Serpentine Diffuser Performance with Emphasis on Future Introduction to a Transonic Fan

Nessler, Chase; Copenhaver, William W.; List, Michael G.

doi:10.2514/6.2013-219

Cited by 7 publications

(3 citation statements)

References 9 publications

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“…Returning to the internal flow field, another important characteristic of S-duct flows is the presence of a loss in total pressure due to separation inside of the duct, particularly that from the second turn, as noted by Wellborn et al [32], Nessler et al [33], and Sanders and List [34], for example. Total pressure was calculated using equation (8), which is identical to equation ( 5), but solved for total pressure.…”

Section: Streamwise Vorticitymentioning

confidence: 96%

Geometric scattering removal in cross-correlation Doppler global velocimetry by structured illumination

Boyda¹,

Byun²,

Saltzman³

et al. 2020

Meas. Sci. Technol.

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The biases introduced by background light contributions in planar, Doppler-based velocimetry are significantly reduced by the application of structured illumination. The method works by measuring and separating desired flow-scattered signals from unwanted reflections and secondary scattering contributions via a sinusoidal intensity modulation across the laser sheet used to interrogate the flow. In the current work we consider the influence of background light on cross-correlation Doppler global velocimetry (CC-DGV) and present the results for measurements in a turbulent free jet with an exit Mach number of 0.5 in a measurement arrangement with high intensity background contributions. It is shown that if the ratio of the particle-scattering (i.e. Mie scattering) intensity to the background solid surface scattering (i.e. geometric scattering) intensity is greater than 10, then the measured signal displays a significant bias away from the true velocity. With structured illumination, the measured intensity corresponding to geometric scattering is reduced to negligible levels, reminiscent of a measurement arrangement with little or no background light influence. Centreline velocity measurements with this background subtraction method are compared with Kiel-type pressure probe measurements, yielding a root-mean-square (RMS) difference between the two of 1.2 m s -1 (less than 1% of the full scale velocity), well within the published uncertainty bound of the CC-DGV technique, underscoring the robustness of this approach. In addition to the centreline validation, the streamwise vorticity and total pressure are also analysed, showing trends indicative of the S-type shape of the duct and aggressive flow entrainment experienced in this environment.

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Section: Streamwise Vorticitymentioning

confidence: 96%

Geometric scattering removal in cross-correlation Doppler global velocimetry by structured illumination

Boyda¹,

Byun²,

Saltzman³

et al. 2020

Meas. Sci. Technol.

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“…Experimental data is, however, necessary for the validation and optimization of the CFD setup. As an example, Vakili et al (1983) present wind tunnel data on a basic s-duct geometry and Nessler et al (2013) concentrate on a test case with a more complex duct geometry. Delot and Scharnhorst (2013) compare the numerical solution, obtained with ten different CFD flow solvers, with experimental results presented by Wellborn et al (1992).…”

Section: Introductionmentioning

confidence: 99%

Influence of Varying Free-Stream Turbulence on S-Duct Aerodynamics

Rademakers

Pohl

Brehm

et al. 2017

European Conference on Turbomachinery Fluid Dynamics and Hermodynamics

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Computational fluid dynamics (CFD) simulations are often used in the design process of s-shaped engine inlet ducts. The results of such simulations need to be compared with experimental data for validation purposes. In contrast to turbulence models, the numerical boundary conditions for turbulence (i.e. intensity and length scale) are rarely considered when CFD for s-duct simulations are validated. However, during earlier work at the Institute of Jet Propulsion it was found that numerical turbulence settings can have a significant influence on the aerodynamics in an engine inlet system. Hence, an experimental setup was established to evaluate these findings. The experimental results show that increasing free-stream turbulence significantly influences the internal duct flow and thus the distortion at the inlet plane of the compressor system. For the presented test case the mean total pressure loss at the compressor intake plane increases, which may have has a negative effect on compressor performance. On the other hand the distortion described by common descriptors is reduced, which is generally advantageous in terms of compressor stability. The results from the numerical simulations qualitatively agree with the experimentally obtained data. KEYWORDS Free-stream turbulence, s-duct aerodynamics, compressor inflow distortion NOMENCLATURE Symbols c p,stat [−] static wall pressure coefficient ∆c p,stat [−] wall pressure difference between top and bottom side c pt,loss [−] total pressure loss coefficient CDI [−] circumferential distortion intensity DC60 [−] 60 •-segment distortion coefficient p t,rel [−] relativ total pressure T u 0,I [%] free-stream turbulence intensity T u L [mm] turbulence length scale x, y, z [mm] cartesian coordinates ∆x ref [mm] axial distance between the turbulence grid and the reference plane Abbreviations AIP aerodynamic interface plane CFD computational fluid dynamics RANS Reynolds-averaged Navier-Stokes (S)ETF (scaled) engine test facility UAS unmanned aerial system

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“…discusses best practices for turbomachinery meshes in STAR-CCM+, as well as the mesh generation process and troubleshooting of errors in the mesh. The best practices discussed are taken from a combination of the STAR-CCM+ manual, turbomachinery specialists at CD-Adapco and Nessler and Sanders[9] [10]. Although the recommendations and best practices outlined in this section are intended for STAR-CCM+, many of the principles can be applied to any turbomachinery CFD mesh.…”

mentioning

confidence: 99%

Implementation of Fourier methods in CFD to analyze distortion transfer and generation through a transonic fan

Peterson¹,

Gorrell²,

List³

et al. 2016

52nd AIAA/SAE/ASEE Joint Propulsion Conference

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Inlet flow distortion is a non-uniform total pressure, total temperature, or swirl (flow angularity) condition at an aircraft engine inlet. Inlet distortion is a critical consideration in modern fan and compressor design. This is especially true as the industry continues to increase the efficiency and operating range of air breathing gas turbine engines. The focus of this paper is to evaluate the Computational Fluid Dynamics (CFD) Harmonic Balance (HB) solver in STAR-CCM+ as a reduced order method for capturing inlet distortion as well as the associated distortion transfer and generation. New methods for quantitatively describing and analyzing distortion transfer and generation are investigated. The geometry used is the rotor 4 fan geometry, consisting of one rotor and one stator. The inlet boundary condition is a 90 • sector total pressure distortion profile with total pressure and swirl held constant. Multiple HB simulations with varying mode combinations and distortion intensities are analyzed and compared against full annulus Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations. Best practices and recommendations for the implementation of the HB solver are given. The pre-existing Society of Automotive Engineers Aerospace Recommended Practice (SAE-ARP) 1420b descriptors are demonstrated to be inadequate for the purposes of analyzing distortion transfer and generation on a stage-to-stage basis. New implementations of Fourier methods are presented as an alternative to the SAE-ARP 1420b descriptors. These Fourier descriptors are shown to describe distortion transfer and generation to a higher degree of fidelity than the SAE-ARP 1420b descriptors. These new descriptors are demonstrated on the analysis of full annulus URANS and HB simulations. The HB solver is shown to be capable of capturing distortion transfer, generation and performance degradation. Recommendations for the optimal implementation of the HB method are given.

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Serpentine Diffuser Performance with Emphasis on Future Introduction to a Transonic Fan

Cited by 7 publications

References 9 publications

Geometric scattering removal in cross-correlation Doppler global velocimetry by structured illumination

Geometric scattering removal in cross-correlation Doppler global velocimetry by structured illumination

Influence of Varying Free-Stream Turbulence on S-Duct Aerodynamics

Implementation of Fourier methods in CFD to analyze distortion transfer and generation through a transonic fan

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