Experimental investigation of stall inception of a low speed contra rotating axial flow fan under circumferential distorted flow condition

Toge, Tegegn Dejene; Pradeep, A. M.

doi:10.1016/j.ast.2017.08.041

Cited by 31 publications

(11 citation statements)

References 20 publications

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“…The exact frequency responsible for the chaotic behavior could be further determined. In addition, the Morlet wavelet is widely used to analyze turbulent or velocity signals [ 14 , 18 , 19 ], which indicates that the Morlet wavelet could be one of the options for the CWT in our study.…”

Section: Introductionmentioning

confidence: 99%

Coherent Structure of Flow Based on Denoised Signals in T-junction Ducts with Vertical Blades

Wang

Mei

2019

Entropy

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The skin friction consumes some of the energy when a train is running, and the coherent structure plays an important role in the skin friction. In this paper, we focus on the coherent structure generated near the vent of a train. The intention is to investigate the effect of the vent on the generation of coherent structures. The ventilation system of a high-speed train is reasonably simplified as a T-junction duct with vertical blades. The velocity signal of the cross duct was measured in three different sections (upstream, mid-center and downstream), and then the coherent structure of the denoised signals was analyzed by continuous wavelet transform (CWT). The analysis indicates that the coherent structure frequencies become abundant and the energy peak decreases with the increase of the velocity ratio. As a result, we conclude that a higher velocity ratio is preferable to reduce the skin friction of the train. Besides, with the increase of velocity ratio, the dimensionless frequency St of the high-energy coherent structure does not change obviously and St = 3.09 × 10−4–4.51 × 10−4.

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Section: Introductionmentioning

confidence: 99%

Coherent Structure of Flow Based on Denoised Signals in T-junction Ducts with Vertical Blades

Wang

Mei

2019

Entropy

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“…According to the unsteady pressure signal in the compressor flow field, two types of stall inception were confirmed: modal type and spike type. [1][2][3][4] In some compressors, both stall inception types even appeared simultaneously 5,6 and transformed from the modal disturbance to the spike-type stall inception during the stall formation process. 7 Geometric variations, such as the axial distance of compressor rows and stagger angle 8 and the circumferential inflow distortion 9 altered the type of stall inception of the compressor.…”

Section: Introductionmentioning

confidence: 99%

Influence of vaned diffuser on the potential effect of volute and stall inception of centrifugal compressor

Yang

Zhang

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part D:

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In the automotive turbochargers centrifugal compressor, the volute has a strong potential effect, leading to circumferential nonuniformity of the impeller flow field and compressor stall. In this study, full-annulus unsteady simulations for centrifugal compressors with vaned/vaneless diffusers are carried out. The influence of the diffuser vane on the potential effect of the volute and stall behavior of a centrifugal compressor is studied in detail. Based on the distribution of the casing static pressure, the formation mechanism of the circumferential distribution of static pressure and the reverse propagation process of pressure waves caused by pressure distortion are revealed. The results of this study show that the diffuser vanes can weaken the potential effect of the volute on the impeller flow field by reducing the degree of static pressure distortion. The number of static pressure peaks in the circumferential direction is related to the number of vanes/blades. The diffuser vanes can change the circumferential position of the stall inception, but cannot eliminate the “locking effect” of the volute tongue on the circumferential position of the stall. In other words, the circumferential position of the stall inception is still determined by the volute tongue for a centrifugal compressor with a vaned diffuser. Although the degree of circumferential static pressure distortion inside the impeller is reduced, the stable operating range of the compressor cannot be significantly widened by adjusting the stagger angle of the diffuser vane when the stall first occurs at the impeller inlet.

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“…Apart from duct design, a counter-rotating system, where two rotors rotate in the opposite direction on the same axis, can increase the thrust and aerodynamic performance of a ducted fan. The counter-rotating system has been successfully applied to wind turbines [9,10], axial flow pumps [11,12], axial fans [13,14], and propellers [15,16]. A key advantage of this system is that it can produce a higher thrust than a single rotor, and the torque produced by the two rotors is canceled by each other.…”

Section: Introductionmentioning

confidence: 99%

Effect of Rotor Spacing and Duct Diffusion Angle on the Aerodynamic Performances of a Counter-Rotating Ducted Fan in Hover Mode

2020

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The aerodynamic performance of a counter-rotating ducted fan in hover mode is numerically analyzed for different rotor spacings and duct diffusion angles. The design of the counter-rotating fan is inspired by a custom-designed single rotor ducted fan used in a previous study. The numerical model to predict the aerodynamic performance of the counter-rotating ducted fan is developed by adopting the frozen rotor approach for steady-state incompressible flow conditions. The relative angle between the front and the rear rotor is examined due to the usage of the frozen rotor model. The results show that the variation of thrust for the different relative angles is extremely low. The aerodynamic performances are evaluated by comparing the thrust, thrust coefficient, power coefficient, and figure of merit (FOM). The thrust, thrust coefficient, and FOM slightly increase with increasing rotor spacing up to 200 mm, regardless of the duct diffusion angle, and reduce on further increase in the rotor spacing. The duct diffusion angle of 0° generates about 9% higher thrust and increases the FOM by 6.7%, compared with the 6° duct diffusion angle. The duct diffusion angle is highly effective in improving the thrust and FOM of the counter-rotating ducted fan, rather than the rotor spacing.

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Experimental investigation of stall inception of a low speed contra rotating axial flow fan under circumferential distorted flow condition

Cited by 31 publications

References 20 publications

Coherent Structure of Flow Based on Denoised Signals in T-junction Ducts with Vertical Blades

Coherent Structure of Flow Based on Denoised Signals in T-junction Ducts with Vertical Blades

Influence of vaned diffuser on the potential effect of volute and stall inception of centrifugal compressor

Effect of Rotor Spacing and Duct Diffusion Angle on the Aerodynamic Performances of a Counter-Rotating Ducted Fan in Hover Mode

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