Tests with two different sized models were conducted in the Marine Propeller Cavitation Tunnel at the Univer- sity of Tokyo.At two angles of attack the developed sheet-cloud and bubble cavitation occurred.Erosion patt...Tests with two different sized models were conducted in the Marine Propeller Cavitation Tunnel at the Univer- sity of Tokyo.At two angles of attack the developed sheet-cloud and bubble cavitation occurred.Erosion pattern was recorded by pure indium specimens and noise was measured with a hydrophone mounted inside the tunnel.The broadband SPL was mainly used for correlation of noise with pit counting results from erosion.In case of sheet- cloud cavitation power law relations between velocity and SPL have been found and there existed a linear relation- ship between SPL values and IgPR values(PR-pitting rate).However in case of bubble cavitation such power law relation does not exist between pitting rate and velocity,and neither between SPL and velocity.It was noticed that the different trends of SPL for these two different types of cavitation could be qualitatively linked to their pitting rates by using some SPL values at high center frequencies.展开更多
Centrifugal forces are commonly created when ships turn, which may cause a ship to capsize in a critical situation. A mathematical model has been developed to optimize the stability coefficients for ship, with the aim...Centrifugal forces are commonly created when ships turn, which may cause a ship to capsize in a critical situation. A mathematical model has been developed to optimize the stability coefficients for ship, with the aim to prevent capsizing and to increase ship maneuverability in high-speed water craft. This model can be used to develop algorithms for control system improvement. The mathematical model presented in this paper optimized the use of multipurpose hydrofoils to reduce heeling and the trimming moment, maintaining an upright ship’s position and lessening the resistance via transverse force. Conventionally, the trimming and heeling of a ship are controlled using ballast water;however, under variable sea conditions it is sometimes difficult to control a ship’s motion using ballast water. In this case, a hydrofoil would be more stable and maneuverable than a ballast tank controlled vessel. A movable hydrofoil could theoretically be adapted from moveable aerofoil technology. This study proves the merit of further investigation into this possibility.展开更多
Excitation function of <sup>51</sup>V（p,n）<sup>51</sup>Cr is measured using stacked foil techniqueover the energy range from 3 to 22 MeV.The target material is high purity naturalvanadium met...Excitation function of <sup>51</sup>V（p,n）<sup>51</sup>Cr is measured using stacked foil techniqueover the energy range from 3 to 22 MeV.The target material is high purity naturalvanadium metal foil.The measured data are listed in table with the total error about6% and compared with the published results.The optimum energy range for the pro-duction of <sup>51</sup>Cr via this reaction is 8-14 MeV.展开更多
Kuiper and Jessup（1993）developed a design method for propellers in a wake based on the Eppler foil design method.The optimized section is transformed into the three-dimensional propeller flow using the approach of t...Kuiper and Jessup（1993）developed a design method for propellers in a wake based on the Eppler foil design method.The optimized section is transformed into the three-dimensional propeller flow using the approach of the effective blade sections.Effective blade sections are two-dimensional sections in two-dimensional flow which have the same chordwise loading distribution as the three-dimensional blade sections of a propeller.However,the design procedure is laborious in two aspects：finding an optimum blade section using the Eppler program requires much skill of the designer,and transforming the two-dimensional blade section into a propeller blade section in three-dimensional flow is complex.In this work,these two problems were coped with.A blade section design procedure was presented using an optimization technique and an alternative procedure for the effective blade section is developed using a lifting surface design method.To validate the method a benchmark model of a naval ship was used.This benchmark model was extended by new appendices and a reference propeller,and designed using conventional design methods.This reference propeller was optimized using the new design procedure and model tests were carried out.Special attention was given to the data of the model and the reference propeller,to make the configuration suitable for the Reynolds-Averaged Navier-Stokes（RANS）calculations.展开更多
文摘Tests with two different sized models were conducted in the Marine Propeller Cavitation Tunnel at the Univer- sity of Tokyo.At two angles of attack the developed sheet-cloud and bubble cavitation occurred.Erosion pattern was recorded by pure indium specimens and noise was measured with a hydrophone mounted inside the tunnel.The broadband SPL was mainly used for correlation of noise with pit counting results from erosion.In case of sheet- cloud cavitation power law relations between velocity and SPL have been found and there existed a linear relation- ship between SPL values and IgPR values(PR-pitting rate).However in case of bubble cavitation such power law relation does not exist between pitting rate and velocity,and neither between SPL and velocity.It was noticed that the different trends of SPL for these two different types of cavitation could be qualitatively linked to their pitting rates by using some SPL values at high center frequencies.
文摘Centrifugal forces are commonly created when ships turn, which may cause a ship to capsize in a critical situation. A mathematical model has been developed to optimize the stability coefficients for ship, with the aim to prevent capsizing and to increase ship maneuverability in high-speed water craft. This model can be used to develop algorithms for control system improvement. The mathematical model presented in this paper optimized the use of multipurpose hydrofoils to reduce heeling and the trimming moment, maintaining an upright ship’s position and lessening the resistance via transverse force. Conventionally, the trimming and heeling of a ship are controlled using ballast water;however, under variable sea conditions it is sometimes difficult to control a ship’s motion using ballast water. In this case, a hydrofoil would be more stable and maneuverable than a ballast tank controlled vessel. A movable hydrofoil could theoretically be adapted from moveable aerofoil technology. This study proves the merit of further investigation into this possibility.
文摘Excitation function of <sup>51</sup>V（p,n）<sup>51</sup>Cr is measured using stacked foil techniqueover the energy range from 3 to 22 MeV.The target material is high purity naturalvanadium metal foil.The measured data are listed in table with the total error about6% and compared with the published results.The optimum energy range for the pro-duction of <sup>51</sup>Cr via this reaction is 8-14 MeV.
文摘Kuiper and Jessup（1993）developed a design method for propellers in a wake based on the Eppler foil design method.The optimized section is transformed into the three-dimensional propeller flow using the approach of the effective blade sections.Effective blade sections are two-dimensional sections in two-dimensional flow which have the same chordwise loading distribution as the three-dimensional blade sections of a propeller.However,the design procedure is laborious in two aspects：finding an optimum blade section using the Eppler program requires much skill of the designer,and transforming the two-dimensional blade section into a propeller blade section in three-dimensional flow is complex.In this work,these two problems were coped with.A blade section design procedure was presented using an optimization technique and an alternative procedure for the effective blade section is developed using a lifting surface design method.To validate the method a benchmark model of a naval ship was used.This benchmark model was extended by new appendices and a reference propeller,and designed using conventional design methods.This reference propeller was optimized using the new design procedure and model tests were carried out.Special attention was given to the data of the model and the reference propeller,to make the configuration suitable for the Reynolds-Averaged Navier-Stokes（RANS）calculations.
