The Experts below are selected from a list of 138 Experts worldwide ranked by ideXlab platform

Mehmet Atlar - One of the best experts on this subject based on the ideXlab platform.

  • An investigation into computational modelling of cavitation in a propeller's slipstream
    2017
    Co-Authors: Naz Yilmaz, Khorasanchi, Mehmet Atlar
    Abstract:

    This paper reports on the ongoing developments of cavitation modelling so far which include preliminary validation studies for simulating the performances of two benchmark model propellers: i.e. PPTC propeller with inclined shaft; and E779A propeller, in non-Cavitating and Cavitating Conditions. The main purpose of this study is to estimate the propeller’s performance in Cavitating Conditions particularly developing tip vortex cavitation. The simulations in open water and Cavitating Conditions were carried out in uniform flow using a commercial CFD package. Firstly, the validation studies were conducted for non-Cavitating Condition. The comparison with the benchmark experimental data showed good agreement for the thrust and torque coefficients as well as for the open water efficiency. Next, the cavitation developed on the propeller was simulated using a numerical model based on the Rayleigh-Plesset equation. Propulsion coefficients (KT, KQ) and the cavity patterns on the benchmark propellers’ blades showed very good agreement with the experimental data. However, the tip vortices off the blades could only be traced for E779A propeller by using a new mesh refinement approach.

  • An experimental investigation of the effect of foul release coating application on performance, noise and cavitation characteristics of marine propellers
    Ocean Engineering, 2012
    Co-Authors: Emin Korkut, Mehmet Atlar
    Abstract:

    A number of ship propellers have been coated with anti-fouling paint, namely foul release, to improve propeller efficiency as a result of dramatic increases in fuel prices. This has recently been coupled with tougher environmental regulations forcing the shipping community to review their anti-fouling policies. With the introduction of a new generation antifouling coatings, it is now possible to apply these coatings not only to keeping the hull free from bio-fouling, but also on propellers to improve their performance. Within the above context an investigation into effect of the coatings on the hydrodynamic performances of marine propellers were carried out. This paper reports on effects of foul release coatings on the efficiency, cavitation and noise characteristics of a marine propeller at model scale. The paper includes the details of these tests conducted in Emerson Cavitation Tunnel of Newcastle University and discusses paint application, surface characterisation issues and analysis of test results for coated and uncoated Conditions. The results indicated that coating may not cause any performance reduction when applied correctly. Cavitation development on blades was slightly reduced by the coating and the coating of blades reduced noise level in non-Cavitating Condition, but increased in developed cavitation Condition, requiring further investigation.

  • An experimental investigation of the effect of foul release coating application on performance, noise and cavitation characteristics of marine propellers
    Ocean Engineering, 2012
    Co-Authors: Emin Korkut, Mehmet Atlar
    Abstract:

    A number of ship propellers have been coated with anti-fouling paint, namely foul release, to improve propeller efficiency as a result of dramatic increases in fuel prices. This has recently been coupled with tougher environmental regulations forcing the shipping community to review their anti-fouling policies. With the introduction of a new generation antifouling coatings, it is now possible to apply these coatings not only to keeping the hull free from bio-fouling, but also on propellers to improve their performance. Within the above context an investigation into effect of the coatings on the hydrodynamic performances of marine propellers were carried out. This paper reports on effects of foul release coatings on the efficiency, cavitation and noise characteristics of a marine propeller at model scale. The paper includes the details of these tests conducted in Emerson Cavitation Tunnel of Newcastle University and discusses paint application, surface characterisation issues and analysis of test results for coated and uncoated Conditions. The results indicated that coating may not cause any performance reduction when applied correctly. Cavitation development on blades was slightly reduced by the coating and the coating of blades reduced noise level in non-Cavitating Condition, but increased in developed cavitation Condition, requiring further investigation. © 2011 Elsevier Ltd. All rights reserved.

W. M. Dempster - One of the best experts on this subject based on the ideXlab platform.

  • A CFD and experimental study on cavitation in positive displacement pumps: Benefits and drawbacks of the 'full' cavitationmodel
    Engineering Applications of Computational Fluid Mechanics, 2016
    Co-Authors: Aldo Iannetti, M T Stickland, W. M. Dempster
    Abstract:

    To fill the gap in the literature in terms of numerical studies of positive displacement (PD) pumps in a Cavitating Condition, a comprehensive and transient computational fluid dynamics (CFD) model of a PD pump, simulating the cavitation arising during the suction stroke, was created. The 'full' cavitation model was utilized to study its capability on PD pump cavitation. A set of three plunger speeds were simulated. Using the highest plunger speed, an assessment was made of the effect of 1.5, 3, 4.5 and 15 parts per million (ppm) of air mass fraction on pump performance and cavitation. An experimental test rig, replicating the CFD model, was designed and built in order to validate the numerical model and find its weaknesses. CFD modeled, in a consistent way, the fluid dynamics phenomena related to cavitation (the chamber pressure approaching the vapor pressure, the vaporization/condensation and the pressure spike occurrence at the end of the suction stroke marking the end of cavitation). On the other hand the CFD pressure trends calculated appeared stretched along the time axis with respect to the experimental data, and this highlighted issues in the multiphase and cavitation models: the vaporization/condensation rate calculated by CFD did not follow the real dynamics correctly because the non-condensable gas expansion was overestimated. This was seen when comparing the CFD/experimental results where the simulated pressure drop gradient at the beginning of the suction stroke and the pressure peaks as the valve closed exhibited a delay in their occurrence. The simulation results were sensitive to the dissolved air mass fraction as the delay depended on the amount of air dissolved in the water. Although the influence of the air mass fraction was considered consistent, the 3 ppm CFD case was the closest to the experimental results, whereas the analyst expected the 15 ppm case to be more accurate.

  • A CFD and experimental study on cavitation in positive displacement pump : benefits and drawbacks of the "full" cavitation model
    Engineering Applications of Computational Fluid Mechanics, 2015
    Co-Authors: Aldo Iannetti, M T Stickland, W. M. Dempster
    Abstract:

    ABSTRACTTo fill the gap in the literature in terms of numerical studies of positive displacement (PD) pumps in a Cavitating Condition, a comprehensive and transient computational fluid dynamics (CFD) model of a PD pump, simulating the cavitation arising during the suction stroke, was created. The ‘full’ cavitation model was utilized to study its capability on PD pump cavitation. A set of three plunger speeds were simulated. Using the highest plunger speed, an assessment was made of the effect of 1.5, 3, 4.5 and 15 parts per million (ppm) of air mass fraction on pump performance and cavitation. An experimental test rig, replicating the CFD model, was designed and built in order to validate the numerical model and find its weaknesses. CFD modeled, in a consistent way, the fluid dynamics phenomena related to cavitation (the chamber pressure approaching the vapor pressure, the vaporization/condensation and the pressure spike occurrence at the end of the suction stroke marking the end of cavitation). On the ot...

Emin Korkut - One of the best experts on this subject based on the ideXlab platform.

  • An experimental investigation of the effect of foul release coating application on performance, noise and cavitation characteristics of marine propellers
    Ocean Engineering, 2012
    Co-Authors: Emin Korkut, Mehmet Atlar
    Abstract:

    A number of ship propellers have been coated with anti-fouling paint, namely foul release, to improve propeller efficiency as a result of dramatic increases in fuel prices. This has recently been coupled with tougher environmental regulations forcing the shipping community to review their anti-fouling policies. With the introduction of a new generation antifouling coatings, it is now possible to apply these coatings not only to keeping the hull free from bio-fouling, but also on propellers to improve their performance. Within the above context an investigation into effect of the coatings on the hydrodynamic performances of marine propellers were carried out. This paper reports on effects of foul release coatings on the efficiency, cavitation and noise characteristics of a marine propeller at model scale. The paper includes the details of these tests conducted in Emerson Cavitation Tunnel of Newcastle University and discusses paint application, surface characterisation issues and analysis of test results for coated and uncoated Conditions. The results indicated that coating may not cause any performance reduction when applied correctly. Cavitation development on blades was slightly reduced by the coating and the coating of blades reduced noise level in non-Cavitating Condition, but increased in developed cavitation Condition, requiring further investigation.

  • An experimental investigation of the effect of foul release coating application on performance, noise and cavitation characteristics of marine propellers
    Ocean Engineering, 2012
    Co-Authors: Emin Korkut, Mehmet Atlar
    Abstract:

    A number of ship propellers have been coated with anti-fouling paint, namely foul release, to improve propeller efficiency as a result of dramatic increases in fuel prices. This has recently been coupled with tougher environmental regulations forcing the shipping community to review their anti-fouling policies. With the introduction of a new generation antifouling coatings, it is now possible to apply these coatings not only to keeping the hull free from bio-fouling, but also on propellers to improve their performance. Within the above context an investigation into effect of the coatings on the hydrodynamic performances of marine propellers were carried out. This paper reports on effects of foul release coatings on the efficiency, cavitation and noise characteristics of a marine propeller at model scale. The paper includes the details of these tests conducted in Emerson Cavitation Tunnel of Newcastle University and discusses paint application, surface characterisation issues and analysis of test results for coated and uncoated Conditions. The results indicated that coating may not cause any performance reduction when applied correctly. Cavitation development on blades was slightly reduced by the coating and the coating of blades reduced noise level in non-Cavitating Condition, but increased in developed cavitation Condition, requiring further investigation. © 2011 Elsevier Ltd. All rights reserved.

Aldo Iannetti - One of the best experts on this subject based on the ideXlab platform.

  • A CFD and experimental study on cavitation in positive displacement pumps: Benefits and drawbacks of the 'full' cavitationmodel
    Engineering Applications of Computational Fluid Mechanics, 2016
    Co-Authors: Aldo Iannetti, M T Stickland, W. M. Dempster
    Abstract:

    To fill the gap in the literature in terms of numerical studies of positive displacement (PD) pumps in a Cavitating Condition, a comprehensive and transient computational fluid dynamics (CFD) model of a PD pump, simulating the cavitation arising during the suction stroke, was created. The 'full' cavitation model was utilized to study its capability on PD pump cavitation. A set of three plunger speeds were simulated. Using the highest plunger speed, an assessment was made of the effect of 1.5, 3, 4.5 and 15 parts per million (ppm) of air mass fraction on pump performance and cavitation. An experimental test rig, replicating the CFD model, was designed and built in order to validate the numerical model and find its weaknesses. CFD modeled, in a consistent way, the fluid dynamics phenomena related to cavitation (the chamber pressure approaching the vapor pressure, the vaporization/condensation and the pressure spike occurrence at the end of the suction stroke marking the end of cavitation). On the other hand the CFD pressure trends calculated appeared stretched along the time axis with respect to the experimental data, and this highlighted issues in the multiphase and cavitation models: the vaporization/condensation rate calculated by CFD did not follow the real dynamics correctly because the non-condensable gas expansion was overestimated. This was seen when comparing the CFD/experimental results where the simulated pressure drop gradient at the beginning of the suction stroke and the pressure peaks as the valve closed exhibited a delay in their occurrence. The simulation results were sensitive to the dissolved air mass fraction as the delay depended on the amount of air dissolved in the water. Although the influence of the air mass fraction was considered consistent, the 3 ppm CFD case was the closest to the experimental results, whereas the analyst expected the 15 ppm case to be more accurate.

  • A CFD and experimental study on cavitation in positive displacement pump : benefits and drawbacks of the "full" cavitation model
    Engineering Applications of Computational Fluid Mechanics, 2015
    Co-Authors: Aldo Iannetti, M T Stickland, W. M. Dempster
    Abstract:

    ABSTRACTTo fill the gap in the literature in terms of numerical studies of positive displacement (PD) pumps in a Cavitating Condition, a comprehensive and transient computational fluid dynamics (CFD) model of a PD pump, simulating the cavitation arising during the suction stroke, was created. The ‘full’ cavitation model was utilized to study its capability on PD pump cavitation. A set of three plunger speeds were simulated. Using the highest plunger speed, an assessment was made of the effect of 1.5, 3, 4.5 and 15 parts per million (ppm) of air mass fraction on pump performance and cavitation. An experimental test rig, replicating the CFD model, was designed and built in order to validate the numerical model and find its weaknesses. CFD modeled, in a consistent way, the fluid dynamics phenomena related to cavitation (the chamber pressure approaching the vapor pressure, the vaporization/condensation and the pressure spike occurrence at the end of the suction stroke marking the end of cavitation). On the ot...

Jeanluc Reboud - One of the best experts on this subject based on the ideXlab platform.

  • experimental and numerical studies in a centrifugal pump with two dimensional curved blades in Cavitating Condition
    Journal of Fluids Engineering-transactions of The Asme, 2003
    Co-Authors: Olivier Coutierdelgosha, M Hofmann, R Fortespatella, Jeanluc Reboud, B Stoffel
    Abstract:

    In the presented study a special test pump with two-dimensional curvature blade geometry was investigated in Cavitating and nonCavitating Conditions using different experimental techniques and a three-dimensional numerical model implemented to study Cavitating flows. Experimental and numerical results concerning pump characteristics and performance breakdown were compared at different flow Conditions. Appearing types of cavitation and the spatial distribution of vapor structures within the impeller were also analyzed. These results show the ability of the model to simulate the complex three-dimensional development of cavitation in a rotating machinery, and the associated effects on the performance.

  • 3D Numerical Simulation of Pump Cavitating Behavior
    Volume 2: Symposia and General Papers Parts A and B, 2002
    Co-Authors: Olivier Coutier-delgosha, Jeanluc Reboud, R. Fortes-patella, B. Pouffary
    Abstract:

    The quasi-steady Cavitating behavior of three pumps was investigated by 3D unsteady viscous computations. The numerical model is based on the commercial code FINE/TURBO™, which was adapted to take into account the cavitation phenomenon. The resolution resorts to a time-marching algorithm initially devoted to compressible flows. A low-speed preConditioner is applied to treat low Mach number flows. The vaporization and condensation processes are controlled by a barotropic state law that links the void ratio evolution to the pressure variations. A radial pump, a centrifugal pump, and a turbopump inducer were calculated and the Cavitating behaviors obtained by the computations were compared to experimental measurements and visualizations. A reliable agreement is obtained for the two pumps concerning both the head drop charts and the extension of the vapor structures. A qualitative good agreement with experiments is also observed in the case of the turbopump inducer. The accuracy of the numerical model is discussed for the three geometries. These simulations are a first attempt to simulate the complete 3D Cavitating flows in turbomachinery. Results are promising, since the quasi-steady behaviors of the pumps in Cavitating Condition are found quantitatively close to the experimental ones. A continuing effort is pursued to improve the prediction accuracy, and to simulate unsteady effects observed in experiments, as, for example, rotating cavitation.Copyright © 2002 by ASME

  • experimental and numerical studies on a centrifugal pump with 2d curved blades in Cavitating Condition
    CAV 2001 symposium, 2001
    Co-Authors: M Hofmann, B Stoffel, Olivier Coutierdelgosha, R Fortespatella, Jeanluc Reboud
    Abstract:

    In the presented study a special test-pump with 2D curvature blade geometry in Cavitating and non-Cavitating Conditions was investigated using different experimental techniques and a 3D numerical model of Cavitating flows. Experimental and numerical results concerning pump characteristics and performance breakdown were compared at different flow Conditions. Appearing types of cavitation and the spatial distribution of vapour structures within the runner were also analysed.