scholarly journals CFD Analysis of Marine Propeller Configurations in Cavitating Conditions

2020 ◽  
Vol 3 (3) ◽  
pp. 251-264
Author(s):  
Ante Sikirica ◽  
Ivana Lučin ◽  
Zoran Čarija ◽  
Bože Lučin
Keyword(s):  
Experimental Data ◽  
Real World ◽  
Cavitating Flow ◽  
Performance Characteristics ◽  
Cfd Analysis ◽  
Marine Propeller ◽  
Performance Differences

Diversely performing propellers as a consequence of design variability are nowadays a commonplace. Fundamental geometric particularities, including size, stipulate performance characteristics, which are usually the only required parameters when deciding on a propeller for specific purpose. With the main focus on the performance, accompanying phenomena, e.g. cavitation, tend to be overlooked. In this paper, propeller configurations in cavitating flow are investigated, with emphasis on real-world performance differences caused by cavitation. Recommended CFD approach is presented with respect to configuration specifics. Available experimental data is used as a baseline for a single propeller, which is then analysed in ducted and tandem configurations with resulting cavitation extents and shape evaluated in the context of current designs.

Numerical Simulation and Vorticity Analysis of Cavitating Flow Around a Marine Propeller Behind the Hull

2019 ◽  
Author(s):  
Yun Long ◽  
Chengzao Han ◽  
Bin Ji ◽  
Xinping Long ◽  
Zhirong Zhang
Keyword(s):  
Experimental Data ◽  
Pressure Fluctuations ◽  
Relative Vorticity ◽  
Cavitating Flow ◽  
Numerical Results ◽  
Tip Vortex ◽  
Marine Propeller ◽  
Thrust Coefficient ◽  
Sheet Cavitation ◽  
Vorticity Transport

Abstract In this paper, the unsteady cavitating turbulent flow around a marine propeller behind the hull is simulated by the k-ω SST turbulence model coupled with the Zwart cavitation model. Three systematic refined structured meshes around the hull and propeller have been generated to study the predicted cavitation patterns and pressure fluctuations. Numerical results indicate that the predicted transient cavitating flow behind the hull wake, including sheet cavitation and tip vortex cavitation, shows quasi-periodic feature and agrees fairly well with the available experimental data. The deviations of pressure fluctuations between experimental data and numerical results are much small. With mesh refining, the cavitation region and the magnitudes of the calculated pressure fluctuations increase, while the differences between two adjacent sets of grids become smaller. In addition, the uncertainty of the thrust coefficient obtained by Factor of Safety method is significantly small. Further, the interaction between the cavitation and the vortex by the relative vorticity transport equation is illustrated. Results show that the magnitude of stretching term is obviously larger than the other three terms, and the dilatation term and the baroclinic term both have an important influence on the generation of vortices.

scholarly journals Performance Characteristics of Breezhaler® and Aerolizer® in the Real-World Setting

2021 ◽  
Author(s):  
Mathieu Molimard ◽  
Ioannis Kottakis ◽  
Juergen Jauernig ◽  
Sonja Lederhilger ◽  
Ivan Nikolaev
Keyword(s):  
Real World ◽  
Performance Characteristics ◽  
The Real ◽  
Real World Setting

A correlation to predict the performance characteristics of centrifugal pumps handling slurries

1997 ◽  
Vol 211 (2) ◽  
pp. 147-157 ◽  
Author(s):  
K A Kazim ◽  
B Maiti ◽  
P Chand
Keyword(s):  
Experimental Data ◽  
Particle Size ◽  
Suspended Solids ◽  
Reduction Factor ◽  
Performance Characteristics ◽  
Centrifugal Pumps ◽  
Pump Performance ◽  
New Correlation ◽  
Effect Of Particle Size ◽  
The Individual

Centrifugal pumps are being used increasingly for transportation of slurries through pipelines. To design a slurry handling system it is essential to have a knowledge of the effects of suspended solids on the pump performance. A new correlation to predict the head reduction factor for centrifugal pumps handling solids has been developed. This correlation takes into account the individual effect of particle size, particle size distribution, specific gravity and concentration of solids on the centrifugal pump performance characteristics. The range of validity of the correlation has been verified by experiment and by using experimental data available from the literature. The present correlation shows better agreement with the experimental data than existing correlations.

Hybrid Analysis of Gas Annular Seals With Energy Equation

2013 ◽  
Author(s):  
Patrick J. Migliorini ◽  
Alexandrina Untaroiu ◽  
William C. Witt ◽  
Neal R. Morgan ◽  
Houston G. Wood
Keyword(s):  
Experimental Data ◽  
Hybrid Method ◽  
Energy Equation ◽  
Flow Analysis ◽  
Experimental Studies ◽  
Rotor System ◽  
Bulk Flow ◽  
Outlet Temperature ◽  
Cfd Analysis ◽  
Annular Seals

Annular seals are used in turbomachinery to reduce secondary flow between regions of high and low pressure. In a vibrating rotor system, the non-axisymmetric pressure field developed in the small clearance between the rotor and the seal generate reactionary forces that can affect the stability of the entire rotor system. Traditionally, two analyses have been used to study the fluid flow in seals, bulk-flow analysis and computational fluid dynamics (CFD). Bulk-flow methods are computational inexpensive, but solve simplified equations that rely on empirically derived coefficients and are moderately accurate. CFD analyses generally provide more accurate results than bulk-flow codes, but solution time can vary between days and weeks. For gas damper seals, these analyses have been developed with the assumption that the flow can be treated as isothermal. Some experimental studies show that the difference between the inlet and outlet temperature temperatures is less than 5% but initial CFD studies show that there can be a significant temperature change which can have an effect on the density field. Thus, a comprehensive analysis requires the solution of an energy equation. Recently, a new hybrid method that employs a CFD analysis for the base state, unperturbed flow and a bulk-flow analysis for the first order, perturbed flow has been developed. This method has shown to compare well with full CFD analysis and experimental data while being computationally efficient. In this study, the previously developed hybrid method is extended to include the effects of non-isothermal flow. The hybrid method with energy equation is then compared with the isothermal hybrid method and experimental data for several test cases of hole-pattern seals and the importance of the use of energy equation is studied.

scholarly journals CFD Analysis of C-D Nozzle Compared with Theoretical & Experimental Data

2018 ◽  
Vol 10 (2) ◽  
pp. 53-64
Author(s):  
KEIR Stewart ◽  
◽  
IVES Rob ◽  
HAMAD Faik ◽  
◽  
...  
Keyword(s):  
Experimental Data ◽  
Cfd Analysis

Expert and Novice End-User Spreadsheet Debugging

2011 ◽  
Vol 23 (2) ◽  
pp. 57-80 ◽  
Author(s):  
Brian Bishop ◽  
Kevin McDaid
Keyword(s):  
Experimental Data ◽  
Real World ◽  
End Users ◽  
End User ◽  
Novel Approach ◽  
Expert And Novice ◽  
Research Studies

The reliability of end-user developed spreadsheets is poor. Research studies find that 94% of ‘real-world’ spreadsheets contain errors. Although some research has been conducted in the area of spreadsheet testing, little is known about the behaviour or processes of individuals during the debugging task. In this paper, the authors investigate the performance and behaviour of expert and novice end-users in the debugging of an experimental spreadsheet. To achieve this aim, a spreadsheet debugging experiment was conducted, with professional and student participants requested to debug a spreadsheet seeded with errors. The work utilises a novel approach for acquiring experimental data through the unobtrusive recording of participants’ actions using a custom built VBA tool. Based on findings from the experiment, a debugging tool is developed, and its effects on debugging performance are investigated.

Assessment of CFD Approaches for Next-Generation Combustor Design

2014 ◽  
Author(s):  
Kumud Ajmani ◽  
Hukam C. Mongia ◽  
Phil Lee
Keyword(s):  
Experimental Data ◽  
Direct Injection ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Cfd Analysis ◽  
Next Generation ◽  
Lean Direct Injection ◽  
Liquid Spray ◽  
Exit Temperature ◽  
Computational Predictions

An effort was undertaken to perform CFD analysis of fluid flow in Lean-Direct Injection (LDI) combustors with axial swirl-venturi elements for next-generation LDI-2 design. The National Combustion Code (NCC) developed at NASA Glenn Research Center was used to perform reacting flow computations on an LDI-2 combustor configuration with thirteen injector elements arranged in four fuel stages. Reacting computations were performed with a consistent approach for mesh-optimization, liquid spray modeling and kinetics modeling. Computational predictions of Emissions Index (EINOx) and combustor exit temperature were compared with two sets of experimental data at medium and high-power operating conditions, for two different pressure-drop conditions in the combustor. The NCC simulations predicted the combustor exit temperature to within 1–2% of experimental data. The accuracy of the EINOx predictions from the NCC simulations was within 10% to 30% of experimental data.

Computational and Experimental Comparison of Different Volute Geometries in a Radial Compressor

2000 ◽  
Author(s):  
Arttu Reunanen ◽  
Harri Pitkänen ◽  
Timo Siikonen ◽  
Harri Heiska ◽  
Jaakko Larjola ◽  
...  
Keyword(s):  
Experimental Data ◽  
Time Dependent ◽  
Experimental Comparison ◽  
Cfd Analysis ◽  
Laboratory Measurements ◽  
Radial Compressor ◽  
Sliding Mesh ◽  
Overall Performance ◽  
Operating Points ◽  
Mesh Technique

Two different volute geometries of a radial compressor at three different operating points have been analyzed using Computational Fluid Dynamics and detailed laboratory measurements. The performance of the volutes were compared using steady-state CFD-analysis, where the volute and the impeller with diffuser were modeled separately. In addition, a time dependent simulation of the complete compressor using the sliding mesh technique was performed for one operation point. Both volutes were manufactured and the overall performance of the compressor, the pressure distribution in the volute and the flow field in the volute inlet were measured with the respective volute geometries. The results obtained from steady, quasi-steady and time-accurate simulations are compared with experimental data.

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