Aerodynamic Characteristics of Tracheostomy Speaking Valves

1993 ◽  
Vol 36 (3) ◽  
pp. 529-532 ◽  
Author(s):  
Lisa Fornataro-Clerici ◽  
David J. Zajac
Keyword(s):  
Steady State ◽  
Speech Production ◽  
Clinical Significance ◽  
Tracheostomy Tube ◽  
Flow Characteristics ◽  
Aerodynamic Characteristics ◽  
Future Research ◽  
Steady State Flow ◽  
Upper Airways ◽  
Flow Rates

Pressure-flow characteristics were determined for four different one-way valves used for speech production in the patient who has had a tracheotomy. Each valve was tested at steady-state flow rates of 150, 250, 350, and 450 ml/sec in isolation and attached to a tracheostomy tube. Results indicated significant differences in resistance among the valves. The resistance of one valve was substantially greater than that of the normal upper airways. It is suggested that future research determine the clinical significance, if any, of these differences relative to speech and respiratory behaviors in tracheostomized patients.

Aerodynamic Characteristics of Tracheostomy Speaking Valves

1999 ◽  
Vol 42 (1) ◽  
pp. 92-100 ◽  
Author(s):  
David J. Zajac ◽  
Lisa Fornataro-Clerici ◽  
Thomas A. Roop
Keyword(s):  
Steady State ◽  
Speech Production ◽  
Atmospheric Pressure ◽  
Aerodynamic Characteristics ◽  
Nasal Resistance ◽  
Steady State Flow ◽  
Aerodynamic Properties ◽  
Average Slope ◽  
Inspiratory Resistance ◽  
Normal Adults

Two analyses were conducted to define some aerodynamic properties of one-way speaking valves designed for use with the tracheotomized patient. In the first analysis, the resistance to airflow of six different valves was determined during steady-state flow testing at rates of .450, .500, and .550 l/s. Significant differences among the valves were established only at the lowest flow rate. All valves exhibited relatively low resistance in the range of nasal resistance reported for normal adults. In the second analysis, the aerodynamic integrity of the valves was assessed during repetition of the syllable /pa/ under a condition used to simulate tracheostomy speech production. Significant differences were found among the valves in terms of air loss occurring during the rise in pressure associated with the production of the consonant /p/. Valves with diaphragms open at atmospheric pressure consistently exhibited air loss. Average slope of the rise in pressure for one of the valves tested was significantly greater, suggesting increased work during speech production. The results of these analyses suggest that although the inspiratory resistance to airflow was similar among various one-way speaking valves, some valves exhibit air loss during speech production.

Flow in a Toroidal Thermosyphon with Angular Displacement of Heated and Cooled Sections

1979 ◽  
Vol 101 (4) ◽  
pp. 672-676 ◽  
Author(s):  
P. S. Damerell ◽  
R. J. Schoenhals
Keyword(s):  
Steady State ◽  
Reverse Flow ◽  
Angular Displacement ◽  
Vertical Plane ◽  
Steady Condition ◽  
Steady State Flow ◽  
Flow Rates ◽  
Flow Phenomenon ◽  
Angular Displacements ◽  
Good Agreement

A toroidal thermosyphon consisting of a fluid-filled torus located in a vertical plane was studied analytically and experimentally. Good agreement was obtained between analytical predictions and measurements for large values of the angular displacement of the heated and cooled sections. For smaller angular displacements, the analytical predictions of steady state flow rates were found to exceed the corresponding experimentally observed values. The discrepancies were attributed to a reverse flow phenomenon. Some analytically predicted flows were not physically achievable. In these situations the flow would either reach a steady condition in the opposite direction, or it would oscillate indefinitely.

scholarly journals On the Measurement and Modeling of High-Pressure Flows in Poppet Valves Under Steady-State and Transient Conditions

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Stephan Mohr ◽  
Henry Clarke ◽  
Colin P. Garner ◽  
Neville Rebelo ◽  
Andrew M. Williams ◽  
...  
Keyword(s):  
Steady State ◽  
Transient Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Valve Lift ◽  
Transient Pressure ◽  
Dynamic Flow ◽  
Steady State Flow ◽  
State Flow ◽  
Piston Cylinder

Flow coefficients of intake valves and port combinations were determined experimentally for a compressed nitrogen engine under steady-state and dynamic flow conditions for inlet pressures up to 3.2 MPa. Variable valve timing was combined with an indexed parked piston cylinder unit for testing valve flows at different cylinder volumes while maintaining realistic in-cylinder transient pressure profiles by simply using a fixed area outlet orifice. A one-dimensional modeling approach describing three-dimensional valve flow characteristics has been developed by the use of variable flow coefficients that take into account the propagation of flow jets and their boundaries as a function of downstream/upstream pressure ratios. The results obtained for the dynamic flow cases were compared with steady-state results for the cylinder to inlet port pressure ratios ranges from 0.18 to 0.83. The deviation of flow coefficients for both cases is discussed using pulsatile flow theory. The key findings include the followings: (1) for a given valve lift, the steady-state flow coefficients fall by up to 21% with increasing cylinder/manifold pressure ratios within the measured range given above and (2) transient flow coefficients deviated from those measured for the steady-state flow as the valve lift increases beyond a critical value of approximately 0.5 mm. The deviation can be due to the insufficient time of the development of steady-state boundary layers, which can be quantified by the instantaneous Womersley number defined by using the transient hydraulic diameter. We show that it is possible to predict deviations of the transient valve flow from the steady-state measurements alone.

THE FLOW OF GASES THROUGH MICROPOROUS CARBON

1965 ◽  
Vol 43 (7) ◽  
pp. 1968-1972 ◽  
Author(s):  
R. F. Bartholemew ◽  
E. A. Flood
Keyword(s):  
Steady State ◽  
Room Temperature ◽  
Microporous Carbon ◽  
Steady State Flow ◽  
Flow Rates ◽  
State Flow

Steady state flow rates are reported for He, Ar, N2, Kr, methane, propane, and n-butane flowing through a microporous carbon rod at room temperature.

Study of Unsteady Orifice Flow Characteristics in Hydraulic Oil Lines

1996 ◽  
Vol 118 (4) ◽  
pp. 743-748 ◽  
Author(s):  
Seiichi Washio ◽  
Satoshi Takahashi ◽  
Yonguang Yu ◽  
Satoshi Yamaguchi
Keyword(s):  
Steady State ◽  
Flow Rate ◽  
Pressure Loss ◽  
Flow Characteristics ◽  
High Fidelity ◽  
Flow Rates ◽  
Hydraulic Oil ◽  
Orifice Flow ◽  
Net Pressure ◽  
Clockwise Hysteresis

A technique to measure fluctuating differential pressures with high fidelity has been developed first. When applied to detecting differential pressures generated by an accelerated or decelerated liquid column, the technique turned out to be effective in finding unsteady flow rates. An experimental study has been carried out on periodically changing hydraulic oil flows through an orifice. The results support the validity of the traditional standpoint that characteristics of an unsteady orifice flow can be approximately represented by those of a steady-state one. When inspected in detail, however, a net pressure loss across an orifice in a periodical flow is delayed against a change of the flow rate. The resulting relation between the pressure loss and the flow rate describes a loop with a counter-clockwise hysteresis and a nonlinear twist along the steady-state one. Pressure recovery in a pulsating orifice flow varies with the flow rate almost along the steady-state relation, which is confirmed when the change is not fast.

On One Class of Boundary Value Problems of the Steady-State Filtration Theory in Porous Grounds

2014 ◽  
Vol 1020 ◽  
pp. 367-372
Author(s):  
Suren M. Mkhitaryan ◽  
H.V. Tokmajyan
Keyword(s):  
Steady State ◽  
Boundary Value Problems ◽  
Boundary Value ◽  
Filtration Theory ◽  
Steady State Flow ◽  
Fluid Filtration ◽  
Flow Rates ◽  
Piecewise Constant ◽  
Coefficient Of Filtration ◽  
The Ideal

:In the framework of Darcy's law of filtration the investigation results of one class of boundary value problems of the steady-state filtration theory in porous ground base are presented. The plane mixed bounadry value problems on the structural analysis of hydrotechnical con­struction of dam type on filtrating ground base in the form of a layer of finite or infinite thickness are considered. The coefficient of filtration is assumed to be constant, piecewise constant, or changing by the depth of base according to the exponential law, the property of anisotropy of filtration is also taken into account. Axis-symmetric and three-dimentional boundary value problems of the theory of steady-state fluid filtration in a three-dimentional layer of a finite or infinite thickness are discussed. These problems are of the type of Lamb well-known hydrodynamic problems in the theory of steady-state flow of the ideal fluid, when through the circular or rectangular openeing of a rigid screen on the upper bound of the layer the liquid with a definite vertical velocity or with a definite pressure is injected into porous ground base. Here, the fields of velocities and pressures in the layer, as well as flow rates of liquid through the certain sections of the ground base are determined.

scholarly journals Comparison of Aerodynamic Characteristics of NACA 0012 and NACA 2412 Airfoil

2021 ◽  
Vol 9 (VII) ◽  
pp. 2037-2045
Author(s):  
S. M Mehady Hasan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Steady State ◽  
Experimental Methods ◽  
Aerodynamic Characteristics ◽  
Steady State Flow ◽  
Pressure Contour ◽  
Computational Fluid Dynamics Cfd ◽  
Velocity Contour ◽  
Naca 0012

A comparison between NACA 0012 and NACA 2412 has been made by comparing the lift co- efficient, drag co-efficient, pressure contour and velocity contour at various angles of attack. The process has been done taking steady state flow around NACA-0012 and NACA-2412 airfoil using 1m chord length and a velocity of 88.65m/s. The main aim is to understand the aerodynamic characteristics of both the airfoils at different angles of attack and draw a conclusion on which performs better under the same conditions. Modelling and numerical analysis has been carried out by using commercially available CFD software, which is a convenient method of analysis since computational methods are more preferred to experimental methods due to low expenses involved. The numerical results demonstrated are compatible with those of the theory. This confirms the validity of using Computational Fluid Dynamics (CFD) as a reliable alternative to experimental procedures.

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