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Blade Passing Frequency

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Zhang Qian – One of the best experts on this subject based on the ideXlab platform.

  • Distribution of unsteady pressure in volute type axial flow pump
    Journal of Vibroengineering, 2018
    Co-Authors: Cao Weidong, Yao Lingjun, Zhang Qian

    Abstract:

    In order to study the distribution of unsteady pressure in volute type axial flow pump, the k-e turbulence model was applied, and ANSYS CFX was provided for numerical simulation calculation. Experiments of external characteristics and pressure fluctuation have been done to verify the results of numerical simulation. The results show that under the design operating condition, the main fluctuation frequencies in the volute, at the inlet and outlet of the impeller are the Blade Passing Frequency. The amplitudes of fluctuation at the inlet of the impeller decrease gradually from the rim to the hub, while those at the export decrease firstly and then increase, the amplitudes at the tongue are much higher than that at other sections of the volute. Under the off-design operating conditions, the main fluctuation Frequency at the inlet and outlet of the impeller is still the Blade Passing Frequency, while that at the tongue is between the twice shaft Frequency and the Blade Passing Frequency, fluctuation amplitudes are both larger than those under the design operating condition. Under the design operating condition, the radial force on the impeller is the minimum, however, the axial force increases with the increase of flow rate. The distributions of unsteady pressure in volute type axial flow pump are different with general centrifugal or axial flow pump.

  • Distribution of unsteady pressure in volute type axial flow pump
    'JVE International Ltd.', 2018
    Co-Authors: Cao Weidong, Yao Lingjun, Zhang Qian

    Abstract:

    In order to study the distribution of unsteady pressure in volute type axial flow pump, the k-ε turbulence model was applied, and ANSYS CFX was provided for numerical simulation calculation. Experiments of external characteristics and pressure fluctuation have been done to verify the results of numerical simulation. The results show that under the design operating condition, the main fluctuation frequencies in the volute, at the inlet and outlet of the impeller are the Blade Passing Frequency. The amplitudes of fluctuation at the inlet of the impeller decrease gradually from the rim to the hub, while those at the export decrease firstly and then increase, the amplitudes at the tongue are much higher than that at other sections of the volute. Under the off-design operating conditions, the main fluctuation Frequency at the inlet and outlet of the impeller is still the Blade Passing Frequency, while that at the tongue is between the twice shaft Frequency and the Blade Passing Frequency, fluctuation amplitudes are both larger than those under the design operating condition. Under the design operating condition, the radial force on the impeller is the minimum, however, the axial force increases with the increase of flow rate. The distributions of unsteady pressure in volute type axial flow pump are different with general centrifugal or axial flow pump

Cao Weidong – One of the best experts on this subject based on the ideXlab platform.

  • Distribution of unsteady pressure in volute type axial flow pump
    Journal of Vibroengineering, 2018
    Co-Authors: Cao Weidong, Yao Lingjun, Zhang Qian

    Abstract:

    In order to study the distribution of unsteady pressure in volute type axial flow pump, the k-e turbulence model was applied, and ANSYS CFX was provided for numerical simulation calculation. Experiments of external characteristics and pressure fluctuation have been done to verify the results of numerical simulation. The results show that under the design operating condition, the main fluctuation frequencies in the volute, at the inlet and outlet of the impeller are the Blade Passing Frequency. The amplitudes of fluctuation at the inlet of the impeller decrease gradually from the rim to the hub, while those at the export decrease firstly and then increase, the amplitudes at the tongue are much higher than that at other sections of the volute. Under the off-design operating conditions, the main fluctuation Frequency at the inlet and outlet of the impeller is still the Blade Passing Frequency, while that at the tongue is between the twice shaft Frequency and the Blade Passing Frequency, fluctuation amplitudes are both larger than those under the design operating condition. Under the design operating condition, the radial force on the impeller is the minimum, however, the axial force increases with the increase of flow rate. The distributions of unsteady pressure in volute type axial flow pump are different with general centrifugal or axial flow pump.

  • Distribution of unsteady pressure in volute type axial flow pump
    'JVE International Ltd.', 2018
    Co-Authors: Cao Weidong, Yao Lingjun, Zhang Qian

    Abstract:

    In order to study the distribution of unsteady pressure in volute type axial flow pump, the k-ε turbulence model was applied, and ANSYS CFX was provided for numerical simulation calculation. Experiments of external characteristics and pressure fluctuation have been done to verify the results of numerical simulation. The results show that under the design operating condition, the main fluctuation frequencies in the volute, at the inlet and outlet of the impeller are the Blade Passing Frequency. The amplitudes of fluctuation at the inlet of the impeller decrease gradually from the rim to the hub, while those at the export decrease firstly and then increase, the amplitudes at the tongue are much higher than that at other sections of the volute. Under the off-design operating conditions, the main fluctuation Frequency at the inlet and outlet of the impeller is still the Blade Passing Frequency, while that at the tongue is between the twice shaft Frequency and the Blade Passing Frequency, fluctuation amplitudes are both larger than those under the design operating condition. Under the design operating condition, the radial force on the impeller is the minimum, however, the axial force increases with the increase of flow rate. The distributions of unsteady pressure in volute type axial flow pump are different with general centrifugal or axial flow pump

Ragni D. – One of the best experts on this subject based on the ideXlab platform.

  • On the effect of the tip-clearance ratio on the aeroacoustics of a diffuser-augmented wind turbine
    'Elsevier BV', 2020
    Co-Authors: Avallone F., Ragni D., Casalino D.

    Abstract:

    Lattice-Boltzmann Very-Large-Eddy Simulations of two Diffuser-Augmented Wind Turbines are carried out to investigate the effect of the tip-clearance (TC) ratio on both the flow field and the far-field noise. The DonQi® wind turbine, a three Blades ducted rotor with nominal TC of 2.5%, is chosen as reference test case. The second configuration has TC equal to 0.7%. The latter shows flow separation on the diffuser suction side causing lower velocity at the rotor plane and a reduction of 5% of the thrust coefficient. Flow separation is associated with the break down of the tip vortex immediately after the rotor plane. The TC has an effect on the far-field noise. For angles between 60∘ and 120∘, where 0∘ corresponds to the axial upstream direction, the Blade tonal noise is the dominant source. For other angular directions, noise increase is found for the smaller TC and it associated to an additional noise source located into the gap that can be modeled as a monopole source. It causes an increase of broadband noise at frequencies higher than the third Blade Passing Frequency and tonal peaks at frequencies equal to 4.5 times the Blade Passing Frequency and higher harmonics.Wind Energ

  • On the Effect of the Tip Clearance on the Aerodynamic and Aeroacoustics of a Diffuser-AugmentedWind Turbine
    AIAA, 2019
    Co-Authors: Avallone F., Casalino D., Ragni D.

    Abstract:

    A computational study of two Diffuser-Augmented Wind Turbines (DAWTs) is carried out to investigate both the hydrodynamic flow field and the far-field noise. The two configurations differ for the tip-clearance ratio, defined as the ratio between the tip clearance and the rotor radius. The DonQi® wind turbine, a three Blades ducted rotor, is adopted as baseline configuration because of the availability of reference data. It has a tip-clearance ratio of 2:5%. The second configuration is obtained from the first one by elongating the rotor radius such to force the interaction between the turbulent boundary layer, developing over the suction side of the diffuser, and the tip of the Blades, thus resulting in a tip-clearance ratio of 0:7%. The rotor with the longer Blades shows a reduction of the thrust coefficient because of the lower lift generated by the diffuser that results in a lower axial velocity at the rotor plane. It is shown that this is caused by the smaller tip gap that forces the break down of the rotor tip vortex in smaller turbulent structures immediately after the rotor plane and that induces earlier flow separation along the suction side of the diffuser. The tip-clearance ratio has also a strong effect on the far-field noise. For angles between 60_ and 120_, where 0_ corresponds to the axial upstream direction, the Blade tonal noise, at Frequency equal to the Blade Passing Frequency and higher harmonics, is the dominant source. For other angular directions, noise increase is found for the smaller tip-clearance ratio case associated to an additional noise source, that becomes dominant, linked to an increase of the energy content of velocity fluctuations in the gap region. This noise source, that can be modeled as a monopole source located in the gap, causes an increase of broadband noise at frequencies higher than the third Blade Passing Frequency and a tonal peak at a Frequency equal to 4:5 times the Blade Passing Frequency and higher harmonics

  • Aerodynamic and Aeroacoustic Effects of Swirl Recovery Vanes Length
    'American Institute of Aeronautics and Astronautics (AIAA)', 2019
    Co-Authors: Avallone F., Ragni D., Casalino D., Van Den Ende Luc, Li Q., Eitelberg G., Veldhuis L.l.m.

    Abstract:

    A numerical investigation of a propeller with swirl recovery vanes, for which experimental data exist, is performed. A second swirl recovery vane geometry, with shorter vanes to avoid the impingement of the propeller tip vortices, is also investigated. For the baseline swirl recovery vanes, the efficiency of the propulsive system increases by 2.4% with respect to the isolated propeller. This is obtained by converting angular momentum in axial momentum. A reduction of the swirl angle in the near wake by 48% is found. Most of the thrust is generated at the root of the vanes. Leading-edge impingement noise is the dominant source. The vanes cause noise to increase by 20 dB with respect to the isolated propeller in the axial direction, where noise from the propeller vanishes. In the axial direction, sound pressure level spectra show tonal peaks at harmonics of the second Blade Passing Frequency, while in the other directions, peaks are present at harmonics of the first Blade Passing Frequency. However, the overall isolated propeller noise is 23 dB higher than the noise generated by the swirl recovery vanes. Shortening the vane length causes a 13% reduction of the thrust generated by the vanes with respect the baseline case but no variation of the far-field noise.Wind EnergyFlight Performance and Propulsio