Reynolds number and fan/inlet coupling effects on subsonic transportinlet distortion

Motycka, D.

doi:10.2514/3.22785

Cited by 27 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other previous investigations have included a spinner geometry 12,14 , but without any representation of the fan blades. Therefore the potentially American Institute of Aeronautics and Astronautics stabilising effects of the fan 22,23 are not accounted for, and the distortions measured in these experiments represent the intrinsic flow instabilities generated within the duct.…”

Section: A Test Casesmentioning

confidence: 99%

Convoluted Intake Distortion Measurements Using Stereo Particle Image Velocimetry

et al. 2017

View full text Add to dashboard Cite

The unsteady distorted flow fields generated within convoluted aero-engine intakes can compromise the engine performance and operability. Therefore there is a need for a better understanding of the complex characteristics of the distorted flow at the exit of S-shaped intakes. This work presents a detailed analysis of the unsteady swirl distortion based on synchronous, high spatial resolution measurements using stereoscopic particle image velocimetry. Two S-duct configurations with different centerline offsets are investigated. The high offset duct shows greater levels of dynamic and steady swirl distortion and a notably greater tendency towards bulk swirl patterns associated with high swirl distortion. More discrete distortion patterns with locally high swirl levels and the potential to impact the engine operability are identified. The most energetic coherent structures of the flow field are observed using proper orthogonal decomposition. A switching mode is identified which promotes the alternating swirl switching mechanism and is mostly associated with the occurrence of potent bulk swirl events. A vertical mode which characterizes a perturbation of the vertical velocity field promotes most of the twin swirl flow distortion topologies. It is postulated that it is associated with the unsteadiness of the centerline shear layer. Nomenclature a = POD temporal coefficient, m/s

show abstract

Section: A Test Casesmentioning

confidence: 99%

Convoluted Intake Distortion Measurements Using Stereo Particle Image Velocimetry

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Typically the engine has a stabilising effect by delaying flow separation and reducing flow distortion generated within the intake, as reported for example by Motycka [27] and Hodder [28]. Therefore it is generally assumed that tests of isolated intakes provide a conservative measure of the distortion levels [27]. The results presented in this work hence represent the intrinsic flow instabilities generated within the S-duct in the absence of the engine turbomachinery.…”

Section: Stereo Particle Image Velocimetrymentioning

confidence: 87%

“…However, it is worth noting that the presence of the engine downstream of the intake is expected to have an effect on the upstream flow field. Typically the engine has a stabilising effect by delaying flow separation and reducing flow distortion generated within the intake, as reported for example by Motycka [27] and Hodder [28]. Therefore it is generally assumed that tests of isolated intakes provide a conservative measure of the distortion levels [27].…”

Section: Stereo Particle Image Velocimetrymentioning

confidence: 99%

Assessment methods for unsteady flow distortion in aero-engine intakes

Gil-Prieto

MacManus

Zachos

et al. 2018

Aerospace Science and Technology

View full text Add to dashboard Cite

Peak events of unsteady total pressure and swirl distortion generated within S-duct intakes can affect the engine stability, even when within acceptable mean distortion levels. Even though the distortion descriptors have been evaluated in S-duct intakes, the associated flow field pattern has not been reported in detail. This is of importance since engine tolerance to distortion is usually tested with representative patterns from intake tests replicated with steady distortion generators. Despite its importance in intake/engine compatibility assessments, the spectral characteristics of the distortion descriptors and the relationship between peak unsteady swirl and both radial and circumferential total pressure distortion has not been assessed previously. The peak distortion data is typically lowpass filtered at a frequency associated with the minimum response time of the engine. However the engine design is not always known a priori in intakes investigations and a standard approach to reporting peak distortion data is needed. In addition, expensive and time-consuming tests are usually required to capture representative extreme distortion levels. This work presents a range of analyses based on Delayed Detached-Eddy Simulation and Stereo Particle Image Velocimetry data to assess these aspects of the unsteady flow distortion. The distorted pattern associated with different swirl distortion metrics is identified based on a conditional averaging technique, which indicates that the most intense swirl events are associated with a single rotating structure.. The main frequencies of the flow distortion descriptors in a representative S-duct intake are found to lie within the range in which the engine stability may be compromised. The peak total pressure and swirl distortion events are found to be not synchronous, which highlights the need to assess both types of distortion. Peak swirl and total-pressure distortion data is reported as a function of its associated time scale in a more general way that can be used in the assessment of intake unsteady flow distortion. Extreme Value Theory has been applied to predict peak distortion values beyond those measured in the available dataset, and whose measurement would otherwise require testing times two orders of magnitude longer than those typically considered.

show abstract

“…In addition to predicting correct size and location of flow separations, distortion levels at the fan face are also desired to assess maximum acceptable limits and intake suitability. Hall and Hynes [4,5], Motycka [38] and Longley and Greitzer [39] have studied inlet distortion effects experimentally, in addition to CFD of inlet distortions by Cao et al [40], Colin et al [6] and Peters et al [41]. These have been studied in a variety of flow conditions.…”

Section: Aero-engine Crosswind Flowsmentioning

confidence: 99%

Numerical Modelling of Shock Wave Boundary Layer Interactions in Aero-Engine Intakes at Incidence

Kalsi

Tucker

2018

Volume 1: Aircraft Engine; Fans and Blowers; Marine

View full text Add to dashboard Cite

During situations of high incidence, high curvature of aero-engine intake lips can locally accelerate flow to supersonic speeds, producing undesirable shock wave boundary layer interactions (SWBLIs). The present work describes simulations of a novel experimental model resembling a lower intake lip at incidence. RANS, LES and hybrid RANS-LES are carried out at two angles of attack, α = 23° and α = 25°, with α = 25° possessing a high degree of shock oscillation. Modifications to the Spalart-Allmaras (SA) RANS turbulence model are proposed to account for re-laminarisation and curvature. These provide an improvement in prediction compared standard SA model. However, RANS models fail to reproduce post shock interaction flow, giving incorrect shape of the flow distortion. LES and hybrid RANS-LES perform well here, with downstream flow distortion in very good agreement with experimental measurements. LES and hybrid RANS-LES also capture the time averaged smearing of the shock which RANS cannot. However, low frequency shock oscillations in the α = 25° case are costly for LES, requiring long simulation time to obtain time averaged flow statistics. Hybrid RANS-LES offers a significant saving in computational cost, costing approximately 20% of LES.

show abstract

Reynolds number and fan/inlet coupling effects on subsonic transportinlet distortion

Cited by 27 publications

References 0 publications

Convoluted Intake Distortion Measurements Using Stereo Particle Image Velocimetry

Convoluted Intake Distortion Measurements Using Stereo Particle Image Velocimetry

Assessment methods for unsteady flow distortion in aero-engine intakes

Numerical Modelling of Shock Wave Boundary Layer Interactions in Aero-Engine Intakes at Incidence

Contact Info

Product

Resources

About