Boundary-Layer Interaction

High-Order Accurate Numerical Simulation of Supersonic Flow Using RANS and LES Guided by Turbulence Anisotropy

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