Showing papers on "Volumetric flow rate published in 1985"

Blood velocity and volumetric flow rate in human retinal vessels.

Abstract: The distributions of blood velocity and volumetric flow rate in individual vessels of the normal human retina were determined as a function of vessel diameter. The mean velocity of blood, Vmean, was calculated from the centerline velocity measured by bidirectional laser Doppler velocimetry (LDV). Volumetric flow rate was determined from Vmean and the vessel diameter, D, measured from monochromatic fundus photographs. Diameter of the arteries and veins at the site of the LDV measurements ranged from 39 to 134 microns and 64 to 177 microns, respectively. Flow velocity correlated with D (P less than 0.001 for both arteries and veins). Volumetric flow rate varied with D at a power of 2.76 +/- 0.16 for arteries and 2.84 +/- 0.12 for veins, in close agreement with Murray's law. Calculated from 12 eyes, the average total arterial and venous volumetric flow rates were 33 +/- 9.6 and 34 +/- 6.3 microliters/min, respectively. The good agreement between both flow rates suggests that the technique and the assumptions for calculating flow yield results that satisfy mass conservation. Total arterial and venous volumetric flow rates correlated with total arterial and venous vessel cross-section. Volumetric flow rate in the temporal retina was significantly greater than in the nasal retina, but the difference is likely to be due to the larger area of the temporal retina. No difference in flow rate was observed between the superior and inferior retinal hemispheres. Finally, blood velocity in the major retinal vessels measured under normal experimental conditions appears remarkably constant over short (hours) and long (months) periods of time.

On the measurement of the mean velocity of blood flow over the cardiac cycle using doppler ultrasound

Abstract: A number of modern duplex scanners now have facilities for determining volumetric blood flow through intact vessels. The methods these machines use to arrive at an answer must presuppose a number of conditions which may not be met in practice. This paper examines the effect that nonuniform insonation of the target blood vessel (using continuous wave or wide-gate pulsed ultrasound) has on the mean velocity, as determined using mean, root mean square (RMS) and maximum frequency processors. It is shown that for a given beam/vessel geometry the error is dependent only on the shape of the mean component of the velocity profile which, depending on the arterial site, may be flat, parabolic or intermediate. Mean processors may overestimate the mean velocity of established flow by up to 33%, but this could be turned to advantage when it is impracticable to insonate a vessel uniformly. Maximum frequency processors are of value when either plugflow or fully established flow of low pulsatility is present in the target vessel. In the first case the mean flow is the same as the maximum flow, while in the second the mean flow is half the time averaged maximum flow, irrespective of the size and shape of the ultrasound beam. RMS processors are probably best avoided in volumetric flow measurement applications.

Peristaltic transport of a non-newtonian fluid: applications to the vas deferens and small intestine

Abstract: The problem of peristaltic transport of a non-Newtonian (Power law) fluid in a uniform and non-uniform tube has been investigated under zero Reynolds number and long wavelength approximation. A comparison of the results with those of Newtonian fluid model shows that the magnitude of pressure rise, under a given set of conditions, is smaller in the case of non-Newtonian fluid, when the flow behavior index n<1, at zero flow rate. Further, the pressure rise decreases as n decreases from 1, at zero flow rate, is independent of n at a certain value of flow rate, and increases if flow rate exceeds further. Also, at a given flow rate, an increase in the wavelength leads to a decrease in pressure rise and increase in the influence of non-Newtonian behavior. Pressure rise, in the case of non-uniform geometry, is found much smaller than the corresponding value in the case of uniform geometry. Finally, the analysis has been applied and compared with observed flow rates in the vas deferens in rhesus monkeys and in the small intestine.

Drop sizes in annular two-phase flow

Abstract: Drop sizes in annular flow have been measured using a diffraction technique. Several series of experiments were carried out to determine the effect of gas velocity, drop concentration, film flow rate and tube diameter on drop size. Film flow rate and tube diameter have been found to have very little influence on the sizes of drops produced. An empirical equation which describes the drop sizes is presented.

Structure of Selective Low Pressure Chemically Vapor‐Deposited Films of Tungsten

Abstract: Tungsten films have been selectively deposited (i.e., deposited on Si and TaSi2 to the exclusion of SiO2) by LPCVD via the reduction of WF6 by either Si or H2. Films formed by H2 reduction can be unlimite in thickness; however, those formed by Si reduction are self-limited in thickness to about 150A. The effects of deposition parameters such as temperature and WF6 and H2 flow rates on the properties of the W films have been investigated. To prevent excessive erosion of Si in window areas, the volumetric flow ratio of H2 to WF6 must be larger than the critical value of about three. Typical films are polycrystalline with an average grain size of 2000A and exhibit a tensile film stres of about 7 X 10Z dyn/cmS. W film resistivity is found to be about 13 -cm for a 1000A film, resulting in sheet resistance of 1.3 . The W films exhibit good contact resistance to N and P Si, and are also found to be excellent diffusion barriers between Al and Si at annealing temperatures up to 450C.

Inhalation ventilator for the aerosol therapy of patients

Abstract: In a device for the inhalation of medicaments with assisted intermittent positive pressure ventilation for the treatment of patients with reduced or disturbed pulmonary function, the breathing air is enriched with medicaments by means of an atomizer, whose output can be adjusted, and administered to the patient at an adjustable flow rate within adjustable pressure limits. At the same time, the breathing air can be enriched in oxygen having a pre-selectable concentration during the inspiration phase, the oxygen concentration being regulated at a constant rate independently of the chosen flow rate. To this end, the inhalation ventilator according to the invention uses an electronic control unit in which the values measured for the ventilation pressure, flow rate, atomizer output and oxygen concentration are determined, compared with specified values and controlled via adjustment members.

Solid-liquid mass-transfer in packed-beds with cocurrent gas-liquid downflow

Abstract: Local instantaneous solid-liquid mass transfer coefficients were measured in two-phase gas-liquid downflow through packed columns for 3 X 3 mm and 6 X 6 mm cylinders. An electrochemical technique was used. Liquid flow rates from 3.0 to 26.6 kg/m/sup 2/ X s and gas flow rates from 0.07 to 1.16 kg/m/sup 2/ X s covered the gas-continuous, ripple, and pulse flow regimes. Time-averaged mass transfer coefficients in trickle flow and in pulse flow for the pulse proper and the base (outside the pulse) were found to increase with increasing gas and liquid rates. Correlations are presented in terms of liquid phase Reynolds numbers and in terms of Kolmogoroff numbers. The mass transfer coefficients in the pulse were found to correspond closely to the coefficients that would be attained in the dispersed bubble flow regime.

Method and apparatus for controlling the temperature and flow rate of a fluid

Abstract: A method and apparatus for controlling the mixing of two fluids to form a mixed fluid, and the volume discharge rate of the mixed fluid. In a particular application, the two fluids are hot and cold water, and the mixing is controlled to effect temperature control of the mixed water. A specially-designed integral temperature control and volume control valve is included as part of the system. Operation of the valve is controlled by two stepper motors, which in turn are controlled by signals developed by a control unit. Means for setting a desired temperature and volume rate discharge, as well as means for displaying the set temperature and volume rate discharge, are also provided.

Mixture control apparatus and mixture control method

Abstract: A mixture control apparatus controls a flow rate of a second fluid to be mixed with a first fluid so as to prepare a third fluid having a predetermined concentration. A set point variable of the flow rate of the second fluid is calculated in accordance with the flow rate of the third fluid so as to improve controllabilty of the apparatus. A gain correction circuit calculates a gain correction quantity using the flow rate of the third fluid. A feed forward circuit calculates a feed forward control component. A feedback circuit calculates a feedback control component. The set point variable of the flow rate of the second fluid is calculated in accordance with the feed forward control component and the feedback control component. The flow rate of the second fluid is controlled to coincide with this set point variable.

Glass fiber‐filled thermoplastics. II. Cavity filling and fiber orientation in injection molding

Abstract: Mold filling of a rectangular cavity of three different thick nesses fed from a reservoir is studied for unfilled and glass fiber-filled polypropylene and polystyrene. The shapes of flow fronts studied by short-shots are affected predominantly by the thickness of the cavity with other parameters playing a less important role. Pressure drop versus volumetric flow rate inside the thinnest cavity is studied experimentally and predictions are made from a computer simulation of mold filling. The orientation of fibers in the cavity is examined using a reflect-type microscope and the orientation is found to depend on cavity thickness, melt temperature, fiber content, and to a lesser extent, on volumetric flow rate. In the thinnest cavity, where the flow is quasi-unidirectional, the fibers remain in the plane of flow oriented either along the flow direction or perpendicular to it, except in the region near the flow front, where they follow a “fountain” flow behavior.

Gas-liquid mass transfer characteristics in a bubble column with suspended sparingly soluble fine particles

Abstract: (To investigate the influence of suspended particles on mass transfer characteristics in a slurry bubble column, physical and chemical absorptions were performed into aqueous slurries of fine calcium hydroxide particles ca. 7 ..mu..m in average size. Such mass transfer parameters as volumetric liquid-side mass transfer coefficient, specific gas-liquid interfacial area, and hence liquid-side mass transfer coefficient were determined under various electrolyte concentrations, solid concentrations, and gas flow rates.) and K /SUB L/ /SUP o/ a could be correlated by the gas flow rate. (The volumetric gas-side mass transfer coefficient was determined and correlated by the gas flow rate. The enhancement factors during absorption of dilute carbon dioxide into aqueous calcium hydroxide slurries were compared with the theoretical predictions based on the film theoryincorporating a finite slurry concept.)

Method and apparatus for determining mass flow rate and quality in a steam line

Abstract: A method and/or apparatus for determining the mass flow rate and the quality of steam in a flowing line. It involves directing the total flow to a liquid-vapor separator. The separated vapor and liquid have the flow of each metered and the flow of one regulated so as to hold the level of the separated liquid constant. Then, by measuring pressure and temperature of the separated flows upstream from the regulation, the mass flow rate and the quality of the steam may be determined.

Flow rate detecting device

Abstract: This disclosure relates to a flow rate detecting device which includes a fixed rotating member (21) for converting a fluid from a straightforward flow to a rotary flow and a spherical member (30). Frictional force acting on the spherical member (30) can be decreased and the rotary orbital track for the spherical member (30) can be stabilized by the arrangement of a spherical member receiver (26), by which the spherical member is supported, having a receiving face (23) perpendicular to the fluid flow and outflow paths (24, 25) at its central and circumferential sides, and as a result, a high performance of the flow rate detecting device can be accomplished.

Method of automatically measuring fluid flow rates

Abstract: A method comprises providing at least two fluid flow channels of different sizes wherein each contain a temperature sensitive resistance fluid flow sensor. An electronic controller is provided with the electrical information from the temperature sensitive resistance fluid flow sensor. The electronic controller is provided with a data base including at least the calibration data between fluid flow rate and the electrical information from the resistance sensor and the designated fluid flow rates at which each of the flow channels other than the smallest that could be opened or closed. Next, the fluid whose flow rate is to be measured is caused to flow through the smallest flow channel. Then the electronic controller compares the flow rate through the smallest flow channel with the designated flow rate for the smallest channel and opens the next larger flow channel to fluid flow if the designated flow rate is exceeded or closes such flow channel if such designated flow rate is not exceeded. If the next largest channel is to be opened, the proceeding three steps are repeated for each succeeding pair of flow channels until the flow rate does not exceed the designated flow rate or until there are no more flow channels to be opened. Finally, the flow rate information from all of the flow channels is combined.

Apparatus for heating fluid by burning liquid fuel

Abstract: An improved apparatus for heating fluid by burning liquid fuel is disclosed. To heat fluid such as water, air or the like medium heat exchanging is effected between the combustion chamber in which liquid fuel is burnt with combustion air introduced therein and the fluid passage through which fluid to be heated flows. The apparatus includes means for controlling rotational speed of a single motor for rotating the fuel pump and the blower, means for controlling a flow rate of fuel to be pumped from the fuel pump, means for controlling a flow rate of combustion air and an electronic control unit into which a variety of parameters relative to the above-mentioned means are inputted. The parameters are processed in the electronic control unit to individually control the means for controlling rotational speed of the motor, the means for controlling a flow rate of fuel and the means for controlling a flow rate of combustion whereby heat exchanging therebetween is achieved without fluctuation in temperature of fluid. Typically, the parameters are rotational speed of the motor and flow rate of fuel pumped from the fuel pump. The parameters may be those as selected from a group of atmosphere pressure, temperature of combustion air, voltage of electric current, temperature of fluid before and behind heating and required heating temperature of fluid.

Fluid flow control process

Abstract: A method is disclosed for controlling flow rates of a primary fluid including aspirating, mixing, and metering the primary fluid with a secondary fluid. The secondary fluid has a high relative vapor pressure to form a gaseous mixture consisting essentially of vapor at constant volume fraction of primary fluid independent of flow rates. In one aspect, the invention includes passing a secondary fluid of diluent gas through a venturi having specified proportions including discharge coefficient; and pumping primary fluid through venturi suction to pass through a primary fluid orifice of specified discharge coefficient wherein the venturi discharge coefficients of the venturi and the liquid orifice form a substantially linear proportionality over a wide range of flow rates through the venturi.

Method of temperature compensating leak rate testing

Abstract: A method of compensating for temperature variations in testing part cavities for leaks by placing a fluid pressure source in communication with the cavity and measuring the flow rate to the cavity to determine the rate of any leakage. The method establishes a temperature compensation function by measuring the shift in flow rates resulting from changes in temperature of a sample test part, which temperature compensation function allows correction of the flow rates during subsequent testing according to the sensed temperature of the test part. Flow rates are measured at two differing temperatures to determine the temperature compensation function by linear regression, since the flow rate shift with temperature varies substantially linearly.

Surface Acoustic Wave Flow Sensor

Abstract: A SAW gas flow rate sensor is realized using the principle of heat transfer with the mass flow. The substrate for the SAY delay line is 128O LiNb03. In addition, a thin film heater is fabricated adjacent to the SAW delay line. The substrate of the SAW delay line is heated at a constant power with the heater. The flow of gas will carry heat with it, thus, lowering the temperature of the substrate resulting in a change in the frequency of the SAW delay line oscillator. The sensitivity of the SAW oscillator frequency to flow rate at various pressures and temperatures of the substrate is presented.

Characterization of two-phase flow in pipes

Abstract: Gamma radiation transmission measurements are made with one-shot-collimation to determine the distribution of voids within a gas-liquid mixture flowing in a pipe. The distribution of voids in selected portions of the pipe, taken together with statistical and logical tests applied thereto, provides information from which are determined: type of flow pattern or flow regime, the profile of a large gas bubble in slug flow, and the gas and the liquid volume flow rates in slug flow.

A theory of plasma-assisted chemical vapor transport processes

Abstract: A theory is presented for plasma‐assisted chemical vapor transport (PACVT) processes, applicable to reactive ion or plasma etching, plasma‐assisted chemical vapor deposition and, in the absence of a plasma, low‐pressure thermally driven chemical vapor transport processes. The central results of this theory are the steady‐state or nonequilibrium gas‐phase chemical concentrations in the vicinity of the reacting surfaces and the rate at which the etch/deposit solid is transported into or out of the reactor volume and/or between reactor surfaces as a function of reactor geometry, (ion‐bombardment‐enhanced) surface reaction rates, diffusion, and flow rates. Taking the rate‐limiting chemical reactions to be heterogeneous leads to a transport equation that predicts behavior for such processes that is essentially in agreement with experiment. Instead of depending on the homogeneous reaction kinetics, this behavior stems from the competition between surface reaction rates, diffusion, and flow rates, yielding a dependence on reactive surface to volume ratios or reactor loading. In contrast to the preceding loading equation, this one is applicable to the entire range of flow for which the transport rate depends on reactor loading, while the reciprocal of the etch rate still exhibits the linear dependence on loading obtained earlier. Also, the theory clarifies some previously observed, but inadequately explained, phenomena unique to PACVT, such as increased flow rate sensitivity for more exoenergetic reactions, flow‐dependent ultrahigh etch selectivity between conducting and insulating films, and etch pattern sidewall deposition for endoenergetic reactions.

Thermal mass flow meter and method of making same

Abstract: A thermal mass flow meter includes a comb-shaped structure having a plurality closely spaced septa carried from a common spine and disposed within the flow stream to be measured for partitioning the flow therein into a plurality of generally parallel elongated ribbon-shaped flow stream portions. Temperature-dependent fluid flow sensing resistor means is coupled in heat-exchanging relation predominantly with the narrow face of at least one of said ribbon-shaped flow stream portions for measuring the fluid flow. In a preferred embodiment, the comb-shaped flow partitioning structure is fabricated by anisotropically etching the parallel flow channels through the (110) face of diamond cubic material such as silicon. In another embodiment, a thermal loading member is disposed in heat-exchanging relation with the temperature dependent fluid flow sensing resistor means for thermally loading same and pushing the critical flow rate up to a higher flow to allow operation of the flow sensor in one mode of operation over a wider range of flow rates.

Analysis of An Intensive Magnetic Field on Blood Flow: Part 2

Abstract: The rate of flow of blood in large blood vessels is affected when exposed to a strong magnetic field. This problem is modelled in terms of the hydroraagnetic Navier-Stokes aquation, and explicit solutions are obtained for the flow velocity and flow rate of blood in a large artery, placed In a magnetic field. Rigorous and general solutions are obtained in terms of ber and bei functions for an axially symmetric case.

Method for the transportation of a particulate material at controlled rate

Abstract: The invention provides an efficient method for controlling the flow rate of a particulate material through a pneumatic transportation pipe at a preset value with a high accuracy and rapid response to an external disturbance added to the system by controlling the flow rate of the booster gas. Different from conventional methods in which the flow rate of the booster gas is controlled with the feedforward factor of the variation in the actual flow rate of the particulate material, the inventive method utilizes the variation in the pressure in the receiving unit as the feedback to control the flow rate of the booster gas so that the above mentioned advantages are obtained in the accuracy of control and rapidness of the response to an external disturbance.

Vacuum vapor transport control

Abstract: A vacuum vapor transport control system and method for controlling the rate of vapor flow from a reagent reservoir into a vacuum system through an orifice calibrated as to size or flow rate using a high purity fixed gas and vapor provided from multiple reservoirs or mixed vapor provided from a single reservoir.

Automated interfacial tensiometer

Abstract: The interfacial tension in a liquid-liquid system is determined by estimating the flow rate of the heavier liquid as it is discharged under constant head through a capillary immersed in a body of the lighter liquid, or conversely, of the lighter liquid as it is discharged under constant head through a capillary immersed in a body of the heavier liquid. A known voltage is applied to each drop which forms at and detaches from the capillary tip and an electrometer is used to measure the total electrical charge per drop and the frequency of drop formation/detachment. The determination is made under conditions in which a plot of interfacial tension versus the square of the applied voltages yields two straight lines whose slopes of ±C/2 where C is the capacitance of the interface per unit area and the positive value is generated from the positive polarity voltage and the negative from the negative polarity. Based upon the value of C determined from the slope, the known voltage and the measured values of dropping frequency and of total charge per drop, the correctness of the estimated flow rate is determined and, in an iterative process, a new flow rate estimation and consequent plots are made until the estimated flow rate equals the flow rate as determined from measurements. The value of the interfacial tension at zero charge is then obtained from the intersection of the two lines.

Volumetric pumping apparatus and method for supplying fluids to sheath stream flow cells

Abstract: Apparatus and method are provided for the precisely controlled and coordinated supply of sample and sheath stream fluids to a sheath stream flow cell, and comprise the use of positive displacement differential pumping means which are operable to insure consistent sample and sheath stream fluid diameters, velocity and volume flow conditions within the flow cell, thereby maximizing the accuracy and reproducibility of successive analyses.