This paper determines the relative importance of interfacial shear stress and dynamic pressure in determining the thickness distribution of a layer of floating oil contained by a barrier above a water current. This is done by use of an equation relating vertical location of the oil-water interface, dynamic pressure, and shear stress. The interfacial shape is measured experimentally. The dynamic pressure is determined by numerical solution of potential flow problem for flow beneath the measured shape. The aforementioned equation then yields the shear stress distribution. The rear portion of restrained oil layers are found to be governed by shear stress as are the forward portions for low current speeds. At higher current speeds, both dynamic pressure and shear stress are important in determining the shape of the forward portions. Large friction coefficients are shown to be due to flow over a rough interface resulting from the generation of Kelvin-Helmholtz waves on the interface. The entrainment of oil droplets into the water flow is shown to be the result of breaking of the Kelvin-Helmholtz waves.
{"title":"MECHANICS OF A RESTRAINED LAYER OF FLOATING OIL ABOVE A WATER CURRENT","authors":"J. S. Milgram, R. V. Houten","doi":"10.2514/3.63119","DOIUrl":"https://doi.org/10.2514/3.63119","url":null,"abstract":"This paper determines the relative importance of interfacial shear stress and dynamic pressure in determining the thickness distribution of a layer of floating oil contained by a barrier above a water current. This is done by use of an equation relating vertical location of the oil-water interface, dynamic pressure, and shear stress. The interfacial shape is measured experimentally. The dynamic pressure is determined by numerical solution of potential flow problem for flow beneath the measured shape. The aforementioned equation then yields the shear stress distribution. The rear portion of restrained oil layers are found to be governed by shear stress as are the forward portions for low current speeds. At higher current speeds, both dynamic pressure and shear stress are important in determining the shape of the forward portions. Large friction coefficients are shown to be due to flow over a rough interface resulting from the generation of Kelvin-Helmholtz waves on the interface. The entrainment of oil droplets into the water flow is shown to be the result of breaking of the Kelvin-Helmholtz waves.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"34 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132433215","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}
In the work presented here, emphasis was placed on performing a sensitivity analysis of the maneuvering control parameters during underway replenishment (UNREP) control simulations. Some approximate nonlinear sea-state excitations acting on the ships' hulls due to a specific irregular sea were added to the simulation model. The mathematical model for both the nonlinear force and moment excitations was developed by using the Volterra series mathematical formalism. The sensitivity studies revealed that measurement errors in the range of 3 to 5% in the maneuvering control variables were acceptable under the simulation condition. The good controllability of both ships when using automatic control during UNREP simulations indicated that automatic control should be considered for collision avoidance during UNREP. The results of the simulation sensitivity control variable analysis will be used for engineering judgments in developing a prototype sensing system for maneuvering control during UNREP.
{"title":"Simulation of Maneuvering Control During Underway Replenishment","authors":"Samuel H. Brown, R. Alvestad","doi":"10.2514/3.63120","DOIUrl":"https://doi.org/10.2514/3.63120","url":null,"abstract":"In the work presented here, emphasis was placed on performing a sensitivity analysis of the maneuvering control parameters during underway replenishment (UNREP) control simulations. Some approximate nonlinear sea-state excitations acting on the ships' hulls due to a specific irregular sea were added to the simulation model. The mathematical model for both the nonlinear force and moment excitations was developed by using the Volterra series mathematical formalism. The sensitivity studies revealed that measurement errors in the range of 3 to 5% in the maneuvering control variables were acceptable under the simulation condition. The good controllability of both ships when using automatic control during UNREP simulations indicated that automatic control should be considered for collision avoidance during UNREP. The results of the simulation sensitivity control variable analysis will be used for engineering judgments in developing a prototype sensing system for maneuvering control during UNREP.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134438733","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 comparison has been made of the resistance characteristics of two of the DTMB series 62 planing hulls obtained from measurements made in a high-speed recirculating water channel and a towing tank. The results showed good agreement at the DTMB standard displacement ratio, provided a correction was applied for shallow water effects due to the restricted working section depth. The results suggest that, with the present size models, resistance measurements can be made for a displacement ratio (AP/V2/3} not less than 7.0. Further work is envisaged on the use of smaller models, in order to extend the range of displacement ratios that may be investigated. Nomenclature A P = projected planing bottom area, excluding spray strips BP = beam over chines, excluding spray strips BPA = mean breadth over chines ,AP/LP BPT = breadth over chines at transom, excluding spray strips BpX = maximum breadth over chines, excluding spray strips Fv = Froude number based on volume displacement,
{"title":"Use of a Water Channel for Model Tests on Planing Hulls","authors":"A. Millward","doi":"10.2514/3.63123","DOIUrl":"https://doi.org/10.2514/3.63123","url":null,"abstract":"A comparison has been made of the resistance characteristics of two of the DTMB series 62 planing hulls obtained from measurements made in a high-speed recirculating water channel and a towing tank. The results showed good agreement at the DTMB standard displacement ratio, provided a correction was applied for shallow water effects due to the restricted working section depth. The results suggest that, with the present size models, resistance measurements can be made for a displacement ratio (AP/V2/3} not less than 7.0. Further work is envisaged on the use of smaller models, in order to extend the range of displacement ratios that may be investigated. Nomenclature A P = projected planing bottom area, excluding spray strips BP = beam over chines, excluding spray strips BPA = mean breadth over chines ,AP/LP BPT = breadth over chines at transom, excluding spray strips BpX = maximum breadth over chines, excluding spray strips Fv = Froude number based on volume displacement,","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117071752","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}
Introduction T theory of the dynamic response of plates and shells submerged in a fluid has been treated extensively in the literature. A small and incomplete list of pertinent publications is provided by Refs. 1-10. When a closed shell is submerged in a fluid, it is subjected to normal fluid pressure acting on its surface. Static pressures of this kind will induce what we shall call initial stresses (or prestresses) and deformations. Subsequently applied static and time-dependent loads will result in incremental deformations and stresses in the shell. Initial stresses can be the cause of radical changes in the dynamical characteristics of the shell which result in significant differences between the transient response of shells with and without prestress. Since all investigations of shellfluid interaction to date seem to neglect this important effect, it was felt that this phenomenon deserves to be investigated. In particular, thz present investigation considers the axisymmetric dynamic response of an initially stressed, elastic cylindrical shell submerged in a fluid. The shell is of unbounded length, with thickness h and mean radius a. It is subjected to static axial and radial prestress, and is subsequently subjected to radially directed transient loads.
{"title":"Dynamics of an Initially Stressed Fluid-Immersed Cylindrical Shell","authors":"Herbert Reismann, G. J. Meyers","doi":"10.2514/3.63121","DOIUrl":"https://doi.org/10.2514/3.63121","url":null,"abstract":"Introduction T theory of the dynamic response of plates and shells submerged in a fluid has been treated extensively in the literature. A small and incomplete list of pertinent publications is provided by Refs. 1-10. When a closed shell is submerged in a fluid, it is subjected to normal fluid pressure acting on its surface. Static pressures of this kind will induce what we shall call initial stresses (or prestresses) and deformations. Subsequently applied static and time-dependent loads will result in incremental deformations and stresses in the shell. Initial stresses can be the cause of radical changes in the dynamical characteristics of the shell which result in significant differences between the transient response of shells with and without prestress. Since all investigations of shellfluid interaction to date seem to neglect this important effect, it was felt that this phenomenon deserves to be investigated. In particular, thz present investigation considers the axisymmetric dynamic response of an initially stressed, elastic cylindrical shell submerged in a fluid. The shell is of unbounded length, with thickness h and mean radius a. It is subjected to static axial and radial prestress, and is subsequently subjected to radially directed transient loads.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124796637","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 basic problem of a flapped NACA-16 foil is its poor pressure distribution around the flapped region. With the flap deflected, the velocity distribution becomes a very unfavorable shape in terms of cavitationinception and boundary-layer separation. This type of flow field results in low flap effectiveness. Based on the present profile design and boundary-layer calculation methods, improved hydrofoil wings with flaps have been developed. The approaches to construct the desired velocity distributions to delay cavitation and boundary-layer separation are discussed. Examples are given for the case that the flap deflection has to compensate the vertical component of the surface wave motion in a seaway.
{"title":"SECTION DESIGN FOR HYDROFOIL WINGS WITH FLAPS","authors":"Young T. Shen, R. Eppler","doi":"10.2514/3.63152","DOIUrl":"https://doi.org/10.2514/3.63152","url":null,"abstract":"The basic problem of a flapped NACA-16 foil is its poor pressure distribution around the flapped region. With the flap deflected, the velocity distribution becomes a very unfavorable shape in terms of cavitationinception and boundary-layer separation. This type of flow field results in low flap effectiveness. Based on the present profile design and boundary-layer calculation methods, improved hydrofoil wings with flaps have been developed. The approaches to construct the desired velocity distributions to delay cavitation and boundary-layer separation are discussed. Examples are given for the case that the flap deflection has to compensate the vertical component of the surface wave motion in a seaway.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114476934","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 method employing the laws of dynamic similarity to scale experimental model data is presented for predicting the powering performance of large surface effect ships. The data are reduced to individual com- ponents, including cushion wavemaking drag, sidewall and appendage frictional and form drags, aerodynamic drag, and seal drag. These components are appropriately scaled by either Froude or Reynolds scaling laws. Water channel and model dimension effects on wavemaking drag are discussed and a technique for calculating sidewall wetted area is presented. An experimentally derived algorithm characterizing seal-induced and frictional drag is explained. Drag predictions are compared with experimental trials data. HE drag prediction technique presently used for scaling the model drag of a surface effect ship (SES) is different from that developed by Froude, in that both the frictional and wavemaking drag terms can be accurately determined. The basic drag components are broken down into two classes: 1) those which are due to lift provided by the pressure region which dimensionally (or Froude) scale, and 2) those which are due to friction and must account for skin-friction coefficient changes with Reynolds number between the model and the prototype. The first theories,1 which were developed to describe the resistance characteristics of the SES, broke the components into the wavemaking drag due to the pressure region and the frictional drag of the sidewalls. Seal drag estimates were based on early British expressions derived for hovercraft. SES technology has been advanced significantly since these early estimations were made. The various drag components have been studied extensively, largely through model experiments, and are now understood in much greater depth. The resistance of an SES is usually estimated either from a theoretical approach (which has usually been correlated with or supplemented by experimental data), or one whereby experimentally derived model data are used extensively. The theoretical approach is used in parametric or sizing studies where one examines the effect of weight, length-to-beam ratio, or other parameters of a generalized design. These parametric prediction programs, however, may not be adequate to estimate the impact of the sometimes subtle physical differences between specific designs such as sidewall deadrise angle or chine effects, airflow rate effects, or the inherent differences between planing or bag and finger seals. These design-related differences can only be evaluated adequately through the use of model experiments and the analysis of the data. This paper summarizes a technique used
{"title":"Powering Prediction for Surface Effect Ships Based on Model Results","authors":"Robert A. Wilson, S. M. Wells, C. E. Heber","doi":"10.2514/3.63157","DOIUrl":"https://doi.org/10.2514/3.63157","url":null,"abstract":"A method employing the laws of dynamic similarity to scale experimental model data is presented for predicting the powering performance of large surface effect ships. The data are reduced to individual com- ponents, including cushion wavemaking drag, sidewall and appendage frictional and form drags, aerodynamic drag, and seal drag. These components are appropriately scaled by either Froude or Reynolds scaling laws. Water channel and model dimension effects on wavemaking drag are discussed and a technique for calculating sidewall wetted area is presented. An experimentally derived algorithm characterizing seal-induced and frictional drag is explained. Drag predictions are compared with experimental trials data. HE drag prediction technique presently used for scaling the model drag of a surface effect ship (SES) is different from that developed by Froude, in that both the frictional and wavemaking drag terms can be accurately determined. The basic drag components are broken down into two classes: 1) those which are due to lift provided by the pressure region which dimensionally (or Froude) scale, and 2) those which are due to friction and must account for skin-friction coefficient changes with Reynolds number between the model and the prototype. The first theories,1 which were developed to describe the resistance characteristics of the SES, broke the components into the wavemaking drag due to the pressure region and the frictional drag of the sidewalls. Seal drag estimates were based on early British expressions derived for hovercraft. SES technology has been advanced significantly since these early estimations were made. The various drag components have been studied extensively, largely through model experiments, and are now understood in much greater depth. The resistance of an SES is usually estimated either from a theoretical approach (which has usually been correlated with or supplemented by experimental data), or one whereby experimentally derived model data are used extensively. The theoretical approach is used in parametric or sizing studies where one examines the effect of weight, length-to-beam ratio, or other parameters of a generalized design. These parametric prediction programs, however, may not be adequate to estimate the impact of the sometimes subtle physical differences between specific designs such as sidewall deadrise angle or chine effects, airflow rate effects, or the inherent differences between planing or bag and finger seals. These design-related differences can only be evaluated adequately through the use of model experiments and the analysis of the data. This paper summarizes a technique used","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115170595","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 analytical solution has been applied to 7/100 scale model of the JEFF(A) with the results shown in Fig. 1. The predicted value of the normalized amplitude of the solution (= IC l / a ) is plotted vs encounter frequency and wavelength for a Froude number of 1.15. The magnitude of the wave forcing term and the linear frequency response are also shown separately since these are the factors which generate the heave response. It may be seen that the heave response of the vehicle is controlled by the form of the wave forcing curve, while the predicted linear frequency response is quite flat at this speed for wavelengths greater than the craft length. For comparison, an experimentally determined heave response obtained from towing tank tests as presented in Ref. 3 is included. The experimental curve behaves roughly in the same manner as the theoretical prediction. This suggests that the model may be relied upon to explain physical mechanisms and the influence of design particulars, though not in precise quantitative terms.
将解析解应用于JEFF(A)的7/100比例模型，结果如图1所示。当弗劳德数为1.15时，将溶液归一化振幅的预测值(= IC l / a)与遇到频率和波长的关系绘制出来。波浪强迫项的大小和线性频率响应也分别显示，因为这些是产生起伏响应的因素。可以看出，飞行器的升沉响应是由波浪强迫曲线的形式控制的，而在此速度下，对于波长大于飞行器长度的预测线性频率响应是相当平坦的。为了进行比较，参考文献3中提出的拖曳箱试验中获得的实验确定的升沉响应包括在内。实验曲线的表现与理论预测大致相同。这表明，该模型可以用来解释物理机制和设计细节的影响，尽管不是精确的定量术语。
{"title":"Comments on \"Controlling the Separation of Laminar Boundary Layers in Water: Heating and Suction'","authors":"A. Wortman","doi":"10.2514/3.63116","DOIUrl":"https://doi.org/10.2514/3.63116","url":null,"abstract":"The analytical solution has been applied to 7/100 scale model of the JEFF(A) with the results shown in Fig. 1. The predicted value of the normalized amplitude of the solution (= IC l / a ) is plotted vs encounter frequency and wavelength for a Froude number of 1.15. The magnitude of the wave forcing term and the linear frequency response are also shown separately since these are the factors which generate the heave response. It may be seen that the heave response of the vehicle is controlled by the form of the wave forcing curve, while the predicted linear frequency response is quite flat at this speed for wavelengths greater than the craft length. For comparison, an experimentally determined heave response obtained from towing tank tests as presented in Ref. 3 is included. The experimental curve behaves roughly in the same manner as the theoretical prediction. This suggests that the model may be relied upon to explain physical mechanisms and the influence of design particulars, though not in precise quantitative terms.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128594340","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 study of air cushion vehicle (ACV) motion in waves is presented for a single cushion ACV having a cellular, peripheral cell-type skirt system. The craft is considered to be traveling at constant speed while encountering regular waves of arbitrary heading. The dynamic equations for pitch, heave, and roll motions are derived using the cushion and cell air flow equations. These equations are solved numerically using a digital computer. The results are shown as frequency response curves giving steady-state motion response amplitudes as a function of encounter frequency or wavelength for fixed craft speed and wave steepness. The theoretical predictions are then compared with experimental data taken from scale model, towing tank tests in head seas. The comparison shows good agreement for pitch motion, while heave motion damping is overpredicted.
{"title":"SEAKEEPING DYNAMICS OF A SINGLE CUSHION, PERIPHERAL CELL-STABILIZED AIR CUSHION VEHICLE","authors":"R. Carrier, A. H. Magnuson, M. Swift","doi":"10.2514/3.48157","DOIUrl":"https://doi.org/10.2514/3.48157","url":null,"abstract":"A study of air cushion vehicle (ACV) motion in waves is presented for a single cushion ACV having a cellular, peripheral cell-type skirt system. The craft is considered to be traveling at constant speed while encountering regular waves of arbitrary heading. The dynamic equations for pitch, heave, and roll motions are derived using the cushion and cell air flow equations. These equations are solved numerically using a digital computer. The results are shown as frequency response curves giving steady-state motion response amplitudes as a function of encounter frequency or wavelength for fixed craft speed and wave steepness. The theoretical predictions are then compared with experimental data taken from scale model, towing tank tests in head seas. The comparison shows good agreement for pitch motion, while heave motion damping is overpredicted.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125263232","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}
Free vibration analysis of the neutrally buoyant inflated cantilevers, made of plastic sandwiched films, is presented, accounting for the added inertia and nonlinear hydrodynamic drag. The significant feature of the analysis is the reduction of the shell equations (the membrane, Fliigge's, and Herrmann-Armenakas') into a single equation which is similar in form to that for a vibrating beam with rotary inertia effects. The natural frequencies obtained are compared with the experimental results and those predicted by the Rayleigh-Ritz method in conjunction with the Washizu and membrane shell theories. The analyses show, and the experimental program confirms, that Fltigge's shell equation in reduced form is capable of predicting free vibration behavior quite accurately. However, the reduction technique should be applied with care, since in several cases it leads to misleading results, e.g., in the case of the Herrmann-Armenakas theory, generally accepted to be one of the most elaborate.
{"title":"Free Vibration of Neutrally Buoyant Inflatable Cantilevers in the Ocean Environment","authors":"V. Modi, D. T. Pooir","doi":"10.2514/3.63115","DOIUrl":"https://doi.org/10.2514/3.63115","url":null,"abstract":"Free vibration analysis of the neutrally buoyant inflated cantilevers, made of plastic sandwiched films, is presented, accounting for the added inertia and nonlinear hydrodynamic drag. The significant feature of the analysis is the reduction of the shell equations (the membrane, Fliigge's, and Herrmann-Armenakas') into a single equation which is similar in form to that for a vibrating beam with rotary inertia effects. The natural frequencies obtained are compared with the experimental results and those predicted by the Rayleigh-Ritz method in conjunction with the Washizu and membrane shell theories. The analyses show, and the experimental program confirms, that Fltigge's shell equation in reduced form is capable of predicting free vibration behavior quite accurately. However, the reduction technique should be applied with care, since in several cases it leads to misleading results, e.g., in the case of the Herrmann-Armenakas theory, generally accepted to be one of the most elaborate.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"46 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120922870","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}
Experimental results are presented for the effects on the lift and drag of a two-dimensional hydrofoil due to the injection of dilute polymer solutions onto its surface. Results are presented for three different polymers, namely, Polyox, Polyacrylamide, and Jaguar; for the purposes of comparison, results are also presented for water injection. The results indicate that, in general, polymer injection leads to a reduction in drag; but the lift can either increase or decrease depending on the polymer, the angle of attack, the surface on which the injection is made, the chordwise location at which injection is made, and the injection velocity. Results for the effects of the injections on the pressure distributions on the hydrofoil are also presented, and these results are consistent with the force measurements. Examination of the pressure distribution data seems to suggest that the observed lift effects may be due to a boundary-layer displacement phenomenon, with the detailed nature of this displacement effect being dependent on the viscoelastic properties of the injected polymer.
{"title":"Lift and drag effects due to polymer injections on a symmetric hydrofoil","authors":"A. M. Sinnarwalla, T. Sundaram","doi":"10.2514/3.48159","DOIUrl":"https://doi.org/10.2514/3.48159","url":null,"abstract":"Experimental results are presented for the effects on the lift and drag of a two-dimensional hydrofoil due to the injection of dilute polymer solutions onto its surface. Results are presented for three different polymers, namely, Polyox, Polyacrylamide, and Jaguar; for the purposes of comparison, results are also presented for water injection. The results indicate that, in general, polymer injection leads to a reduction in drag; but the lift can either increase or decrease depending on the polymer, the angle of attack, the surface on which the injection is made, the chordwise location at which injection is made, and the injection velocity. Results for the effects of the injections on the pressure distributions on the hydrofoil are also presented, and these results are consistent with the force measurements. Examination of the pressure distribution data seems to suggest that the observed lift effects may be due to a boundary-layer displacement phenomenon, with the detailed nature of this displacement effect being dependent on the viscoelastic properties of the injected polymer.","PeriodicalId":157493,"journal":{"name":"Journal of Hydronautics","volume":"1145 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131558904","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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