A Numerical Study on the Influence of Vane-Blade Spacing on a Compressor Stage at Sub- and Transonic Operating Conditions

Zachcial, Andreas; ̈rnberger, Dirk Nu

doi:10.1115/gt2003-38020

Cited by 10 publications

(4 citation statements)

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“…Additionally, an opposite trend in efficiency was also observed in literature. 8,9 They performed simulations of a subsonic compressor configuration on a two-dimensional plane at about mid-span and the casing, respectively. Both of their numerical results showed an increase in efficiency when the axial gap was increased.…”

Section: Introductionmentioning

confidence: 99%

A numerical study on the unsteady effect of axial spacing on the performance in a contra-rotating axial compressor

Mao

Liu

2016

Proceedings of the Institution of Mechanical Engineers, Part C:

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Unsteady numerical simulations are conducted to investigate the unsteady effects of axial spacing on the performance of a contra-rotating axial compressor. The results show that the stage efficiency is dominant by unsteady effects between two rotors at lower axial gap ranges. As the axial spacing is increased, the variation of aerodynamic force is different for the two rotors. As a whole, the oscillation on the pressure surface is much stronger than that on the suction side in rotor1. For rotor2, however, the local maximum amplitude is just located at the blade leading edge, especially near the tip region. Additionally, the maximum amplitude of the pressure fluctuations generally decreases with an increase of axial spacing. The dominating frequency is different for monitors located at different positions and varies with the increasing of axial gaps. As the axial gap is increased, the potential effects decay in the process of propagating. Meanwhile, the incoming wakes are mixed out more sufficiently which would reduce the fluctuations at leading edge of rotor2. Therefore, a proper axial spacing should be chosen in the design process of a contra-rotating axial compressor considering both the performance and structure.

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Section: Introductionmentioning

confidence: 99%

A numerical study on the unsteady effect of axial spacing on the performance in a contra-rotating axial compressor

Mao

Liu

2016

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…However, shorter axial gaps will tend to increase the extent of turbulence and near wall losses due to earlier transition [18][19][20]. A decreased axial gap also excites forced response [21]. A coupled sensitivity study of aerodynamic and aeroelastic effects due to axial gap variations is not present in open literature.…”

Section: Engine Performance and Aerodynamicsmentioning

confidence: 99%

Aerodynamic and Aeroelastic Effects of Design-Based Geometry Variations on a Low-Pressure Compressor

Eggers

Kim

Bittner

et al. 2020

IJTPP

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In modern aircraft engines, the low-pressure compressor (LPC) is subjected to a flow characterized by strong wakes and secondary flows from the upstream fan. This concerns ultra-high bypass ratio (UHBR) turbofan engines, in particular. This paper presents the aerodynamic and aeroelastic sensitivities of parametric variations on the LPC, driven by the design considerations in the upstream fan. The goal of this investigation was to determine the influence of design-based geometry parameter variations on the LPC performance under realistic inlet flow distributions and the presence of an s-duct. Aerodynamic simulations are conducted at the design and off-design operating points with the fan outflow as the inlet boundary conditions. Based on the aerodynamic results, time-linearized unsteady simulations are conducted to evaluate the vibration amplitude at the resonance operating points. First, the bypass ratio is varied by reducing the channel height of the LPC. The LPC efficiency decreases by up to 1.7% due to the increase in blockage of the core flow. The forced response amplitude of the rotor decreases with increasing bypass ratio due to increased aerodynamic damping. Secondly, the fan cavity leakage flow is considered as it directly affects the near hub fan flow and thus the inflow of the LPC. This results in an increased total-pressure loss for the s-duct due to mixing losses. The additional mixing redistributes the flow at the s-duct exit leading to a total-pressure loss reduction of 4.3% in the first rotor at design point. This effect is altered at off-design conditions. The vibration amplitude at low speed resonance points is increased by 19% for the first torsion and 26% for second bending. Thirdly, sweep and lean are applied to the inlet guide vane (IGV) upstream of the LPC. Despite the s-duct and the variable inlet guide vane (VIGV) affecting the flow, the three-dimensional blade design achieves aerodynamic and aeroelastic improvements of rotor 1 at off-design. The total-pressure loss reduces by up to 18% and the resonance amplitude more than 10%. Only negligible improvements for rotor 1 are present at the design point. In a fourth step, the influence of axial gap size between the stator and the rotor rows in the LPC is examined in the range of small variations which shows no distinct aerodynamic and aeroelastic sensitivities. This finding not only supports previous studies, but it also suggests a correlation between mode shapes and locally increased excitaion with increasing axial gap size. As a result, potential design improvements in future fan-compressor design are suggested.

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“…Another fact is that IGVs' wakes do not mix completely prior to entering the blades passages and thus affect the turbulent transition and result in high entropy production. Zachcial and Nürnberger 30 concluded that axial inter‐distance allows for the wake mixing prior to entering the rotor blade passage. On the other hand, the tip vortex does not reach blade span below 80% for the farthest inter‐distance, whereas for the closest inter‐distance it may reach around 40% span as it drifts to the lower span sections.…”

Section: Flow Characterizationmentioning

confidence: 99%

Characterization of flow interactions in an axial fan stage

Ghenaiet

2020

Engineering Reports

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The aim of this study is to characterize the steady and unsteady flows of a high-speed axial fan stage and assess its aerodynamic performance parameters. The flow unsteadiness is related to the stator-rotor interaction originated mainly by two mechanisms: the first is attributed to the potential effect and the second to the wake-blade interaction and the mixing through the blades' passages. Such effects are dependent on the circumferential positions of blades and inter-distance between stator and rotor, which could be alleviated by understanding these flow interactions. The pressure waves' main diametrical modes (two blades interacting with two vanes) and their sequences are predicted analytically. FFT analysis of the computed static pressure fluctuations at different monitor points allowed identifying the prevailing modes of interaction and their frequencies and sequence. The assessment of inter-distance is an important step toward identifying the detrimental effects of axial interdistance on the aerodynamic performance. The closer the blade-rows of this fan stage can be spaced, the more compact the cooling system of an automotive could be designed.

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A Numerical Study on the Influence of Vane-Blade Spacing on a Compressor Stage at Sub- and Transonic Operating Conditions

Cited by 10 publications

References 0 publications

A numerical study on the unsteady effect of axial spacing on the performance in a contra-rotating axial compressor

A numerical study on the unsteady effect of axial spacing on the performance in a contra-rotating axial compressor

Aerodynamic and Aeroelastic Effects of Design-Based Geometry Variations on a Low-Pressure Compressor

Characterization of flow interactions in an axial fan stage

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