The Experts below are selected from a list of 141 Experts worldwide ranked by ideXlab platform

Yoshitaka Ukon - One of the best experts on this subject based on the ideXlab platform.

  • MEASUREMENT OF SHAPE OF CAVITY ON A MODEL Propeller BLADE
    Journal of the Society of Naval Architects of Japan, 2009
    Co-Authors: Tatsuro Kudo, Yoshitaka Ukon, Yuzo Kurobe, Hidetake Tanibayashi
    Abstract:

    In order to improve theoretical prediction of Propeller induced pressure fluctuations, it is indispensable to investigate the behaviour of unsteady cavity on the Propeller blades, since the pressure fluctuations are roughly in proportion to the second time derivative of the cavity volume. To this end, several methods of measuring cavity shape have been proposed such as using stereo photography, pin gauge and laser beam scattering.This paper describes a Highly advanced method of measuring the three-dimensional cavity shape using a laser beam coupled with a CCD (Charge Coupled Device) camera and image processor to make measurement faster and more detailed. Model experiments on two Propellers-a conventional and a Highly Skewed Propeller-of a training ship SEIUN-MARU have endorsed the usefulness of the present measurement technique both in its speed and accuracy.Further, some features of cavity behaviour of Highly Skewed Propellers have been found in terms of cavity thickness distribution and its variation over the blades and the blade angle positions.

  • MEASUREMENT OF PRESSURE DISTRIBUTION AND CAVITY SHAPE ON CONVENTIONAL AND Highly Skewed Propeller MODEL
    Naval architecture and ocean engineering, 1992
    Co-Authors: Yoshitaka Ukon, Tatsuro Kudo, Yuzo Kurobe
    Abstract:

    This paper describes two kinds of Highly advanced measurement techniques recently developed by the Ship Research Institute of Japan and the measurement results by these techniques. One is the measurement of pressure distribution on the blades of Propeller models working in uniform flow and non-uniform flow behind wire mesh screen under non-cavitating condition. The other is the measurement of cavity thickness distribution on the Propeller blades working behind a complete ship model. Each measurement was performed on two kins of Propellers, i.e. a conventional and Highly Skewed Propeller of the Seiun-maru, on which various full scale measurements had been conducted. Two measurements showed that a Highly Skewed Propeller has different hydrodynamic characteristics from that of a conventional one, not only on pressure distribution but also on cavity volume. Regarding the pressure measurement, the wavy distributions were obtained, especially at the suction side of a Highly Skewed Propeller. On th other hand, the second derivatives on time of cavity volume measured at a Highly Skewed Propeller were smaller than that at a conventional one. Those accurate measurements have provided a number of invaluable data to validate the numerical techniques on Propeller and cavitation.

  • Measurement of Pressure Distribution on a Full Scale Propeller
    Journal of the Society of Naval Architects of Japan, 1990
    Co-Authors: Yoshitaka Ukon, Hikaru Kamiirisa, Hironao Kubo, Hajime Yuasa, Tatsuro Kudo, Yuzo Kurobe, Yoshiki Itadani
    Abstract:

    In the previous paper, authors have developed a new technique to measure the pressure distribution around the blades of a full scale Propeller. The full scale measurements were performed on the conventional Propeller, CP in short, of the training ship “Seiun-Maru”. From the results of full scale measurement, the measured pressure distributions were similar at each Propeller loading condition, except cavitation region. Comparing with an existing Propeller lifting surface theory, good agreements were found at most of the measurement points on the back side except near the Propeller tip. This paper describes the measurement of pressure distribution on a Highly Skewed Propeller, HSP in short, of the same ship “Seiun-Maru”. First of all, the special pressure pick-up was improved taking account of the experience in the previous measurement. The same measurement instruments were employed. The measurements were also performed with the same procedure as the previous ones under several working conditions of Propeller revolution rate 70, 90, 110 and 149 rpm. At the Propeller revolution rates more than 110 rpm, the thrust coefficient KT and the advance coefficient J are 0.190 and 0.66, respectively. The accuracy of the present measurement was estimated to be the same as that of the previous one, i. e, ± 0.03 kg/cm2.The measured pressure distributions were compared with the theoretical one with using an estimated nominal full scale wake distribution. Excellent agreements with the theory were found at most of the measurement points, especially in the fore part of the blades. These results indicate the usefulness of the lifting surface theory and the estimated wake for a Highly Skewed Propeller in full scale.On the other hand, the following unforeseen findings were obtained. The measured pressure at 90% radial position tends to decrease toward the trailing edge and completely differs from the theory. This suggests us the hydrodynamic load in the vicinity of the trailing edge at 90% radial position was remarkably heavier than that predicted by the theory. This cyclic load might cause the break-off of the Propeller tip due to rapid fatigue crack growth, if a Propeller blade is damaged at the trailing edge.The measured pressure in the region of sheet cavitation on HSP was higher than the vapor pressure while that on CP was equal to or lower than the vapor pressure.The present full scale measurements indicated that there still exist some problems on the existing Propeller theory and some improvements are necessary on the modelling of a Propeller theory including separation vortex from the leading edge.The present measurement of pressure distribution on both Propellers also provides us a number of invaluable standard data to develop and validate a new Propeller theory.

Yuzo Kurobe - One of the best experts on this subject based on the ideXlab platform.

  • MEASUREMENT OF SHAPE OF CAVITY ON A MODEL Propeller BLADE
    Journal of the Society of Naval Architects of Japan, 2009
    Co-Authors: Tatsuro Kudo, Yoshitaka Ukon, Yuzo Kurobe, Hidetake Tanibayashi
    Abstract:

    In order to improve theoretical prediction of Propeller induced pressure fluctuations, it is indispensable to investigate the behaviour of unsteady cavity on the Propeller blades, since the pressure fluctuations are roughly in proportion to the second time derivative of the cavity volume. To this end, several methods of measuring cavity shape have been proposed such as using stereo photography, pin gauge and laser beam scattering.This paper describes a Highly advanced method of measuring the three-dimensional cavity shape using a laser beam coupled with a CCD (Charge Coupled Device) camera and image processor to make measurement faster and more detailed. Model experiments on two Propellers-a conventional and a Highly Skewed Propeller-of a training ship SEIUN-MARU have endorsed the usefulness of the present measurement technique both in its speed and accuracy.Further, some features of cavity behaviour of Highly Skewed Propellers have been found in terms of cavity thickness distribution and its variation over the blades and the blade angle positions.

  • MEASUREMENT OF PRESSURE DISTRIBUTION AND CAVITY SHAPE ON CONVENTIONAL AND Highly Skewed Propeller MODEL
    Naval architecture and ocean engineering, 1992
    Co-Authors: Yoshitaka Ukon, Tatsuro Kudo, Yuzo Kurobe
    Abstract:

    This paper describes two kinds of Highly advanced measurement techniques recently developed by the Ship Research Institute of Japan and the measurement results by these techniques. One is the measurement of pressure distribution on the blades of Propeller models working in uniform flow and non-uniform flow behind wire mesh screen under non-cavitating condition. The other is the measurement of cavity thickness distribution on the Propeller blades working behind a complete ship model. Each measurement was performed on two kins of Propellers, i.e. a conventional and Highly Skewed Propeller of the Seiun-maru, on which various full scale measurements had been conducted. Two measurements showed that a Highly Skewed Propeller has different hydrodynamic characteristics from that of a conventional one, not only on pressure distribution but also on cavity volume. Regarding the pressure measurement, the wavy distributions were obtained, especially at the suction side of a Highly Skewed Propeller. On th other hand, the second derivatives on time of cavity volume measured at a Highly Skewed Propeller were smaller than that at a conventional one. Those accurate measurements have provided a number of invaluable data to validate the numerical techniques on Propeller and cavitation.

  • Measurement of Pressure Distribution on a Full Scale Propeller
    Journal of the Society of Naval Architects of Japan, 1990
    Co-Authors: Yoshitaka Ukon, Hikaru Kamiirisa, Hironao Kubo, Hajime Yuasa, Tatsuro Kudo, Yuzo Kurobe, Yoshiki Itadani
    Abstract:

    In the previous paper, authors have developed a new technique to measure the pressure distribution around the blades of a full scale Propeller. The full scale measurements were performed on the conventional Propeller, CP in short, of the training ship “Seiun-Maru”. From the results of full scale measurement, the measured pressure distributions were similar at each Propeller loading condition, except cavitation region. Comparing with an existing Propeller lifting surface theory, good agreements were found at most of the measurement points on the back side except near the Propeller tip. This paper describes the measurement of pressure distribution on a Highly Skewed Propeller, HSP in short, of the same ship “Seiun-Maru”. First of all, the special pressure pick-up was improved taking account of the experience in the previous measurement. The same measurement instruments were employed. The measurements were also performed with the same procedure as the previous ones under several working conditions of Propeller revolution rate 70, 90, 110 and 149 rpm. At the Propeller revolution rates more than 110 rpm, the thrust coefficient KT and the advance coefficient J are 0.190 and 0.66, respectively. The accuracy of the present measurement was estimated to be the same as that of the previous one, i. e, ± 0.03 kg/cm2.The measured pressure distributions were compared with the theoretical one with using an estimated nominal full scale wake distribution. Excellent agreements with the theory were found at most of the measurement points, especially in the fore part of the blades. These results indicate the usefulness of the lifting surface theory and the estimated wake for a Highly Skewed Propeller in full scale.On the other hand, the following unforeseen findings were obtained. The measured pressure at 90% radial position tends to decrease toward the trailing edge and completely differs from the theory. This suggests us the hydrodynamic load in the vicinity of the trailing edge at 90% radial position was remarkably heavier than that predicted by the theory. This cyclic load might cause the break-off of the Propeller tip due to rapid fatigue crack growth, if a Propeller blade is damaged at the trailing edge.The measured pressure in the region of sheet cavitation on HSP was higher than the vapor pressure while that on CP was equal to or lower than the vapor pressure.The present full scale measurements indicated that there still exist some problems on the existing Propeller theory and some improvements are necessary on the modelling of a Propeller theory including separation vortex from the leading edge.The present measurement of pressure distribution on both Propellers also provides us a number of invaluable standard data to develop and validate a new Propeller theory.

Tatsuro Kudo - One of the best experts on this subject based on the ideXlab platform.

  • MEASUREMENT OF SHAPE OF CAVITY ON A MODEL Propeller BLADE
    Journal of the Society of Naval Architects of Japan, 2009
    Co-Authors: Tatsuro Kudo, Yoshitaka Ukon, Yuzo Kurobe, Hidetake Tanibayashi
    Abstract:

    In order to improve theoretical prediction of Propeller induced pressure fluctuations, it is indispensable to investigate the behaviour of unsteady cavity on the Propeller blades, since the pressure fluctuations are roughly in proportion to the second time derivative of the cavity volume. To this end, several methods of measuring cavity shape have been proposed such as using stereo photography, pin gauge and laser beam scattering.This paper describes a Highly advanced method of measuring the three-dimensional cavity shape using a laser beam coupled with a CCD (Charge Coupled Device) camera and image processor to make measurement faster and more detailed. Model experiments on two Propellers-a conventional and a Highly Skewed Propeller-of a training ship SEIUN-MARU have endorsed the usefulness of the present measurement technique both in its speed and accuracy.Further, some features of cavity behaviour of Highly Skewed Propellers have been found in terms of cavity thickness distribution and its variation over the blades and the blade angle positions.

  • MEASUREMENT OF PRESSURE DISTRIBUTION AND CAVITY SHAPE ON CONVENTIONAL AND Highly Skewed Propeller MODEL
    Naval architecture and ocean engineering, 1992
    Co-Authors: Yoshitaka Ukon, Tatsuro Kudo, Yuzo Kurobe
    Abstract:

    This paper describes two kinds of Highly advanced measurement techniques recently developed by the Ship Research Institute of Japan and the measurement results by these techniques. One is the measurement of pressure distribution on the blades of Propeller models working in uniform flow and non-uniform flow behind wire mesh screen under non-cavitating condition. The other is the measurement of cavity thickness distribution on the Propeller blades working behind a complete ship model. Each measurement was performed on two kins of Propellers, i.e. a conventional and Highly Skewed Propeller of the Seiun-maru, on which various full scale measurements had been conducted. Two measurements showed that a Highly Skewed Propeller has different hydrodynamic characteristics from that of a conventional one, not only on pressure distribution but also on cavity volume. Regarding the pressure measurement, the wavy distributions were obtained, especially at the suction side of a Highly Skewed Propeller. On th other hand, the second derivatives on time of cavity volume measured at a Highly Skewed Propeller were smaller than that at a conventional one. Those accurate measurements have provided a number of invaluable data to validate the numerical techniques on Propeller and cavitation.

  • Measurement of Pressure Distribution on a Full Scale Propeller
    Journal of the Society of Naval Architects of Japan, 1990
    Co-Authors: Yoshitaka Ukon, Hikaru Kamiirisa, Hironao Kubo, Hajime Yuasa, Tatsuro Kudo, Yuzo Kurobe, Yoshiki Itadani
    Abstract:

    In the previous paper, authors have developed a new technique to measure the pressure distribution around the blades of a full scale Propeller. The full scale measurements were performed on the conventional Propeller, CP in short, of the training ship “Seiun-Maru”. From the results of full scale measurement, the measured pressure distributions were similar at each Propeller loading condition, except cavitation region. Comparing with an existing Propeller lifting surface theory, good agreements were found at most of the measurement points on the back side except near the Propeller tip. This paper describes the measurement of pressure distribution on a Highly Skewed Propeller, HSP in short, of the same ship “Seiun-Maru”. First of all, the special pressure pick-up was improved taking account of the experience in the previous measurement. The same measurement instruments were employed. The measurements were also performed with the same procedure as the previous ones under several working conditions of Propeller revolution rate 70, 90, 110 and 149 rpm. At the Propeller revolution rates more than 110 rpm, the thrust coefficient KT and the advance coefficient J are 0.190 and 0.66, respectively. The accuracy of the present measurement was estimated to be the same as that of the previous one, i. e, ± 0.03 kg/cm2.The measured pressure distributions were compared with the theoretical one with using an estimated nominal full scale wake distribution. Excellent agreements with the theory were found at most of the measurement points, especially in the fore part of the blades. These results indicate the usefulness of the lifting surface theory and the estimated wake for a Highly Skewed Propeller in full scale.On the other hand, the following unforeseen findings were obtained. The measured pressure at 90% radial position tends to decrease toward the trailing edge and completely differs from the theory. This suggests us the hydrodynamic load in the vicinity of the trailing edge at 90% radial position was remarkably heavier than that predicted by the theory. This cyclic load might cause the break-off of the Propeller tip due to rapid fatigue crack growth, if a Propeller blade is damaged at the trailing edge.The measured pressure in the region of sheet cavitation on HSP was higher than the vapor pressure while that on CP was equal to or lower than the vapor pressure.The present full scale measurements indicated that there still exist some problems on the existing Propeller theory and some improvements are necessary on the modelling of a Propeller theory including separation vortex from the leading edge.The present measurement of pressure distribution on both Propellers also provides us a number of invaluable standard data to develop and validate a new Propeller theory.

Y Ukon - One of the best experts on this subject based on the ideXlab platform.

  • pressure distribution and blade stress on a Highly Skewed Propeller
    1994
    Co-Authors: Y Ukon, H Yuasa
    Abstract:

    This paper describes the extensive investigations on pressure and stress on the blade of a Highly Skewed Propeller. The measurement of pressure distribution on the blades of Propeller models working in uniform flow and non-uniform flow behind wire mesh screen and the measurement of pressure distribution and stress on the Propeller blades of the Highly Skewed Propeller in full scale were performed. These were carried out on a conventional Propeller as well, of which various full scale measurements have been conducted. On the Highly Skewed Propeller, complicated and peculiar phenomena in the pressure measurements were found, which could not be predicted by the existing theory. Furthermore, the measurement of blade stress was performed on the Highly Skewed Propeller working behind the complete ship model with flow liners in the cavitation tunnel. The measurements on the model corresponded well with those on the full scale. The present measurements indicated that there still remain some problems to be improved on Propeller theories particularly for a Highly Skewed Propeller.

  • FULL SCALE MEASUREMENT OF Propeller BLADE PRESSURE AND INFLOW VELOCITY DISTRIBUTIONS
    1990
    Co-Authors: H Kato, Y Ukon
    Abstract:

    In 1982 a full scale measurement was made on a conventional Propeller and a Highly Skewed Propeller on the training ship SEIUN MARU. Measurements included cavitation observation including cavity thickness measurement, fluctuating pressure on the hull and noise measurements. Pressure distribution on the Propeller blade and inflow velocity to the Propeller were omitted from the measurement, this data is invaluable for Propeller performance prediction and as a yard stick for the evaluation of computational methods at high Reynolds numbers. This paper describes full scale measurements of these two items carried out by the Shipbuilding Research Association of Japan. The study is on-going.

Ching-yeh Hsin - One of the best experts on this subject based on the ideXlab platform.

  • Boundary element method for the analysis of the unsteady flow aroundextreme Propeller geometries
    AIAA Journal, 1992
    Co-Authors: Spyros A. Kinnas, Ching-yeh Hsin
    Abstract:

    The unsteady flow around a marine Propeller subject to a spatially nonuniform inflow is analysed by utilizing a time-marching potential-based low-order boundary element method. Constant strength dipole or source distributions are used on each of the quadrilateral panels representing the Propeller blades and their trailing wakes. Linear dipole distributions are used at the first wake panels adjacent to the blade trailing edge in order to render the method insensitive to the time step size. An efficient algorithm is implemented in order to ensure an explicit Kutta condition (i.e., pressure equality) at the blade trailing edge at each time step. The numerical method is shown to be consistent with known analytic solutions for two-dimensional unsteady flows. The robustness of the method is tested in the case of a Highly Skewed Propeller in a given wake inflow and the results are shown to converge quickly with number of panels for a broad range of reduced frequencies.

  • Boundary Element Method for the Analysis of the Unsteady-Flow around Extreme Propeller Geometries
    AIAA Journal, 1992
    Co-Authors: Spyros A. Kinnas, Ching-yeh Hsin
    Abstract:

    The unsteady flow around a marine Propeller subject to a spatially nonuniform inflow is analysed by utilizing a time-marching potential-based low-order boundary element method. Constant strength dipole or source distributions are used on each of the quadrilateral panels representing the Propeller blades and their trailing wakes. Linear dipole distributions are used at the first wake panels adjacent to the blade trailing edge in order to render the method insensitive to the time step size. An efficient algorithm is implemented in order to ensure an explicit Kutta condition (i.e., pressure equality) at the blade trailing edge at each time step. The numerical method is shown to be consistent with known analytic solutions for two-dimensional unsteady flows. The robustness of the method is tested in the case of a Highly Skewed Propeller in a given wake inflow and the results are shown to converge quickly with number of panels for a broad range of reduced frequencies.