Modeling of a gas slug rising in a cylindrical duct and possible applications to volcanic scenarios

2021 ◽  
Vol 31 (4) ◽  
pp. 917-937
Author(s):  
Angiolo Farina ◽  
Jacopo Matrone ◽  
Chiara P. Montagna ◽  
Fabio Rosso
Keyword(s):  
Cylindrical Duct

scholarly journals ON EFFICIENCY OF SOME METHODS FOR DETERMINING THE AZIMUTHAL STRUCTURE OF NOISE IN CYLINDRICAL DUCT

Akustika ◽  
2019 ◽  
Vol 32 ◽  
pp. 130-134
Author(s):  
Vadim Palchikovskiy ◽  
Yuliy Bersenev ◽  
Ivan Korin
Keyword(s):  
Least Squares ◽  
Dynamic Range ◽  
Least Squares Method ◽  
Microphone Array ◽  
Aircraft Engine ◽  
Circular Array ◽  
Noise Measurements ◽  
Air Intake ◽  
Experimental Values ◽  
Cylindrical Duct

The determination of azimuthal sound modes propagating in a cylindrical duct is considered based on the results of noise measurements on experimental setup with a duct diameter of 1.8 m, which corresponds to the air intake of aircraft engine. The experiments were carried out in PNRPU anechoic chamber. Spinning modes were generated by a circular array of 40 acoustic drivers. Noise in duct was recorded with circular array of 100 microphones with optimized arrangement to reach maximum dynamic range. The following methods for determining the azimuthal structure of noise were compared: modal decomposition method, cross-correlation with a reference channel method; least-squares method. The mathematical foundations and specifics of these methods are briefly outlined. According to the results of the azimuthal structure extraction, it was found that the least-squares method provides the best agreement between the generated and extracted modes and the distribution of the computed and experimental values of acoustic pressures on microphone array.

scholarly journals Heavy Oil Laminar Flow in Corrugated Ducts: A Numerical Study Using the Galerkin-Based Integral Method

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1363
Author(s):  
Valdecir Alves dos Santos Júnior ◽  
Severino Rodrigues de Farias Neto ◽  
Antonio Gilson Barbosa de Lima ◽  
Igor Fernandes Gomes ◽  
Israel Buriti Galvão ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Reynolds Number ◽  
Laminar Flow ◽  
Heavy Oil ◽  
Integral Method ◽  
Numerical Study ◽  
Temperature Dependent ◽  
Flow Through ◽  
Fanning Friction Factor ◽  
Cylindrical Duct

Fluid flow in pipes plays an important role in different areas of academia and industry. Due to the importance of this kind of flow, several studies have involved circular cylindrical pipes. This paper aims to study fully developed internal laminar flow through a corrugated cylindrical duct, using the Galerkin-based integral method. As an application, we present a study using heavy oil with a relative density of 0.9648 (14.6 °API) and temperature-dependent viscosities ranging from 1715 to 13000 cP. Results for different fluid dynamics parameters, such as the Fanning friction factor, Reynolds number, shear stress, and pressure gradient, are presented and analyzed based on the corrugation number established for each section and aspect ratio of the pipe.

Behavior of a Drone in a Cylindrical Duct

2019 ◽  
Vol 2019.25 (0) ◽  
pp. 18B12
Author(s):  
Masayoshi OGAWA ◽  
Wakana TSURU ◽  
Kazuhiko YOKOTA
Keyword(s):  
Cylindrical Duct

Sound radiation from a cylindrical duct. Part 1. Ray structure of the duct modes and of the external field

1994 ◽  
Vol 281 ◽  
pp. 293-311 ◽  
Author(s):  
C. J. Chapman
Keyword(s):  
Piecewise Linear ◽  
Azimuthal Angle ◽  
Polar Angle ◽  
Directivity Pattern ◽  
Acoustic Mode ◽  
Inhomogeneous Waves ◽  
Alternative Description ◽  
Geometrical Theory Of Diffraction ◽  
Pass Through ◽  
Cylindrical Duct

This paper determines the ray structure of a spinning acoustic mode propagating inside a semi-infinite circular cylindrical duct, and thereby determines the ray structure of the field radiated from the end of the duct. Inside the duct, but outside of a caustic cylindrical surface, the rays are piecewise linear helices; on striking the rim of the end-face of the duct, these rays produce ‘Keller cones’ of diffracted rays. The cones determine the structure of the radiated field: for example, no rays penetrate two cone-shaped far-field quiet zones centred on the duct axis; two rays pass through each point in a forward loud zone; and one ray passes through each point in a rearward loud zone. The two rays through each point in the forward loud zone interfere to produce an oscillatory directivity pattern. One quarter of the rays on each cone point back inside the duct and produce the reflected field. Thus the rim of the end-face of the duct acts as a ‘ring source’, in which the radiated and reflected fields have their origin. Every propagating duct mode determines a polar angle and an azimuthal angle; these are taken as parameters specifying the mode and are used to calculate the positions and angles of all the rays. The mathematical method on which the paper is based is Debye's approximation for the Bessel function which appears in the expression for the duct modes; the approximation shows also that the duct contains a region of smooth helical rays on which the field consists of inhomogeneous waves: this region is the inner cylinder, lying inside the annulus of piecewise linear helical rays. The results of the paper are very promising for the application of Keller's geometrical theory of diffraction to detailed calculations of the sound radiated from aeroengine ducts. An alternative description of the field, using Cargill's meridional rays, is summarized.

Generation of a single cylindrical duct mode using a mode synthesiser

2016 ◽  
Vol 114 ◽  
pp. 56-70 ◽  
Author(s):  
Anna Snakowska ◽  
Łukasz Gorazd ◽  
Jerzy Jurkiewicz ◽  
Karolina Kolber
Keyword(s):  
Cylindrical Duct

Shear driven two-phase flows in vertical cylindrical duct

2012 ◽  
Vol 39 ◽  
pp. 205-215 ◽  
Author(s):  
Yuri Gaponenko ◽  
Aliaksandr Mialdun ◽  
Valentina Shevtsova
Keyword(s):  
Two Phase Flows ◽  
Two Phase ◽  
Cylindrical Duct

Second-Law Analysis of Heat Transfer in Swirling Flow Through a Cylindrical Duct

1987 ◽  
Vol 109 (2) ◽  
pp. 308-313 ◽  
Author(s):  
P. Mukherjee ◽  
G. Biswas ◽  
P. K. Nag
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Swirling Flow ◽  
Tangential Velocity ◽  
Merit Function ◽  
Second Law ◽  
Constant Wall Temperature ◽  
Boundary Layer Equations ◽  
Second Law Analysis ◽  
Cylindrical Duct

A second-law analysis is made on a swirling flow in a cylindrical duct with constant wall temperature. A purely tangential entry of the fluid is considered and a simplified model, consisting of a central air core enclosed by a potential, free vortex region and a boundary layer, is assumed. The approximate hydrodynamic boundary layer equations, and the continuity equation, are set up and solved numerically for the velocity gradients in the boundary layer. Similarly, the temperature gradients within the thermal boundary layer are obtained from the energy equation. The local Nusselt number and rate of entropy generation are calculated and used to evaluate the rate of heat transfer and loss of available energy, respectively. A merit function, defined as the ratio of exergy transferred to the sum of exergy transferred and exergy destroyed, is evaluated for various values of Reynolds number, based on the inlet tangential velocity, and conclusions are drawn about the influence of inlet swirl on irreversibility.

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