Side Orifice Research Articles

Hydraulics of Perforated Riser Inlets for Underground-Outlet Terraces

ABSTRACT Ageneral depth-discharge relationship for perforated riser inlets with bottom orifices is derived from basic principles. An idealized pressure distribution inside the riser is the key simplifying assumption. The shape of the depth-discharge curve depends upon the values of two nondimensional parameters. To assess the validity of the theoretical relationships, depth-discharge data for nine riser-inlet configurations were measured in the laboratory. The theoretical depth-discharge curves for these nine configurations fit the experimental data very closely. Three guidelines for designing hydraulically efficient riser inlets are: (a) the total side-orifice area should be large relative to the bottom-orifice area; (b) the side orifices should be concentrated near the bottom of the riser; and (c) the bottom orifice plate should be installed as far below the side orifices as is feasible

Hydraulics of Perforated Terrace Inlet Risers

ABSTRACT TERRACE inlet risers perforated with circular and slot orifices were tested in the laboratory. The orifice discharge coefficient for a circular orifice in the cylindrical surface of a riser was found to be significantly larger than for a circular orifice in a flat plate. A simple theoretical equation was found to provide good estimates for riser discharge when correct values of discharge coefficient are used. Side orifices should be evenly distributed around the circumference of the riser to reduce vibration.

Pulsatile flow velocity and shear stress measurements on the St. Jude bileaflet valve prosthesis.

The velocity and turbulent shear stress fields in the immediate vicinity of the St. Jude bileaflet valve were measured under pulsatile flow conditions with a two-dimensional laser Doppler anemometer system. The valve was studied in both aortic and mitral positions. In both positions, the valve created relatively centralized flow fields. However, a major portion of the flow occurred through the two side orifices. Regions of flow separation were observed adjacent to the valve sewing ring in the area of the valve pivot (hinge) mechanism. Elevated turbulent shear stresses were measured in both positions. Peak values of 760 dynes/cm2 and 2 000 dynes/cm2 were observed in the mitral and aortic flow chambers, respectively. Such turbulent shears could cause sublethal and/or lethal damage to blood elements. The regions of flow separation adjacent to the pivot mechanism could lead to tissue overgrowth and/or thrombus formation, which in turn could impede proper motion of the valve leaflets.

Bileaflet, tilting disc and porcine aortic valve substitutes: In vitro hydrodynamic characteristics

The desire for a low profile mechanical valve with better fluid dynamic performance led to the design and development of the St. Jude Medical bileaflet prosthesis. Comparative in vitro flow studies indicate that it has better pressure drop characteristics than the Björk-Shiley (convexo-concave) and Carpentier-Edwards porcine valves in current clinical use, especially in the small sizes. In the 21 to 27 mm aortic valve size range the St. Jude valve has an average performance index of 0.66, compared with 0.46 and 0.32 for the Björk-Shiley and Carpentier-Edwards valves, respectively. In contrast, the St. Jude valve has larger regurgitant volumes than both the Björk-Shiley and Carpentier-Edwards valves. Velocity measurements with a laser-Doppler anemometer indicate relatively centralized flow with small amounts of turbulence downstream of the St. Jude valve. The flow is unevenly distributed between the central and side orifices. The turbulent shear stresses are, however, large enough to cause sublethal or lethal damage to blood elements. Wall shear stresses are smaller than those measured downstream of the Björk-Shiley valve. Regions of flow separation were observed just downstream from the sewing ring, which could lead to excess tissue growth along the sewing ring. The results of this study indicate that overall in vitro fluid dynamic performance of the St. Jude valve is superior to that of the two other commonly used prostheses.

Effects of glucagon and secretin on food- or morphine-induced motor activity of the distal colon, rectum, and anal sphincter.

The effects of glucagon and secretin on food- or morphine-induced motor activity of the distal colon, rectum, and internal anal sphincter were investigated in 12 healthy subjects. Intraluminal pressure changes were measured using a triple-lumen polyvinyl tube assembly with 3 side orifices. Glucagon, administered intravenously, caused significant inhibition of food- or morphine-induced motor activity of both the distal colon and rectum. In contrast, secretin did not suppress morphine-induced motor activity but did significantly inhibit food-stimulated motor activity of the distal colon. The inhibitory effect of secretin on motor activity of the rectum was insignificant. Morphine, but not food, elevated the pressure of the anal sphincter which was not effected by glucagon or secretin. Hyperglycemia, produced by the infusion of 5% glucose, had no effect on motor activity. These studies demonstrate that glucagon but not secretin, in the doses employed, inhibits morphine-induced motor wave activity of both the distal colon and rectum and that this inhibitory effect is not secondary to hyperglycemia. Furthermore, the rise in anal sphincter pressure is not affected by glucagon or secretin.

SINGLE LUMEN PERFUSED CATHETER MANOMETRICS: A SENSITIVE NEW TECHNIQUE FOR MEASUREMENT OF LOWER ESOPHAGEAL SPHINCTER PRESSURES IN YOUNG INFANTS

Lower esophageal sphincter pressures (LESP) are generally measured during esophageal motility studies using multilumen water perfused catheters. Because of the large size of this assembly, gagging occurs, sedation is required and acceptable tracings may not be obtained. We have compared a large catheter assembly (three 1.2 mm single lumen catheters bound together with a 4.0 mm total diameter) with a 1.2 mm single lumen catheter with 1.0 mm side orifice. Triplicate studies were obtained by perfusing the catheters with water at 1.3 cc/min and slowly withdrawing from the stomach to LES. LESP were obtained in 10 fullterm newborns 3 hours after feeding; infants were then sedated and 90 min. later triplicate studies repeated. LESP were as follows:In two patients, gagging prevented the recording of adequate tracings from triple lumen catheters. Our data indicates that LESP can be successfully measured in the unsedated infant using a small single lumen catheter, and that higher pressures are obtained with the single lumen assembly.

Modifications of single and double-barrel potassium specific microelectrodes for physiological experiments

1. The shape parameters of glass microcapillaries for making ion specific microelectrodes were studied. It was found, that the greater the angle set by the walls, the more advantageous is the shape for filling the microelectrode. The time response of the precisely prepared microelectrode does not exceed severall msec. 2. The preparation of the double-barrel ion specific microelectrodes is described. One barrel was filled with organic ion exchanger and the other with NaCl solution (reference channel). These electrodes are convenient for measurement of ion movements in the excitable tissues (brain, spinal cord etc) where it is necessary to avoid the electrical activity of the cells. 3. A side-pore type of ion specific microelectrode was developed for measurement of extracellular K+ concentration during muscle contraction. This type of electrode does not cut the muscle fibres during contractions and the side orifice of the channel prevents the undesirable movement of the ion exchanger during insertion into the muscle.

A Consideration of the Measuring Mechanism of Some Freeness Testers

The theoritical correlation of CSF value and continuous freeness recorder's value are considered.CSF values, which is the drainage volume from side orifice of CSF tester, is represented by next equation.CSF=Q2/VbKr+Q+VbKr (lnVbKr/VbKr+Q+Q/VbKr+Q)-qbwhere, Kr=RWηQC1/ρgSFrom this equation, if Q, Vb, qb are known values, CSF value is function of Kγ which is decided by RW.At the continuous freeness recorders, assuming that there is a discontinuous change in the concentration of the pulp mat under the wire screen from that of the surrounding slurry, we will obtain the following equation. (See Fig. 7)h2_??_2ρgh0/RWη, (1-αC1)(C2-C1)/C1C2tThis equation means that the correlation of h2 and t depend on the RW value.As a result, CSF value and continuous freeness recorder's value are represented by same physical value RW or Kγ.

The lack of influence of end and side orifices in cardiac catheters on venous pressure recording

The lack of influence of end and side orifices in cardiac catheters on venous pressure recording