scholarly journals Study of Unsteady Flow in a Heat Exchanger by the Method of Characteristics

1992 ◽  
Vol 114 (4) ◽  
pp. 459-463 ◽  
Author(s):  
Yuan Mao Huang
Keyword(s):  
Heat Exchanger ◽  
Unsteady Flow ◽  
Transfer Rate ◽  
Method Of Characteristics ◽  
Governing Equations ◽  
One Dimensional ◽  
The Method Of Characteristics ◽  
Improvement Factor ◽  
The One ◽  
Good Agreement

The one-dimensional, unsteady flow in an air-to-air heat exchanger is studied. The governing equations are derived and the method of characteristics with the uniform interval scheme is used in the analysis. The effect of the fin improvement factor on the air temperature in the heat exchanger and the heat transfer rate of the heat exchanger, and air properties in the heat exchanger are analyzed. The numerical results are compared and show good agreement with the available data.

The interaction of a fibre tangle with an airflow

1967 ◽  
Vol 27 (3) ◽  
pp. 561-580 ◽  
Author(s):  
Paul A. Taub
Keyword(s):  
Unsteady Flow ◽  
Numerical Solution ◽  
Analytical Model ◽  
Method Of Characteristics ◽  
Solution Procedure ◽  
Governing Equations ◽  
Stress Strain ◽  
One Dimensional ◽  
The Method Of Characteristics ◽  
Flow Configurations

An analytical model of the interaction of a fibre tangle with an airflow is proposed. This model replaces the discrete fibres by a continuum medium with a non-linear stress-strain law. The governing equations have been examined for one-dimensional unsteady flow configurations and have been found to possess five characteristic directions.A numerical-solution procedure, based upon the method of characteristics, has been outlined and applied to the flow within a dilation chamber. A fibre sample is located at the centre of the chamber, which is alternately pressurized and depressurized.

scholarly journals Solutions of problems for the wave equation with conditions on the characteristics

2021 ◽  
Vol 57 (2) ◽  
pp. 148-155
Author(s):  
V. I. Korzyuk ◽  
O. A. Kovnatskaya
Keyword(s):  
Wave Equation ◽  
Analytical Solution ◽  
Classical Solution ◽  
Method Of Characteristics ◽  
Matching Conditions ◽  
One Dimensional ◽  
The Method Of Characteristics ◽  
The One ◽  
The Given ◽  
Dimensional Wave

In this paper we obtain a classical solution of the one-dimensional wave equation with conditions on the characteristics for different areas this problem is considered in. The analytical solution is constructed by the method of characteristics. In addition, the uniqueness of the obtained solution is proved. The necessity and sufficiency of the matching conditions for given functions of the problem are proved. When these conditions are satisfied and the given functions are smooth enough, the classical solution of the considered problem exists.

Study of the Fluid Flow in the Elliptical Duct by the Method of Characteristics

1993 ◽  
Vol 115 (1) ◽  
pp. 80-84 ◽  
Author(s):  
Yuan Mao Huang ◽  
C. H. Ho
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Method Of Characteristics ◽  
Numerical Results ◽  
Hyperbolic Type ◽  
Governing Equations ◽  
The Method Of Characteristics ◽  
The Finite Difference Method ◽  
The Heat Transfer Coefficient ◽  
Good Agreement

This study develops a mathematical model to determine the properties of laminar flow in the elliptical duct. With some assumptions, the nonlinear governing equations of the air in the elliptical duct are transformed into the hyperbolic type. The method of characteristics is then applied. Numerical results are obtained by using the finite difference method and the uniform interval scheme. The air properties in the elliptical duct are analyzed. The local Nusselt number and the heat transfer coefficient along the duct are studied. The numerical results are compared and show good agreement with the available data.

Liquid Rocket Engine Feed System Dynamics by the Method of Characteristics

1968 ◽  
Vol 90 (4) ◽  
pp. 561-568 ◽  
Author(s):  
J. C. Eschweiler ◽  
H. W. Wallace
Keyword(s):  
Attitude Control ◽  
Method Of Characteristics ◽  
Rocket Engine ◽  
Feed System ◽  
New Approach ◽  
One Dimensional ◽  
The Method Of Characteristics ◽  
Liquid Rocket ◽  
The One ◽  
State Relations

A new approach was developed to predict pressure and flow transients in rocket engine feed systems. The one-dimensional equations of momentum and continuity were reduced by the method of characteristics from partial derivatives to a set of total derivatives describing state properties along specified paths. System components, e.g., valves and tanks, are represented by pseudo-steady state relations at discrete junctions in the system. Experiments were run on a typical attitude control feed system employing monomethylhydrazine (MMH) and nitrogen telroxide (NTO) as the propellant combination. The essential aspects of the analytical model mere verified by the excellent correlation achieved between the predicted and observed transjents.

Effect of leakage and blockage on the acoustic behavior of particle filters

2019 ◽  
Vol 67 (6) ◽  
pp. 483-492
Author(s):  
Seonghyeon Baek ◽  
Iljae Lee
Keyword(s):  
Transfer Matrix ◽  
Particle Filters ◽  
Acoustic Analysis ◽  
Transmission Loss ◽  
One Dimensional ◽  
Filter System ◽  
The Difference ◽  
The One ◽  
Analytical Approaches ◽  
Good Agreement

The effects of leakage and blockage on the acoustic performance of particle filters have been examined by using one-dimensional acoustic analysis and experimental methods. First, the transfer matrix of a filter system connected to inlet and outlet pipes with conical sections is measured using a two-load method. Then, the transfer matrix of a particle filter only is extracted from the experiments by applying inverse matrices of the conical sections. In the analytical approaches, the one-dimensional acoustic model for the leakage between the filter and the housing is developed. The predicted transmission loss shows a good agreement with the experimental results. Compared to the baseline, the leakage between the filter and housing increases transmission loss at a certain frequency and its harmonics. In addition, the transmission loss for the system with a partially blocked filter is measured. The blockage of the filter also increases the transmission loss at higher frequencies. For the simplicity of experiments to identify the leakage and blockage, the reflection coefficients at the inlet of the filter system have been measured using two different downstream conditions: open pipe and highly absorptive terminations. The experiments show that with highly absorptive terminations, it is easier to see the difference between the baseline and the defects.

scholarly journals Post-liquefaction reconsolidation of sand

2016 ◽  
Vol 472 (2186) ◽  
pp. 20150745 ◽  
Author(s):  
O. Adamidis ◽  
G. S. P. Madabhushi
Keyword(s):  
Void Ratio ◽  
One Dimensional ◽  
Geotechnical Centrifuge ◽  
Significant Damage ◽  
Pore Water Pressures ◽  
The One ◽  
Crucial Parameter ◽  
Excess Pore ◽  
Good Agreement ◽  
Made In

Loosely packed sand that is saturated with water can liquefy during an earthquake, potentially causing significant damage. Once the shaking is over, the excess pore water pressures that developed during the earthquake gradually dissipate, while the surface of the soil settles, in a process called post-liquefaction reconsolidation. When examining reconsolidation, the soil is typically divided in liquefied and solidified parts, which are modelled separately. The aim of this paper is to show that this fragmentation is not necessary. By assuming that the hydraulic conductivity and the one-dimensional stiffness of liquefied sand have real, positive values, the equation of consolidation can be numerically solved throughout a reconsolidating layer. Predictions made in this manner show good agreement with geotechnical centrifuge experiments. It is shown that the variation of one-dimensional stiffness with effective stress and void ratio is the most crucial parameter in accurately capturing reconsolidation.

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