StreamVane Turbofan Inlet Swirl Distortion Generator: Mean Flow and Turbulence Structure

Guimarães, Tamara; Lowe, K. Todd; O’Brien, Walter F.

doi:10.2514/1.b36422

Cited by 18 publications

(13 citation statements)

References 33 publications

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“…More recently, 3D printing techniques have been used for the generation of pressure profiles, to simulate the operation of the intake with a thick boundary layer profile [19]. Methods with CFD and experimental calibrations showed the possibility to reproduce swirl patterns [20], generalized pressure distortions [21] and combined pressure and swirl distortion [22]. There is little previous work on the effect of the different inlet boundary layer heights to the unsteady flow distortion at the aerodynamic interface plane of an S-duct intake.…”

Section: Introductionmentioning

confidence: 99%

The impact of inlet boundary layer thickness on the unsteady aerodynamics of S-duct intakes

Migliorini

Zachos

MacManus

2019

AIAA Propulsion and Energy 2019 Forum

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The need to reduce aero-engine emissions and direct operating costs is driving the civil aerospace sector towards considering more integrated propulsion systems. Many of the proposed novel aircraft architectures employ convoluted intakes for either the aero-engine or propulsion system. These intakes are characterized by unsteady distortion that can hinder the performance and operability of the propulsion system. This work assesses the impact of the inlet boundary layer on the unsteady aerodynamics of an S-duct intake using time-resolved particle image velocimetry at the aerodynamic interface plane. An increase in the boundary layer thickness at the intake inlet increases the flow unsteadiness on the swirl angle by up to 40% relative to the baseline case. The azimuthal orientation of the inlet boundary layer modifies the intensity and topology of the most frequent swirl distortion pattern. For a relatively thick inlet boundary layer, the reduction of the dominant frequencies associated with the unsteady swirl angle is postulated to be beneficial for the engine stability. Overall, this works gives guidelines for the integration between the intake and the engine across the range of potential inlet operating conditions.

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Section: Introductionmentioning

confidence: 99%

The impact of inlet boundary layer thickness on the unsteady aerodynamics of S-duct intakes

Migliorini

Zachos

MacManus

2019

AIAA Propulsion and Energy 2019 Forum

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“…gradients. The Reynolds shear stresses, u 0 i u 0 j =u 2 z ; i 6 ¼ j, presented in Figs [16][17][18]. exhibit structures that can be related with the ones of the gradients of the axial velocity component presented in…”

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confidence: 79%

“…Here, the StreamVane TM technology [13,17] is used to generate a distortion profile inspired by the base distortion features of an extreme flight condition for an experimental design of a HWB engine inlet. Prior findings on StreamVane aerodynamics indicate that the dominant secondary flow dynamics are Reynolds number independent [17,18], and that the generation of the distortions is Mach number independent until vanes choke [19]. For low-speed small scale wind tunnel experiments of single vortex distortions, secondary flow development is well-predicted by inviscid dynamics of axial vorticity [20].…”

Section: Introductionmentioning

confidence: 93%

Complex Flow Generation and Development in a Full-Scale Turbofan Inlet

Guimarães

Lowe

O’Brien

2018

Journal of Engineering for Gas Turbines and Power

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The future of aviation relies on the integration of airframe and propulsion systems to improve aerodynamic performance and efficiency of aircraft, bringing design challenges, such as the ingestion of nonuniform flows by turbofan engines. In this work, we describe the behavior of a complex distorted inflow in a full-scale engine rig. The distortion, as in engines on a hybrid wing body (HWB) type of aircraft, is generated by a 21-in diameter StreamVane, an array of vanes that produce prescribed secondary flow distributions. Data are acquired using stereoscopic particle image velocimetry (PIV) at three measurement planes along the inlet of the research engine (Reynolds number of 2.4 × 106). A vortex dynamics-based model, named StreamFlow, is used to predict the mean secondary flow development based on the experimental data. The mean velocity profiles show that, as flow develops axially, the vortex present in the profile migrates clockwise, opposite to the rotation of the fan, and toward the spinner of the engine. The turbulent stresses indicate that the center of the vortex meanders around a preferred location, which tightens as flow gets closer to the fan, yielding a smaller radius mean vortex near the fan. Signature features of the distortion device are observed in the velocity gradients, showing the wakes generated by the distortion screen vanes in the flow. The results obtained shed light onto the aerodynamics of swirling flows representative of distorted turbofan inlets, while further advancing the understanding of the complex vane technology presented herein for advanced ground testing.

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“…A thousand images were acquired in each measurement slice at 4 Hz, with a time delay of 5 µs between the first and second frame of the image. Further details of the setup were previously presented in Guimarães et al [29]. Table 1 summarizes the main properties of the small-scale and the full-scale experiments.…”

Section: Full-scale Testing Rigmentioning

confidence: 99%

Vortical flow development in round ducts across scales for engine inlet applications

2019

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Turbofan engine performance depends highly on the characteristics and conditions of the inlet flow. Swirl distortions, caused by non-uniformities in flows arising from boundary layer or ground/fuselage vortex ingestion are of concern and need to be fully understood to guarantee efficiency and safety of propulsion systems. To investigate a fundamental single-vortex distortion development in a duct at different Reynolds numbers, a StreamVane distortion generating device was designed and experimentally analyzed in a small-scale low-speed wind tunnel (Re D 500 × 10 3 ) and in a full-scale engine testing rig (Re D 3 × 10 6 ). Stereoscopic particle image velocimetry was used to measure the three-component velocity fields at discrete measurement planes downstream of the distortion device. Results show that the secondary flow is generated and develops very similarly in both scales, and is mostly driven by two-dimensional (2D) vortex dynamics. Induced velocities arising from the proximity of the vortex to the duct wall causes the vortex center to convect circumferentially around the duct, in the same sense as the vortex rotation, as it travels downstream. Small-scale turbulence results show small-scale instabilities related to the development of the vortex. This work shows that the development of this vane-generated, vortex-dominated flow is largely Reynolds number independent for the covered range, so that details of similar duct-bounded flows can be analyzed in depth in small-scale experiments, decreasing development efforts and cost. arXiv:1808.07273v1 [physics.flu-dyn]

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StreamVane Turbofan Inlet Swirl Distortion Generator: Mean Flow and Turbulence Structure

Cited by 18 publications

References 33 publications

The impact of inlet boundary layer thickness on the unsteady aerodynamics of S-duct intakes

The impact of inlet boundary layer thickness on the unsteady aerodynamics of S-duct intakes

Complex Flow Generation and Development in a Full-Scale Turbofan Inlet

Vortical flow development in round ducts across scales for engine inlet applications

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