This paper describes the towing tank test procedure used for conducting propulsion tests of the Rolls-Royce Naval Marine (previously Bird-Johnson Co.) Advanced Waterjet 21 (AWJ-21™) propulsor. The tests were conducted on hull model 5565-1, an existing 22.5 scale model of a hull form representative of a future tumblehome naval destroyer. AII the test work described here took place at the Naval Surface Warfare Center, Carderock Divisions, David Taylor Model Basin. Design of the waterjet was carried out by Rolls-Royce Naval Marine in 1999 and the towing tank experiments were conducted in October 2000 and February 2001. The test procedure follow the guidelines for the "momentum flux" method as described in Appendix A of the 21st International Towing Tank Conference (ITTC) Waterjet Group Report (1996] and reproduced in the Quality Manual of the 22nd ITTC Special Committee on Waterjets Report [1999]. However, the ITTC procedure does not address the methods for obtaining the required data and does not provide guidance for scaling the model data to the full size ship. The paper deals with these issues and some of the measurement procedures that are specific to the AWJ-21™ test program. In particular, an accurate survey of the inflow and discharge velocity distribution is required to obtain the mass flow and head rise through the propulsor. In the present case, a Laser Doppler Velocimeter (LDV) is used to carry out these surveys. Because conducting LDV surveys is very time-consuming, it is not practical to determine the mass flow and head rise at every test speed by this method. In our case, the LDV surveys were conducted at only two speeds. · These data · are then used. to characterize the flow non-uniformity and to correlate with pitot-static probes located in the inlet and discharge of the jet system. With this correlation, the pitot-static probes are used to obtain the performance over the entire speed range. While a Laser Doppler Velocimeter provides a very accurate means of obtaining velocity, it does not provide the required static pressure in the flow. It was found that by locating the inlet and discharge survey planes properly, the variation in static pressure over the survey area is small compared to the dynamic pressure and can be neglected. This permits the single static tap on the pitot-static probe to provide the required mean pressure. This paper describes the procedure for using the LDV survey to obtain the waterjet performance.
{"title":"Procedure for Conducting a Towing Tank Test of a Waterjet Propelled Craft using Laser Doppler Velocimetery to Determine the Momentum and Energy Flux","authors":"O. Scherer, Ian Mutnick, Frank Lanni","doi":"10.5957/attc-2001-008","DOIUrl":"https://doi.org/10.5957/attc-2001-008","url":null,"abstract":"This paper describes the towing tank test procedure used for conducting propulsion tests of the Rolls-Royce Naval Marine (previously Bird-Johnson Co.) Advanced Waterjet 21 (AWJ-21™) propulsor. The tests were conducted on hull model 5565-1, an existing 22.5 scale model of a hull form representative of a future tumblehome naval destroyer. AII the test work described here took place at the Naval Surface Warfare Center, Carderock Divisions, David Taylor Model Basin. Design of the waterjet was carried out by Rolls-Royce Naval Marine in 1999 and the towing tank experiments were conducted in October 2000 and February 2001.\u0000 The test procedure follow the guidelines for the \"momentum flux\" method as described in Appendix A of the 21st International Towing Tank Conference (ITTC) Waterjet Group Report (1996] and reproduced in the Quality Manual of the 22nd ITTC Special Committee on Waterjets Report [1999]. However, the ITTC procedure does not address the methods for obtaining the required data and does not provide guidance for scaling the model data to the full size ship. The paper deals with these issues and some of the measurement procedures that are specific to the AWJ-21™ test program. In particular, an accurate survey of the inflow and discharge velocity distribution is required to obtain the mass flow and head rise through the propulsor. In the present case, a Laser Doppler Velocimeter (LDV) is used to carry out these surveys.\u0000 Because conducting LDV surveys is very time-consuming, it is not practical to determine the mass flow and head rise at every test speed by this method. In our case, the LDV surveys were conducted at only two speeds. · These data · are then used. to characterize the flow non-uniformity and to correlate with pitot-static probes located in the inlet and discharge of the jet system. With this correlation, the pitot-static probes are used to obtain the performance over the entire speed range.\u0000 While a Laser Doppler Velocimeter provides a very accurate means of obtaining velocity, it does not provide the required static pressure in the flow. It was found that by locating the inlet and discharge survey planes properly, the variation in static pressure over the survey area is small compared to the dynamic pressure and can be neglected. This permits the single static tap on the pitot-static probe to provide the required mean pressure. This paper describes the procedure for using the LDV survey to obtain the waterjet performance.","PeriodicalId":107471,"journal":{"name":"Day 1 Mon, July 23, 2001","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121248676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Physical model tests are an invaluable asset to naval architecture and ocean engineering research, development, and education. However, the actual value of laboratory testing depends not only on the physical plant and technology available but also on the experience and expertise of the users. Recognizing this, the authors have undertaken a three-year effort to develop a high-quality record of numerous laboratory experiments performed within several naval architecture and ocean engineering courses at the U.S. Naval Academy (USNA). The archive includes more than a dozen experiments performed in the Hydromechanics Laboratory (Hydro Lab) at USNA, ranging from ship maneuvering to. sediment transport studies. Each experiment record includes background information, experimental setup descriptions, and details, data records with analyses, as well as high-quality photos and video recordings of the experiments underway. An archive of this depth and quality has never been assimilated and it is anticipated that the naval architecture and ocean engineering community both inside and outside USNA will be able to reap many benefits from it. In order to provide the widest and easiest access to the work, a website is being created so as to make all of the products accessible via the Internet. This paper discusses the project, its development, and some of the details of the results obtained.
{"title":"The Development of an archive of Naval Architecture and Ocean Engineering Laboratory Experiments","authors":"J. Waters, G. White","doi":"10.5957/attc-2001-013","DOIUrl":"https://doi.org/10.5957/attc-2001-013","url":null,"abstract":"Physical model tests are an invaluable asset to naval architecture and ocean engineering research, development, and education. However, the actual value of laboratory testing depends not only on the physical plant and technology available but also on the experience and expertise of the users. Recognizing this, the authors have undertaken a three-year effort to develop a high-quality record of numerous laboratory experiments performed within several naval architecture and ocean engineering courses at the U.S. Naval Academy (USNA).\u0000 The archive includes more than a dozen experiments performed in the Hydromechanics Laboratory (Hydro Lab) at USNA, ranging from ship maneuvering to. sediment transport studies. Each experiment record includes background information, experimental setup descriptions, and details, data records with analyses, as well as high-quality photos and video recordings of the experiments underway. An archive of this depth and quality has never been assimilated and it is anticipated that the naval architecture and ocean engineering community both inside and outside USNA will be able to reap many benefits from it. In order to provide the widest and easiest access to the work, a website is being created so as to make all of the products accessible via the Internet. This paper discusses the project, its development, and some of the details of the results obtained.","PeriodicalId":107471,"journal":{"name":"Day 1 Mon, July 23, 2001","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124727143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lifting surfaces are used both for propulsion and control of sea vessels and must meet performance criteria such as lift, drag, and (in some military applications) hydroacoustic noise limits. Design tools suitable to predict such criteria must handle complex flow phenomena and manage the wide range of flow scales inherent in marine applications (Reynolds numbers ~10^8). To date, the development of such tools has been limited by the lack of controlled experimental data in this high Reynolds numbers range. Lifting surface flow is the focus of current high Reynolds number experiments involving a two-dimensional hydrofoil in the world's largest water tunnel, the US Navy's William B. Morgan Large Cavitation Channel (LCC). The goal of these experiments is to provide a unique high Reynolds number experimental dataset at chord-based Reynolds numbers (Re) approaching those of full-scale propulsors ( ~ 10^8). This data will be used for validation of scaling laws and computational models, with particular emphasis given to the unsteady, separated, turbulent flow at the trailing edge. In addition, these experiments will provide fundamental insight into the fluid mechanics of trailing-edge noise generation in marine propulsion systems. This paper describes the experimental equipment and methods employed in the test program. Described herein is the use of the LCC's Laser Doppler Velocimetry (LDV) capability to acquire flow velocity mean and turbulence quantities, as well as estimates of boundary layer transition. Also presented is a Particle Imaging Velocimetry (PN) system developed for these experiments and employs seed injection upstream of the channel's flow straightener. Finally, a description is given of instrumentation mounted in the foil for measurement of vibration and surface static and dynamic pressures. [Significant assistance provided by personnel from NWSC-CD, Sponsored by Code 333 of the Office of Naval Research].
{"title":"Hydrofoil Testing At High Reynolds Number","authors":"D. A. Bourgoyne, Carolyn Q. Judge, J. Hamel","doi":"10.5957/attc-2001-015","DOIUrl":"https://doi.org/10.5957/attc-2001-015","url":null,"abstract":"Lifting surfaces are used both for propulsion and control of sea vessels and must meet performance criteria such as lift, drag, and (in some military applications) hydroacoustic noise limits. Design tools suitable to predict such criteria must handle complex flow phenomena and manage the wide range of flow scales inherent in marine applications (Reynolds numbers ~10^8). To date, the development of such tools has been limited by the lack of controlled experimental data in this high Reynolds numbers range.\u0000 Lifting surface flow is the focus of current high Reynolds number experiments involving a two-dimensional hydrofoil in the world's largest water tunnel, the US Navy's William B. Morgan Large Cavitation Channel (LCC). The goal of these experiments is to provide a unique high Reynolds number experimental dataset at chord-based Reynolds numbers (Re) approaching those of full-scale propulsors ( ~ 10^8). This data will be used for validation of scaling laws and computational models, with particular emphasis given to the unsteady, separated, turbulent flow at the trailing edge. In addition, these experiments will provide fundamental insight into the fluid mechanics of trailing-edge noise generation in marine propulsion systems.\u0000 This paper describes the experimental equipment and methods employed in the test program. Described herein is the use of the LCC's Laser Doppler Velocimetry (LDV) capability to acquire flow velocity mean and turbulence quantities, as well as estimates of boundary layer transition. Also presented is a Particle Imaging Velocimetry (PN) system developed for these experiments and employs seed injection upstream of the channel's flow straightener. Finally, a description is given of instrumentation mounted in the foil for measurement of vibration and surface static and dynamic pressures. [Significant assistance provided by personnel from NWSC-CD, Sponsored by Code 333 of the Office of Naval Research].","PeriodicalId":107471,"journal":{"name":"Day 1 Mon, July 23, 2001","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134201506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
During April 1998, tests were run in the Webb Model Basin on a 1/12 scale model of a fast trawler type motorboat designed by Bruce King for Pacific Seacraft. The tests involved measurements of resistance, heave and trim at the design displacement and two others over a range of speeds of the hull and CG as designed. The test matrix was planned to take one test day (approximately 40 runs). The client (designer) was to be present. The model scale was 12. The design speed was in the neighborhood of 25 knots and the design displacement 25000 pounds, putting the craft definitely in the planning hull range. The craft lines are given in Figure 3 and show a moderate Vee bow with a chine and flat run in the stern. The model, as designed, was tested in the morning at the design displacement and center of gravity over a speed range of 12 to 30 knots. The results are shown in Figure 1 (solid lines with symbols) and the data is given in Table 1. It was apparent, visually and in looking at the data, especially the trim that was almost 7 degrees in the planing range over 18 knots, that the craft needed some redesign. Also, the resistance was correspondingly somewhat excessive, over 12 percent of the weight. We needed to get the trim down to 5 degrees, known to be ideal for planning conditions. Rather than continuing the test series at the other displacements, the team, including the designer, broke for an early lunch to discuss the situation. Normally, there would ensue a test report prepared and mailed showing the trouble, the model returned for changes, and another test day planned to hopefully complete the study*. But, we were all together, including the designer, and had lots of waterproof tapes, modeling clay, and strips of sheet aluminum available to adjust the stern lines. So, we went to the tank and back to work!
{"title":"Advantages of Running Model Tank Tests with the Client Present","authors":"L. W. Ward","doi":"10.5957/attc-2001-017","DOIUrl":"https://doi.org/10.5957/attc-2001-017","url":null,"abstract":"During April 1998, tests were run in the Webb Model Basin on a 1/12 scale model of a fast trawler type motorboat designed by Bruce King for Pacific Seacraft. The tests involved measurements of resistance, heave and trim at the design displacement and two others over a range of speeds of the hull and CG as designed. The test matrix was planned to take one test day (approximately 40 runs). The client (designer) was to be present.\u0000 The model scale was 12. The design speed was in the neighborhood of 25 knots and the design displacement 25000 pounds, putting the craft definitely in the planning hull range. The craft lines are given in Figure 3 and show a moderate Vee bow with a chine and flat run in the stern.\u0000 The model, as designed, was tested in the morning at the design displacement and center of gravity over a speed range of 12 to 30 knots. The results are shown in Figure 1 (solid lines with symbols) and the data is given in Table 1. It was apparent, visually and in looking at the data, especially the trim that was almost 7 degrees in the planing range over 18 knots, that the craft needed some redesign.\u0000 Also, the resistance was correspondingly somewhat excessive, over 12 percent of the weight. We needed to get the trim down to 5 degrees, known to be ideal for planning conditions. Rather than continuing the test series at the other displacements, the team, including the designer, broke for an early lunch to discuss the situation.\u0000 Normally, there would ensue a test report prepared and mailed showing the trouble, the model returned for changes, and another test day planned to hopefully complete the study*. But, we were all together, including the designer, and had lots of waterproof tapes, modeling clay, and strips of sheet aluminum available to adjust the stern lines. So, we went to the tank and back to work!","PeriodicalId":107471,"journal":{"name":"Day 1 Mon, July 23, 2001","volume":"207 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123734086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An iterative technique for the prediction of the performance of two-component propulsors, including the effects of sheet cavitation, is presented. A vortex-lattice method, originally developed for the prediction of the performance of cavitating single propellers in non-axisymmetric inflow, is applied to each one of the components. The "effective" wake for each component is determined via an Euler solver, based on a finite volume method, in which both components· are represented via body forces. The axisymmetric version of the method is used to predict the mean performance of a contra-rotating propulsor and of a pre-swirl stator/rotor combination. The non-axisymmetric version of the method is used to predict the non-axisymmetric flow-field in the wake of a pre-swirl stator, and the unsteady cavitating flow performance of the rotor subject to that flow-field.
{"title":"A General Computational Technique for the Prediction of Cavitation on Two-Stage Propulsors","authors":"S. Kinnas, Jin-Keun Choi, K. Kakar, H. Gu","doi":"10.5957/attc-2001-001","DOIUrl":"https://doi.org/10.5957/attc-2001-001","url":null,"abstract":"An iterative technique for the prediction of the performance of two-component propulsors, including the effects of sheet cavitation, is presented. A vortex-lattice method, originally developed for the prediction of the performance of cavitating single propellers in non-axisymmetric inflow, is applied to each one of the components. The \"effective\" wake for each component is determined via an Euler solver, based on a finite volume method, in which both components· are represented via body forces. The axisymmetric version of the method is used to predict the mean performance of a contra-rotating propulsor and of a pre-swirl stator/rotor combination. The non-axisymmetric version of the method is used to predict the non-axisymmetric flow-field in the wake of a pre-swirl stator, and the unsteady cavitating flow performance of the rotor subject to that flow-field.","PeriodicalId":107471,"journal":{"name":"Day 1 Mon, July 23, 2001","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115041415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
For standard maneuvering experiments, the Institute for Marine Dynamics (IMO) has traditionally used the classic approach - deploying free running models executing standard maneuvers such as turning circles and zig zags in an ocean basin environment. The primary disadvantage of using free-running models is the large planar area required for experiments. Often this limits the model size to a scale not deemed suitable for resistance/propulsion experiments and in many cases resulted in the requirement for two physical models when carrying out a full experimental program for a new hull form. In 1991, the effective working area of IMD's Ocean Engineering Basin (OEB) was reduced due to the installation of wavemakers and beaches. Free running ship maneuvering experiments are now impractical except for very small models. This paper describes a new approach for carrying out standard maneuvering experiments under development by IMO that involves the derivation of hydrodynamic coefficients from Planar Motion Mechanism (PMM) experiments for input to a numerical simulation routine capable of generating standard ship maneuvers. An extensive experimental program was carried out to verify possible options in using PMM efficiently and to verify various testing configurations. The effort underway to build the analysis procedures into a compact site package, evaluate the methodology and develop a versatile on-line stand-alone analysis tool enabling immediate data verification and for complete on-line analysis is defined. Plans for validation the entire procedure against full-scale data are also described.
{"title":"Development of New Standard Manoeuvring Test Methodology at the Institute for Marine Dynamics","authors":"P. Waclawek, O. Cumming, G. Earle","doi":"10.5957/attc-2001-012","DOIUrl":"https://doi.org/10.5957/attc-2001-012","url":null,"abstract":"For standard maneuvering experiments, the Institute for Marine Dynamics (IMO) has traditionally used the classic approach - deploying free running models executing standard maneuvers such as turning circles and zig zags in an ocean basin environment. The primary disadvantage of using free-running models is the large planar area required for experiments. Often this limits the model size to a scale not deemed suitable for resistance/propulsion experiments and in many cases resulted in the requirement for two physical models when carrying out a full experimental program for a new hull form. In 1991, the effective working area of IMD's Ocean Engineering Basin (OEB) was reduced due to the installation of wavemakers and beaches. Free running ship maneuvering experiments are now impractical except for very small models.\u0000 This paper describes a new approach for carrying out standard maneuvering experiments under development by IMO that involves the derivation of hydrodynamic coefficients from Planar Motion Mechanism (PMM) experiments for input to a numerical simulation routine capable of generating standard ship maneuvers. An extensive experimental program was carried out to verify possible options in using PMM efficiently and to verify various testing configurations. The effort underway to build the analysis procedures into a compact site package, evaluate the methodology and develop a versatile on-line stand-alone analysis tool enabling immediate data verification and for complete on-line analysis is defined. Plans for validation the entire procedure against full-scale data are also described.","PeriodicalId":107471,"journal":{"name":"Day 1 Mon, July 23, 2001","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123501670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A three-velocity-component Laser Doppler Velocimetry (LDV) system has been developed at the David Taylor Model Basin (DTMB) for use in obtaining the flow field around tow-tank surface ship models. The system configuration and operation is described and a detailed analysis of the uncertainty associated with the system measurements is presented. Results of measurements on a waterjet-powered destroyer hull are presented. On this hull, velocity fields are shown ahead of the inlet, inside the inlet, and at the exit of the jet. Pitot tube measurements are combined with the velocity measurements at the propulsor exit to obtain the static pressure field. It is shown how these measurements are used to obtain mass-flow and flow distortion coefficients so that the propulsive performance may be evaluated.
{"title":"3-D LDV Mapping of the Flow About a Waterjet-Powered Hull in a Tow Tank","authors":"C. Chesnakas","doi":"10.5957/attc-2001-006","DOIUrl":"https://doi.org/10.5957/attc-2001-006","url":null,"abstract":"A three-velocity-component Laser Doppler Velocimetry (LDV) system has been developed at the David Taylor Model Basin (DTMB) for use in obtaining the flow field around tow-tank surface ship models. The system configuration and operation is described and a detailed analysis of the uncertainty associated with the system measurements is presented. Results of measurements on a waterjet-powered destroyer hull are presented. On this hull, velocity fields are shown ahead of the inlet, inside the inlet, and at the exit of the jet. Pitot tube measurements are combined with the velocity measurements at the propulsor exit to obtain the static pressure field. It is shown how these measurements are used to obtain mass-flow and flow distortion coefficients so that the propulsive performance may be evaluated.","PeriodicalId":107471,"journal":{"name":"Day 1 Mon, July 23, 2001","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132518861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Until recently, model propellers tested at the US Navy's David Taylor Model Basin (DTMB) incorporated relatively sharp trailing edges without fall scale features such as anti-singing trailing edges. These propellers have shown good agreement between design calculations and model measurements. With the advent of NURBS surface representation of model propeller geometry, new propeller models have been manufactured with fall scale trailing edge details. Problems have arisen in achieving predicted open water performance. Discrepancies have been attributed to trailing edge flows over beveled edges, and variations in trailing edge shape due to manufacturing problems. The analysis included detailed trailing edge measurements, an open water test. and panel method computations.
{"title":"Effect of Model Propeller Trailing Edge Details on Powering Performance","authors":"T. J. Michael, S. Jessup","doi":"10.5957/attc-2001-007","DOIUrl":"https://doi.org/10.5957/attc-2001-007","url":null,"abstract":"Until recently, model propellers tested at the US Navy's David Taylor Model Basin (DTMB) incorporated relatively sharp trailing edges without fall scale features such as anti-singing trailing edges. These propellers have shown good agreement between design calculations and model measurements. With the advent of NURBS surface representation of model propeller geometry, new propeller models have been manufactured with fall scale trailing edge details. Problems have arisen in achieving predicted open water performance. Discrepancies have been attributed to trailing edge flows over beveled edges, and variations in trailing edge shape due to manufacturing problems. The analysis included detailed trailing edge measurements, an open water test. and panel method computations.","PeriodicalId":107471,"journal":{"name":"Day 1 Mon, July 23, 2001","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114666134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carolyn Q. Judge, G. F. Oweis, S. Ceccio, S. Jessup, C. Chesnakas, D. Fry
The tip-leakage vortex occurring on a ducted rotor was examined using both three component Laser Doppler Velocimetry (LDV) and planar Particle Imaging Velocimetry (PIV). The vortex strength and core size were examined for different vortex cross sections downstream of the blade trailing edge. The variability of these quantities are observed with PIV and the average quantities are compared between LDV and PIV. Developed cavitation is also examined for the leakage vortex. The implication of vortex variability on cavitation inception is discussed.
{"title":"PIV Measurements of a Tip Leakage Vortex","authors":"Carolyn Q. Judge, G. F. Oweis, S. Ceccio, S. Jessup, C. Chesnakas, D. Fry","doi":"10.5957/attc-2001-005","DOIUrl":"https://doi.org/10.5957/attc-2001-005","url":null,"abstract":"The tip-leakage vortex occurring on a ducted rotor was examined using both three component Laser Doppler Velocimetry (LDV) and planar Particle Imaging Velocimetry (PIV). The vortex strength and core size were examined for different vortex cross sections downstream of the blade trailing edge. The variability of these quantities are observed with PIV and the average quantities are compared between LDV and PIV. Developed cavitation is also examined for the leakage vortex. The implication of vortex variability on cavitation inception is discussed.","PeriodicalId":107471,"journal":{"name":"Day 1 Mon, July 23, 2001","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124684636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The interaction of gas bubbles with a vortex is investigated experimentally to clarify the role of the initial bubble position on its trajectory around the tip vortex shed from a large hydrofoil. The experiments performed with 4-6 mm bubbles show they can undergo no capture, quick capture into the tip vortex or slow capture with a spiral trajectory around the vortex. The results also reveal a scaling problem, analysis of the bubbles shows that while the bubbles in the large-scale foil tests, have a spherical -elliptical shape when they are scaled to cavitation tunnel they are spherical microbubbles.
{"title":"Bubble Capture Tests with a Large Hydrofoil Towing Tank Test","authors":"R. Latorre, J. Billard, F. Moutant, O. Roussel","doi":"10.5957/attc-2001-003","DOIUrl":"https://doi.org/10.5957/attc-2001-003","url":null,"abstract":"The interaction of gas bubbles with a vortex is investigated experimentally to clarify the role of the initial bubble position on its trajectory around the tip vortex shed from a large hydrofoil. The experiments performed with 4-6 mm bubbles show they can undergo no capture, quick capture into the tip vortex or slow capture with a spiral trajectory around the vortex. The results also reveal a scaling problem, analysis of the bubbles shows that while the bubbles in the large-scale foil tests, have a spherical -elliptical shape when they are scaled to cavitation tunnel they are spherical microbubbles.","PeriodicalId":107471,"journal":{"name":"Day 1 Mon, July 23, 2001","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130618205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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