Development and Verification of a One-Dimensional Ablation Code Including Pyrolysis Gas Flow

2009 ◽  
Vol 23 (1) ◽  
pp. 59-71 ◽  
Author(s):  
A. J. Amar ◽  
B. F. Blackwell ◽  
J. R. Edwards
Keyword(s):  
Gas Flow ◽  
Pyrolysis Gas ◽  
One Dimensional

On the theory of electrohydrodynamically driven capillary jets

1997 ◽  
Vol 335 ◽  
pp. 165-188 ◽  
Author(s):  
ALFONSO M. GAÑÁN-CALVO
Keyword(s):  
Surface Charge ◽  
Electric Fields ◽  
Gas Flow ◽  
Wave Speed ◽  
Propagation Speed ◽  
Field Equations ◽  
Steady Regime ◽  
One Dimensional ◽  
Relaxation Effects ◽  
Capillary Jets

Electrohydrodynamically (EHD) driven capillary jets are analysed in this work in the parametrical limit of negligible charge relaxation effects, i.e. when the electric relaxation time of the liquid is small compared to the hydrodynamic times. This regime can be found in the electrospraying of liquids when Taylor's charged capillary jets are formed in a steady regime. A quasi-one-dimensional EHD model comprising temporal balance equations of mass, momentum, charge, the capillary balance across the surface, and the inner and outer electric fields equations is presented. The steady forms of the temporal equations take into account surface charge convection as well as Ohmic bulk conduction, inner and outer electric field equations, momentum and pressure balances. Other existing models are also compared. The propagation speed of surface disturbances is obtained using classical techniques. It is shown here that, in contrast with previous models, surface charge convection provokes a difference between the upstream and the downstream wave speed values, the upstream wave speed, to some extent, being delayed. Subcritical, supercritical and convectively unstable regions are then identified. The supercritical nature of the microjets emitted from Taylor's cones is highlighted, and the point where the jet switches from a stable to a convectively unstable regime (i.e. where the propagation speed of perturbations become zero) is identified. The electric current carried by those jets is an eigenvalue of the problem, almost independent of the boundary conditions downstream, in an analogous way to the gas flow in convergent–divergent nozzles exiting into very low pressure. The EHD model is applied to an experiment and the relevant physical quantities of the phenomenon are obtained. The EHD hypotheses of the model are then checked and confirmed within the limits of the one-dimensional assumptions.

Diabatic Nozzle Flow with Constant Small Stage Efficiency

1960 ◽  
Vol 64 (598) ◽  
pp. 632-635 ◽  
Author(s):  
R. A. A. Bryant
Keyword(s):  
Gas Flow ◽  
Nozzle Flow ◽  
Flow Conditions ◽  
One Dimensional ◽  
Real Flow ◽  
Stage Efficiency ◽  
Frictional Effects

The concept of small stage efficiency is introduced when studying one-dimensional gas flow in nozzles in order to permit a closer approximation of real flow conditions than is possible from an isentropic analysis. It is more or less conventional to assume the flow conditions are adiabatic whenever the small stage efficiency is used. That is to say, small stage efficiency is generally considered in relation to flows contained within adiabatic boundaries, in which case it becomes a measure of the heat generated by internal frictional effects alone.

The Mechanics and Thermodynamics of Steady One-Dimensional Gas Flow

1947 ◽  
Vol 14 (4) ◽  
pp. A317-A336 ◽  
Author(s):  
Ascher H. Shapiro ◽  
W. R. Hawthorne
Keyword(s):  
Heat Transfer ◽  
Dimensional Analysis ◽  
High Speed ◽  
Gas Flow ◽  
Gas Injection ◽  
Wall Friction ◽  
Analytical Treatment ◽  
Area Change ◽  
One Dimensional ◽  
Recent Developments

Abstract Recent developments in the fields of propulsion, flow machinery, and high-speed flight have emphasized the need for an improved understanding of the characteristics of compressible flow. A one-dimensional analysis for flow without shocks is presented which takes into account the simultaneous effects of area change, wall friction, drag of internal bodies, external heat exchange, chemical reaction, change of phase, injection of gases, and changes in molecular weight and specific heat. The method of selecting independent and dependent variables, and the organization of the working equations, leads, it is believed, to a better understanding of the influence of the foregoing effects, and also simplifies greatly the analytical treatment of particular problems. Examples are given first of several simple types of flow, including (a) area change only; (b) heat transfer only; (c) wall friction only; and (d) gas injection only. In addition, examples of flow with combined effects are given, including (a) simultaneous friction and area change; (b) simultaneous friction and heat transfer; and (c) simultaneous liquid injection and evaporation. A one-dimensional analysis for flow through a discontinuity is presented, allowing for energy, shock, drag, and gas-injection effects, and for changes in gas properties. This analysis is applicable to such processes as: (a) the adiabatic normal shock; (b) combustion; (c) moisture condensation shocks; and (d) steady explosion waves.

scholarly journals One-Dimensional Gas Flow Analysis of the Intake and Exhaust System of a Single Cylinder Diesel Engine

2020 ◽  
Vol 8 (12) ◽  
pp. 1036
Author(s):  
Kyong-Hyon Kim ◽  
Kyeong-Ju Kong
Keyword(s):  
Diesel Engine ◽  
Gas Flow ◽  
Discharge Coefficient ◽  
Flow Analysis ◽  
Exhaust System ◽  
Maximum Pressure ◽  
Exhaust Pipe ◽  
One Dimensional ◽  
Average Mass ◽  
Bent Pipe

In order to design a diesel engine system and to predict its performance, it is necessary to analyze the gas flow of the intake and exhaust system. Gas flow analysis in a three-dimensional (3D) format needs a high-resolution workstation and an enormous amount of time for analysis. Calculation using the method of characteristics (MOC), which is a gas flow analysis in a one-dimensional (1D) format, has a fast calculation time and can be analyzed with a low-resolution workstation. However, there is a problem with poor accuracy in certain areas. It was assumed that the reason was that 1D could not implement the shape. The error that occurs in the shape of the bent pipe used in the intake and exhaust ports of the diesel engine was analyzed and to find a solution to the low accuracy, the results of the experiment and 1D analysis were compared. The discharge coefficient was calculated using the average mass flow rate, and as a result of applying it, the accuracy was improved for the maximum negative pressure by 0.56–1.93% and the maximum pressure by 3.11–7.86% among the intake pipe pressure results. The difference in phase of the exhaust pipe pressure did not improve. It is considered as a limitation of 1D analysis that does not improve even by applying the discharge coefficient. In the future, we intend to implement a bent pipe that cannot be realized in 1D using a 3D format and to prepare a method to supplement the reliability by using 1D–3D coupling.

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