Theoretical characterization of stability in axial-flow compressor rotors

Benavides, Efrén Moreno

doi:10.1243/09544100jaero348

Cited by 4 publications

(25 citation statements)

References 7 publications

(33 reference statements)

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“…Although the stability hypothesis was introduced by [ the Operation Theorem presented in this paper as a logical conclusion of the Stability Theorem. Therefore, the empirical validation of the Operation Theorem supports also the validity of the Stability Theorem and hence the validity of the logical argumentations which were developed by [2] and [4]. However, the unsolved question is what combination of parameters must be changed in order to accommodate the new restriction imposed by the Operation Theorem over the region c D 1.…”

Section: Discussionmentioning

confidence: 62%

“…As a result, a theoretical stability coefficient that locates the theoretical stability line in the compressor map was established. As it was shown by [2], errors lied in the 1-7 percent range for the cases studied (a set of 46 points), in addition [3] shown that the stability margin coefficient could be used to classify different experimental arrangements attending to its stability and [4] used an improved version of the stability theorem to calculate the performance also over the instable region. However these experimental validations were conducted mainly for rotors.…”

Section: Nomenclaturementioning

confidence: 84%

“…It is interesting to note that the Stability Theorem holds as a necessary and sufficient condition only for a theoretical flow pattern, which is defined by [2]. In any other case, for example under flow separation or non-stationary conditions, the necessary and sufficient conditions cannot be assured at the same time (see [2]).…”

Section: Description Of the Theorymentioning

confidence: 99%

“…In any other case, for example under flow separation or non-stationary conditions, the necessary and sufficient conditions cannot be assured at the same time (see [2]). That is why one of the aims of this article is to check the Stability Theorem with a large amount of experimental data coming from real flow patterns.…”

Section: Description Of the Theorymentioning

confidence: 99%

“…This model was based on the comparison of two characteristic times. This preliminary attempt was improved by the theory presented in [2] where an analytical model to calculate the stability of axial-flow compressor rotors was described. This characterization of stability was related to the minimum value of the ratio of two well-defined times whose exact definitions were obtained in a rational way for high-performance rotors subjected to non-small disturbances.…”

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confidence: 99%

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Theoretical Calculation of Stability for NASA Stage 57 Stator

Benavides

Juste

2011

International Journal of Turbo and Jet Engines

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The stability of 595 operational points, belonging to 25 different experimental arrangements of the NASA stage 57, is studied by means of a theoretical calculation based on a theorem recently presented in the scientific literature. This large number of tests is used for checking the results of the theory for a wide variation of the operational and the design parameters. This study completes a previous one by adding the calculations for the stator. Both rotor and stator results are related with the stage stability. While only seven test points appear as potentially unstable due to the rotor, nine test points do due to the stator. IntroductionIn order to improve the performance and to reduce the weight, volume, and cost of fans and compressors, a tentative solution to the problem of predicting the minimum number of blades per stage that assures the stability at the design point was presented in [1]. This model was based on the comparison of two characteristic times. This preliminary attempt was improved by the theory presented in [2] where an analytical model to calculate the stability of axial-flow compressor rotors was described. This characterization of stability was related to the minimum value of the ratio of two well-defined times whose exact definitions were obtained in a rational way for high-performance rotors subjected to non-small disturbances. In [3], this model was used to establish the theoretical stability of the NASA stage 35 rotor. Although this model was only derived for rotors, [4] has shown that its applicability could be extended to stators. As a result, a theoretical stability coefficient that locates the theoretical stability line in the compressor map was established. As it was shown by [2], errors lied in the 1-7 percent range for the cases studied (a set of 46 points), in addition [3] shown that the stability margin coefficient could be used to classify different experimental arrangements attending to its stability and [4] used an improved version of the stability theorem to calculate the performance also over the instable region. However these experimental validations were conducted mainly for rotors. Therefore, the main aim of this paper is to investigate if the theorem can be used to predict possible instabilities due to the stator, just as it has been suggested by [4]. For this purpose, the same set of 595 test points presented by Brought to you by | Purdue University Libraries Authenticated Download Date | 6/15/15 2:34 PM

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Section: Discussionmentioning

confidence: 62%

Section: Nomenclaturementioning

confidence: 84%

Section: Description Of the Theorymentioning

confidence: 99%

Section: Description Of the Theorymentioning

confidence: 99%

mentioning

confidence: 99%

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Theoretical Calculation of Stability for NASA Stage 57 Stator

Benavides

Juste

2011

International Journal of Turbo and Jet Engines

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The effect of different clearance geometry configurations on aerodynamic performance in a high-load compressor cascade

Chen

Sun

Lan

et al. 2013

Proceedings of the Institution of Mechanical Engineers, Part G:

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The clearance flow of compressor variable stator vanes has a significant impact on compressor performance. Most clearance flow experimental research work has been carried out in compressor cascades with lower turning angle (lower load). The clearance flow in a higher load compressor cascade is relatively more complicated due to three-dimensional (3D) flow separation. In the present work, the effects of different heights and locations of clearances in a compressor cascade on aerodynamic performance and separation flow were investigated experimentally in a low-speed plane cascade wind tunnel. The objective of this investigation is to study the characteristics of different clearance configurations depending on the clearance height and the clearance axial position, and make an attempt to verify the possibility of a local clearance flow that improves the performance. The cascade outlet section aerodynamic parameters were measured by ''L'' five-hole probe. The ink-trace flow visualizations on the cascade surface and lower end wall were performed. The results show that with the increase in clearance size, the core area of high loss is moving to the end wall and the morphology of limiting streamlines on the suction surface changes gradually from separation lines to reattachment lines. The separation lines on end wall gradually moved to the middle of the cascade and the separation area increased gradually. The above reasons caused high loss zone gradually extended to the end wall. Thus, the loss at mid-span declined slightly while the loss on the end wall was increasing. Otherwise, cascade load reduced significantly when the clearance height became 3 mm, and the change magnitude of limiting streamline morphology in the flow field which was influenced by clearance flow at the rear of the blade reached to a minimum. So the loss and load came to a minimum, respectively. The impact of the clearance in the rear of a blade on loss and flow is weaker than the other schemes, with a slightly larger loss and separation with respect to the original scheme without a clearance. It may be expected to improve the cascade performance further by an appropriate design of clearance near the trailing.

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Analytical Calculation of Stall-inception and Surge Points for an Axial-flow Compressor Rotor

Benavides¹,

Juste²

2012

Int. J. Turbo Jet-Engines

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Recently, a theoretical criterion to calculate the stability of an axial-flow compressor rotor has been presented in the scientific literature. This theoretical criterion was used for determining the locus of the stability line over the rotor map and for predicting the post-stall evolution of the constant-speed line of a rotor. The main objective of this paper is to improve the predictions of such a model. To do that, the paper proposes a different characterization of the characteristic azimuthal length and a calculation of the ratio of specific heats based on a polytropic exponent. Thanks to these new values, the model predicts two bifurcation points in the behaviour of the flow: the inception point of the instability and the surge point. Experimental data from a pure axial compressor are used to validate the model showing that the prediction of the flow coefficient at the surge point has an error inferior to 5%. For the rotor studied, the paper provides a quantitative and qualitative description of the inception of the instability and of the mechanism involved in the instable region of the compressor map. The paper also discusses the role of rotor efficiency in the position of the bifurcations and gives a sensitivity analysis of its position. Finally, it presents a discussion about how the model can explain the different behaviours exhibited by the same rotor when the flow coefficient is reduced.

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Theoretical characterization of stability in axial-flow compressor rotors

Cited by 4 publications

References 7 publications

Theoretical Calculation of Stability for NASA Stage 57 Stator

Theoretical Calculation of Stability for NASA Stage 57 Stator

The effect of different clearance geometry configurations on aerodynamic performance in a high-load compressor cascade

Analytical Calculation of Stall-inception and Surge Points for an Axial-flow Compressor Rotor

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