Numerical Study on Performance of Surface Piercing Propeller using RANS Approach

2015 ◽  
Author(s):  
Kohei Himei ◽  
Hajime Yamaguchi
Keyword(s):  
Standardized Test ◽  
Numerical Study ◽  
High Reliability ◽  
Experimental Studies ◽  
Performance Estimation ◽  
Experimental Results ◽  
Ventilated Cavitation ◽  
Wide Range ◽  
Physical Phenomena ◽  
Surface Piercing Propeller

Surface Piercing Propeller (SPP) can achieve high propulsive efficiency on high-speed vessels planing to reduce the frictional resistance of hull. It has the characteristic blade section and works partially submerged condition. The blades repeat entry to and exit from the water free surface and the suction sides and trailing edge of blades are exposed to ventilated cavitation while they are under the water. And interface near SPP is severely deformed by the high rotating blades. This working condition of SPP, therefore, makes it hard that propeller open characteristics are estimated with high reliability. Because SPP is unusual propeller having above difficulty of the performance estimation, the studies for SPP are few compared with large sized propellers for merchant ships. Although the various model tests had been carried out to understand the physical phenomena around various SPPs and their effects on propeller performances, they were not universal approach with standardized test conditions and propeller shape, as mentioned in 23th ITTC report and recommendation (2002). In applying the conventional calculation based on potential theory to SPP, there are many difficulties to model the physical phenomena theoretically. In calculations by Furuya (1984, 1985), thickness of blade and ventilated cavitation were non-consideration, and it was assumed that the suction side of the blade was fully ventilated in the water. In calculations by Young and Kinnas (2001), the interface deformation near SPP was not modeled theoretically. Therefore, they attributed the difference from experimental results to the effect of incompleteness of numerical modeling. On the other hand, CFD analysis can treat the effects of physical phenomena including thick ventilated cavitation and the sharp deformation of interface around SPP. In addition, the characteristic blade shape is modeled accurately without the geometric limitation in CFD. In this paper, typical SPP with experimental results open to the public is analyzed by CFD-RANS approach using Volume of Fluid (VOF) method based on interface-capturing algorithm at wide range of propeller advance coefficient J. Regarding propeller open characteristics, the 6-component force/moment fluctuations by blade rotations, and ventilation patterns, analyses results are compared with measured values. Moreover, the results of simulations in various Froude numbers and Weber numbers are evaluated whether their effects were negligible when they are sufficiently high, in the same manner as the results found by the other’s experimental studies (Shiba, 1953; Brandt, 1973).

Experimental Studies on Cooling Effectiveness of the Double-Decker Air Jet Impingement With Film Outflow

2007 ◽  
Author(s):  
Junkui Mao ◽  
Wen Guo ◽  
Zhenxiong Liu ◽  
Jun Zeng
Keyword(s):  
Infrared Radiation ◽  
Experimental Studies ◽  
Jet Impingement ◽  
Experimental Results ◽  
Thermal Camera ◽  
Local Cooling ◽  
Cooling Effectiveness ◽  
Air Jet ◽  
Double Decker ◽  
Wide Range

Experiments were carried out to investigate the cooling effectiveness of a lamellar double-decker impingement/effusion structure. Infrared radiation (I.R.) thermal camera was used to measure the temperature on the outside surface of the lamellar double-decker. Experimental results were obtained for a wide range of governing parameters (blowing rate M (0.0017∼0.0066), the ratio of the jet impingement distance to the diameter of film hole H/D (0.5∼1.25), the ratio of the distance between the jet hole and film hole to the diameter of the film hole P/D (0, 3, 4), and the material of double-decker (Steel and Copper)). It was observed that the local cooling effectiveness η varies with all these parameters in a complicated way. All the results show that higher cooling effectiveness η is achieved in larger blowing rate cases. A certain range of H/D and P/D can be designed to result in the maximum cooling effectiveness η. And η is less sensitive to the material type compared with those parameters such as H/D, M and P/D.

A New Analytical Model of a Centrifugal Compressor and Validation by Experiments

2010 ◽  
Vol 26 (1) ◽  
pp. 37-45 ◽  
Author(s):  
H. Pourfarzaneh ◽  
A. Hajilouy-Benisi ◽  
M. Farshchi
Keyword(s):  
Conceptual Design ◽  
Centrifugal Compressor ◽  
Experimental Studies ◽  
Design Tool ◽  
Operating Conditions ◽  
Experimental Results ◽  
Design Phase ◽  
Robust Model ◽  
Conceptual Design Phase ◽  
Wide Range

AbstractIn the conceptual design phase of a turbocharger, where emphasis is mainly on parametric studies, before manufacturing and tests, a generalized and robust model that implies over a wide range properly, is unavoidable. The critical inputs such as compressor maps are not available during the conceptual design phase. Hence, generalized compressor models use alternate methods that work without any supplementary tests and can operate on wide range. One of the common and applicable modeling methods in design process is the ‘Dimensionless Modeling’ using the constant coefficient scaling (CCS). This method almost can predict the compressor characteristics at design point. However, at off design conditions, error goes up as mass flow and speed parameters increase. Therefore, the results are not reliable at these points. In this paper, a variable coefficient scaling (VCS) method is described. Then, a centrifugal compressor is modeled using the VCS method. To evaluate the model and compare it with the experimental results, some supplementary experiments are performed. Experimental studies are carried out on the compressor of a S2B model of the Schwitzer turbocharger in the turbocharger Lab., at Sharif University of Technology. The comparison between the experimental results and those obtained by the VCS method indicates a good agreement. It also suggests that the present model can be used as an effective design tool for all operating conditions.

Elastohydrodynamic Film Thickness in Concentrated Contacts: Part 2: Correlation of Experimental Results with Elastohydrodynamic Theory

1986 ◽  
Vol 200 (3) ◽  
pp. 219-226 ◽  
Author(s):  
R J Chittenden ◽  
D Dowson ◽  
C M Taylor
Keyword(s):  
Film Thickness ◽  
Experimental Studies ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Experimental Results ◽  
Experimental Techniques ◽  
Dimensionless Parameters ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Computational Procedures

The existence of a coherent film of lubricant between highly loaded machine elements has been recognized for many years. Over this period of time measurements of film thickness have gone hand in hand with theoretical analyses in the field now known as elastohydrodynamic lubrication. The experimental techniques of capacitance, electrical resistance and X-ray measurement have been supplemented by the use of optical interferometry while the analytical expressions obtained with the use of elegant simplifications have been superseded by those developed from extensive and comprehensive computational procedures. These developments in experimental techniques have yielded a substantial number of measurements of both minimum and central film thickness. Likewise, the advent of the digital computer has allowed the derivation of a large number of solutions to the problem of elastohydrodynamic lubrication of concentrated contacts. All these results, covering a wide range of geometrical conditions, are to be found in the literature, yet little attempt appears to have been made to assemble a representative set of experimental data to permit a detailed evaluation of the theoretical formulae for elliptical contacts. The second part of this paper therefore considers the correlation between a number of experimental studies covering a wide range of operating conditions and geometries, and the predictions of recent elastohydrodynamic theory. Some of the important aspects of each set of experimental results are then considered and examples are provided which illustrate the following points: 1. Good estimates of lubricant film thickness may be obtained from the theoretical expressions recently derived, even when the dimensionless parameters involved are outside the ranges considered in the derivation of the formulae. 2. The discrepancies which exist between theoretical predictions and some of the measured film thicknesses are nevertheless quite large, even when the dimensionless parameters are within their usual limits. On the whole there is good agreement between experiment and theory, while the general trend of the results indicates that theoretical predictions may underestimate the minimum film thickness by about 10 per cent and the central film thickness by about 25 per cent. This measure of agreement is quite remarkable when the extreme difficulty of interpreting the magnitudes of effective and very thin mean film thicknesses between machined components in various forms of experimental equipment is considered.

Testing and Modelling of an Advanced Motorcycle Shock Absorber

2010 ◽  
Author(s):  
Vittore Cossalter ◽  
Alberto Doria ◽  
Roberto Pegoraro ◽  
Luca Trombetta
Keyword(s):  
Hysteresis Loop ◽  
Shock Absorber ◽  
Oil And Gas ◽  
Hysteresis Loops ◽  
Experimental Results ◽  
Total Force ◽  
Complete Model ◽  
Specific Test ◽  
Wide Range ◽  
Physical Phenomena

In shock absorbers damper-rod force not only depends on damper-rod velocity, but also on position and acceleration. Since hydraulic losses are responsible for velocity-dependent forces, other phenomena are responsible for the dependence of force on position and acceleration, they are: compliances of the chambers and of the seals, compressibility of oil and gas and inertia of oil. The presence of position and/or acceleration-dependent terms in the force causes a hysteresis loop in the force-velocity diagram and a delay between force and velocity in the force-time diagram, which affect the performance of the shock absorber. Usually test benches measure only the damper-rod force, hence, it is difficult to recognize the physical phenomena that generate the hysteresis loop. This paper deals with a research program in which a high performance motorcycle shock absorber was tested by means of a specific test bench which includes the measurement of pressures inside the cambers during harmonic tests (frequency range 1–7 Hz). The experimental results with proper mathematical models made it possible to analyze the hysteresis loops of the pressures in the various chambers and the generation of the hysteresis loop and time delay of damper-rod force. First some experimental results dealing with pressures inside compression, rebound and compensation chambers are shown. Then a simplified mathematical model is presented, it is able to capture the most relevant physical phenomena that generate the hysteresis loop of the total force. Finally a complete model of the shock absorber is described, it takes into account details of oil motion inside the valves and it is able to predict the behavior of the shock absorber for a wide range of working conditions. Some numerical results obtained with the complete model are presented and compared with experimental results.

Heat and Mass Transfers in a Heated Concrete Element: 20 to 600°C

2006 ◽  
Author(s):  
A. Noumowe ◽  
M. V. G. de Morais ◽  
M. Kanema ◽  
J. L. Gallias ◽  
R. Cabrillac
Keyword(s):  
High Temperature ◽  
Vapor Pressure ◽  
Numerical Study ◽  
Water Vapor Pressure ◽  
Experimental Studies ◽  
Experimental Results ◽  
Chemical Transformations ◽  
Concrete Element ◽  
Parametric Analyses ◽  
Mass Transfers

The aim of this work is to carry out a numerical study on the coupled heat and mass transfers in a concrete element exposed to elevated temperature in order to explain the behaviour observed during experimental studies. Comparisons were drawn on numerical and experimental results on the thermo-hydrous behavior of a concrete element. Parametric analyses were carried out in order to underline main parameters involved in concrete behavior at high temperature. The numerical and experimental results included thermal gradient, water vapor pressure, relative humidity, concrete mass losses due to dehydration, water content for a concrete element heated from 20 to 600 °C. The results show high thermal gradients and high vapor pressure in the concrete element in addition to the damage due to concrete chemical transformations at high temperature.

scholarly journals Preliminary Experimental and Numerical Study of Metal Element with Notches Reinforced by Composite Materials

2021 ◽  
Vol 5 (5) ◽  
pp. 134
Author(s):  
Paweł J. Romanowicz ◽  
Bogdan Szybiński ◽  
Mateusz Wygoda
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Numerical Study ◽  
Correlation Method ◽  
Industrial Applications ◽  
Experimental Results ◽  
Image Correlation ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Wide Range

The presented study is related to the application of the composite overlays used in order to decrease the effect of the stress concentrations around the cut-outs in structural metal elements. The proposed approach with the application of the digital image correlation extends the recently presented studies. Such structural elements with openings of various shapes have been accommodated for a wide range of industrial applications. These structures exhibit certain stress concentrations which decrease their durability and strength. To restore their strength, various reinforcing overlays can be used. In the present paper, the flat panel structure without and with the composite overlays made of HEXCEL TVR 380 M12/26%/R-glass/epoxy is under the experimental and the numerical study. Particular attention is paid to the investigation of the samples with the rectangular holes, which for smooth rounded corners offer a higher durability than the samples with the circular hole of the same size. The experimental results are obtained for the bare element and are reinforced with composite overlay samples. The experimental results are obtained with the use of the Digital Image Correlation method, while the numerical results are the product of the Finite Element Analysis. In the numerical analysis, the study of the shape, size and fiber orientation in applied overlays is done. The reduction of the stress concentration observed in opening notches has confirmed the effectiveness of the overlay application. In the investigated example, the application of the square composite overlay increased the structure strength even by 25%.

COLUMN BUCKLING TESTS OF 420 MPA HIGH STRENGTH STEEL SINGLE EQUAL ANGLES

2013 ◽  
Vol 13 (02) ◽  
pp. 1250069 ◽  
Author(s):  
H. Y. BAN ◽  
G. SHI ◽  
Y. J. SHI ◽  
Y. Q. WANG
Keyword(s):  
High Strength Steel ◽  
Experimental Studies ◽  
High Strength ◽  
Experimental Results ◽  
Test Results ◽  
Design Strength ◽  
Buckling Modes ◽  
Wide Range ◽  
Current Design ◽  
Design Values

This paper presents the results of the experimental studies conducted on the buckling behavior of 420 MPa high strength steel, hot-rolled, equal angle columns, numbering a total of 66 specimens with a wide range of column slenderness and section sizes. Based on the test results, the buckling modes and capacities were analyzed and the nondimensional buckling strengths were obtained and compared with the design strength predicted from Eurocode 3, ANSI/AISC 360-10 and Chinese standards GB50017-2003. The experimental results in previous studies were also employed in the comparison. The effect of width to thickness ratio of legs of an angle on buckling modes and strengths were investigated. It was found that the buckling strengths from test results were much higher than the corresponding design values and current design approaches were too conservative. Based on present and previous experimental results, a new design approach is suggested for the design of angle columns with 420 MPa high strength steel.

Fluid Flow Separation in Down Comer During a Safety Injection Scenario: Quantitative Experimental Results

Volume 4 ◽  
2004 ◽  
Author(s):  
Th. Bichet ◽  
A. Martin ◽  
F. Beaud
Keyword(s):  
Fluid Flow ◽  
Experimental Model ◽  
Flow Separation ◽  
Cold Water ◽  
Numerical Study ◽  
Salt Water ◽  
Numerical Results ◽  
Experimental Results ◽  
Flow Density ◽  
Physical Phenomena

Within the framework of the nuclear power plant lifetime issue, the assessment of the French 900 MWe (3-loops) series Reactor Pressure Vessel (RPV) integrity was performed. A simplified analysis has shown that one of the most severe loading condition is given by the small break loss of coolant accidents (SBLOCA) due to the pressurized injection of cold water (9°C) into the cold leg and down comer of the RPV. Two main physical phenomena, considered important for the RPV cooling transient, were identified during numerical application obtained with EDF CFD tools. These phenomena are the fluid flow separation and the plume oscillations in the down comer. In order to consolidate these numerical results with the EDF home code, called Code_Saturne, an experimental study has been carried out with the new EDF R&D facility. This transparent experimental model is based on the representation at 1/2 scale of a cold leg and a third of down comer including a thermal shield. The experiments were realized by injecting of salt water flow (density effects) in the cold leg according to a similitude study based on Froude number conservation between experiments and reactor scenarios. Firstly, this paper presents the main qualitative experimental results, based essentially on visualizations of different injections of dyed salt water in the cold leg and in the down comer. The physical phenomena observed showed a qualitative good agreement between visualizations and numerical results. Secondly, this paper presents the first experimental results of the assessment of the fluid flow separation in the experimental model obtained with temperature probes inserted in the down comer. We showed, in the experiments analysis, the fluid flow separation and the jet oscillations were detected. The next step will consist to compare these quantitative experiments with numerical study which will be carry out with Code_Saturne.

Numerical Study of Turbulent Helical Pipe Flow With Comparison to the Experimental Results

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Anup Kumer Datta ◽  
Yasutaka Hayamizu ◽  
Toshinori Kouchi ◽  
Yasunori Nagata ◽  
Kyoji Yamamoto ◽  
...  
Keyword(s):  
Experimental Data ◽  
Turbulent Flow ◽  
Secondary Flow ◽  
Pipe Flow ◽  
Numerical Study ◽  
Circular Cross Section ◽  
Turbulence Models ◽  
Experimental Results ◽  
Helical Pipe ◽  
Wide Range

Turbulent flow through helical pipes with circular cross section is numerically investigated comparing with the experimental results obtained by our team. Numerical calculations are carried out for two helical circular pipes having different pitches and the same nondimensional curvature δ (=0.1) over a wide range of the Reynolds number from 3000 to 21,000 for torsion parameter β (=torsion /2δ  = 0.02 and 0.45). We numerically obtained the secondary flow, the axial flow and the intensity of the turbulent kinetic energy by use of three turbulence models incorporated in OpenFOAM. We found that the change to fully developed turbulence is identified by comparing experimental data with the results of numerical simulations using turbulence models. We also found that renormalization group (RNG) k−ε turbulence model can predict excellently the fully developed turbulent flow with comparison to the experimental data. It is found that the momentum transfer due to turbulence dominates the secondary flow pattern of the turbulent helical pipe flow. It is interesting that torsion effect is more remarkable for turbulent flows than laminar flows.

On the nominal transverse shear strain to characterize the severity of creasing

TAPPI Journal ◽  
2018 ◽  
Vol 17 (04) ◽  
pp. 231-240
Author(s):  
Douglas Coffin ◽  
Joel Panek
Keyword(s):  
Shear Strain ◽  
Transverse Shear ◽  
Elastic Limit ◽  
Experimental Results ◽  
Transverse Shear Strain ◽  
Maximum Strain ◽  
Machine Direction ◽  
Engineering Approach ◽  
Wide Range ◽  
Analytic Expression

A transverse shear strain was utilized to characterize the severity of creasing for a wide range of tooling configurations. An analytic expression of transverse shear strain, which accounts for tooling geometry, correlated well with relative crease strength and springback as determined from 90° fold tests. The experimental results show a minimum strain (elastic limit) that needs to be exceeded for the relative crease strength to be reduced. The theory predicts a maximum achievable transverse shear strain, which is further limited if the tooling clearance is negative. The elastic limit and maximum strain thus describe the range of interest for effective creasing. In this range, cross direction (CD)-creased samples were more sensitive to creasing than machine direction (MD)-creased samples, but the differences were reduced as the shear strain approached the maximum. The presented development provides the foundation for a quantitative engineering approach to creasing and folding operations.

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