Analysis of Venturi Performance for Gas-Particle Flows

1990 ◽  
Vol 112 (1) ◽  
pp. 121-127 ◽  
Author(s):  
F. D. Shaffer ◽  
R. A. Bajura
Keyword(s):  
Single Phase ◽  
Stokes Number ◽  
Differential Pressure ◽  
Mass Loading ◽  
Flow Data ◽  
Basic Principles ◽  
Pressure Flow ◽  
Experimental Calibration ◽  
Particle Flows ◽  
Improve Correlation

In recent years, use of the venturi for measurement of gas-particle flows has received considerable attention. The technology for the venturi as a single-phase flowmeter has matured to the point that application is routine. Much more research, however, is required to establish the venturi as an acceptable gas-particle flowmeter. The first part of this paper consists of a discussion of the basic principles of venturi pressure-flow performance for gas-particle flows. This is followed by a description of the experimental calibration of a venturi for measurement of gas-particle flows with particle-to-gas mass-loading ratios up to 35. Next, a modified Stokes number is presented and shown to improve correlation of venturi pressure-flow data. Finally, the predictions of a model presented by Doss are compared with the pressure-flow data of the venturi calibration performed in this work. The Doss model provides good predictions of venturi differential pressures for particle-to-gas mass-loading ratios less than ten but tends to overpredict the differential pressure, by as much as 45 percent, for particle-to-gas mass-loading ratios above 10.

Pressure-Flow Measurements for Selected Oral and Nasal Sound Segments Produced by Normal Adults

1992 ◽  
Vol 29 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Meri L. Andreassen ◽  
Bonnie E. Smith ◽  
Thomas W. Guyette
Keyword(s):  
Limited Information ◽  
Flow Data ◽  
Female Adult ◽  
Flow Measurements ◽  
Pressure Flow ◽  
Orifice Area ◽  
Normative Pressure ◽  
Categorization Scheme ◽  
Velopharyngeal Function ◽  
Normal Adults

Pressure-flow data are often used to provide information about the adequacy of velopharyngeal valving for speech. However, there is limited information available concerning simultaneous pressure-flow measurements for oral and nasal sound segments produced by normal speakers. This study provides normative pressure, flow, and velopharyngeal orifice area measurements for selected oral and nasal sound segments produced by 10 male and 10 female adult speakers. An aerodynamic categorization scheme of velopharyngeal function, including one typical category and three atypical categories (open, closed, and mixed) is proposed.

Perceptual Evaluation of Velopharyngeal Competency

1980 ◽  
Vol 89 (5_suppl) ◽  
pp. 153-157 ◽  
Author(s):  
Betty Jane Philips
Keyword(s):  
Public School ◽  
Education And Training ◽  
Flow Data ◽  
Speech Language Pathologists ◽  
Pressure Flow ◽  
Perceptual Evaluation ◽  
Speech Characteristics ◽  
Velopharyngeal Incompetence ◽  
And Training

Eight public school speech/language pathologists estimated velopharyngeal competence on the basis of perceptual evaluation of speech characteristics of 24 subjects. These evaluations were made from tape-recorded speech samples. After orientation to a system for scoring speech characteristics associated with velopharyngeal incompetence they reevaluated the same 24 subjects. The evaluations were found to improve significantly with orientation and to correlate well with experts' live evaluations as well as evaluations based on instrumentation which included telefluorography, manometric and pressure-flow data. It was concluded that speech/language pathologists, who by nature of their education and training have expertise in identification of speech deviations, can apply their skills effectively in identifying velopharyngeal incompetence. Further it was suggested that orientation to a system for weighing speech characteristics related to velopharyngeal competency can improve their estimates.

scholarly journals On the transition between turbulence regimes in particle-laden channel flows

2018 ◽  
Vol 845 ◽  
pp. 499-519 ◽  
Author(s):  
Jesse Capecelatro ◽  
Olivier Desjardins ◽  
Rodney O. Fox
Keyword(s):  
Reynolds Number ◽  
Fluid Phase ◽  
Stokes Number ◽  
Channel Flows ◽  
High Mass ◽  
Inertial Particles ◽  
Mass Loading ◽  
Two Phase ◽  
Phase Dynamics ◽  
Wide Range

Turbulent wall-bounded flows exhibit a wide range of regimes with significant interaction between scales. The fluid dynamics associated with single-phase channel flows is predominantly characterized by the Reynolds number. Meanwhile, vastly different behaviour exists in particle-laden channel flows, even at a fixed Reynolds number. Vertical turbulent channel flows seeded with a low concentration of inertial particles are known to exhibit segregation in the particle distribution without significant modification to the underlying turbulent kinetic energy (TKE). At moderate (but still low) concentrations, enhancement or attenuation of fluid-phase TKE results from increased dissipation and wakes past individual particles. Recent studies have shown that denser suspensions significantly alter the two-phase dynamics, where the majority of TKE is generated by interphase coupling (i.e.  drag) between the carrier gas and clusters of particles that fall near the channel wall. In the present study, a series of simulations of vertical particle-laden channel flows with increasing mass loading is conducted to analyse the transition from the dilute limit where classical mean-shear production is primarily responsible for generating fluid-phase TKE to high-mass-loading suspensions dominated by drag production. Eulerian–Lagrangian simulations are performed for a wide range of particle loadings at two values of the Stokes number, and the corresponding two-phase energy balances are reported to identify the mechanisms responsible for the observed transition.

Development of Design Support System for Piping Route and Differential Pressure Flowmeter by Three-Dimensional Fluid Analysis

2020 ◽  
Author(s):  
Takatsugu Miura ◽  
Kingo Igarashi ◽  
Tomoyuki Hosaka ◽  
Takumi Kitagawa ◽  
Tatsurou Yashiki ◽  
...  
Keyword(s):  
Conventional Method ◽  
Flow Rate ◽  
Flow Measurement ◽  
Lower Cost ◽  
Differential Pressure ◽  
Pipe Axis ◽  
Pressure Flow ◽  
Fluid Analysis ◽  
Analysis System ◽  
Analysis Models

Abstract In power plants that becoming more compact, it will expend much time and effort to satisfy the requirement for the differential pressure flow measurement according to ISO’s standards. Therefore, it is difficult for engineers in the design phase to completely remove the potential for large errors in flow measurement. This paper presents the 3D fluid analysis system that is a lower cost than the conventional method to confirm the soundness of such measurement in the phase of piping route design. This system has the function to automatically generate the analysis models from general 3D piping CAD data. The analysis program is written by the open source code to reduce a license fee. Also, this system has the function of calculating the swirl strength along the pipe axis as one of the means for efficiently supporting the design change. In order to verify and validate the analysis system, we analyzed several flow paths, confirmed the response of the swirl strength and flow rate indication value of the differential pressure flowmeter model. The analysis result well simulated the increase or decrease swirl strength in the complex flow path, and fluctuation of the flow rate indication value. Also, the system supports to set the flowmeter in the appropriate position by providing visualization of the swirl strength along the pipe axis. In the flow path analysis in this validation, it took about one month to visualization of the swirl strength along the pipe axis from the generation of the analysis models. The 3D fluid analysis system collaborative with 3D piping CAD design system has been developed. This system enable to confirm the effects of swirl strength on flow measurement and the soundness of the differential pressure flow measurement at a lower cost in comparison with conventional method.

The rapid distortion of two-way coupled particle-laden turbulence

2019 ◽  
Vol 877 ◽  
pp. 82-104 ◽  
Author(s):  
M. Houssem Kasbaoui ◽  
Donald L. Koch ◽  
Olivier Desjardins
Keyword(s):  
Single Phase ◽  
Density Fluctuations ◽  
Gravitational Potential Energy ◽  
Inertial Particles ◽  
Mass Loading ◽  
Number Density ◽  
Turbulence Statistics ◽  
Preferential Sampling ◽  
Gravitational Loading ◽  
Two Phases

In this study, we address the modification of sheared turbulence by dispersed inertial particles. The preferential sampling of the straining regions of the flow by inertial particles in turbulence leads to an inhomogeneous distribution of particles. The strong gravitational loading exerted by the highly concentrated regions results in anisotropic alteration of turbulence at small scales in the direction of gravity. These effects are investigated in a rapid distortion theory (RDT) extended for two-way coupled particle-laden flows. To make the analysis tractable, we assume that particles have small but non-zero inertia. In the classical results for single-phase flows, the RDT assumption of fast shearing compared to the turbulence time scales leads to the distortion and shear-induced production of turbulence. In particle-laden turbulence, the coupling between the two phases under rapid shearing induces number density fluctuations that convert gravitational potential energy to turbulent kinetic energy and modulate the turbulence spectrum in a manner that increases with mass loading. Turbulence statistics obtained from RDT are compared with Euler–Lagrange simulations of homogeneously sheared particle-laden turbulence.

A Comparison of Single and Multiphase Jets in a Crossflow Using Large Eddy Simulations

2005 ◽  
Vol 129 (1) ◽  
pp. 61-68 ◽  
Author(s):  
Mirko Salewski ◽  
Dragan Stankovic ◽  
Laszlo Fuchs
Keyword(s):  
Single Phase ◽  
Stokes Number ◽  
Large Eddy Simulations ◽  
Droplet Breakup ◽  
Frequency Spectra ◽  
Flow Solver ◽  
Large Eddy ◽  
Horseshoe Vortices ◽  
Fuel Mass Fraction ◽  
Breakup Model

Large eddy simulations (LES) are performed for single and multiphase jets in crossflow (JICF). The multiphase JICF are compared to the single-phase case for the same momentum and mass flow ratios but with droplets of different sizes. Multiphase JICF have stronger counterrotating vortex pairs (CVPs) than a corresponding single-phase JICF. Moreover, their trajectories are higher and their induced wakes weaker. The smaller the Stokes number of the droplets, the more the solution approaches the solution for single-phase flow. The computed results show the formation of a CVP and horseshoe vortices, which are convected downstream. LES also reveals the intermittent formation of upright wake vortices from the horseshoe vortices on the ground toward the CVP. The dispersion of polydisperse spray droplets is computed using the stochastic parcel method. Atomization and droplet breakup are modeled by a combination of the breakup model by Reitz and the Taylor analogy breakup model (see Caraeni, D., Bergström, C., and Fuchs, L., 2000, Flow, Turbul. Combust., 65(2), pp. 223–244). Evaporation and droplet collision are also modeled. The flow solver uses two-way coupling. Averages of the velocity and gaseous fuel mass fraction are computed. The single-phase JICF is validated against experimental data obtained by PIV. Additionally, the PDFs and frequency spectra are presented.

A Turbulent Model for Gas-Particle Jets

2000 ◽  
Vol 122 (3) ◽  
pp. 505-509 ◽  
Author(s):  
J. Garcı´a ◽  
A. Crespo
Keyword(s):  
Mixing Layer ◽  
Stokes Number ◽  
Particle Dispersion ◽  
Lagrangian Model ◽  
Grid Turbulence ◽  
Mean Velocity ◽  
Dissipation Term ◽  
Particle Flows ◽  
Integral Scales ◽  
Kolmogorov Constant

This work is concerned with turbulent diffusion in gas-particle flows. The cases studied correspond to dilute flows and small Stokes number, this implies that the mean velocity of the particles is very similar to that of the fluid element. The classical k-ε method is used to model the gas-phase, modified with additional terms for the k and ε equations, that takes into account the effect of particles on the carrier phase. The additional dissipation term included in the equation for k is due to the slip between phases at an intermediate scale, far from both the Kolmogorov and the integral scales. This term has a proportionality constant equal to 3/2 of Kolmogorov constant, C0. In this paper, a value of 3.0 has been used for this constant as suggested by Du et al., 1995, “Estimation of the Kolmogorov Constant C0 for the Langarian Structure Using a Second-Order Lagrangian Model of Grid Turbulence,” Phys. Fluids 7, (12), pp. 3083–3090. The additional source term for the ε equation is taken as proportional to ε/k, as is usually done. In all experiments analyzed the particles increased the dissipation of turbulent kinetic energy. A comparison is made between the results obtained with the model proposed in this work and the experiments of Shuen et al., 1985, “Structure of Particle-Laden Jets: Measurements and Predictions,” AIAA Journal, 23, No. 3, and Hishida et al., 1992, “Experiments on Particle Dispersion in a Turbulent Mixing Layer,” ASME Journal of Fluids Engineering, 119, pp. 181–194. [S0098-2202(00)02103-9]

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