Performance Characteristics of Regenerative Flow Compressors for Natural Gas Compression Application

2005 ◽  
Vol 127 (1) ◽  
pp. 7-14 ◽  
Author(s):  
Mukarrum Raheel ◽  
Abraham Engeda
Keyword(s):  
Mathematical Model ◽  
Natural Gas ◽  
Three Dimensional ◽  
Governing Equations ◽  
One Dimensional ◽  
Gas Compression ◽  
And Performance ◽  
Regenerative Flow ◽  
Performance Results ◽  
Channel Region

In this paper we discuss the application of regenerative flow compressors (RFC) for low-pressure natural gas compression required by microturbine systems. A brief overview of fundamentals and the hypothesis of the operation of RFC is presented. A mathematical model to describe the complex three-dimensional corkscrew flow pattern in RFC is discussed. Governing equations for the blade and channel region are developed. A one-dimensional (1-D) performance prediction code for RFC based on governing equations and loss models is developed and performance results are compared with experimental data on a multistage RFC. Excellent agreement between theoretical and experimental results is observed, thus validating the proposed mathematical model.

scholarly journals Introducing a particular mathematical model for predicting the resistance and performance of prismatic planing hulls in calm water by means of total pressure distribution

2015 ◽  
Vol 12 (2) ◽  
pp. 73-94 ◽  
Author(s):  
P. Ghadimi ◽  
S. Tavakoli ◽  
M. A. Feizi Chekab ◽  
A. Dashtimanesh
Keyword(s):  
Mathematical Model ◽  
Pressure Distribution ◽  
Total Pressure ◽  
Center Of Gravity ◽  
Governing Equations ◽  
Calm Water ◽  
Hydrodynamic Study ◽  
Pass Through ◽  
And Performance

Mathematical modeling of planing hulls and determination of their characteristics are the most important subjects in hydrodynamic study of planing vessels. In this paper, a new mathematical model has been developed based on pressure distribution. This model has been provided for two different situations: (1) for a situation in which all forces pass through the center of gravity and (2) for a situation in which forces don not necessarily pass through the center of gravity. Two algorithms have been designed for the governing equations. Computational results have been presented in the form of trim angle, total pressure, hydrodynamic and hydrostatic lift coefficients, spray apex and total resistance which includes frictional, spray and induced resistances. Accuracy of the model has been verified by comparing the numerical findings against the results of Savitsky's method and available experimental data. Good accuracy is displayed. Furthermore, effects of deadrise angle on trim angle of the craft, position of spray apex and resistance have been investigated.

Nonlinear waves in compacting media

1986 ◽  
Vol 164 ◽  
pp. 429-448 ◽  
Author(s):  
Victor Barcilon ◽  
Frank M. Richter
Keyword(s):  
Mathematical Model ◽  
Solitary Waves ◽  
Nonlinear Waves ◽  
Nonlinear Interaction ◽  
Phase Speed ◽  
Governing Equations ◽  
One Dimensional ◽  
The Earth ◽  
Permanent Shape ◽  
The Mathematical Model

An investigation of the mathematical model of a compacting medium proposed by McKenzie (1984) for the purpose of understanding the migration and segregation of melts in the Earth is presented. The numerical observation that the governing equations admit solutions in the form of nonlinear one-dimensional waves of permanent shape is confirmed analytically. The properties of these solitary waves are presented, namely phase speed as a function of melt content, nonlinear interaction and conservation quantities. The information at hand suggests that these waves are not solitons.

Time-Split Inflow Boundary Treatment

1985 ◽  
Author(s):  
Siu Shing Tong
Keyword(s):  
Three Dimensional ◽  
Internal Flow ◽  
Leading Edge ◽  
Two Dimensional ◽  
Governing Equations ◽  
Internal Flows ◽  
One Dimensional ◽  
Boundary Treatment

This paper describes a new non-reflective inflow treatment for viscous and inviscid internal flow calculations. The method approximates the multi-dimensional governing equations at the inflow boundary in a series of one-dimensional split equations. This treatment allows the artificial inflow boundary to be brought in just in front of the leading edge, while allowing upstream running waves to penetrate without significant reflection. Calculation examples of two dimensional inviscid internal flows are presented. Extension of the method to three-dimensional problems is also discussed.

scholarly journals A tool for multi-scale modelling of the renal nephron

2011 ◽  
Vol 1 (3) ◽  
pp. 417-425 ◽  
Author(s):  
David P. Nickerson ◽  
Jonna R. Terkildsen ◽  
Kirk L. Hamilton ◽  
Peter J. Hunter
Keyword(s):  
Mathematical Model ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Scale Model ◽  
Model Description ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
One Dimensional ◽  
Multi Scale ◽  
The Mathematical Model

We present the development of a tool, which provides users with the ability to visualize and interact with a comprehensive description of a multi-scale model of the renal nephron. A one-dimensional anatomical model of the nephron has been created and is used for visualization and modelling of tubule transport in various nephron anatomical segments. Mathematical models of nephron segments are embedded in the one-dimensional model. At the cellular level, these segment models use models encoded in CellML to describe cellular and subcellular transport kinetics. A web-based presentation environment has been developed that allows the user to visualize and navigate through the multi-scale nephron model, including simulation results, at the different spatial scales encompassed by the model description. The Zinc extension to Firefox is used to provide an interactive three-dimensional view of the tubule model and the native Firefox rendering of scalable vector graphics is used to present schematic diagrams for cellular and subcellular scale models. The model viewer is embedded in a web page that dynamically presents content based on user input. For example, when viewing the whole nephron model, the user might be presented with information on the various embedded segment models as they select them in the three-dimensional model view. Alternatively, the user chooses to focus the model viewer on a cellular model located in a particular nephron segment in order to view the various membrane transport proteins. Selecting a specific protein may then present the user with a description of the mathematical model governing the behaviour of that protein—including the mathematical model itself and various simulation experiments used to validate the model against the literature.

scholarly journals Study of Unsteady Airflow in Muffler and Air Box Equivalent Geometries

2013 ◽  
Author(s):  
Nicolas-Ivan Hatat ◽  
François Lormier ◽  
David Chalet ◽  
Pascal Chesse
Keyword(s):  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Internal Combustion ◽  
Physical Models ◽  
One Dimensional ◽  
1D Modeling ◽  
Air Intake ◽  
And Performance

The Internal Combustion Engines (ICE) are inherently sources of the flow’s unsteadiness in the intake and exhaust ducts. Unsteady flow has a direct impact on the engine’s behavior and performance by influencing the filling and emptying of the cylinder. Air intake boxes as well as muffler geometries, which are very commonly used on the two-wheeled vehicles, have an impact on pressure levels and so, on air filling and performances levels. Thus, the purpose of this paper is to identify and analyze different typical geometries of these elements (air box and muffler) by comparing the test bench results with those obtained by 3D and 1D calculations. In this way, it is possible to establish a methodology for modeling the air box and muffler based on experimental tests and the development of 3D and then 1D model. In a beginning, studies consist in describing the geometry of the air box and muffler using a combination of tubes and simple volumes. During one-dimensional simulations, the gases properties in a volume must be calculated taking into account a method of filling and emptying. Under transient conditions, the pipe element is considered essentially as one-dimensional. The gas dynamic is described by a system of equations: the equations of continuity, momentum and energy. In the three-dimensional case, all tubes and volumes are meshed and solved using various physical models, equations and hypotheses that will be detailed subsequently. The study is performed on a shock tube bench. One of the main points is that this type of experimental test allows to test easily different pressure ratios, different geometries and to measure direct and inverse flow. In this way, the propagation of a shock wave is studied in our different geometries and is compared to the pressure signals obtained with 1D and 3D simulations. Once the 1D modeling is obtained, it must be validated in order to be applied in a simulation for Internal Combustion Engine. Validation will be done by direct comparison of results at each stage to ensure that the models and assumptions used in the calculations are correct.

A Mathematical Model for Optimizing the Structure of a Flat Micro Heat Pipe with Fiber Wick

2011 ◽  
Vol 187 ◽  
pp. 261-265
Author(s):  
Tian Han ◽  
Xiao Wei Liu ◽  
Rui Zhang ◽  
Chao Wang
Keyword(s):  
Mathematical Model ◽  
Contact Angle ◽  
Heat Pipe ◽  
Control Volume ◽  
Three Dimensional ◽  
Heat Conducting ◽  
Governing Equations ◽  
Micro Heat Pipe ◽  
Changing Rate

A three-dimensional mathematical model is developed for a kind of micro heat pipe with fiber wick. The effects of phase changing, the contact angle, gravity, and heat conducting between the fibers are accounted in the model. The governing equations are formulated in the control volume and calculated by iteration. The calculated results of the model present the velocity of the working material and the phase changing rate of the liquid. The structure of the micro heat pipe is optimized by the calculated results of the model and the two levels of fibers are enough for this kind of flat micro heat pipe.

scholarly journals A three dimensional localiser for autonomous robot vehicles

Robotica ◽  
1995 ◽  
Vol 13 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Lindsay Kleeman
Keyword(s):  
Kalman Filter ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Autonomous Robot ◽  
Minimum Number ◽  
Position And Orientation ◽  
Filter Approach ◽  
And Performance ◽  
Performance Results ◽  
Orientation Determination

SummaryA novel design of a three dimensional localiser intended for autonomous robot vehicles is presented. A prototype is implemented in air using ultrasonic beacons at known positions, and can be adapted to underwater environments where it has important applications, such as deep sea maintenance, data collection and reconnaissance tasks. The paper presents the hardware design, algorithms for position and orientation determination (six degrees of freedom), and performance results of a laboratory prototype. Two approaches are discussed for position and orientation determination – (i) fast single measurement set techniques and (ii) computationally slower Kalman filter based techniques. The Kalman filter approach allows the incorporation of robot motion information, more accurate beacon modelling and the capability of processing data from more than four beacons, the minimum number required for localisation.

The performance characteristics of single-stage and multistage regenerative flow compressors for natural gas compression application

2003 ◽  
Vol 217 (11) ◽  
pp. 1221-1239 ◽  
Author(s):  
M Raheel ◽  
A Engeda ◽  
D Hamrin ◽  
G Rouse
Keyword(s):  
Experimental Data ◽  
Natural Gas ◽  
Test Data ◽  
Single Stage ◽  
Performance Characteristics ◽  
Performance Parameters ◽  
Working Fluids ◽  
Gas Compression ◽  
Wide Range ◽  
Regenerative Flow

The compact size, high reliability and low maintenance required by regenerative flow compressors (RFCs) have made them very useful for low-pressure (0.2–15 lb/in2 gauge) natural gas compression required by microturbine systems. Very limited test data are available in the literature on gases as working fluids in regenerative turbomachines, resulting in a scarcity of design information. Most of the testing conducted in the past was on single-stage RFCs and no evidence of experimental data on multistage RFCs is available in the literature. This paper presents a large amount of single-stage test data along with an investigation for the first time of performance characteristics of a four-stage RFC. Testing is carried out over a wide range of speeds using natural gas and air as working fluids. Experimental data are presented in terms of various non-dimensional performance parameters. Several correlations are developed between these non-dimensional performance parameters and RFC geometry. Single-stage test data are used to study the effect of blade geometry, channel geometry, channel area ratio and pitch-cord ratio on performance. A few important sources of losses in RFCs are identified. Moreover, through the presented non-dimensional test data and available test data in the literature, a generalized design procedure is proposed, which can be very useful for designers and engineers working in regenerative turbomachinery.

scholarly journals On Maxwell Electrodynamics in Multi-Dimensional Spaces

Universe ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 20
Author(s):  
Alexei M. Frolov
Keyword(s):  
Electromagnetic Field ◽  
Maxwell Equations ◽  
Three Dimensional ◽  
Governing Equations ◽  
Tensor Form ◽  
Action Function ◽  
One Dimensional ◽  
Least Action ◽  
Maxwell Electrodynamics ◽  
Principle Of Least Action

The governing equations of Maxwell electrodynamics in multi-dimensional spaces are derived from the variational principle of least action, which is applied to the action function of the electromagnetic field. The Hamiltonian approach for the electromagnetic field in multi-dimensional pseudo-Euclidean (flat) spaces has also been developed and investigated. Based on the two arising first-class constraints, we have generalized to multi-dimensional spaces a number of different gauges known for the three-dimensional electromagnetic field. For multi-dimensional spaces of non-zero curvature the governing equations for the multi-dimensional electromagnetic field are written in a manifestly covariant form. Multi-dimensional Einstein’s equations of metric gravity in the presence of an electromagnetic field have been re-written in the true tensor form. Methods of scalar electrodynamics are applied to analyze Maxwell equations in the two and one-dimensional spaces.

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