Stereoscopic PIV measurements in a turbofan engine inlet with tailored swirl distortion

Guimarães, Tamara; Lowe, K. Todd; Nelson, Michael A.; O’Brien, Walter F.; Kirk, Caroline

doi:10.2514/6.2015-2866

Cited by 15 publications

(4 citation statements)

References 5 publications

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“…A new approach to swirl pattern generation, the StreamVane TM , has been developed 4 to capitalize on emerging additive manufacturing capabilities to produce user-specified, complex inlet velocity fields and flow angularity. 5 Resultantly, StreamVanes offer a rapid and cost effective solution to generate complex swirl patterns with a simple device.…”

Section: Introductionmentioning

confidence: 99%

Computational and Experimental Evaluation of a Complex Inlet Swirl Pattern Generation System

Sanders¹,

Nessler²,

Copenhaver³

et al. 2016

52nd AIAA/SAE/ASEE Joint Propulsion Conference

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An assessment was conducted to determine the suitability of subscale, low-Mach-number, particle image velocimetry (PIV) testing and computational fluid dynamics (CFD) analysis to evaluate swirling flow downstream of a swirl pattern generation system composed of continuous patterns of turning vanes. Successful demonstration of the evaluation methods required acceptable comparison of the PIV and CFD to an independent five-hole probe measurement performed at the design Mach number and full-scale geometry. The focus of the investigation was on direct comparison of flow angles and flow features one diameter downstream of the swirl pattern generator. Both the subscale PIV and the CFD provide adequate representation of the swirling flow produced by the full-scale generator. The subscale PIV and CFD may be used to predict the performance of the full-scale swirl pattern generator and allow for inexpensive testing and analysis to be performed during the design process, thus improving the accuracy of generating a desired swirl pattern.

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Section: Introductionmentioning

confidence: 99%

Computational and Experimental Evaluation of a Complex Inlet Swirl Pattern Generation System

Sanders¹,

Nessler²,

Copenhaver³

et al. 2016

52nd AIAA/SAE/ASEE Joint Propulsion Conference

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“…We approach this analysis presuming that the dominant effect of turbulent motions is turbulent diffusion of the secondary flow profile generated immediately downstream of the vanes. A number of factors influence the magnitude of the diffusion, including mixing from wakes of the turning vanes, shear-driven turbulence from velocity gradients in the swirl pattern, and azimuthal stretching due to the bulk swirl induced potential field of the rotor [21].…”

Section: Resultsmentioning

confidence: 99%

“…A thousand images are acquired with a 7 ls delay at 4 Hz for each position of the StreamVane, which is rotated 30 deg counterclockwise between measurements to allow for some overlap in order to improve statistics. The measurements are obtained and processed in LaVision DaVis 8.3.3, and the slices of data are further processed and stitched together through polar binning [21] in MATLAB. The images are processed using stereo cross-correlation with background subtraction and time filter subtraction based on a Gaussian average of nine images. Multipass processing is used, with the first pass consisting of a square window of 64 Â 64 pixels with a 50% overlap.…”

Section: Introductionmentioning

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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“…This nonuniform flow developed in a straight connecting duct before being ingested by the turbofan. The StreamVane method has been previously proven to accurately generate specific swirl distortion for both wind tunnel [18] and turbofan engine [19][20][21] testing. To mitigate the risk of stalling/surging the fan compression system under the distorted flow conditions, the fan speed was limited to 65% design maximum, corresponding to an inlet mass flow rate of approximately 45 lbm/s (20 kg/s) and fan inlet Mach number of approximately 0.3.…”

Section: Experimental Methodsmentioning

confidence: 99%

Experimental Quantification of Fan Rotor Effects on Inlet Swirl Using Swirl Distortion Descriptors

Frohnapfel

Lowe

O’Brien

2018

Journal of Engineering for Gas Turbines and Power

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The prominence of highly integrated engine/airframe architectures in modern commercial aircraft design concepts has led to significant research efforts investigating the use of conventional turbofan engines in unconventional installations where severe inlet distortions can arise. In order to determine fan rotor capabilities for reducing or eliminating a complex inlet swirl distortion, an experimental investigation using a StreamVaneTM swirl distortion generator was conducted in a turbofan engine research platform. Three-dimensional (3D) flow data collected at two discrete planes surrounding the fan rotor indicated that the intensity of the swirl distortion was decreased by the fan rotor; however, substantial swirl distortion effects remained in the fan exit flow. Flow angle magnitudes and swirl intensity (SI) decreased by approximately 30–40% across the fan rotor, while the presence of large-scale features within the distortion profile was nearly eliminated. Secondary flow streamlines indicated that small-scale features of the distortion were less affected by the rotating component and remained coherent at the fan rotor outlet plane. These results led to the conclusion that swirl distortion survived interactions with the fan rotor, leading to off-design conditions cascading through downstream engine components.

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Stereoscopic PIV measurements in a turbofan engine inlet with tailored swirl distortion

Cited by 15 publications

References 5 publications

Computational and Experimental Evaluation of a Complex Inlet Swirl Pattern Generation System

Computational and Experimental Evaluation of a Complex Inlet Swirl Pattern Generation System

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

Experimental Quantification of Fan Rotor Effects on Inlet Swirl Using Swirl Distortion Descriptors

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