Numerical Investigation of Impeller-Vaned Diffuser Interaction in a Centrifugal Compressor

Bardelli, Matteo; Marini, Mauro; Cravero, Carlo; Milingi, Omar

doi:10.3390/app9081619

Cited by 17 publications

(14 citation statements)

References 24 publications

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“…where n could represent the number of stall cells in the present case; ω = ω real − iσ , the real and imaginary parts represent the angular frequency and growth rate of the instability, respectively. By substituting Equation (11) and Equation ( 12) into Equations (6-10), the governing equations of the unsteady flow field are as follows:…”

Section: Analysis Of the Propagation Velocity Coefficient Kmentioning

confidence: 99%

“…Carretta et al [10] adopted a stability parameter (SP) to predict the stability limit; the contribution of each component to the compressor stability was specifically analyzed, and the results showed that the vaned diffuser was responsible for the compressor instability. Bardelli et al [11] investigated the flow in the centrifugal stage of a compressor by different CFD models; unsteady phenomena captured by steady and unsteady simulations have been carefully compared with experimental data in the available literature. Among the instabilities in compressors, one unsteady flow phenomenon, which is known as a rotating stall, has been reported in both centrifugal [12][13][14] and axial [15][16][17][18] compressors.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Analysis Of the Propagation Velocity Coefficient Kmentioning

confidence: 99%

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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“…In this scenario, surge prevention in gas turbinebased advanced cycles is an important aspect to be investigated from both an academic and an industrial point of view because vibrations due to surge can damage plant mechanical components [18]. Regarding surge subject, the authors suggest C. Cravero's Computational Fluid Dynamics papers [19,20], G.L. Arnulfi's experimental and numerical works [21,22] and E.M. Greitzer's works [23].…”

Section: Introductionmentioning

confidence: 99%

Operation extension in gas turbine-based advanced cycles with a surge prevention tool

et al. 2022

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This work aims to present the development and testing of an innovative tool for surge prevention in advanced gas turbine cycles. The presence of additional components, such as a saturator in humid cycles, a heat exchanger for an external combustor, a solar receiver or fuel cell stack in a hybrid system, implies the presence of larger size volumes between compressor outlet and recuperator or expander inlet. This large volume increases the risk of incurring in surge instability, especially during dynamic operations. For these reasons, at the University of Genoa, the Thermochemical Power Group (TPG) has implemented four surge precursors in a new diagnostic real-time software which can recognise a surge incipience condition comparing the precursor values with a set of moving thresholds. The most innovative aspects of this work are: (i) operational range extension and safer management of advanced gas turbine systems for energy generation, (ii) positive impact in energy efficiency due to this range extension of high efficiency systems, (iii) development of a new diagnostic tool for surge prevention using standard probes, (iv) small impact of this tool on the control and sensor costs, (v) software flexibility for adaptation to different conditions and machines. This very important final aspect is obtained with thresholds able to change automatically to adapt themselves to the plant and machine operational regime. From the cost point of view, the utilization of standard measurements is an essential requirement to equip commercial machines without significant impact on the capital costs. The software performance has been demonstrated using experimental data from a test rig composed of a T100 microturbine connected with a modular vessel, which permits to generate the effect of additional components (especially from the volume size point of view). Vibro-acoustic data, collected during machine transients from a stable operative condition to surge, were used to tune all the software parameters and to obtain a good surge predictivity.

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“…Furthermore, the addition of short blades indirectly increases the number of blades in the middle and rear sections of the impeller, and enhances the ability of the blade to shear bubbles and the pump to work; the use of short blades can smash the remaining bubbles and discharge them out of the pump [19]. Otherwise, this paper also refers to the research results of other scholars for the centrifugal compressor [20,21].…”

Section: Introductionmentioning

confidence: 99%

Effect of Short Blade Circumferential Position Arrangement on Gas-Liquid Two-Phase Flow Performance of Centrifugal Pump

et al. 2020

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In order to study the internal flow characteristics of centrifugal pumps with a split impeller under gas-liquid mixed transportation conditions, this paper conducted a steady calculation of the flow field in the centrifugal pump under the conditions of different inlet gas volume fractions based on the Eulerian-Eulerian heterogeneous flow model, using air and water as the working media and the Schiller Nauman model for the interphase resistance. This paper takes a low specific speed centrifugal pump as the research object, through the controlling variables, using the same pump body structure and pump body geometric parameters and setting three different arrangements of long and short blades (each plan uses the same long and short blades) to explore the influence of the short blade arrangement on the low specific speed centrifugal pump performance under a gas-liquid two-phase flow. The research results show that, under pure water conditions, the reasonable arrangement of the short blade circumferential position can eliminate the hump of the centrifugal pump under low-flow conditions, can make the flow velocity in the impeller more uniform, and can optimize the performance of the pump. Under the design conditions and the gas-liquid two-phase inflow conditions, when the circumferential position of the short blades is close to the suction surface of the long blades, some of the bubbles on the suction surface of the long blade can be broken under the work of the pressure surface of the short blade and flow out of the impeller with the liquid, which improves the flow state of the flow field in the impeller.

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Numerical Investigation of Impeller-Vaned Diffuser Interaction in a Centrifugal Compressor

Cited by 17 publications

References 24 publications

Stall Mode Transformation in the Wide Vaneless Diffuser of Centrifugal Compressors

Stall Mode Transformation in the Wide Vaneless Diffuser of Centrifugal Compressors

Operation extension in gas turbine-based advanced cycles with a surge prevention tool

Effect of Short Blade Circumferential Position Arrangement on Gas-Liquid Two-Phase Flow Performance of Centrifugal Pump

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