An Experimental Study of Loss Sources in a Fan Operating With Continuous Inlet Stagnation Pressure Distortion

Gunn, E. J.; Tooze, Sarah E.; Hall, Cesare A.; Colin, Y.

doi:10.1115/1.4007835

Cited by 66 publications

(27 citation statements)

References 17 publications

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“…As a result, the total pressure loss at the outlet plane increased by up to 7% relative to the clean case. Similar conclusions were reached by Gunn et al [20], who measured a 4.6% reduction in fan efficiency due to a 60° sector of total pressure loss. The measurements revealed that the loss in efficiency is due to the fact that the rotor operates at an off-design condition around the entire annulus.…”

supporting

confidence: 88%

Influence of Upstream Total Pressure Profiles on S-Duct Intake Flow Distortion

McLelland

MacManus

Zachos

et al. 2020

Journal of Propulsion and Power

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For some embedded engine arrangements, the nature of the inlet distortion is influenced by the boundary layer characteristics at the inlet plane of the intake. This research presents the first quantitative assessment on the influence of inlet boundary layer thickness and asymmetry on the swirl distortion at the exit of an S-shaped intake. Measurements of high spatial and temporal resolution have been acquired at the outlet plane of the S-duct using time-resolved particle image velocimetry. When boundary layer profiles typical of embedded engines are introduced, the characteristic secondary flows at the outlet plane are intensified. Overall, the peak swirl intensity increases by 40% for a boundary layer which is 7 times thicker than the reference case. The unsteady modes of the S-duct remain, although the dominant fluctuations in the flow arise at a frequency 50% lower. When the inlet boundary layer profile becomes asymmetric about the intake centerline the peak swirl events at the hub are reduced by up to 40%. At the tip the peak swirl intensity increases by 29%. The results demonstrate that the effects of inlet boundary layer thickness and asymmetry must be carefully considered as part of engine compatibility tests for complex intakes. Nomenclature ai(t) = Temporal coefficient for i th mode in Proper Orthogonal Decomposition [ms -1 ] Ain = S-duct inlet plane area [m 2 ] Aout = S-duct outlet plane area [m 2 ] Din = S-duct inlet plane diameter [m]

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supporting

confidence: 88%

Influence of Upstream Total Pressure Profiles on S-Duct Intake Flow Distortion

McLelland

MacManus

Zachos

et al. 2020

Journal of Propulsion and Power

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“…• Co-rotating swirl at the entry of the distortion • Counter-rotating swirl at the exit of the distortion • Alteration and change of shape of the distortion on its way downstream through the compressor • Variation of incidence and blade loading • Mass flow redistribution They were also described by Gunn et al [24], who analysed another fan geometry operating with a continuous inlet stagnation pressure distortion, although their distortion was generated in a different way by a 60 • sector gauze.…”

Section: The Distortion In Generalmentioning

confidence: 94%

Full Annulus Simulations of a Transonic Axial Compressor Stage with Distorted Inflow at Transonic and Subsonic Blade Tip Speed

Haug

Niehuis

2018

IJTPP

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This article reports on systematic numerical studies on an axial compressor stage with distorted inflow. Four operating points at two speedlines were simulated with an inflow distortion generated by a 120 • -sector segment with a wedge-type cross-section. With this setup, the interaction between the distorted inflow and the rotor flow was studied. The focus was put on the differences of the interaction between the distorted inflow and rotor flow as well as on the compressor behaviour at subsonic and transonic blade tip speeds, as the general mechanisms have been analysed in more detail in previous publications. The distorted flow itself is not influenced by the blade tip speed, but the interaction phenomena depend strongly on the spool speed and operating point. Additionally, the blade tip speed influences the circumferential sector of the compressor stage exit, which is affected by the distorted flow. The impact reaches from a small sector at 65% spool speed, with the peak efficiency operating point up to nearly the entire annulus at 100% spool speed, near the stall operating point.

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“…Another study done by Govardhan and Viswanath [12] reports the combined effect of inlet flow distortion and swirl on an axial fan stage and it was found that swirl causes deterioration in performance in addition to that caused by distortion. Gunn et al [13] have conducted experiments on a low speed, low aspect ratio axial fan stage operating under 60° sector inlet total pressure distortion to understand fluid mechanics governing the upstream distortion interaction and distortion transfer through stage. They found substantial flow separation near the tip region in rotor and near the hub region of stator under the influence of distortion and thereby causes reduction in performance of stage.…”

Section: Introductionmentioning

confidence: 99%

Propagation of Different Types of Inflow Distortions through a Contra Rotating Fan Stage

Mistry

Pradeep

2015

International Journal of Turbo &Amp; Jet-Engines

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This paper aims to explain the propagation of different types of inflow distortions through a contra rotating fan stage. Inflow distortions like circumferential, radial and complex distortions were artificially generated using meshes of different porosities. The overall effects of these distortions are determined in the terms of the fan performance map. It is attempted to explain the propagation of inflow distortion using distortion descriptors like circumferential intensity, circumferential extent and radial intensity at the design mass flow rate. These are described for different speed combinations of both the rotors at the inlet, the exit of rotor-1 and at the exit of rotor-2. It is important to observe here that even for purely circumferential inflow distortion, the distortion does not remain purely circumferential, rather it propagates both circumferentially and radially along the stage. For the hub-strong complex inflow distortion, the higher magnitude of circumferential intensity and circumferential extent at the exit of rotor-1 clearly indicates the strong distortion effect that leads to poor performance of the stage amongst all distortion configurations studied. With radial inflow distortion, the radial redistribution of the flow at the exit of rotor-1 plays an important role in the performance of the rotor-2 and thereby for the stage.

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An Experimental Study of Loss Sources in a Fan Operating With Continuous Inlet Stagnation Pressure Distortion

Cited by 66 publications

References 17 publications

Influence of Upstream Total Pressure Profiles on S-Duct Intake Flow Distortion

Influence of Upstream Total Pressure Profiles on S-Duct Intake Flow Distortion

Full Annulus Simulations of a Transonic Axial Compressor Stage with Distorted Inflow at Transonic and Subsonic Blade Tip Speed

Propagation of Different Types of Inflow Distortions through a Contra Rotating Fan Stage

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