Effects of vortex structure on performance characteristics of a multiblade fan with inclined tongue

Self Cite

The effects of single-arc blade profile length on the performance of a forward multiblade fan are investigated in this paper by computational fluid dynamics and experimental measurement. The present work emphasizes that the use of a properly reduced blade inlet angle (β1A) and properly improved blade outlet angle (β2A) is to increase the length blade profile, which suggests a good physical understanding of internal complex flow characteristics and the aerodynamic performance of the fan. Numerical results indicate that the gradient of the absolute velocity among the blades in model-L (reducing the blade inlet angle and improving blade outlet angle) is clearly lower than that of the baseline model and model-S (improving the blade inlet angle and reducing blade outlet angle), where a number of secondary flows arise on the exit surface of baseline model and model-S. However, no secondary flow occurs in model-L, and the flow loss at the exit surface of the volute (scroll-shaped flow patterns) for model-L is obviously lower than that of the baseline model at the design point. The comparison of the test results further shows that to improve the blade profile length is to increase the static pressure and the efficiency of the static pressure, since the improved static pressure of the model-L rises as much as 22.5 Pa and 26.2%, and the improved static pressure efficiency of the model-L rises as much as 5 % at the design flow rates. It is further indicated that increasing the blade working area provides significant physical insight into increasing the static pressure, total pressure, the efficiency of the static pressure and the total pressure efficiency.

Section: Computational Model and Grid Of Fanmentioning

confidence: 69%

Section: Computational Model and Grid Of Fanmentioning

confidence: 99%

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Effects of Single-arc Blade Profile Length on the Performance of a Forward Multiblade Fan

Wei

Ying²,

Xu³

et al. 2019

Self Cite

“…The maximum value of pressure is on monitoring point T2 and the minimum value of pressure is on monitoring point T3. This is because the shedding vortex on the blade hits the volute tongue and causes large pressure fluctuations [50][51][52][53]. To clearly explain how the STTE profile affects unsteady pulsations, the DES model is used in a transient-state simulation to capture the fluctuating pressure signals and the flow patterns.…”

Section: Pressure Pulsations For the Two Pumpsmentioning

confidence: 99%

The Role of Blade Sinusoidal Tubercle Trailing Edge in a Centrifugal Pump with Low Specific Speed

Jia

et al. 2019

Pressure pulsations may cause high-amplitude vibrations during the process of a centrifugal pump. The trailing edge shape of the blade has a critical influence on the pump’s pressure fluctuation and hydraulic characterization. In this paper, inspired by the humpback whale flipper, the authors research the impact of applying the sinusoidal tubercles to the blade suction side of the trailing edge. Numerical calculation and experiments are carried out to investigate the impact of the trailing edge shape on the pressure pulsations and performance of a centrifugal pump with low specific speed. Two designed impellers are tested, one is a sinusoidal tubercle trailing edge (STTE) impeller and the other is the original trailing edge (OTE) prototype. The detailed study indicates that the sinusoidal tubercle trailing edge (STTE) reduces pressure pulsation and enhances hydraulic performance. In the volute tongue region, the pressure pulsation amplitudes of STTE at fBPF decrease significantly. The STTE impeller also effectively changes the vortex structure and intensity in the blade trailing edge area. This investigation will be of great benefit to the optimal design of pumps.

“…However, the fin on the bottom wall had a tiny effect on the streamline and temperature distributions. The effect of natural convection on the flow in an enclosed space has also been considered in other applications [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Effect of Orientation and Aspect Ratio of an Internal Flat Plate on Natural Convection in a Circular Enclosure

Wang

Ying²,

Wang³

et al. 2019

This work presents a numerical investigation on natural convection in a circular enclosure with an internal flat plate at Ra = 106. The cross-section area of the plate was fixed at three values, H·W/D2 = 0.01, 0.04, and 0.09, in which H and W are the height and width of the plate and D is the diameter of the enclosure while the aspect ratio changes, which makes the plate vertically placed (H > W) or horizontally placed (H < W). The objective of this work was to explore the effects of the orientation and aspect ratio of the plate on the characteristics of natural convection in various aspects. The numerical results reveal that the overall heat transfer rate is higher for the vertically placed plate and increases with the cross-section area, while the width of the plate has almost no effect for the horizontally placed plate, especially for the plate with a relatively large cross-section area. Depending on the orientation and aspect ratio, there can be one primary vortex, one primary and one secondary vortex, or one secondary and two separated vortices to each side of the plate, and the thermal plume structure may appear at the sharp top corners of the plate. Consequently, local heat transfer on the surfaces of the enclosure and plate is affected. Synergy analysis reveals that the enhancement of heat transfer from the fluid circulation is the most significant at the center of the vortices and at the boundary between them.