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Research Papers: Gas Turbines: Turbomachinery

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

[+] Author and Article Information
Tamara Guimarães

Turbomachinery and Propulsion
Research Laboratory,
Department of Mechanical Engineering,
Virginia Tech,
Blacksburg, VA 24061
e-mail: tgbucalo@vt.edu

K. Todd Lowe

Kevin T. Crofton Department of Aerospace
and Ocean Engineering,
Virginia Tech,
Blacksburg, VA 24061
e-mail: kelowe@vt.edu

Walter F. O'Brien

Turbomachinery and Propulsion
Research Laboratory,
Department of Mechanical Engineering,
Virginia Tech,
Blacksburg, VA 24061
e-mail: walto@vt.edu

1Corresponding author.

Contributed by the Turbomachinery Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received October 5, 2017; final manuscript received November 7, 2017; published online May 14, 2018. Editor: David Wisler.

J. Eng. Gas Turbines Power 140(8), 082606 (May 14, 2018) (10 pages) Paper No: GTP-17-1545; doi: 10.1115/1.4039179 History: Received October 05, 2017; Revised November 07, 2017

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.

Copyright © 2018 by ASME
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References

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Figures

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Fig. 1

Left: NASA's HWB aircraft concept (Image courtesy of NASA Langley). Right: swirl angle distortion profile resulting of a computational fluid dynamics (CFD) simulation of the flow in the inlet of an engine in a similar configuration as one on a HWB aircraft.

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Fig. 2

Left: CFD profile of the secondary velocities in the inlet of a HWB turbofan engine. Right: the HWB StreamVane distortion generator based on this profile [13].

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Fig. 3

Measurement planes along research engine inlet, located at 1.15, 0.44, and 0.27 diameters upstream of the fan face. The StreamVane is positioned at 1.68 diameters upstream of the fan face.

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Fig. 4

Experimental setup for measurements of the flow on the research engine

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Fig. 5

Left: measurement volume for two rotations in the 1.15 and 0.44D planes, and positive orientation of radial and azimuthal velocity components. Right: measurement volume for full rotation in the 0.27D plane.

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Fig. 6

Secondary velocity profile for the design and measurement plane cases. Lines represent the mean direction of the flow and the color plot shows the velocity intensities, normalized by the average bulk axial velocity.

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Fig. 7

Normalized streamwise vorticity profiles for the measured planes. Vorticity is normalized by duct diameter and average bulk axial velocity.

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Fig. 8

Comparison between the streamwise vorticity at the 0.27D (black), 0.44D (red) and 1.15D (blue) measurement planes at r/R = 0.8 (1), 0.86 (2), and 0.92 (3)

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Fig. 9

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 engine

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Fig. 10

Normalized axial velocity profile. Note different scale between design plot and experimental results, for highlighting present features in both.

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Fig. 11

Normal component of the Reynolds stress tensor for the axial velocity uz′uz′¯, normalized by the axial average bulk velocity, uz2¯

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Fig. 12

Normal component of the Reynolds stress tensor for the radial velocity ur′ur′¯, normalized by the axial average bulk velocity, uz2¯

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Fig. 13

Normal component of the Reynolds stress tensor for the azimuthal velocity uθ′uθ′¯, normalized by the axial average bulk velocity, uz2¯

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Fig. 14

Axial velocity gradient in the radial direction, (∂uz/∂r)

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Fig. 15

Axial velocity gradient in the azimuthal direction, ((1/r)(∂uz/∂θ)

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Fig. 16

Shear component of the Reynolds stress tensor between the axial and radial velocities ur′uz′¯, normalized by the axial average bulk velocity, uz2¯

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Fig. 17

Shear component of the Reynolds stress tensor between the azimuthal and axial velocities uθ′uz′¯, normalized by the axial average bulk velocity, uz2¯

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Fig. 18

Shear component of the Reynolds stress tensor between the radial and azimuthal velocities ur′uθ′¯, normalized by the axial average bulk velocity, uz2¯

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