Effects of tip clearance size on the unsteady flow behaviors and performance in a counter-rotating axial flow compressor

Mao, Xiaochen; Liu, Bo; Zhao, Hao

doi:10.1177/0954410017745901

Cited by 10 publications

(7 citation statements)

References 41 publications

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“…Because the number of nodes required for LES simulation of stator-rotor configurations with tip clearance modelling is significantly high (up to several dozens of million cells), unsteady RANS (URANS) modelling is still being used by a number of researchers as a useful approach, with an acceptable compromise between accuracy and computational cost. Effectively, recent investigations have provided valuable information, showing that it is feasible to accurately simulate these three-dimensional, vortical structures using URANS modelling (Zhang et al, 2015;Jung and Joo, 2018;Mao et al, 2019). Moreover, when the fullunsteady sliding mesh technique is used in multistage environments, the URANS approach turns to be the more realistic and practicable option.…”

Section: Hff 3010mentioning

confidence: 99%

Stator–rotor interaction in the tip leakage flow of an inlet vaned low-speed axial fan

Gonzalez

Meana-Fernández

Fernández

2020

HFF

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Purpose The purpose of the paper is to quantify the impact of the non-uniform flow generated by the upstream stator on the generation and convection of the tip leakage flow (TLF) structures in the passages of the rotor blades in a low-speed axial fan. Design/methodology/approach A full three dimensional (3D)-viscous unsteady Reynolds-averaged Navier-stokes (RANS) (URANS) simulation of the flow within a periodic domain of the axial stage has been performed at three different flow rate coefficients (φ = 0.38, 0.32, 0.27) using ReNormalization Group k-ε turbulence modelling. A typical tip clearance of 2.3 per cent of the blade span has been modelled on a reduced domain comprising a three-vaned stator and a two-bladed rotor with circumferential periodicity. A non-conformal grid with hybrid meshing, locally refined O-meshes on both blades and vanes walls with (100 × 25 × 80) elements, a 15-node meshed tip gap and circumferential interfaces for sliding mesh computations were also implemented. The unsteady motion of the rotor has been covered with 60 time steps per blade event. The simulations were validated with experimental measurements of the static pressure in the shroud of the blade tip region. Findings It has been observed that both TLF and intensities of the tip leakage vortex (TLV) are significantly influenced by upstream stator wakes, especially at nominal and partial load conditions. In particular, the leakage flow, which represents 12.4 per cent and 11.3 per cent of the working flow rate, respectively, has shown a clear periodic fluctuation clocked with the vane passing period in the relative domain. The periodic fluctuation of the TLF is in the range of 2.8-3.4 per cent of the mean value. In addition, the trajectory of the tip vortex is also notably perturbed, with root-mean squared fluctuations reaching up to 18 per cent and 6 per cent in the regions of maximum interaction at 50 per cent and 25 per cent of the blade chord for nominal and partial load conditions, respectively. On the contrary, the massive flow separation observed in the tip region of the blades for near-stall conditions prevents the formation of TLV structures and neglects any further interaction with the upstream vanes. Research limitations/implications Despite the increasing use of large eddy simulation modelling in turbomachinery environments, which requires extremely high computational costs, URANS modelling is still revealed as a useful technique to describe highly complex viscous mechanisms in 3D swirl flows, such as unsteady tip flow structures, with reasonable accuracy. Originality/value The paper presents a validated numerical model that simulates the unsteady response of the TLF to upstream perturbations in an axial fan stage. It also provides levels of instabilities in the TLV derived from the deterministic non-uniformities associated to the vane wakes.

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Section: Hff 3010mentioning

confidence: 99%

Stator–rotor interaction in the tip leakage flow of an inlet vaned low-speed axial fan

Gonzalez

Meana-Fernández

Fernández

2020

HFF

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“…Previous studies indicated that the capacity of MCRFs can be modified by optimizing the design of the impeller structures and the angles of installation. (10)(11)(12)(13)(14) Some studies (15)(16)(17)(18)(19) found that optimizing the gap between the impeller tips of rotors may significantly improve the efficiency and stability of operation for an MCRF system. This is because the gap size of R1 may affect the occurrence and development of a turbulence trail in the impeller tip region, and thus the flow conditions in the impellers of R2.…”

Section: Introductionmentioning

confidence: 99%

Adaptive Variable-speed Control for Enhancing the Performance of a Mine Counter-rotating Fan System

Ai¹,

Qin²,

Wang³

et al. 2021

Sensors and Materials

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The mine counter-rotating fan (MCRF) is important in tunnel construction and is also widely used for ventilation in mining. The need to improve the performance of MCRF systems has been attracting the interest of researchers. An MCRF is composed of two vane rotors that rotate in opposite directions. We propose a novel adaptive variable-speed (AVS) control method to improve the performance of an MCRF system. The proposed method is based on the concept of adaptively controlling the speed of the second vane rotor according to changes in the working conditions of the whole fan system. To evaluate the performance of our proposed AVS control method, experiments were performed using various sensors to detect pressure and mass flow rates when using our newly designed MCRF system. Results show that, with the proposed AVS control method, the problem of the rotor output torque rising and falling markedly during large and small mass flows, respectively, is overcome. Furthermore, the problems of overload and a low blocking margin are solved. As a result, the overall pressure increase and performance of the whole fan system are improved.

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“…While improving the pathological characteristics of AD, can it improve the gamma rhythm that is closely related to cognitive function, and provide neuro-physiological mechanisms of cell function for aerobic exercise to improve the behavior of the AD model. 1…”

Section: Introductionmentioning

confidence: 99%

Experimental Research on Forecasting Index of Biological Image Aerobic Exercise Analysis of Artificial Neural Network

Lin

2021

Rev Bras Med Esporte

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Objective: The paper uses artificial neural network images to explore the effects of aerobic exercise on the gamma rhythm of theta period in the awake hippocampal CA1 area of APP/PS1/tau mice and the low-frequency gamma rhythm of the sleep state hippocampal CA1 area SWR period. Methods: Clean grade 6-month-old APP/PS1/tau mice were randomly divided into quiet group (AS) and exercise group (AE), C57BL/6J control group mice were randomly divided into quiet group (CS) and exercise group (CE). The AE group and the CE group performed 12-week treadmill exercise, 5d/week, 60min/d, the first 10min exercise load was 12m/min, the last 50min was 15m/min treadmill slope was 0°. Eight-arm maze detection of behavioral changes in mice; multi-channel in vivo recording technology to record the electrical signals of the awake state and sleep state in the hippocampal CA1 area, MATLAB extracts the awake state theta period and sleep state SWR period, multi-window spectrum estimation method Perform time-frequency analysis and power spectral density analysis. Results: 12 weeks of aerobic exercise can significantly improve the working memory and reference memory of the AS group, increase the gamma energy in theta period of the awake hippocampus CA1 area and the low-frequency gamma energy in the sleep state CA1 area SWR period. Conclusions: Aerobic exercise can improve the neural network state of the AD model and increase the gamma energy in theta period of the hippocampus CA1 area, and the low-frequency gamma energy in the SWR period is one of the neural network mechanisms for its overall behavioral improvement. Level of evidence II; Therapeutic studies - investigation of treatment results.

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Effects of tip clearance size on the unsteady flow behaviors and performance in a counter-rotating axial flow compressor

Cited by 10 publications

References 41 publications

Stator–rotor interaction in the tip leakage flow of an inlet vaned low-speed axial fan

Stator–rotor interaction in the tip leakage flow of an inlet vaned low-speed axial fan

Adaptive Variable-speed Control for Enhancing the Performance of a Mine Counter-rotating Fan System

Experimental Research on Forecasting Index of Biological Image Aerobic Exercise Analysis of Artificial Neural Network

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