Aerodynamic Effects in a Transonic Compressor With Nonaxisymmetric Tip Clearance

Jüngst, Maximilian; Liedtke, Samuel; Schiffer, Heinz-Peter; Becker, Bernd

doi:10.1115/gt2018-75404

Cited by 11 publications

(8 citation statements)

References 8 publications

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“…These disturbances are spread between EO10 and EO19 and are already visible 1000 revolutions prior to stall, with increasing intensity during stall inception. These findings provide strong similarities to the investigations of the aeroelastic effects due to asymmetric tip clearance, as shown by Jüngst et al (2018), although some differences are noticeable. The eccentric tip gap also causes various circumferential operating conditions, with low pre-stall disturbances and no fluid-structure interaction for some parts of the annulus.…”

Section: Figure 8 Circumferential Variation Of Unsteady Pressure Fielsupporting

confidence: 80%

“…by varying blade pitch or stagger angles, and adjacent components. Jüngst et al (2018) and Jüngst (2019) presented non-axisymmetric rotor casing geometries enabling a novel approach of aerodynamic mistuning. Large-scale stationary asymmetric features, such as eccentric tip clearance and partial casing treatments, show the potential to reduce non-synchronous blade vibrations.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Varying Inlet Guide Vane Pattern on Aerodynamic Mistuning in Transonic Compressors

Franke¹,

Foret²,

Klausmann³

et al. 2020

Proceedings of Global Power &Amp; Propulsion Society

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This paper investigates the effects of a 1.5-stage transonic axial compressor with applied aerodynamic mistuning via circumferential variation of the inlet guide vane stagger angle. The experiments were carried out at the Darmstadt Transonic Compressor at Technical University of Darmstadt. The test rig represents a modern front stage high-pressure compressor of a jet engine. Using extensive steady and unsteady instrumentation, the global compressor characteristics and performance as well as the transient behavior, focusing on aerodynamic and aeromechanic phenomena, are analyzed.In order to suppress non-synchronous blade vibration of the BLISK rotor, triggered by modal pattern of aerodynamic disturbances, asymmetric rotor inflow conditions are applied via circumferential pattern of varying pre-swirl, given by the inlet guide vane stagger angle. The experimental study provides proof of concept and snapshot measurements regarding global performance as well as steady and unsteady aerodynamic effects. Comparing different aerodynamic mistuning pattern, the influence on performance, circumferential flow variation, synchronous vibration as well as the behavior during stall inception varies. For all configurations, the circumferential variation of the rotors operating condition is evident within the radial and circumferential aerodynamics as well as unsteady flow at the rotor tip. These findings provide similarities to effects presented for asymmetric casing geometries and related mistuning capabilities.

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Section: Figure 8 Circumferential Variation Of Unsteady Pressure Fielsupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Effects of Varying Inlet Guide Vane Pattern on Aerodynamic Mistuning in Transonic Compressors

Franke¹,

Foret²,

Klausmann³

et al. 2020

Proceedings of Global Power &Amp; Propulsion Society

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“…Due to the high circumferential speed, operating at transonic conditions is possible, resulting in a relative Mach number of about 1.35 at the rotor tip and 0.7 at rotor hub. The test facility is in operation for about 25 years, contributing a great extent of fundamental knowledge in compressor research, as for example presented in [2] and [3].…”

Section: Test Facilitymentioning

confidence: 99%

Experimental Investigation of a Transonic Compressor with High Aspect Ratio Rotor Design

Hormel¹,

Franke²,

Foret³

et al. 2019

Proceedings of Global Power &Amp; Propulsion Society

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This paper presents the results of an experimental investigation of a high aspect ratio rotor design. Future axial compressor designs for jet engines require increased efficiency in conjunction with reduced weight and size. Therefore, the investigation determines the influence of a decreased chord length on the rotor behavior. The experiments were carried out at the transonic compressor test rig at TU Darmstadt. The test rig represents a modern front stage highpressure compressor of a jet engine. The analysis is based on several measurements, using extensive steady and unsteady instrumentation, to obtain data for global compressor characteristics and performance as well as transient behavior, focusing on aerodynamic and aeromechanical phenomena. This paper compares the aerodynamic behavior of different transonic compressor stage setups, including an inlet guide vane and stator as well as three varying rotor designs. The baseline geometry design represents a modern low aspect ratio rotor (Rotor A). Based on that, the second rotor (Rotor B) is designed with an increased aspect ratio, resulting from an average chord length reduction of more than 20 % across the blade height. The blade height and rotors tip clearance as well as the solidity is kept constant, resulting in an increased blade count. By retaining constant testing conditions, all measurement data and observations can be merged, in order to describe the effects with respect to varying rotor aspect ratios. Therefore, the IGV and stator vanes as well as the entire instrumentation stays untouched during a rotor BLISK change. Five-hole-probe measurements at the rotor inlet show equal flow conditions for all setups. Comparing the compressor characteristics at design and part speed operation, the investigation shows a significant loss in stall margin and total pressure ratio. The aim of the desired future rotor design is to recover the losses due to a higher aspect ratio. Therefore, the investigation of this paper also includes a third rotor design (Rotor C). The mechanical and geometrical design parameters are the same as for Rotor B. The design is based on a numerical 3D optimization process. The experimental study is in line with the numerical predictions. Rotor C shows an equivalent behavior in total pressure rise and stall margin compared to the baseline (Rotor A) geometry. As a conclusion, this paper indicates the possibility to design a compressor rotor with a considerable reduced chord length and 3D optimized blading, without suffering significant losses in stall margin or total pressure rise.

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“…However, Cameron et al 9,10 and Kumar et al 11 found that the introduction of small levels of steady and unsteady tip clearance asymmetry did not significantly alter the time-averaged performance of the stage. In an aero-engine where tip clearance size and eccentricity change during each flight cycle and over the life of the compressor, 12 the redistribution of flow massively influences stall inception during throttling, 13,14 and the stall will occur in nonuniform clearance configurations once the minimum mass flow reaches to the local stall mass flow. 15,16 Recently, Sun et al 17 proposed a tip clearance prediction model for rotor and stator based on raw experimental data.…”

Section: Introductionmentioning

confidence: 99%

Some effects of non-axisymmetric tip clearance layout on axial compressor aerodynamics

Zhang

Zhuang

Teng

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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A steady and unsteady numerical research is carried out to explore some effects of a specific non-axisymmetric tip clearance layout on the overall performance and stability of an axial compressor stage. For a 4-stage low-speed research compressor (LSRC) in Shanghai Jiao Tong University (SJTU), one-eighth annulus of the inlet guide vane and the first stage rotor was modeled for this study. After the validation for the uniform tip clearance case, a specific non-axisymmetric tip clearance layout is chosen from several random cases generated by the Gaussian Probabilistic Density Function method. Unsteady time-averaged results at the near stall condition show that the chosen non-axisymmetric layout can improve the isentropic efficiency by 1.3% and extend the stall margin by 4%. Detailed analyses on flow fields are carried out to interpret the performance improvement. Due to the circumferential layout of clearance sizes, the inlet mass flow and incidence are redistributed in both the radial and circumferential directions. It leads to blade loading and tip leakage flow varying with the tip clearance size. The quantification of blockage manifests that the blockage arising from the tip leakage flow is significantly alleviated in the non-axisymmetric layout, which leads to improvements in overall performance and stall margin. Transient flow fields at the rotor tip are also analyzed at the near stall condition. For the non-axisymmetric layout, low-momentum regions originating from larger clearance sizes oscillate and develop downstream in one blade passage period.

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Aerodynamic Effects in a Transonic Compressor With Nonaxisymmetric Tip Clearance

Cited by 11 publications

References 8 publications

Effects of Varying Inlet Guide Vane Pattern on Aerodynamic Mistuning in Transonic Compressors

Effects of Varying Inlet Guide Vane Pattern on Aerodynamic Mistuning in Transonic Compressors

Experimental Investigation of a Transonic Compressor with High Aspect Ratio Rotor Design

Some effects of non-axisymmetric tip clearance layout on axial compressor aerodynamics

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