O armored cable generates a twist moment under tension. An assembly of armored and armorless cables therefore represents a twist moment and twist deformation problem as well as a tension problem. Under certain conditions involving moment and tension, a section of cable may relieve twist by looping. If the yield stress of the armor wires is exceeded by subsequent pulling of a looped section, a kink will result. In the installation of communications cables in deep water, the twist properties of the coaxial cable are important. ] Excessive twist deformation can produce cable failure. Kinks in cable make recovery difficult or impossible. Model tests which duplicate the full-scale installation appear attractive for making comparisons of different laying schemes and determining the conditions under which looping and fouling are likely. In order for model tests to be valid, certain conditions must be satisfied by the model. These conditions are embodied in the dimensionless similarity parameters, which must have the same value in the model as in the full-scale operation. In Ref. 2, the similarity parameters were worked out for cases in which twist, bending, looping, and kinking are not important. More precisely, the shear forces associated with twist and bending are small compared to the tension. Only cable weight and tangential and normal drag appear in the equilibrium equations. This is the case for most cable configuration problems. The additional considerations lead to more terms in the equations defining the configurations, and hence to ad-
{"title":"Similarity in the Modeling of Cable Twisting and Looping","authors":"A. Shashaty","doi":"10.2514/3.63162","DOIUrl":"https://doi.org/10.2514/3.63162","url":null,"abstract":"O armored cable generates a twist moment under tension. An assembly of armored and armorless cables therefore represents a twist moment and twist deformation problem as well as a tension problem. Under certain conditions involving moment and tension, a section of cable may relieve twist by looping. If the yield stress of the armor wires is exceeded by subsequent pulling of a looped section, a kink will result. In the installation of communications cables in deep water, the twist properties of the coaxial cable are important. ] Excessive twist deformation can produce cable failure. Kinks in cable make recovery difficult or impossible. Model tests which duplicate the full-scale installation appear attractive for making comparisons of different laying schemes and determining the conditions under which looping and fouling are likely. In order for model tests to be valid, certain conditions must be satisfied by the model. These conditions are embodied in the dimensionless similarity parameters, which must have the same value in the model as in the full-scale operation. In Ref. 2, the similarity parameters were worked out for cases in which twist, bending, looping, and kinking are not important. More precisely, the shear forces associated with twist and bending are small compared to the tension. Only cable weight and tangential and normal drag appear in the equilibrium equations. This is the case for most cable configuration problems. The additional considerations lead to more terms in the equations defining the configurations, and hence to ad-","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124680197","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}
Eqs. (1), (7), and (8) into Eq. (16) to find ( r j ) , and using this together with Eqs. (14) and (15), one can derive an equation for rjc. After rjc is determined, the velocity is calculated using Eq. (7), which in turn is used to calculate critical Reynolds number from Eq. (17). This procedure must be done numerically and iteratively. However, the computational effort is minimal. Calculation of Flow in the Tail Region of a Body of Revolution
{"title":"Calculation of Flow in the Tail Region of a Body of Revolution","authors":"E. Geller","doi":"10.2514/3.48173","DOIUrl":"https://doi.org/10.2514/3.48173","url":null,"abstract":"Eqs. (1), (7), and (8) into Eq. (16) to find ( r j ) , and using this together with Eqs. (14) and (15), one can derive an equation for rjc. After rjc is determined, the velocity is calculated using Eq. (7), which in turn is used to calculate critical Reynolds number from Eq. (17). This procedure must be done numerically and iteratively. However, the computational effort is minimal. Calculation of Flow in the Tail Region of a Body of Revolution","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125145903","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}
{"title":"Definition of a Yaw Meter Sensitivity for the \"Null Reading\" Technique","authors":"A. Millward","doi":"10.2514/3.63159","DOIUrl":"https://doi.org/10.2514/3.63159","url":null,"abstract":"","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"91 8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131234153","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}
Studies are presented on application of advanced composites to hydrofoil structural components such as struts and foils. It is shown that to satisfy the strut/foil structural requirements and constraints, the most cost-effective and structurally efficient designs are achieved by using hybrid composites consisting of a combination of high-strength and high-modulus graphite fibers. Typical curves are presented for determining the various mechanical properties of hybrid composites as a function of the amounts and orientations of the constituent materials. To make a realistic assessment of efficiency of hybrid composites as applied to hydrofoil structural components, the various mechanical properties of 0.5-in. thick multilayer, multidirectional hybrid composites are evaluated experimentally. The experimental results for strength and elastic properties of hybrid composites show excellent correlation with predictions and verify the efficiency of these materials as applied to structural components of advanced naval hydrostructures. Preliminary results are also presented on fabrication and testing of a 60-in. long hybrid composite, tapered box beam structure simulating the forward foil on the PCH.
{"title":"Applications of Hybrid Composites to Hydrofoil Structures","authors":"L. B. Greszcuk, A. Hawley, W. Couch","doi":"10.2514/3.63156","DOIUrl":"https://doi.org/10.2514/3.63156","url":null,"abstract":"Studies are presented on application of advanced composites to hydrofoil structural components such as struts and foils. It is shown that to satisfy the strut/foil structural requirements and constraints, the most cost-effective and structurally efficient designs are achieved by using hybrid composites consisting of a combination of high-strength and high-modulus graphite fibers. Typical curves are presented for determining the various mechanical properties of hybrid composites as a function of the amounts and orientations of the constituent materials. To make a realistic assessment of efficiency of hybrid composites as applied to hydrofoil structural components, the various mechanical properties of 0.5-in. thick multilayer, multidirectional hybrid composites are evaluated experimentally. The experimental results for strength and elastic properties of hybrid composites show excellent correlation with predictions and verify the efficiency of these materials as applied to structural components of advanced naval hydrostructures. Preliminary results are also presented on fabrication and testing of a 60-in. long hybrid composite, tapered box beam structure simulating the forward foil on the PCH.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"197 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116470819","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}
{"title":"Estimates of critical Reynolds number for a heated flat plate in water","authors":"W. S. King","doi":"10.2514/3.48172","DOIUrl":"https://doi.org/10.2514/3.48172","url":null,"abstract":"","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126531559","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}
Rayleigh's classical approach to hydraulic jumps is discussed and extended to allow for the added presence of finite amplitude disturbance waves. In this paper the decrease of mean flow energy through the jump discontinuity is accounted for by the sudden appearance of enhanced downstream radiating waves. Without appealing to turbulent dissipation, the proposed model, which applies only to weak inviscid bores, relates the mean height, the mean speed, the wave energy density, and the wavenumber fore and aft of the jump through the conservation laws for total mass, total momentum, total energy, and wave crest number. The model, in shallow water, completely describes the undulatory character of the wavy downstream flow, yielding results in agreement with observed features of bores in nature. "Deep water jumps," although somewhat speculative, are also briefly described, with the aim of stimulating further discussion. The relationships between the present hydraulic model and some work of Benjamin and Lighthill and others are also cited for completeness. The basic notions are then extended to "wave discontinuities" in arbitrary continuous media using ideas derived from kinematic wave theory, and a further stability analysis points to the conditions under which the postulated jumps exist.
{"title":"Kinematic Wave Approach to Hydraulic Jumps with Waves","authors":"W. Chin","doi":"10.2514/3.48171","DOIUrl":"https://doi.org/10.2514/3.48171","url":null,"abstract":"Rayleigh's classical approach to hydraulic jumps is discussed and extended to allow for the added presence of finite amplitude disturbance waves. In this paper the decrease of mean flow energy through the jump discontinuity is accounted for by the sudden appearance of enhanced downstream radiating waves. Without appealing to turbulent dissipation, the proposed model, which applies only to weak inviscid bores, relates the mean height, the mean speed, the wave energy density, and the wavenumber fore and aft of the jump through the conservation laws for total mass, total momentum, total energy, and wave crest number. The model, in shallow water, completely describes the undulatory character of the wavy downstream flow, yielding results in agreement with observed features of bores in nature. \"Deep water jumps,\" although somewhat speculative, are also briefly described, with the aim of stimulating further discussion. The relationships between the present hydraulic model and some work of Benjamin and Lighthill and others are also cited for completeness. The basic notions are then extended to \"wave discontinuities\" in arbitrary continuous media using ideas derived from kinematic wave theory, and a further stability analysis points to the conditions under which the postulated jumps exist.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134473163","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}
response curve since with a nonlinear curve the value given will be neither an average nor the value at a particular yaw angle. It would therefore be advantageous to redefine the yaw meter sensitivity C^ which would be appropriate when the yaw meter is kept stationary and the flow angle is evaluated by using a calibration curve. In this case it would be useful to know the average sensitivity over the range of yaw angles being considered, viz.
{"title":"Effect of Hydrostatic Pressure on Underwater Towed Body Cable Confuguration","authors":"T. Goodman, D. Valentine","doi":"10.2514/3.63161","DOIUrl":"https://doi.org/10.2514/3.63161","url":null,"abstract":"response curve since with a nonlinear curve the value given will be neither an average nor the value at a particular yaw angle. It would therefore be advantageous to redefine the yaw meter sensitivity C^ which would be appropriate when the yaw meter is kept stationary and the flow angle is evaluated by using a calibration curve. In this case it would be useful to know the average sensitivity over the range of yaw angles being considered, viz.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130571924","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}
Measurements of vertical profiles of both horizontal components of ocean current were made approximately 6 kilometers from the western shore of St. Croix, U.S. Virgin Islands, with a vertical array of current meters, and using the technique of acoustically tracking slowly sinking floats. During some of the drops, the local profile of Vaisala frequency was measured by lowering a CTD (conductivity, temperature, depth) from a ship positioned directly over the descending profiler. Richardson numbers computed from these data were typicaly between 1 and 10, with values as small as 0.25 occurring occasionally. Simultaneous drops at different locations showed significant loss of similarity at separations of 2 km, and drops made at a fixed location became decorrelated in several hours. HE spectrum of internal waves in the ocean has been shown to be remarkably homogenous, as evidenced by the ability of Garrett and Munk1'2 and Desaubies3 to fit a universal spectral model to a diverse set of observations. This homogeneity of the oceanic internal wave field is suggestive of either a homogenous forcing mechanism or saturation of the wave field, or both. It has been pointed out by Wunsch4 that it is the departures from homogeneous models that should be studied in order to gain an understanding of the mechanisms by which internal waves are generated and dissipated. All of the measurements presented in this artical were made in proximity to the island of St. Croix and therefore might be expected to differ somewhat from similar observations made in the open ocean. Since it was not known how nearby topography would affect the distribution of internal wave energy with respect to frequency and vector wave number, several types of measurements were performed. To charac- terize the vertical current structure, 58 current profiler drops were made to a maximum depth of 400 m. Drops were made at a fixed location every 1 to 4 h to assess temporal variability of the profile, and simultaneous, spatially separated drops were made with two profilers to determine spatial variability. Also, an array of vector-averaging current meters was deployed to supplement the current profile measurements. The data presented here are only a fraction of those available, and were chosen to show the kind of information that was obtained and to illustrate some of the more salient features of the current structure and variability that were observed.
{"title":"Measurements of vertical profiles of oceanic current and Richardson number near St. Croix, U.S.V.I","authors":"D. C. Wenstrand","doi":"10.2514/3.48168","DOIUrl":"https://doi.org/10.2514/3.48168","url":null,"abstract":"Measurements of vertical profiles of both horizontal components of ocean current were made approximately 6 kilometers from the western shore of St. Croix, U.S. Virgin Islands, with a vertical array of current meters, and using the technique of acoustically tracking slowly sinking floats. During some of the drops, the local profile of Vaisala frequency was measured by lowering a CTD (conductivity, temperature, depth) from a ship positioned directly over the descending profiler. Richardson numbers computed from these data were typicaly between 1 and 10, with values as small as 0.25 occurring occasionally. Simultaneous drops at different locations showed significant loss of similarity at separations of 2 km, and drops made at a fixed location became decorrelated in several hours. HE spectrum of internal waves in the ocean has been shown to be remarkably homogenous, as evidenced by the ability of Garrett and Munk1'2 and Desaubies3 to fit a universal spectral model to a diverse set of observations. This homogeneity of the oceanic internal wave field is suggestive of either a homogenous forcing mechanism or saturation of the wave field, or both. It has been pointed out by Wunsch4 that it is the departures from homogeneous models that should be studied in order to gain an understanding of the mechanisms by which internal waves are generated and dissipated. All of the measurements presented in this artical were made in proximity to the island of St. Croix and therefore might be expected to differ somewhat from similar observations made in the open ocean. Since it was not known how nearby topography would affect the distribution of internal wave energy with respect to frequency and vector wave number, several types of measurements were performed. To charac- terize the vertical current structure, 58 current profiler drops were made to a maximum depth of 400 m. Drops were made at a fixed location every 1 to 4 h to assess temporal variability of the profile, and simultaneous, spatially separated drops were made with two profilers to determine spatial variability. Also, an array of vector-averaging current meters was deployed to supplement the current profile measurements. The data presented here are only a fraction of those available, and were chosen to show the kind of information that was obtained and to illustrate some of the more salient features of the current structure and variability that were observed.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125774175","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 results of experiments concerned with linearity in the pitch, heave and roll motions of air-cushion-s upported vehicles are presented. Response linearity is demonstrated through regular wave response data with varying wave amplitude at a fixed frequency of encounter. Regular wave seakeeping transfer functions are correlated with spectral analysis results from irregular seas. Response operators are applied to appropriate sea spectra to demonstrate the response of the vehicles in a seaway. Finally, a vertical plane frequency domain simulation based upon captive model results shows reasonably good correlation with regular wave seakeeping transfer functions.
{"title":"Seakeeping Quality of Advanced Marine Vehicles for Design Applications","authors":"M. Ochi, D. D. Moran","doi":"10.2514/3.48169","DOIUrl":"https://doi.org/10.2514/3.48169","url":null,"abstract":"The results of experiments concerned with linearity in the pitch, heave and roll motions of air-cushion-s upported vehicles are presented. Response linearity is demonstrated through regular wave response data with varying wave amplitude at a fixed frequency of encounter. Regular wave seakeeping transfer functions are correlated with spectral analysis results from irregular seas. Response operators are applied to appropriate sea spectra to demonstrate the response of the vehicles in a seaway. Finally, a vertical plane frequency domain simulation based upon captive model results shows reasonably good correlation with regular wave seakeeping transfer functions.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131381758","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}
Two similarity laws for a thick, axisymmetric, turbulent boundary layer on a long circular cylinder are presented. In the law-of-the-wall region, the validity of the assumption of a constant-stress moment is analyzed and a new logarithmic mixing-length model, which takes into account the transverse-curvature effect on turbulence, is proposed. Using this mixing-length model, a law of the wall is derived which is given in terms of the exponential integral in the logarithmic portion. When the boundary layer is very thick relative to the radius of the cylinder, the flow in the outer region of the boundary layer is similar to an axisymmetric wake. With this analogy, a velocity-defect law is derived in terms of confluent hypergeometric functions known as Kummer functions. Both similarity laws are compared with the available data.
{"title":"Thick axisymmetric turbulent boundary layer on a circular cylinder","authors":"Nuray Denli, L. Landweber","doi":"10.2514/3.48170","DOIUrl":"https://doi.org/10.2514/3.48170","url":null,"abstract":"Two similarity laws for a thick, axisymmetric, turbulent boundary layer on a long circular cylinder are presented. In the law-of-the-wall region, the validity of the assumption of a constant-stress moment is analyzed and a new logarithmic mixing-length model, which takes into account the transverse-curvature effect on turbulence, is proposed. Using this mixing-length model, a law of the wall is derived which is given in terms of the exponential integral in the logarithmic portion. When the boundary layer is very thick relative to the radius of the cylinder, the flow in the outer region of the boundary layer is similar to an axisymmetric wake. With this analogy, a velocity-defect law is derived in terms of confluent hypergeometric functions known as Kummer functions. Both similarity laws are compared with the available data.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129806124","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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