Swirling Flow Evolution Part 2: StreamFlow 2D+t Model Validated with Stereo PIV Measurements

Schneckiii, William C.; Guimarães, Tamara; Frohnapfel, Dustin J.; Lowe, K. Todd; O’Brien, Walter F.; Copenhaver, William W.

doi:10.2514/6.2017-1622

Cited by 12 publications

(4 citation statements)

References 15 publications

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“…They seem to mix quite quickly, and are almost unobservable at the 1.50D plane. The small-scale data have previously been successfully compared to an inviscid and incompressible low order flow development model, in which the in-plane velocity set as the initial condition was determined from the same goal profiles used to design the experimental distortion screen, and the axial development of the flow was treated as the time evolution of the profile [35]. The similarities of the small-scale flow with the full-scale experiment indicate that there are no further physics that need to be described for the higher Reynolds number flow that is far enough upstream of the engine fan face and outside of the duct inner-diameter boundary layer.…”

Section: Resultsmentioning

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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Section: Resultsmentioning

confidence: 99%

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

2019

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“…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]. This makes the StreamVane an effective tool in generating distortions.…”

Section: Introductionmentioning

confidence: 94%

“…Predicted development of experimental flow at the 1.15D plane (top), and at the 0.44D plane (bottom), using the StreamFlow model[20] compared to the experimental data from the engineFig. 10Normalized axial velocity profile.…”

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confidence: 99%

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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“…The target profile (at the AIP) was used to produce a corresponding profile at the StreamVane TM trailing edge, using StreamFlow, a computational method developed at Virginia Tech. A conceptually similar technique, operating on a pressure-velocity formulation and utilizing the open-source CFD code OpenFOAM, can be found at [16]. While the method described was effective at solving the forward problem (producing a downstream AIP profile based on a known StreamVane TM exit profile), it was not suitable for directly solving the inverse problem (finding the necessary StreamVane TM exit profile to produce a desired AIP profile) due to numerical instability.…”

Section: Streamvane Design Using Cfdmentioning

confidence: 99%

Swirl Distortion Using Stream Vanes for Boundary Layer Ingestion Research

Stephens

Celestina

Hughes

2019

Volume 2A: Turbomachinery

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The swirl distortion of a StreamVane™ was investigated in the NASA Glenn Research Center W8 test facility. The StreamVane™ was designed and generated by Virginia Tech based on CFD simulations and included a center body at the aerodynamic interface plane. The swirl pattern generated by the distortion was evaluated using a dense grid of 5-hole Pitot probe measurements captured using a rotating array of probes. Good agreement was found between the design intent and the results at 38.5 kg/s mass flow. The StreamVane™ swirl results were compared to clean facility flow at 5 inlet mass flows and found to be consistent. Additionally, the axial location of the StreamVane™ relative to the measurement plane was investigated to determine the impact on downstream total pressure loss generated by the vanes. The intent of this work was to assess the viability of using a StreamVane™ to generate a Type I or Type II distortion into a Boundary Layer Ingesting propulsor to assess its aerodynamic performance and aeromechanic response.

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Swirling Flow Evolution Part 2: StreamFlow 2D+t Model Validated with Stereo PIV Measurements

Cited by 12 publications

References 15 publications

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

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

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

Swirl Distortion Using Stream Vanes for Boundary Layer Ingestion Research

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