Experimental Investigation of Effects of Reynolds Number and Incidence Angle on Secondary Flow within a Linear Blade Cascade

Flídr, Erik; Jelı́nek, Tomáš; Kladrubský, M.

doi:10.1007/s11630-021-1455-y

Cited by 4 publications

(5 citation statements)

References 15 publications

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“…The method presented here, in the author's opinion, better describes the situation, as the mentioned assumption about the flow superposition is not correct, as mentioned in section 5. Moreover, in [2], flow separation on the blade suction surface occurred. This separation then overwhelmed the effects of the end-wall flows completely, although the vortices and end-wall structures were clearly visible.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Kinetic Energy Dissipation Caused by the Vortical Structures in Linear Blade Cascade

Flídr

2024

Topical Problems of Fluid Mechanics 2024

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The dissipation of kinetic energy in a linear blade cascade has been extensively studied from both experimental and numerical perspectives. Nevertheless, the impact of vortices on kinetic energy dissipation in the cascade is often assessed under several assumptions that significantly simplify the situation and may underestimate their influence. The presented paper focuses on the kinetic energy dissipation caused by vortical structures. This investigation is based on a new approach to evaluate individual contributions to the overall kinetic energy dissipation in the cascade. Vortices are identified using the H criterion in this paper. A comparison of this new method with the commonly used approach is presented. The experimental research was performed on linear blade cascade with pitch-to-chord ratio t/c = 0.9 for both constant Mach and Reynolds numbers (M2,is =0.4 and Re2,is = 2.5 × 105) and for three different inlet flow angles (α1 = −20°; 5° and 30°).

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Section: Discussionmentioning

confidence: 99%

“…Such an approach is used by several authors, e.g. [2,3,4]. This approach relies on the assumption of the superposition of the flow in the end-wall region of the cascade and the idealized 2D flow at the blade mid-span.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Energy Dissipation Caused by the Vortical Structures in Linear Blade Cascade

Flídr

2024

Topical Problems of Fluid Mechanics 2024

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“…It is evident that the location of the vortices evaluated by the H criterion differed from the locations suggested by the higher stream-wise vorticity. The stream-wise vorticity was utilised in a past study [23] to localise and describe the evolution of the vortices. The qualitative results remained consistent with the past study; that is, the vortices were more shifted towards the blade mid-span and enhanced in strength with increasing inlet flow angle due to larger centrifugal forces.…”

Section: Vortices Identificationmentioning

confidence: 99%

“…The paper aims to identify vortex structures in the linear blade cascade as precisely as possible from a new perspective. This motivation stems from the earlier work of Flidr et al [23], where the conventional approach for calculating the (KED) caused by the vol. 64 no.…”

Section: Introductionmentioning

confidence: 99%

On the vortex identification within a linear blade cascade - an experimental research

Flídr

2024

Acta Polytech

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This paper deals with the identification of the individual vortical structures within a linear blade cascade based on H criteria. The experimental data obtained from the pressure measurement at the cascade outlet were evaluated by a standard procedure to obtain the velocity field in one plane. Then, the vorticity in the flow field was evaluated based on Crocco’s theorem, and in the final step, the helicity density was calculated. The impact of the inlet flow angle on the velocity field as well as on the vortical structures was investigated. The effect of the value of the H threshold on the vortex identification is discussed in the last part of the paper.

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“…1,2 In the highly loaded axial compressor, inevitably, the boundary layer separation always leads to significant stagnation pressure loss, which limits the further improvement of the performance. 3,4 Aiming at achieving higher blade load while effectively controlling the flow separation in compressors, a series of flow control methods were developing over the past decades, such as vortex-generator jet, 5 air injection, 6 boundary layer suction, 7 and 3D shaped blade 8 et al, which were extensively investigated.…”

Section: Introductionmentioning

confidence: 99%

Control mechanism of vortex-generator jet on turbulent separation in a highly loaded compressor cascade

Cao

Song²,

Guo

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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The active flow control technique of vortex-generator jet (VGJ) was used to control the turbulent separation of a highly loaded compressor cascade at a high incidence. VGJ schemes on suction surface with different jet locations, skewed angles, pitch angles were numerically performed and the control mechanism of VGJ parameters on the flow field of the cascade was revealed. For avoiding the effect of endwall boundary layer, both endwall surfaces of the cascade were set to translational periodicity boundary (TPB). Results show that VGJ significantly eliminates the turbulent separation and improves the performance of cascade. The overall loss coefficient of cascade is reduced by 52.3% at most. The optimal VGJ location in this study is not separation location but 7% axial chord downstream of it, which is probably due to the ultra-high loading of the cascade. The spanwise location and intensity of jet vortices are mainly affected by skewed angle, and will increase with the skewed angle. The VGJ case with a higher pitch angle features better control effect on suction surface but increases the pitchwise scale of the low-velocity region. In addition, as pitch angle increases, the mixing loss between mainstream and jet flow increases, which brings a negative effect on cascade performance. In order to enhance the momentum transporting between mainstream flow and separation flow, counter vortex-generator jet (CVGJ) schemes were designed and studied. Though CVGJ strengthens the jet vortices near the trailing edge and achieves minimum loss near TPB sections at 150% axial chord section, the interaction of jet vortices with opposite rotating direction brings extra loss, which leads to the control effect of CVGJ is weaker than that of VGJ.

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Experimental Investigation of Effects of Reynolds Number and Incidence Angle on Secondary Flow within a Linear Blade Cascade

Cited by 4 publications

References 15 publications

Kinetic Energy Dissipation Caused by the Vortical Structures in Linear Blade Cascade

Kinetic Energy Dissipation Caused by the Vortical Structures in Linear Blade Cascade

On the vortex identification within a linear blade cascade - an experimental research

Control mechanism of vortex-generator jet on turbulent separation in a highly loaded compressor cascade

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