Browsing by Author "Killen, John M."
Now showing 1 - 20 of 21
Results Per Page
Sort Options
Item An Acoustic Study of Gaseous Micro-Bubbles In Boundary Layers and Propeller Wakes(St. Anthony Falls Hydraulic Laboratory, 1962-12) Ripken, John F.; Killen, John M.This report deals with exploratory tests to measure the nature of the free gas which occurs in natural water due to the dynamic disturbance of a ship. Acoustic attenuation measurements serve to show that micro gas bubbles are evolved from dissolved gases by the shear dynamics of a boundary layer and that the rate of evolution increases as some function of the intensity and duration of the disturbance and of the pressure, viscosity, and gas content of the water. The tests were conducted in the Laboratory, in large scale simulations of a ship's boundary layer and propeller, and in wakes of actual ship propeller's. These exploratory tests indicate the need for more extensive tests in sea water under a wide variety of naval operating conditions. Such tests are necessary to a better determination of the role that these bubbles play in cavitation and acoustic detection problems.Item A Capacitive Wave Profile Recorder(St. Anthony Falls Hydraulic Laboratory, 1952-10) Killen, John M.Research studies at the St. Anthony Falls Hydraulic Laboratory necessitated the development of a device for measuring and recording the profile of surface waves. The initial phase of these studies involved waves with periods ranging from 1/3 to 1 sec and with heights ranging from 1/2 to 3 inches. Existing methods of measuring and recording the profiles of these waves were considered to be not entirely satisfactory. A method has been developed whereby wave heights are measured electrically with a recording oscillograph; the deflections correspond to the depths of submergence of an insulated wire into the water. This insulated wire acts as a small capacitor whose capacity varies directly with the wetted area of the wire. The system has a linear calibration. Thus, accurate and continuous wave profiles can be recorded. Hysteresis effects due to surface tension are about 0.003 ft. A sensitivity up to 1/2 cm pen deflection per O.OO1-ft variation in water level is possible. The method may be used for greater wave heights, however some adjustment in oscillator may be required in extreme instances.Item Effect of Air Ingestion on performance of a Centrifugal Pump(1981-07) Killen, John M.; Wetzel, Joseph M.The full scale model test described here was initiated to examine the effect of suspended air bubbles on the performance of a CGN 38 seawater circulating pump. A Carver pump*Type 13N, Serial No. 110709, was chosen as the test model. This is a single suction, vertical discharge, horizontal suction pump. It has a single stage impeller and is capable of delivering 3000 gpm at a total dynamic head of 10 psi at 1150 rpm. The impeller was trimmed by the pump manufacturer to provide the desired head-discharge curve near the rated flow condition.Item The Effect of Dilute Solutions of Drag Reducing Polymers on Radiated Flow Noise(St. Anthony Falls Laboratory, 1967-07) Killen, John M.; Crist, Scott D.The influence of a drag reducing polymer additive in water on radiated flow noise was experimentally determined. The test facility was a rotating cylinder mounted in the center of a large cylindrical tank which served as an echoic chamber for the sound power measurements. Sound power radiated from the boundary layer of the rotating cylinder was measured for concentrations of 0, 10, 100, and 1000 ppmw of Polyox WSR 301 dissolved in the water. Sound power reductions greater than 20 decibels were noted in a frequency range of 20 to 100 kHz for a concentration of 1000 ppmw. Little influence could be found in a frequency range of 1 to 20 kHz. The effect of polymer additive on the drag coefficient of a rotating cylinder is also shown.Item An Electrical Method for Measuring Air Concentration in Flowing Air-Water Mixtures(St. Anthony Falls Hydraulic Laboratory, 1950-03) Lamb, Owen P.; Killen, John M.An electrical instrument has been developed to measure the air concentration in flowing air-water mixtures as part of an investigation of the mechanism by which atmospheric air is entrained in flowing water. The theory, development, and verification of this instrument are described in this report. The instrument is shown in Figs. 6c and 7, and the electrical circuit is shown in Fig. 9b. The electrical measurement of air concentration was chosen after examining possible mechanical, chemical, and magnetic methods. The method consists basically of a measurement of the difference between the conductivity of a mixture of air and water and conductivity of water alone. A mechanical strut supporting a pair of electrical probes has been combined with the electrical circuit in such a manner that air-concentration measurements may be made, not at a point, but at least in a small region of the flow. With this instrument it is now possible to traverse the flow cross section both vertically and laterally and to obtain the distribution of air in the flowing mixture. The relation between the instrument readings and air-concentration values are determined theoretically and the instrument is direct reading. by checking the results of the electrical method against a direct mechanical sampling method, it has been determined that the values of air concentration computed form theoretical conditions alone were sufficiently accurate for experimental work without further calibration. The instrument is now designed for application in an experimental laboratory channel, but with the use of a more rugged strut and supporting structure the method could be applied equally well in large flumes and spillways.Item An Experimental Investigation of the influence of an air bubble layer on radiated noise and surface pressure fluctuations in a turbulent boundary layer(1981-09-31) Killen, John M.between the noise spectra of a layer of air bubbles in a turbulent flow and' a maximum stable bubble size which can exist in the same flow. An air bubbie layer with individual bubble sizes greater than a maximum stable size was introduced into the boundary layer of water flowing along a smooth flat plate. It was found that the maximum stable bubble size was related to the turbulent kinetic energy dissipation as had been previously shown by other investigatorsItem Extended Phase A-2, Large Cavitation Channel, Davld Taylor Naval Ship Research and Development Center(St. Anthony Falls Laboratory, 1984-08) Arndt, Roger E. A.; Song, Charles C. S.; Silberman, Edward; Killen, John M.; Wetzel, Joseph M.; Yuan, MingshunIt was suggested that a mild contraction located immediately upstream of the pump may improve the quality of flow which is expected to be quite nonuniform coming from the diffuser and the first and second elbow. To investigate the effect of the contraction ratio, the AROl computer model previously used in the Phase A-2 studies for the Large Cavitation Channel (LCC) main contraction design was applied to the pump contraction. As shown in Fig. 1, the contraction is assumed to be 5.563 m long and of circular cross section. Area contraction ratios of 0, 10, 20 and 30 percent were used. There is a fixed shaft of constant diameter along the centerline of the contraction. Two different shaft diameters, 0.508 m and · 1.016 m, were used based on information available at the time the study was conducted~ Initially, a fifth order polynomial was used for the contraction profile. The profile was later changed to a straight line because the contraction is so mild that the flow is not significantly affected by the boundary shape. Due to symmetry about the vertical plane, only half of the flow region was modeled. Different types of nonuniform inflow velocity profiles were studied. A total of 46 modeling runs covering various geometrical and flow conditions as well as different modeling parameters were made.Item Hydraulic Model Studies of The Lake Avenue Control Structure Site 45(St. Anthony Falls Laboratory, 1985-03) Killen, John M.; Wetzel, Joseph M.The tunnel system for the Combined Sewer Overflow .Abatement Project (CSOAP) for the City of Rochester, New York, requires numerous control structures. Site 45 is the designated name and location of one such control structure. It is located on the west bank of the Genesee River and receives flow from the Lake Avenue Tunnel and the Tiger Carlisle Tunnel. The Site 45 control structure performs three functions. First, it contains a centrally located chamber which provides relief from waterhammer and surge pressures that will occur in the tunnels as a result of stormwater inflows. Second, if the inflow volume is great enough, the structure provides overflow relief by directing excess stormwater to two dropshafts which lead to the Genesee River below. Third, the structure controls the rate of flow through two parallel conduits which cross over to the east side of the Genesee River, and to additional structures located downstream, including the Frank E. Van Lare Sewage Treatment Plant. The control structure at Site 45 is designed to pass up to 375 cfs across the Genesee River to the Van Lare Treatment Plant. Flows greater than 375 cfs will exceed the capacity of the treatment plant and will be directed via the overflow relief to the Genesee River. The design maximum inflow to the Site 45 structure is 3000 cfs. Control of the rate of flow to the sewage treatment plant will be accomplished by means of control gates within the Site 45 structure. The gate openings will be set automatically to pass a given flow with a range· of head differences. These head differences are dependent on the water surface elevation in the surge chamber within the structure and the head required to establish a specific flow to the sewage treatment plant. A model of the Site 45 structure was built at the St. Anthony Falls Hydraulic Laboratory from drawings of the proposed structure supplied by Harza Engineering Company (Dwg. 1330 HYD 4500 RJ). Figures 1 and 2 show the plan and elevation of the structure obtained from these drawings. Photographs of the model are shown in Photos 1 and 2. The details of the specific parts of the model will be explained as the functions of the various components are discussed. Froude law scaling was used to establish dynamic similarity between the model and prototype, as gravity is the dominant force producing motion. The following expressions were used to convert the geometric, kinematic, and dynamic quantities from the model to the prototype.Item Hydrodynamic Analysis of the Hykat(St. Anthony Falls Hydraulic Laboratory, 1987-06) Song, Charles C. S.; Wetzel, Joseph M.; Yuan, M.; Arndt, Roger E. A.; Killen, John M.The St. Anthony Falls Hydraulic Laboratory has carried out a hydrodynamic analysis of several critical components of a preliminary design configuration of the HYKAT. A sketch of this configuration is shown in Fig. 1. The components subjected to detailed analysis were those of the upper leg, including the contraction, turning vanes of the first elbow, and the turbulent management system. Head loss computations were made for the entire flow circuit. Mathematical modeling was used extensively for analysis of the contraction and the turning vanes. Based on the results of this study, recommendations have been made for some modification to the preliminary design. Some of the results presented here have been previously included in progress reports, and results of additional studies are summarized.Item Model Study Of The Van Lare Overflow Distribution Structure(Saint Anthony Falls Laboratory, 1978-07) Killen, John M.; Song, Charles C. S.The Van Lare sewage treatment facilities in Monroe County, New York must eventually receive waste from an increased number of waste effluent conduits. The combined flow to the Van Lare treatment facilities is limited to 230 mgd and must enter the facility through two-six-foot diameter conduits. Each conduit must carry half of the total maximum flow.Item A New Facility for Evaluation of Materials Subject to Erosion and Cavitation Damage(St. Anthony Falls Laboratory, 1965-03) Ripken, John F.; Killen, John M.; Crist, Scott D.For nearly forty years various investigators have attempted to develop and routinely employ test procedures which would realistically evaluate the service resistance of fabricated materials exposed to erosion by water impact. These evaluations were necessary for the design selection of materials for steam turbine blades, for hydraulic machinery, and more recently for underwater ship appendages and for aircraft windshields.Item Phase A-2, Large Cavitation Channel, David Taylor Naval Ship Reasearch And Development Center(St. Anthony Falls Laboratory, 1983-08) Wetzel, Joseph M.; Bintz, David W.; Arndt, Roger E. A.; Morel, T.; Sharadchandra, Gavali; Song, Charles C. S.; Killen, John M.The Large Cavitation Channel (LCC) has very tight performance specifications for the flow quality in the test section, both for uniformity of the mean velocity profiles and turbulence levels. The mean velocity profiles have been addressed experimentally in the Task A report, and mathematically in the Task B report. This task is concerned with the turbulence levels in the test section. Turbulence levels are partially controlled bY,honeycomb design. Model studies of honeycombs should be conducted at as high a Reynolds number as possible to reduce scale effects. Thus, the decision was made not to utilize the undistorted 1 to 10 scale model of the preliminary Kempf and Remmers (K&R) contraction, test section, and diffuser that was used in the Task A studies as the Reynolds number based on honeycomb parameters was judged to be too low to obtain meaningful results. The existing wind tunnnel facility was modified for the turbulence measurements in rather an unique manner so that full scale honeycombs could be evaluated. These modifications were made after the tests of the Task A program were completed. Results of the turbulence measurements and recommendations for a turbulence management system for the LCC are discussed in the following sections.Item Physical and Mathematical Modeling of the HYKAT(St. Anthony Falls Laboratory, 1988-12) Song, Charles C. S.; Wetzel, Joseph M.; Killen, John M.HYKAT is an acronym for a water tunnel that will be used for both hydroacoustic and cavitation testing. It has a somewhat different configuration than conventional water tunnels, and therefore has been subjected to conHiderable analysis. The first studies carried out at the St. Anthony Falls llydraulic Laboratory were primarily concerned with the overall characteristics of the facility. These studies resulted in a recommendation for the shape of the contraction for a given contraction ratio, analysis of the turning vanes in the first elbow, turbulence management system, and overall headloss estimations. The entire effort was a "paper" study, and consisted of mathematical modeling and other analysis based on previous studies and available data. The results have been reported earlier [1]. As a result of the above mentioned work, it was recommended that additional work be carried out to verify the performance of the preliminary design. The overall configuration of the HYKA T that was to be evaluated is Hhown in Fig. 1. This configuration is slightly different than that originally proposed. The second elbow has been changed from a round to square cross-section, and the number of turning vanes in the elbows has been increased. The study was to include both physical and mathematical modeling. The math modeling was to be verified by the physical model so that it could then be used to predict the performance of the full-scale IIYKAT. The math model would also be useful in guiding the experimental programs and possibly be used in defining new boundary shapes, if deemed necessary. A combination of both types of modeling has proven to be very effective, particularly with the opportunity for close liaison being available between the two modeling groups at the Laboratory. The results of these efforts are discussed in detail in the following sections.Item Research and Development Studies for a Low-Level Free-Air Velocity Measuring System(St. Anthony Falls Hydraulic Laboratory, 1957-04) Ripken, John F.; Killen, John M.This report describes the development effort involved in creating an instrument capable of measuring the speed (0 to 50 fps) and direction of an air-flow vector at any selected point ranging from 0 to 1000 ft above the earth's surface. The sensitive instrument element was an electrically heated thermistor rod producing an electrical signal variation as a result of the convective cooling action of the measured air flow. The electrical signal from the elevated instrument station was conveyed to the ground readout station by a transmission cable. The instrument was stably supported and selectively positioned in the air flow by a tethered kite-type balloon. The development resulted in a complete and practical field measuring instrument having good accuracy and response.Item Research and Development Studies for a Low-Level Wind-Measuring System(St. Anthony Falls Hydraulic Laboratory, 1955-12) Ripken, John F.; Killen, John M.This report describes the research and development effort involved in creating an instrument capable of measuring the speed and direction of winds ranging from 1 to 50 ft per sec at any selected point between 0 and 1000 ft above the earth's surface. The sensitive instrument element was an electrically heated Thermistor rod producing an electrical signal variation as a result of the convective cooling action of the measured wind. The electrical signal from the elevated instrument station was conveyed to the ground indicator station by a transmission cable. The instrument was stabily supported and selectively positioned in the wind by a tethered kite-type balloon.Item The Sonic Surface-Wave Transducer(St. Anthony Falls Hydraulic Laboratory, 1959-07) Killen, John M.A wave height measuring instrument is described which measures the height of water surface waves by means of sonic ranging technique in air. This system is advantageous for wave amplitude measurements from a moving towing carriage since the sensing elements or its supports do not disturb the water surface. The design operation range of the instrument is 2-in. to 2-ft wave height. The accuracy of measurement depends on the incremental slope of the water surface at the point of measurement. An intrinsic error of +/- 0.8 per cent average over the wave would occur for a 2-ft wave with a slope at mid-height of 0.2. This error increases to +/- 3.2 per cent for a 2-in. wave of the same slope. The error is much reduced for both these conditions with less steep waves.Item A Study of The Influence of Gas Nuclei on Scale Effects and Acoustic Noise for Incipient Cavitation in a Water Tunnel(St. Anthony Falls Hydraulic Laboratory, 1959-09) Ripken, John F.; Killen, John M.Cavitation inception studies made on models in a recirculating water tunnel fail to correlate with similar studies on prototype bodies. This report considers the effect which free-gas nuclei in the water may contribute to this problem. Cavitation model tests were conducted using new instrumentation to measure the amount and size of the gas nuclei present in the flow. The inception of cavitation and the acoustic noise resulting from cavitation were both determined to be profoundly influenced by the character of the gas nuclei present in the liquid.Item A Study of the Influence of Microbubbles on Hydrodynamic Flow Noise(St. Anthony Falls Hydraulic Laboratory, 1966-04) Killen, John M.; Crist, Scott D.A test facility has been constructed for the measurement of flow noise generated by a rotating cylinder in water. Measurements were made of radiated flow noise in water for a frequency range of 5 to 80 kiloHertz. The surface velocities of the cylinder were varied from 44 to 100 fps. The total air content of the water was varied from 7 to 27 ppm. The radiated flow noise was observed to increase as the sixth power of the surface velocity for low frequencies. For high frequencies, the flow noise increased as the tenth power of the velocity. Release of air bubbles by shear had no effect on radiated flow noise other than to reduce the measured level of the noise.Item The Usse of SONAR to Measure Ice Thickness(St. Anthony Falls Hydraulic Laboratory, 1991-09) Killen, John M.; Gulliver, John S.The need frequently arises among individuals whose work must be carried out on the ice in rivers, lakes, and reservoirs for an instrument which conveniently measures ice layer thickness. Safety is possibly the most important consideration. In addition scientific studies of the processes involved in ice jam formation or of the effect of the ice layer on the ecology of the river lake or reservoir could be enhanced by an instrument that could conveniently and quickly measure ice thickness. At present ice thickness can be reliably determined by drilling a hole and measuring the thickness by some form of hook gage. This procedure requires, however, that individuals venture out on what is possibly "too thin" ice to make the measurement. For a number of thickness measurements over an area, surface drilling becomes a time consuming process. The various forms of nondestructive measuring devices currently in use employ an echo ranging technique with electromagnetic or acoustic waves. These devices are known by a number of acronyms such as; LASER ranging, RADAR, and SON AR. Their usefulness for ice- layer thickness measurements would depend, in addition to other considerations, on the strength of the reflection from an ice water interface. The expected distance to be measured is estimated from 1 cm to 100 cm (in the Minnesota Region) from the ice surface to the ice-water interface below. The velocity of propagation of electromagnetic waves of nearly 300,000,000 mls indicates echo ranging with electromagnetic waves would require the measurement of very small time intervals to infer distances as small as one centimeter. The time required for distance measurement using ultrasound, with a sound wave velocity of 3200 mls in ice, would be considerably longer, typically a few hundred microseconds. While the technology exists for the measurement of the extremely short transit time of electromagnetic pulses, the cost and complexity compared to the measurement of a considerably longer time for a acoustic pulse to travel the same distance is considerably greater.Item Velocity Measurement of Air-Water Mixtures(St. Anthony Falls Hydraulic Laboratory, 1952-03) Straub, Lorenz G.; Killen, John M.; Lamb, Owen P.A troublesome aspect of experimental studies of flow phenomena in air-water mixtures has long been that of making accurate velocity measurements. In the pas, bulk-flow measurements have been made variously with surface floats, injected dyes or salt clouds, and relationships between the discharge and depth of flow. Point measurements of velocity have been attempted by measuring stagnation pressures in the air-water mixture. These methods have not been of sufficient accuracy for many purposes. An instrument for making accurate point velocity measurements throughout a section of an aerated flow stream has been invented and developed at the St. Anthony Falls Hydraulic Laboratory. The transit time, between two fixed electrodes, of minute cloudlets of salt solution injected repetitively into the flowing air-water mixture is measured electronically. A rate of 15 injections per sec permits a direct measure of the mean flow velocity over a short stream filament. In the present form of the instrument, this mean velocity is indicated directly on a meter calibrated in feet per second. Measurements can be made in aerated flows with air concentrations exceeding 70 or 80 per cent and at very high velocities. Velocity measurements with the new velocity meter in nonaerated flows check within 1 or 2 per cent of those made with a Pitot tube. The integrated water discharge inan aerated flow stream, taking into account both the measured air distribution and the velocity distribution and making reasonable estimates of the water discharge through the boundary areas have also checked the water discharge through the boundary areas have also checked the water discharge measured directly with an accuracy of 1.5 per cent.