Development of a Two-Dimensional Streamline Curvature Code

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Ioannis Templalexis ◽  
Pericles Pilidis ◽  
Vassilios Pachidis ◽  
Petros Kotsiopoulos
Keyword(s):  
Flow Simulation ◽  
Two Dimensions ◽  
Simulation Software ◽  
Design Tool ◽  
Operating Conditions ◽  
Teaching Tool ◽  
Two Dimensional ◽  
Streamline Curvature ◽  
Cascade Models ◽  
Inlet Conditions

Two-dimensional (2D) compressor flow simulation software has always been a very valuable tool in compressor preliminary design studies, as well as in compressor performance assessment operating under uniform and non-uniform inlet conditions. This type of software can also be used as a supplementary teaching tool. In this context, a new streamline curvature (SLC) software has been developed capable of analyzing the flow inside a compressor in two dimensions. The software was developed to provide great flexibility, in the sense that it can be used as: (a) a performance prediction tool for compressors of a known design, (b) a development tool to assess the changes in performance of a known compressor after implementing small geometrical changes, (c) a design tool to verify and refine the outcome of a preliminary compressor design analysis, and (d) a teaching tool to provide the student with an insight of the 2D flow field inside a compressor and how this could be effectively predicted using the SLC method combined with various algorithms and cascade models. Apart from describing in detail the design, structure, and execution of the SLC software, this paper also stresses the importance of developing robust, well thought-out software and highlights the main areas a potential programmer should focus on in order to achieve this. This text also highlights the programming features incorporated into the development of the software in order to make it amenable for teaching purposes. The paper reviews in detail the set of cascade models incorporated for subsonic and supersonic flow, for design and off-design operating conditions. Moreover, the methods used for the prediction of surge and choke are discussed in detail. The code has been validated against experimental results, which are presented in this paper together with the strong and weak points of this first version of the software and the potential for future development. Finally, an indicative case study is presented in which the shift of streamlines and radial velocity profiles is demonstrated under the influence of two sets of compressor inlet boundary conditions.

Development of a 2-D Compressor Streamline Curvature Code

2006 ◽  
Author(s):  
Ioannis Templalexis ◽  
Pericles Pilidis ◽  
Vassilios Pachidis ◽  
Petros Kotsiopoulos
Keyword(s):  
Flow Field ◽  
Two Dimensions ◽  
Simulation Software ◽  
Operating Conditions ◽  
Two Dimensional ◽  
Streamline Curvature ◽  
Cycle Simulation ◽  
Application Procedure ◽  
Displacement Thickness ◽  
Loss Models

Two-dimensional compressor flow simulation software has always been a very valuable tool in compressor preliminary design studies, as well as in compressor performance assessment, operating under uniform and non-uniform inlet conditions. In this context, a new streamline curvature (SLC) software has been developed capable of analyzing the flow inside a compressor in two dimensions. The software was developed to provide great flexibility, in the sense that it can be used as: a) A performance prediction tool for compressors of a known design, b) A development tool to assess the changes in performance of a known compressor after implementing small geometry changes, c) A design tool to verify and refine the outcome of a preliminary compressor design analysis, d) A teaching tool to provide the student with an insight of the two-dimensional flow field inside a compressor and how this could be effectively predicted using the SLC method, combined with various algorithms and loss models, e) A 2-D compressor model that can be integrated into a conventional 0-D gas turbine engine cycle simulation code for the investigation of the influence of non-uniform radial pressure profiles on whole engine performance. Apart from describing in detail the design, structure and execution of the SLC software, this paper also stresses the importance of developing robust, well thought-out software and highlights the main areas a potential programmer should focus on in order to achieve this. This manuscript highlights briefly the programming features incorporated into the development of software before continuing to explain the internal workings of individual algorithms. The paper reviews in detail the set of equations used for the prediction of the meridional flow field. Numerical aspects of the application procedure of the full radial equilibrium equation are examined. The loss models incorporated for subsonic and supersonic flow are presented for design and off design operating conditions. Deviation angle rules are presented, together with the parameters for quantifying the diffusion process. Moreover, the methods used for the prediction of surge and choke are discussed in detail. Finally, the end wall boundary layer displacement thickness calculation is discussed briefly, in conjunction with the blockage factor computation. The code has been validated against experimental results which are presented in this paper together with the strong and weak points of this first version of the software and the potential for future development.

Prediction of Engine Performance Under Compressor Inlet Flow Distortion Using Streamline Curvature

2006 ◽  
Author(s):  
Vassilios Pachidis ◽  
Pericles Pilidis ◽  
Ioannis Templalexis ◽  
Theodosios Alexander ◽  
Petros Kotsiopoulos
Keyword(s):  
Three Dimensional ◽  
Engine Performance ◽  
Radial Pressure ◽  
Two Dimensional ◽  
Component Level ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Streamline Curvature ◽  
Inlet Flow Distortion ◽  
Inlet Conditions

Traditionally, engine performance has been simulated based on non-dimensional maps for compressors and turbines. Component characteristic maps assume by default a given state of inlet conditions which can not be easily altered in order to simulate two-dimensional or three-dimensional flow phenomena. Inlet flow distortion, for example, is usually simulated by applying empirical correction factors and modifiers to default component characteristics, alternatively, the parallel compressor theory may be applied. The accuracy of the above methods has been rather questionable since they are unable to capture in sufficient fidelity component-level, complex physical processes and analyze them in the context of the whole engine performance. The technique described in this paper integrates a zero-dimensional (non-dimensional) gas turbine modeling and performance simulation system and a two-dimensional, streamline curvature compressor software. The two-dimensional compressor software can fully define the characteristics of a compressor at several operating condition and is subsequently used in the zero-dimensional cycle analysis to provide a more accurate, physics-based estimate of compressor performance under clean and distorted inlet conditions, replacing the default compressor maps. The high-fidelity component communicates with the lower fidelity cycle via a fully automatic and iterative process for the determination of the correct operating point. This study discusses in detail the development, validation and integration of the two-dimensional, streamline curvature compressor software and presents the various loss models used in the code. It also discusses the relative changes in the performance of a two-stage, experimental compressor with different types of radial pressure distortion obtained by running the two-dimensional streamline curvature compressor software independently. Moreover, the performance of a notional engine model, utilizing the coupled, two-dimensional compressor, under distorted conditions is discussed in detail and compared against the engine performance under clean conditions.

scholarly journals COMBUSTION ANALYSIS OF HCCI ENGINE AT DIFFERENT OPERATING CONDITIONS

2021 ◽  
Author(s):  
CHANDRASEKHARYADAV Y ◽  
◽  
Dr. SREEKANTH D.V ◽  
Dr. SAURAV DAS ◽  
◽  
...  
Keyword(s):  
Working Conditions ◽  
Soot Formation ◽  
Direct Injection ◽  
Flow Simulation ◽  
Simulation Software ◽  
Operating Conditions ◽  
Phase System ◽  
Ic Engine ◽  
Cold Flow ◽  
Hcci Engine

Automobile pollution is causing a huge trouble worldwide and there is an urgent need to reduce it. Researches are being carried out for ways of reducing automobile pollution. The most common tool for converting liquid and gas fuel into useful mechanical work is the internal combustion (IC) engine. The explanation for its well-accepted efficiency, economics, longevity, controllability and other competitive alternatives can be explained by its general appearance. NOx and soot formation are due to the heterogeneous non-premixed combustion of high local temperatures and the local oxygen shortage in the traditional direct injection diesel powered engine. The adjustment to the combustion cycle to boost engine output is an alternative to rising engine efficiency and reducing engine emissions. A simulation software with CFD code was implemented in this context. The cold flow of the working conditions for HCCI engine control by creating a comprehensive model. Furthermore, the use of the in-cylinder model potential for cold flow simulation in the SI engine has been demonstrated. All strokes are replicated, pulling, compressing, expansion and exhaust. The Discrete Phase System is used for injecting, evaporating and boiling water, where the simulation depicts the working conditions of the engine for unravelling the flow physics taking place.

Prediction of Engine Performance Under Compressor Inlet Flow Distortion Using Streamline Curvature

2006 ◽  
Vol 129 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Vassilios Pachidis ◽  
Pericles Pilidis ◽  
Ioannis Templalexis ◽  
Theodosios Korakianitis ◽  
Petros Kotsiopoulos
Keyword(s):  
Engine Performance ◽  
Two Dimensional ◽  
Physical Processes ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Streamline Curvature ◽  
Simulation Strategy ◽  
Flow Phenomena ◽  
Inlet Flow Distortion ◽  
Inlet Conditions

Traditionally, engine performance has been simulated based on nondimensional maps for compressors and turbines. Component characteristic maps assume by default a given state of inlet conditions that cannot be easily altered in order to simulate two- or three-dimensional flow phenomena. Inlet flow distortion, for example, is usually simulated by applying empirical correction factors and modifiers to default component characteristics. Alternatively, the parallel compressor theory may be applied. The accuracy of the above methods has been rather questionable over the years since they are unable to capture in sufficient fidelity component-level, complex physical processes and analyze them in the context of the whole engine performance. The technique described in this paper integrates a zero-dimensional (nondimensional) gas turbine modelling and performance simulation system and a two-dimensional, streamline curvature compressor software. The two-dimensional compressor software can fully define the characteristics of any compressor at several operating conditions and is subsequently used in the zero-dimensional cycle analysis to provide a more accurate, physics-based estimate of compressor performance under clean and distorted inlet conditions, replacing the default compressor maps. The high-fidelity, two-dimensional compressor component communicates with the lower fidelity cycle via a fully automatic and iterative process for the determination of the correct operating point. This manuscript firstly gives a brief overview of the development, validation, and integration of the two-dimensional, streamline curvature compressor software with the low-fidelity cycle code. It also discusses the relative changes in the performance of a two-stage, experimental compressor with different types of radial pressure distortion obtained by running the two-dimensional streamline curvature compressor software independently. Moreover, the performance of a notional engine model, utilizing the coupled, two-dimensional compressor, under distorted conditions is discussed in detail and compared against the engine performance under clean conditions. In the cases examined, the analysis carried out by this study demonstrated relative changes in the simulated engine performance larger than 1%. This analysis proves the potential of the simulation strategy presented in this paper to investigate relevant physical processes occurring in an engine component in more detail, and to assess the effects of various isolated flow phenomena on overall engine performance in a timely and affordable manner. Moreover, in contrast to commercial computational fluid dynamics tools, this simulation strategy allows in-house empiricism and expertise to be incorporated in the flow-field calculations in the form of deviation and loss models.

scholarly journals TOWEL DRYER AS AN ELEMENT OF THE MODERN HEAT SUPPLY SYSTEM

2021 ◽  
Vol 30 (1) ◽  
pp. 132-139
Author(s):  
S. Tkachenko ◽  
◽  
N. Stepanova ◽  
D. Stepanov ◽  
O. Stepanov ◽  
...  
Keyword(s):  
Thermal Power ◽  
Flow Simulation ◽  
Heat Supply System ◽  
Simulation Software ◽  
Operating Conditions ◽  
Heat Output ◽  
Water Type ◽  
Software Module ◽  
Significant Discrepancy ◽  
Polished Stainless Steel

The operating conditions of the water-type towel dryer made of polished stainless steel AISI 304 are established, the declared capacity of towel dryers of almost the same design of different manufacturers is compared and a significant discrepancy is revealed; analyzed four methods for determining the nominal heat output of the towel dryer, taking into account the forced movement of the coolant inside the towel dryer, free or forced air movement near the surface of the towel dryer under different boundary conditions in compliance with regulations; modeling of towel dryer operation by means of Flow Simulation software module in SolidWorks; he influence of uncertainty of degree of blackness of a towel dryer surface on nominal thermal power of a towel dryer is investigated; influence of speed of washing of a heat exchange surface of a towel dryer by air on its thermal power is estimated, the received results of researches by four methods are analyzed.

Could biomass-fueled boilers be operated at higher steam temperatures? Part 3: Initial analysis of costs and benefits

TAPPI Journal ◽  
2014 ◽  
Vol 13 (8) ◽  
pp. 65-78 ◽  
Author(s):  
W.B.A. (SANDY) SHARP ◽  
W.J. JIM FREDERICK ◽  
JAMES R. KEISER ◽  
DOUGLAS L. SINGBEIL
Keyword(s):  
Flue Gas ◽  
Power Plants ◽  
Superheated Steam ◽  
Black Liquor ◽  
Simulation Software ◽  
Operating Conditions ◽  
Costs And Benefits ◽  
Steam Generation ◽  
Fireside Corrosion ◽  
Corrosion Resistant

The efficiencies of biomass-fueled power plants are much lower than those of coal-fueled plants because they restrict their exit steam temperatures to inhibit fireside corrosion of superheater tubes. However, restricting the temperature of a given mass of steam produced by a biomass boiler decreases the amount of power that can be generated from this steam in the turbine generator. This paper examines the relationship between the temperature of superheated steam produced by a boiler and the quantity of power that it can generate. The thermodynamic basis for this relationship is presented, and the value of the additional power that could be generated by operating with higher superheated steam temperatures is estimated. Calculations are presented for five plants that produce both steam and power. Two are powered by black liquor recovery boilers and three by wood-fired boilers. Steam generation parameters for these plants were supplied by industrial partners. Calculations using thermodynamics-based plant simulation software show that the value of the increased power that could be generated in these units by increasing superheated steam temperatures 100°C above current operating conditions ranges between US$2,410,000 and US$11,180,000 per year. The costs and benefits of achieving higher superheated steam conditions in an individual boiler depend on local plant conditions and the price of power. However, the magnitude of the increased power that can be generated by increasing superheated steam temperatures is so great that it appears to justify the cost of corrosion-mitigation methods such as installing corrosion-resistant materials costing far more than current superheater alloys; redesigning biomassfueled boilers to remove the superheater from the flue gas path; or adding chemicals to remove corrosive constituents from the flue gas. The most economic pathways to higher steam temperatures will very likely involve combinations of these methods. Particularly attractive approaches include installing more corrosion-resistant alloys in the hottest superheater locations, and relocating the superheater from the flue gas path to an externally-fired location or to the loop seal of a circulating fluidized bed boiler.

Urbanicity, City Delegations, and Two-Dimensional Liberalism

2018 ◽  
Author(s):  
Thomas K. Ogorzalek
Keyword(s):  
National Level ◽  
Two Dimensions ◽  
Political Order ◽  
Two Dimensional ◽  
Local Institutions ◽  
Horizontal Integration ◽  
National Politics ◽  
United Front ◽  
Strategies For Success

This theoretical chapter develops the argument that the conditions of cities—large, densely populated, heterogeneous communities—generate distinctive governance demands supporting (1) market interventions and (2) group pluralism. Together, these positions constitute the two dimensions of progressive liberalism. Because of the nature of federalism, such policies are often best pursued at higher levels of government, which means that cities must present a united front in support of city-friendly politics. Such unity is far from assured on the national level, however, because of deep divisions between and within cities that undermine cohesive representation. Strategies for success are enhanced by local institutions of horizontal integration developed to address the governance demands of urbanicity, the effects of which are felt both locally and nationally in the development of cohesive city delegations and a unified urban political order capable of contending with other interests and geographical constituencies in national politics.

scholarly journals Interface Roughening in Two Dimensions

2021 ◽  
Vol 182 (3) ◽  
Author(s):  
Gernot Münster ◽  
Manuel Cañizares Guerrero
Keyword(s):  
Field Theory ◽  
Monte Carlo ◽  
Capillary Wave ◽  
System Size ◽  
Two Dimensions ◽  
Two Dimensional ◽  
Wave Approximation ◽  
Statistical Field ◽  
Statistical Field Theory ◽  
Interface Roughening

AbstractRoughening of interfaces implies the divergence of the interface width w with the system size L. For two-dimensional systems the divergence of $$w^2$$ w 2 is linear in L. In the framework of a detailed capillary wave approximation and of statistical field theory we derive an expression for the asymptotic behaviour of $$w^2$$ w 2 , which differs from results in the literature. It is confirmed by Monte Carlo simulations.

scholarly journals Is contact angle a cause or an effect? – A cautionary tale

2020 ◽  
Vol 146 ◽  
pp. 03004
Author(s):  
Douglas Ruth
Keyword(s):  
Contact Angle ◽  
Solid Surface ◽  
Contact Angles ◽  
Two Dimensions ◽  
Experimental Results ◽  
Flow In Porous Media ◽  
Two Dimensional ◽  
Wide Range ◽  
Fluid Drop ◽  
Surrounding Fluid

The most influential parameter on the behavior of two-component flow in porous media is “wettability”. When wettability is being characterized, the most frequently used parameter is the “contact angle”. When a fluid-drop is placed on a solid surface, in the presence of a second, surrounding fluid, the fluid-fluid surface contacts the solid-surface at an angle that is typically measured through the fluid-drop. If this angle is less than 90°, the fluid in the drop is said to “wet” the surface. If this angle is greater than 90°, the surrounding fluid is said to “wet” the surface. This definition is universally accepted and appears to be scientifically justifiable, at least for a static situation where the solid surface is horizontal. Recently, this concept has been extended to characterize wettability in non-static situations using high-resolution, two-dimensional digital images of multi-component systems. Using simple thought experiments and published experimental results, many of them decades old, it will be demonstrated that contact angles are not primary parameters – their values depend on many other parameters. Using these arguments, it will be demonstrated that contact angles are not the cause of wettability behavior but the effect of wettability behavior and other parameters. The result of this is that the contact angle cannot be used as a primary indicator of wettability except in very restricted situations. Furthermore, it will be demonstrated that even for the simple case of a capillary interface in a vertical tube, attempting to use simply a two-dimensional image to determine the contact angle can result in a wide range of measured values. This observation is consistent with some published experimental results. It follows that contact angles measured in two-dimensions cannot be trusted to provide accurate values and these values should not be used to characterize the wettability of the system.

Sign in / Sign up

Export Citation Format

Share Document