scholarly journals Investigations of Inducers Operating With High Rotational Speed

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Björn Gwiasda ◽  
Matthias Mohr ◽  
Martin Böhle
Keyword(s):  
Rotational Speed ◽  
Test Bench ◽  
Pressure Rise ◽  
Working Fluid ◽  
Cfd Simulations ◽  
High Rotational Speed ◽  
Rotating Speed ◽  
Performance Pressure ◽  
Computational Fluid Dynamics Cfd ◽  
Suction Performance

Suction performance, pressure rise, and efficiency for four different inducers are examined with computational fluid dynamics (CFD) simulations and experiments performed with 18,000 rpm and 24,000 rpm. The studies originate from a research project that includes the construction of a new test bench in order to judge the design of the different inducers. This test bench allows to conduct experiments with a rotational speed of up to 40,000 rpm and high pressure ranges from 0.1 bar to 40 bar with water as working fluid. Experimental results are used to evaluate the accuracy of the simulations and to gain a better understanding of the design parameter. The influence of increasing the rotating speed from 18,000 rpm to 24,000 rpm on the performance is also shown.

NUMERICAL ANALYSIS OF AN AXIAL BLOOD PUMP WITH DIFFERENT IMPELLER BLADE HEIGHTS

2012 ◽  
Vol 12 (03) ◽  
pp. 1250045 ◽  
Author(s):  
JIAXING QI ◽  
YANHONG ZHOU ◽  
DONGFANG WANG ◽  
LIANG ZHONG
Keyword(s):  
Shear Stress ◽  
Flow Rate ◽  
Reverse Flow ◽  
Blood Pump ◽  
Shear Stresses ◽  
Cfd Simulations ◽  
Impeller Blade ◽  
Rotating Speed ◽  
Shear Stress Level ◽  
Computational Fluid Dynamics Cfd

Computational fluid dynamics (CFD) simulations of the flow in an axial blood pump with different blade heights (BH150, BH200 and BH250) were performed in the present study. The flow in the pump was assumed as steady and turbulent, and blood was treated as incompressible and Newtonian fluid. The flow rate increased with the rise in blade heights. At the impeller rotating speed of 20,000 rpm and a pressure of 100 mm Hg, the pump produces a flow rate up to 5 L/min in BH200 and BH250 models. The reverse flow and vortices have been identified in the BH150 and BH200 models in the outlet regions, but not for BH250 model. The high shear stress of the flow in the pump mainly occurred at the blade tips. The BH200 model achieved an expected flow rate up to 5 L/min with 90% of the shear stresses less than 500 Pa and the exposure time less than 22 ms, which has the acceptable shear stress level in the literature.

Understanding Lift Force Discontinuity of Pressure Safety Valve

2019 ◽  
Author(s):  
Chao Yong Zong ◽  
Feng Jie Zheng ◽  
Xue Guan Song
Keyword(s):  
Flow Pattern ◽  
Lift Force ◽  
Dynamic Instability ◽  
Safety Valve ◽  
Working Fluid ◽  
Key Factors ◽  
Cfd Simulations ◽  
Valve Body ◽  
Valve Opening ◽  
Computational Fluid Dynamics Cfd

Abstract A pressure safety valve (PSV) is a safety valve designed to protect a vessel or a system during an overpressure event. For pressure safety valve to perform its function, the lift force as one of the key factors influencing the overall performance must be predicted. However, the lift force shows discontinuity with the increase of the valve opening under certain situations. This discontinuity could cause a series of problems, such as dynamic instability. In order to deeply explore the mechanism of the discontinuities numerical and experimental investigation were performed on a direct operated PSV in this paper. A test rig was constructed to measure the steady state lift forces at different valve openings. The working fluid was air and the valve body was removed. To obtain the details of the flow inside the valve, a series of computational fluid dynamics (CFD) simulations were conducted. The simulation indicated that the changing flow pattern is the main cause of the lift force discontinuity and the flow pattern is very sensitive to the valve nozzle thickness and the position of the adjustment ring. Thus, the lift force discontinuity could be weakened or even eliminated by proper valve design.

scholarly journals Transient 3D CFD Simulation of a Stationary Vane, Oil Free, Rotary Compressor

2019 ◽  
Vol 63 (4) ◽  
pp. 308-318 ◽  
Author(s):  
Balázs Farkas ◽  
Jenő Miklós Suda
Keyword(s):  
Cfd Simulation ◽  
Piston Compressor ◽  
Working Fluid ◽  
Rotary Compressor ◽  
Heat Sources ◽  
Cfd Model ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Rolling Piston ◽  
Good Agreement

The evaluation of a newly designed oil-free rotary compressor is presented based on transient 3D Computational Fluid Dynamics (CFD) simulations. The simulations are performed at low compression ratios and low pressure ratios and low rotational speeds. To place the results into context, the data presented in related literature was processed and summarized. The methods related to the CFD model of the newly designed compressor were developed, summarized and evaluated. The accessed CFD data are in good agreement with the results of the former rolling piston compressor related investigations. The oil free operation prevents the contamination of the working fluid from lubricant. Since the compressor is planned to work in open cycle within the sensitive environment of thermal heat sources contamination free operation has to be accomplished. However, oil-free operation also results in significantly lower performance based on the modelling results.

System Matched 3D Radial Impeller Design With Variable Inlet Angle Distributions

2012 ◽  
Author(s):  
Matthias Semel ◽  
Henrik Smith ◽  
Philipp Epple ◽  
Oliver Litfin ◽  
Antonio Delgado ◽  
...  
Keyword(s):  
Rotational Speed ◽  
High Efficiency ◽  
Low Flow ◽  
Hydraulic Efficiency ◽  
Linear Variation ◽  
Cfd Simulations ◽  
High Rotational Speed ◽  
Flow Rates ◽  
Lower Flow ◽  
Inlet Angle

In vacuum cleaners radial impellers with high rotational speed are very often used. A high rotational speed is connected with a best efficiency point of the radial impeller at a high flow rate. This is contrary to the working point of the whole system. Thus there is need for a radial impeller designs having a high efficiency at low flow rates under the restriction of a high rotational speed. One important parameter connected to the hydraulic efficiency characteristics of the radial impeller is the blade inflow angle β1. In order to shift the best efficiency point towards lower flow rates radial impellers with double curved blades and a linear β1 distribution were designed and CFD simulations were done in order to investigate the effect of this approach. A linear variation of the inflow angle β1 enables the designer to shift the efficiency characteristics of the impeller towards lower flow rates with a gain in hydraulic efficiency and pressure increase.

Liquid Atomization in a High-Speed Slinger Atomizer

2019 ◽  
Author(s):  
Arnab Chakraborty ◽  
Srikrishna Sahu
Keyword(s):  
Liquid Flow ◽  
Rotational Speed ◽  
High Speed ◽  
Working Fluid ◽  
Light Illumination ◽  
Atmospheric Conditions ◽  
Atomization Process ◽  
High Rotational Speed ◽  
Jet Breakup ◽  
Liquid Atomization

Abstract The present research aims to investigate the liquid atomization process in a slinger atomizer test rig that houses a high-speed motor which allows high rotational speed of the slinger disc. Instead of delivering the liquid directly on the slinger disc, which is commonly reported in the literature, a stationary manifold was designed that receives the liquid from the pump and supply multiple liquid jets that impinge on the rotating slinger disc. The liquid jet breakup process was visualized using front light illumination technique. All experiments were performed using water as the working fluid and under atmospheric conditions. Four different water flow rates, ranging from 0.2 lpm up to 0.8 lpm were considered. The rotational speed of the slinger was varied from 5000 rpm up to 30000 rpm, which has been rarely reported in the past. The paper reports a comprehensive study on the differences in the liquid breakup modes due to higher liquid flow rate for the same rotational speed and vice-versa. Mostly the liquid was found to attach to the side of the slinger holes that is opposite to the direction of rotation indicating the strong influence of Coriolis forces on the liquid flow within the slinger and hence the atomization process. The droplet size in the spray was measured using the Interferometric Laser Imaging for Droplet Sizing (ILIDS) technique.

Scaled Experiments and CFD Simulations Supporting the Design of the Spallation Neutron Source Mercury Target

2000 ◽  
Author(s):  
W. David Pointer ◽  
Mark W. Wendel ◽  
Jason M. Crye ◽  
Arthur E. Ruggles ◽  
David K. Felde ◽  
...  
Keyword(s):  
Neutron Source ◽  
Cfd Simulation ◽  
Complete Characterization ◽  
Experimental Program ◽  
Working Fluid ◽  
Spallation Neutron Source ◽  
Cfd Simulations ◽  
Liquid Mercury ◽  
Computational Fluid Dynamics Cfd

Abstract A combination of experimental and computational methods is necessary to adequately characterize the flow patterns in the liquid mercury target of the Spallation Neutron Source (SNS). Since liquid mercury is completely opaque and corrosive to many materials, the use of liquid mercury as the working fluid makes complete characterization of the flow field by experiment difficult. Furthermore, flow asymmetries and quasi-periodic instabilities that are observed in early target flow experiments are difficult to capture in computational fluid dynamics (CFD) simulations of the system. Therefore, an experimental program using several scaled experiments is combined with CFD simulation for the design and development of the SNS mercury target.

A Low Speed Axial Compressor With a Cascade of Magnus Rotors to Replace the Aerofoils of the Stator

2004 ◽  
Author(s):  
M. G. Rose
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Flow Coefficient ◽  
Recovery Coefficient ◽  
High Rotational Speed ◽  
Aerodynamic Efficiency ◽  
Low Speed ◽  
Conventional Machine

The low speed axial research compressor ‘Rheinfall’ in the Turbomachinery Labs at ETH Zu¨rich has been modified to include a novel stator row. The conventional stator’s vanes have been replaced with a cascade of rotating cylinders or ‘Magnus Rotors’. The initial aim was to demonstrate that such a cascade could reproduce the effect of the aerofoils. This paper gives an overview of the design, experimental results and conclusions drawn from simple modeling of the experiment. The behaviour of the compressor is essentially preserved; the conventional rotor stalls at a slightly higher flow coefficient (φ = 0.4). The pressure rise across the compressor is a function of the cylinder rotational speed. The pressure recovery coefficient Cpr across the stator can be increased by up to 60% compared to the conventional aerofoils with high rotational speed. The stator pressure rise is maintained at much lower flow coefficient (φ = 0.23). Lift coefficients of up to 7.0 have been stably demonstrated. The stator is capable of very high turning (>60°), to axial and beyond. From simple flow modeling the aerodynamic efficiency appears to be about the same as the conventional machine. However, the parasitic losses in the high-speed Magnus spindles double the power absorbed. The recorded characteristics show strong hysteresis across the whole flow range.

scholarly journals Using CFD to Evaluate Natural Ventilation through a 3D Parametric Modeling Approach

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2197
Author(s):  
Nayara Rodrigues Marques Sakiyama ◽  
Jurgen Frick ◽  
Timea Bejat ◽  
Harald Garrecht
Keyword(s):  
Natural Ventilation ◽  
Parametric Modeling ◽  
Cfd Simulations ◽  
3D Design ◽  
Post Process ◽  
Test House ◽  
Model Set ◽  
Computational Fluid Dynamics Cfd ◽  
Set Up ◽  
Passive Strategy

Predicting building air change rates is a challenge for designers seeking to deal with natural ventilation, a more and more popular passive strategy. Among the methods available for this task, computational fluid dynamics (CFD) appears the most compelling, in ascending use. However, CFD simulations require a range of settings and skills that inhibit its wide application. With the primary goal of providing a pragmatic CFD application to promote wind-driven ventilation assessments at the design phase, this paper presents a study that investigates natural ventilation integrating 3D parametric modeling and CFD. From pre- to post-processing, the workflow addresses all simulation steps: geometry and weather definition, including incident wind directions, a model set up, control, results’ edition, and visualization. Both indoor air velocities and air change rates (ACH) were calculated within the procedure, which used a test house and air measurements as a reference. The study explores alternatives in the 3D design platform’s frame to display and compute ACH and parametrically generate surfaces where air velocities are computed. The paper also discusses the effectiveness of the reference building’s natural ventilation by analyzing the CFD outputs. The proposed approach assists the practical use of CFD by designers, providing detailed information about the numerical model, as well as enabling the means to generate the cases, visualize, and post-process the results.

scholarly journals Dependence of the Flue Gas Flow on the Setting of the Separation Baffle in the Flue Gas Tract

2021 ◽  
Vol 11 (7) ◽  
pp. 2961
Author(s):  
Nikola Čajová Kantová ◽  
Alexander Čaja ◽  
Marek Patsch ◽  
Michal Holubčík ◽  
Peter Ďurčanský
Keyword(s):  
Particulate Matter ◽  
Flue Gas ◽  
Gas Flow ◽  
Negative Impact ◽  
Combustion Process ◽  
Cfd Simulations ◽  
Piv Measurements ◽  
Computational Fluid Dynamics Cfd ◽  
Particle Imaging ◽  
Combustion Of Solid Fuels

With the combustion of solid fuels, emissions such as particulate matter are also formed, which have a negative impact on human health. Reducing their amount in the air can be achieved by optimizing the combustion process as well as the flue gas flow. This article aims to optimize the flue gas tract using separation baffles. This design can make it possible to capture particulate matter by using three baffles and prevent it from escaping into the air in the flue gas. The geometric parameters of the first baffle were changed twice more. The dependence of the flue gas flow on the baffles was first observed by computational fluid dynamics (CFD) simulations and subsequently verified by the particle imaging velocimetry (PIV) method. Based on the CFD results, the most effective is setting 1 with the same boundary conditions as those during experimental PIV measurements. Setting 2 can capture 1.8% less particles and setting 3 can capture 0.6% less particles than setting 1. Based on the stoichiometric calculations, it would be possible to capture up to 62.3% of the particles in setting 1. The velocities comparison obtained from CFD and PIV confirmed the supposed character of the turbulent flow with vortexes appearing in the flue gas tract, despite some inaccuracies.

Performances of HSK Tool Interfaces under High Rotational Speed

CIRP Annals ◽  
2001 ◽  
Vol 50 (1) ◽  
pp. 281-284 ◽  
Author(s):  
T. Aoyama ◽  
I. Inasaki
Keyword(s):  
Rotational Speed ◽  
High Rotational Speed
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