Aerodynamic Influence of a Bleed on the Last Stage of a Low-Pressure Compressor and S-Duct

Spanelis, Apostolos; Walker, Donald G.

doi:10.1115/1.4052134

Cited by 5 publications

(3 citation statements)

References 24 publications

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“…Building upon the aforementioned studies on bleed effects, numerous investigations [17][18][19][20][21][22][23] have demonstrated that effective control of compressor leakage flow through a well-designed bleed arrangement is crucial for enhancing compressor performance. Therefore, it is of great value to analyze overall performance parameters of the rotor, the distribution of key aerodynamic parameters, and structural changes in the flow field at the blade tip.…”

Section: Introductionmentioning

confidence: 99%

Non-uniform flow characteristics and rotating instability of a transonic high-pressure compressor rotor with cavity bleed

Xu,

Chen,

Gong

2024

Proceedings of the Institution of Mechanical Engineers, Part G:

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The presence of bleed in an aero engine’s compressor can significantly impact its flow characteristics and contribute to rotating instability. This study focuses on the impact of a typical cavity bleed structure on the internal flow characteristics of a compressor, specifically its circumferential non-uniformity and aerodynamic stability. A numerical simulation involving multiple flow passages was conducted on the transonic high-pressure rotor of the E3 compressor, considering its typical bleed structure. The study delves deep into the non-uniform flow characteristics and the mechanisms behind their generation in the compressor flow field. Furthermore, the influence of bleed on the rotating instability of the compressor is explored by comparing changes in compressor instability and adiabatic efficiency under uniform and non-uniform flow field conditions. The findings indicate that the axial position of the cavity bleed structure plays a crucial role in influencing key parameters such as rotor stall margin, peak efficiency, and total pressure ratio under near-stall conditions. The circumferential non-uniformity, resulting from the presence of the cavity bleed, intensifies with higher bleed air flow rates. For the upstream bleed configuration applied to the rotor, with a total bleed rate of 5%, the maximum variation in absolute flow angle at the inlet of different rotor channels can reach up to 1°. Additionally, the maximum difference in inlet flow coefficient can reach 0.0392. These findings demonstrate that the non-uniformity caused by the typical bleed structure leads to a loss in stall margin for the rotor when compared to a uniform flow field scheme.

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Section: Introductionmentioning

confidence: 99%

Non-uniform flow characteristics and rotating instability of a transonic high-pressure compressor rotor with cavity bleed

Xu,

Chen,

Gong

2024

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…However, in the bypass duct of a gas turbine, the preferred option is flush or submerged off-takes as they can minimise the aerodynamic effect on the bypass stream and the associated impact in efficiency and SFC. Examples of work em ploying flush off-takes in the bypass duct can be found at Walker et al [1,5] and Spanelis and Walker [6].…”

Section: Introductionmentioning

confidence: 99%

“…See for example A'Barrow et al [11] who illustrates that the presence of a diffusing off-take downstream of a compressor can have an upstream effect on the compressor and similarly the compressor's exit conditions will also affect the performance of the diffusing off-take. Additionally, Spanelis and Walker [6] who investigated the effects of an annular bleed between the stator and the rotor of a low-pressure compressor, showed that the position of the bleed is responsible for severe flow bias in the radial direction which can reduce the OGV stall margin and alter the OGV stall topology itself. The current system can be described by a large set of closely coupled design variables which define the aerodynamic shape.…”

Section: Introductionmentioning

confidence: 99%

A Multi-Objective Factorial Design Methodology for Aerodynamic Off-Takes and Ducts

Spanelis

Walker

2022

Aerospace

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Fluid off-takes and complex delivery ducts are common in many engineering systems but designing them can be a challenging task. At the conceptual design phase many system parameters are open to consideration and preliminary design studies are necessary to instruct the conceptualisation process in an iterative development of design ideas. This paper presents a simple methodology to parametrically design, explore and optimise such systems at low cost. The method is then applied to an aerodynamic system including an off-take followed by a complex delivery duct. A selection of nine input variables is explored via a fractional factorial design approach that consists of three individual seven-level cubic factorial designs. Numerical predictions are characterised based on multiple aerodynamic objectives. A scaled representation of these objectives allows for a scalarisation technique to be employed in the form of a global criterion which indicates a set of trade-off geometries. This leads to the selection of a set of nominal designs and the determination of their robustness which will eventually instruct the next conceptual design iteration. The results are presented and discussed based on criterion space, design variable space and contours of several flow quantities on a selection of optimal geometries.

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Experimental investigation of intermediate compressor duct

et al. 2023

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The intermediate duct connects high-pressure and low-pressure compressors. It comprises flow channels and struts that fix the relative positions of the hub and shroud. The mechanism of airflow movement around the struts in the downstream intermediate ducts is experimentally investigated based on four cases, including two types of struts and two shapes of meridional flow channels. The measurement parameters of the intermediate duct under the same conditions are measured in the wind tunnel, including the total pressure loss coefficient at the outlet and axial wall pressure distribution. In addition, the flow characteristics near the wall are obtained through the oil flow test, and the frequency of the shedding vortex is captured by the dynamic pressure probes. The results demonstrate that the strut and channel with the modified profile can reduce the total pressure loss and eliminate wake oscillation by changing the flow characteristic. The total pressure losses of the modified profile at 0.2, 0.25, 0.3, 0.35, 0.4, and 0.45 Ma conditions are reduced by 60%, 63%, 83%, 89%, 85%, and 87%, respectively.

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Aerodynamic Influence of a Bleed on the Last Stage of a Low-Pressure Compressor and S-Duct

Cited by 5 publications

References 24 publications

Non-uniform flow characteristics and rotating instability of a transonic high-pressure compressor rotor with cavity bleed

Non-uniform flow characteristics and rotating instability of a transonic high-pressure compressor rotor with cavity bleed

A Multi-Objective Factorial Design Methodology for Aerodynamic Off-Takes and Ducts

Experimental investigation of intermediate compressor duct

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