Characteristics of Swirl Angle in Pump Intake Flow Near the Minimum Inlet Submergence

2019 ◽  
Author(s):  
Tajul Ariffin Norizan ◽  
Zambri Harun ◽  
Wan Hanna Melini Wan Mohtar ◽  
Shahrir Abdullah
Keyword(s):  
Free Surface ◽  
Swirling Flow ◽  
Pump Efficiency ◽  
Angle Distribution ◽  
Pump Impeller ◽  
Load Imbalance ◽  
Swirl Angle ◽  
Free Surface Vortex ◽  
Pump Inlet ◽  
Intake Flow

Abstract Swirling flow in pump sump intake has been the subject of discussion for the past decades due to the detrimental effects brought about by its existence. Among the effects of swirling flow are reduced pump efficiency, cavitation, excessive vibration and load imbalance at the pump impeller which are caused by hydraulic problems associated to swirling flow such as swirls and vortices. One of the remedial measures for preventing such occasion is by keeping the pump inlet submerged above a defined value known as the minimum inlet submergence. It is the minimum submergence required to reduce the probability of the occurrence of free surface vortices. However, this requirement may not be fulfilled in some situations due to on site conditions or operational restrictions. In this paper, an experimental study was conducted to investigate the characteristics of swirl angle in the pump intake flow when the pump inlet is submerged near the value of minimum inlet submergence. The ratio of pump submergence to the minimum submergence was varied between 0.8 to 1.2 with constant inlet Froude Number which referred to as submergence ratio. The strength of the swirl in the intake flow was determined by measuring the swirl angle which was accomplished using a swirl meter attached in the suction pipe. Measurements using Acoustic Doppler Velocimeter (ADV) was performed to capture the velocity profile in the intake sump. The swirl angle distribution across the range of submergence ratios was dominated by a subsurface vortex formed at the sump floor. As soon as the submergence was reduced below the minimum submergence, a free surface vortex emerged near the pump inlet and brought a swirl retardation effect to the swirl meter rotation resulting in a bigger fluctuation of the swirl meter reading. An anti vortex device (AVD) called the floor splitter commonly used to reduce vorticity at pump inlet was installed and its effect on the reduction of swirls and vortices was evaluated.

Numerical prediction on the effect of free surface vortex on intake flow characteristics for tidal power station

2017 ◽  
Vol 101 ◽  
pp. 617-628 ◽  
Author(s):  
Soo-Hwang Ahn ◽  
Yexiang Xiao ◽  
Zhengwei Wang ◽  
Xuezhi Zhou ◽  
Yongyao Luo
Keyword(s):  
Free Surface ◽  
Flow Characteristics ◽  
Numerical Prediction ◽  
Power Station ◽  
Tidal Power ◽  
Free Surface Vortex ◽  
Intake Flow ◽  
Surface Vortex

Numerical Analysis on the CO-NO Formation Production near Burner Throat in Swirling Flow Combustion System

2014 ◽  
Vol 69 (2) ◽  
Author(s):  
Mohamad Shaiful Ashrul Ishak ◽  
Mohammad Nazri Mohd Jaafar
Keyword(s):  
Swirling Flow ◽  
Reverse Flow ◽  
Flow Behavior ◽  
Recirculation Region ◽  
Mixing Enhancement ◽  
Ansys Fluent ◽  
Pressure Losses ◽  
No Formation ◽  
Swirl Angle ◽  
Air Mixing

The main purpose of this paper is to study the Computational Fluid Dynamics (CFD) prediction on CO-NO formation production inside the combustor close to burner throat while varying the swirl angle of the radial swirler. Air swirler adds sufficient swirling to the inlet flow to generate central recirculation region (CRZ) which is necessary for flame stability and fuel air mixing enhancement. Therefore, designing an appropriate air swirler is a challenge to produce stable, efficient and low emission combustion with low pressure losses. A liquid fuel burner system with different radial air swirler with 280 mm inside diameter combustor of 1000 mm length has been investigated. Analysis were carried out using four different radial air swirlers having 30°, 40°, 50° and 60° vane angles. The flow behavior was investigated numerically using CFD solver Ansys Fluent. This study has provided characteristic insight into the formation and production of CO and pollutant NO inside the combustion chamber. Results show that the swirling action is augmented with the increase in the swirl angle, which leads to increase in the center core reverse flow, therefore reducing the CO and pollutant NO formation. The outcome of this work will help in finding out the optimum swirling angle which will lead to less emission.  

Performance characteristics of flow in annular diffuser using CFD

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hardial Singh ◽  
Bharat Bhushan Arora
Keyword(s):  
Swirling Flow ◽  
Flow Behavior ◽  
Pressure Recovery ◽  
Ansys Fluent ◽  
Pressure Loss Coefficient ◽  
Swirl Angle ◽  
Swirl Intensity ◽  
Annular Diffuser ◽  
Inlet Swirl ◽  
Total Pressure Loss Coefficient

Abstract An annular diffuser is a critical component of the turbomachinery, and its prime function is to reduce the flow velocity. The current work is carried to study the effect of four different geometrical designs of an annular diffuser using the ANSYS Fluent. The numerical simulations were carried out to examine the effect of fully developed turbulent swirling and non-swirling flow. The flow behavior of the annular diffuser is analyzed at Reynolds number 2.5 × 105. The simulated results reveal pressure recovery improvement at the casing wall with adequate swirl intensity at the diffuser inlet. Swirl intensity suppresses the flow separation on the casing and moves the flow from the hub wall to the casing wall of the annulus region. The results also show that the Equal Hub and Diverging Casing (EHDC) annular diffuser in comparison to other diffusers has a higher static pressure recovery (C p  = 0.76) and a lower total pressure loss coefficient of (C L  = 0.12) at a 17° swirl angle.

scholarly journals Mechanism Investigation on a Novel Oil Recovery Skimmer Coupling Free Surface Vortex and Cyclone Separation

ACS Omega ◽  
2021 ◽  
Author(s):  
Wei An ◽  
Qingfan Zhang ◽  
Jianping Zhao ◽  
Liang Qu ◽  
Shuo Liu ◽  
...  
Keyword(s):  
Free Surface ◽  
Oil Recovery ◽  
Free Surface Vortex ◽  
Surface Vortex

Similitude in Free-Surface Vortex Formations

1974 ◽  
Vol 100 (11) ◽  
pp. 1565-1581 ◽  
Author(s):  
Larry L. Daggett ◽  
Garbis H. Keulegan
Keyword(s):  
Free Surface ◽  
Free Surface Vortex ◽  
Surface Vortex

Discussion of “Similitude in Free-Surface Vortex Formations”

1975 ◽  
Vol 101 (11) ◽  
pp. 1449-1453
Author(s):  
James A. Weller ◽  
Akalank K. Jain ◽  
Kittur G. RangaRaju
Keyword(s):  
Free Surface ◽  
Free Surface Vortex ◽  
Surface Vortex

A Computational Fluid Dynamics (CFD) Guided Engineering Solution for Performance Improvement of a Multistage Pump

2021 ◽  
Author(s):  
Teymour Javaherchi ◽  
Susheel Brahmeshwarkar ◽  
Raja Faruq ◽  
Chinmay Deshpande
Keyword(s):  
Performance Improvement ◽  
Test Data ◽  
Industrial Applications ◽  
Pump Efficiency ◽  
Pump Impeller ◽  
Methodology Development ◽  
Engineering Team ◽  
Initial Hypothesis ◽  
Computational Fluid Dynamics Cfd ◽  
Multistage Pump

Abstract This work will demonstrate how the Energy Recovery Inc. (ERI) engineering team improved the efficiency of a multistage pump by about 10% at the first stage, which translated into a 3% increase in the overall multistage pump efficiency; according to a set of engineering calculations and review of the archived in-house test data for the legacy multistage pumps, it was hypothesized that the performance pain-point of the pump was inefficient performance of the first stage, due to the formation of a strong pre-swirl right before its inlet. The validity of this hypothesis then was confirmed via RANS CFD simulations of the flow field inside the inlet suction housing and pump impeller. Same CFD methodology was used to evaluate multiple engineering solutions to reduce the strength of the inflow pre-swirl by modifying the inlet suction housing geometry. The obtained RANS CFD solutions guided the engineering team towards the most promising hardware modification proposal. The proposed geometrical modification of the inlet suction housing was implemented and tested on different multistage pumps. All of the test results validated the obtained RANS CFD numerical solution. The state of the art in this successful performance improvement process was first the on-point hypothesis development based on fundamentals of engineering and archived test data. Second, the proper RANS CFD methodology development to model/confirm the initial hypothesis and vet all possible engineering solutions to maximize the multistage pump efficiently and accurately. This can be a great example for various relevant turbomachinery industrial applications.

Numerical Understanding of Free Surface Vortex Driven by Rotational Field Inside Viscous Liquid

2019 ◽  
Vol 41 (15-16) ◽  
pp. 1382-1396
Author(s):  
Mihir Prajapati ◽  
Parmod Kumar ◽  
Arup K. Das ◽  
Sushanta K. Mitra
Keyword(s):  
Free Surface ◽  
Viscous Liquid ◽  
Free Surface Vortex ◽  
Rotational Field ◽  
Surface Vortex

Inhomogeneity in the Network Order of Device Quality a-Si:H

1993 ◽  
Vol 297 ◽  
Author(s):  
G. Morell ◽  
R.S. Katiyar ◽  
S.Z. Weisz ◽  
M. Gomez ◽  
I. Balberg
Keyword(s):  
Free Surface ◽  
Dihedral Angle ◽  
Hydrogen Concentration ◽  
Angle Distribution ◽  
Length Scales ◽  
Bond Stretching ◽  
Degree Of Order

In this paper we show that the degree of order of the Si network in a-Si:H is increasing with two length scales from the surface into the bulk. The major manifestation of the disorder is the variation in the Si-Si bond-stretching rather than the variation in the width of the dihedral angle distribution. The results are interpreted in terms of the decrease of the hydrogen concentration from the free surface into the bulk.

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