Analysis of Vaneless Diffuser Stall Instability in a Centrifugal Compressor

Sundström, Elias; Mihăescu, Mihai; Giachi, Marco; Belardini, Elisabetta; Michelassi, Vittorio

doi:10.3390/ijtpp2040019

Cited by 13 publications

(4 citation statements)

References 23 publications

(26 reference statements)

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“…A bounded central differencing scheme is used as a convection scheme. This scheme has been utilized previously in past studies 37,38 utilizing the LES approach in STAR-CCM + .…”

Section: Methodsmentioning

confidence: 99%

Particle behavior in a turbulent flow within an axially corrugated geometry

Majal

Wittberg

Mihăescu

2021

Advances in Mechanical Engineering

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In this numerical study particle behavior inside a sinusoidal pipe geometry is analyzed. The 3D geometry consists of three identical modules, with a periodic boundary condition applied to the flow in the stream wise direction. The incompressible, turbulent gas flow is modeled using a Large Eddy Simulation (LES) approach. Furthermore, the particle dynamics are simulated using a Lagrangian point force approach incorporating the Stokes drag and slip correction factor. Four different sizes of particles, corresponding to a Stokes number less than unity, are considered along with two different inflow conditions: continuous and pulsatile. The pulsatile inflow has an associated flow frequency of 80 Hz. The fluid flow through the sinusoidal pipe is characterized by weak flow separation in the expansion zones of the sinusoidal pipe geometry, where induced shear layers and weak recirculation zones are identified. Particle behavior under the two inflow conditions is quantified using particle dispersion, particle residence time, and average radial position of the particle. No discernible difference in the particle behavior is observed between the two inflow conditions. As the observed recirculation zones are weak, the particles are not retained within the cavities for a long duration of time, thereby reducing their likelihood of agglomerating.

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“…A bounded central differencing scheme is used as a convection scheme. This scheme has been utilized previously in past studies 37,38 utilizing the LES approach in STAR-CCM + .…”

Section: Methodsmentioning

confidence: 99%

Particle behavior in a turbulent flow within an axially corrugated geometry

Majal

Wittberg

Mihăescu

2021

Advances in Mechanical Engineering

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“…LES proved able to predict the frequencies associated with the early stage of stall, while the detailed flow visualizations were helpful in following the stall mechanism in view of an improved redesign. More recently, the problem of a vaneless diffuser stall was investigated by LES of a simplified diffuser-like geometry that included the cavities around the impeller trailing edge [136]. In that case, LES shed some light on the development of reverse flow in the radial diffuser when running the compressor close to the left operating limit, revealing the close link that exists between the periodic perturbations from the impeller and the diffuser instability.…”

Section: Centrifugal Compressorsmentioning

confidence: 99%

The Current State of High-Fidelity Simulations for Main Gas Path Turbomachinery Components and Their Industrial Impact

Sandberg

Michelassi²

2019

Flow Turbulence Combust

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Over the past two decades high-fidelity simulations have become feasible for most main gas path turbomachinery components. This paper introduces the key challenges of simulating and modelling turbomachinery flows and presents an overview of possible simulation strategies. A comprehensive overview is given of which particular design challenges have to date been addressed by high-fidelity simulations, with a particular focus on high-pressure and centrifugal compressors, and high-pressure and low-pressure turbines. Recommendations are provided for how quality and accuracy can be ensured for high-fidelity simulations, using direct numerical simulations of a low-pressure turbine as a case study. It is argued that industrial impact from high-fidelity simulations can be achieved in two ways, either by conducting design-of-experiment-like studies that can provide designers with insight into certain physical mechanisms and phenomena, or by helping mature and improve lower-order models. The latter is discussed with particular emphasis on recent advances in machine learning for model assessment and improvement, and the potential of one selected data-driven approach is demonstrated on predictions of wake mixing for low-pressure and high-pressure turbines.

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“…A well-designed diffuser decreases the flow instabilities coming from the impeller outlet, as well as energy losses. However, under off-design conditions, the flow field within the vaneless diffuser could be stalled due to boundary layer separation or core flow instability; the mechanisms and characteristics of this type of rotating stall have been extensively studied, theoretically [22][23][24][25], experimentally [26][27][28][29][30][31][32], and numerically [33][34][35][36][37][38][39]. The topology of rotating stall cells in the vaneless diffuser is shown in Figure 2, the characteristics of which can be briefly summarized as follows:…”

Section: Introductionmentioning

confidence: 99%

Stall Mode Transformation in the Wide Vaneless Diffuser of Centrifugal Compressors

Heng

Jiang

et al. 2020

Energies

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A review on the rotating stall in the vaneless diffuser of centrifugal compressors is presented showing that different stall modes characterized by different numbers of cells can be detected within the diffuser even if the operating condition remains unchanged. The interaction between the inlet perturbation and the stall cells near the diffuser outlet is supposed to be the trigger of the stall mode transformation. In order to determine if the inlet perturbation will interact with the downstream stall cells, a characteristic time analysis is proposed to estimate the characteristic time of the perturbation in radial and tangential directions. An additional theoretical model which focused on the development of the vaneless diffuser rotating stall is presented to determine the propagation velocity of the cells. The comparison between the characteristic time in two directions shows that one stall mode is able to evolve into another stall mode if a critical condition is met, and the stall mode transformation is more likely to start from a mode with a higher number of cells and is more likely to occur in the diffuser with a large radius ratio. Experimental results are also employed to validate the proposed critical condition, and good agreements are obtained.

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Analysis of Vaneless Diffuser Stall Instability in a Centrifugal Compressor

Cited by 13 publications

References 23 publications

Particle behavior in a turbulent flow within an axially corrugated geometry

Particle behavior in a turbulent flow within an axially corrugated geometry

The Current State of High-Fidelity Simulations for Main Gas Path Turbomachinery Components and Their Industrial Impact

Stall Mode Transformation in the Wide Vaneless Diffuser of Centrifugal Compressors

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