Realistic Inlet Distortion Patterns Interacting with a Transonic Compressor Stage

Wartzek, Fabian; Holzinger, Felix; Brandstetter, Christoph; Schiffer, Heinz-Peter

doi:10.1007/978-3-319-21127-5_17

Cited by 8 publications

(10 citation statements)

References 7 publications

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“…Before entering the rotor, the flow is completely reattached. At all calculated operating points the following features are exhibited by the distortion, as also stated by Lesser and Niehuis (2014) and Wartzek et al (2015). They are also described by Gunn et al (2012), who analyzed another fan geometry operating with a continuous inlet stagnation pressure distortion, although their distortion is generated on a different way by a 60…”

Section: Resultsmentioning

confidence: 59%

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

Haug¹,

Niehuis²

2017

European Conference on Turbomachinery Fluid Dynamics and Hermodynamics

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It is reported on systematic numerical studies on an axial compressor stage with distorted inflow. Four operating points at two speedlines have been 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 is studied. The focus is 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 speed, as the general mechanisms are analyzed 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. Also, 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, peak efficiency operating point up to nearly the entire annulus at 100% spool speed, near stall operating point. KEYWORDS INTRODUCTIONThe design process of new aircraft engines heavily depends on reliable simulation environments, due to demanding and ambitious design goals as defined for instance by the ACARE group in Europe by the European Commission (2011). The requirements on aircraft concerning lower specific fuel consumption and less noise emissions are challenging. Today's modern compressors need to provide higher pressure ratios to achieve higher thermal efficiency while the number of turbomachinery stages and the weight is reduced by the usage of lightweight materials. To obtain this goal with less turbomachinery stages the remaining stages become higher loaded which makes the compressor stages prone to deviations from their designated operating range. Flow distortions induced by the integration and the intake of the jet engine also impact the performance and surge margin of the compressor as investigated by Schnell et al. (2015). As the deviations from the designated operating range are likely to occur in flight situations like high angle of attack or strong crosswinds, the compressor stages have to withstand them without significant loss in surge margin for safety reasons. As the surge margin of compressors decreases with inlet distortions, investigations on the behavior of compressors with distorted inflow are still necessary. Hah et al. (1998) have shown the loss in surge margin in their experimental and numerical studies on the effects of an inflow distortion on an axial compressor stage. While their approach with distortion screens and modified numerical boundary conditions gives insight into the reaction of the compressor on the inflow distortion, the upstream influence of the compressor on the distorted flow cannot be investigated. Requirements for the design process of low pressure compressors and fans are simulation tools capable of resolving strong secondary flow phenomena within turbomachines, the interaction between secondary flow phenomena and inf...

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Section: Resultsmentioning

confidence: 59%

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

Haug¹,

Niehuis²

2017

European Conference on Turbomachinery Fluid Dynamics and Hermodynamics

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“…The rotor runs at a peak efficiency point (10.6kg/s) with 65% rotational speed (1361.31rad/s). Figure 3 compares the performance map from the numerical simulation with the experiment data from Wartzek [10]. The result shows that this mixed-fidelity method can characterize the general trend of the pressure ratio for the cases with a smooth casing and the distortion generator.…”

Section: Mixed-fidelity Methodsmentioning

confidence: 99%

“…where s is the fraction of span. The force is proportional to ρu u u 2 rel and the coefficient k is calibrated using the performance data at the design point from experiments [10]. Further details regarding the implementation of this relation in the compressible Navier-Stokes equations, as well as details concerning blockage models, can be found in [28].…”

Section: Numerical Frameworkmentioning

confidence: 99%

“…Experimental tests [7][8][9] for inlet distortion and fan performance provide details of the flow features which may be used for validation of the simulations. Among these works, Wartzek [10] investigated distortion patterns in a transonic compressor stage and found that the distorted flow from the inlet can cause a global alteration in the downstream fan behavior. To investigate the influence of the fan on the distortion, Cao et al [11] and Mauro Carnevale [12] developed a range of models aimed at reducing the cost of full, three-dimensional (3D) computational fluid dynamics (CFD) simulations.…”

Section: Introductionmentioning

confidence: 99%

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Comparative Studies of RANS Versus Large Eddy Simulation for Fan–Intake Interaction

Vadlamani

Cui

et al. 2018

Journal of Fluids Engineering

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The present research applied a mixed-fidelity approach to examine the fan–intake interaction. Flow separation induced by a distortion generator (DG) is either resolved using large eddy simulation (LES) or modeled using the standard k–ω model, Spalart–Allmaras (SA) model, etc. The immersed boundary method with smeared geometry (immersed boundary method with smeared geometry (IBMSG)) is employed to represent the effect of the fan and a wide range of test cases is studied by varying the (a) height of the DG and (b) proximity of the fan to the DG. Comparisons are drawn between the LES and the Reynolds-averaged Navier–Stokes (RANS) approaches with/without the fan effect. It is found that in the “absence of fan,” the discrepancies between RANS and LES are significant within the separation and reattachment region due to the well-known limitations of the standard RANS models. “With the fan installed,” the deviation between RANS and LES decreases substantially. It becomes minimal when the fan is closest to the DG. It implies that with an installed fan, the inaccuracies of the turbulence model are mitigated by the strong flow acceleration at the casing due to the fan. More precisely, the mass flow redistribution due to the fan has a dominant primary effect on the final predictions and the effect of turbulence model becomes secondary, thereby suggesting that high fidelity eddy resolving simulations provide marginal improvements to the accuracy for the installed cases, particularly for the short intake–fan strategies with fan getting closer to intake lip.

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“…Measurements by Lieser [16] and Bitter [30] show that the compressor perfor-mance is most sensitive to the distortions encountered at the tip. Hence, a periodic distortion generator is placed upstream of the tip of the fan in order to reproduce the distortion encoun- Table 1 and further details of relevant parameters can be found in [19]. The influence of the fan on inlet distortion is investigated using a simplified test case.…”

Section: Numerical Frameworkmentioning

confidence: 99%

A Mixed-Fidelity Numerical Study for Fan-Distortion Interaction

Cui

Vadlamani

et al. 2018

Volume 1: Aircraft Engine; Fans and Blowers; Marine

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Inlet distortion often occurs at off-design points when flow separates within an intake. This unsteady phenomenon could seriously impact fan performance. Fan-distortion interaction is a highly unsteady aerodynamic phenomenon. High-fidelity simulation can provide a detailed insight into these interactions. However, due to computational resource limitations, the use of eddy resolving methods for a fully resolved fan calculation is currently infeasible for industry. To solve this problem, a mixed-fidelity CFD method is proposed. This method uses the Large Eddy Simulation (LES) to resolve the turbulence associated with separation, and the Immersed Boundary Method with Smeared Geometry (IBMSG) for the fan. The method is validated by an experiment of Darmstadt Rotor, which shows a good agreement in terms of total pressure distributions. A detailed investigation is then conducted on a subsonic rotor with an annular beam generating inlet distortion. A range of studies are performed to investigate fan influence on distortions. Compared to the case without fan, it shows that a fan has a significant effect in reducing distortions. Three fan locations are examined. The fan nearer to the inlet tends to have a higher pressure recovery. Three beams with different heights are also tested to generate various degrees of distortions. The results indicate that the fan can suppress the distortions and its recovery effect is proportional to the degree of inlet distortion.

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Realistic Inlet Distortion Patterns Interacting with a Transonic Compressor Stage

Cited by 8 publications

References 7 publications

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

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

Comparative Studies of RANS Versus Large Eddy Simulation for Fan–Intake Interaction

A Mixed-Fidelity Numerical Study for Fan-Distortion Interaction

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