Model Analysis of High-Fogging Effects on the Work of Compression

2003 ◽  
Author(s):  
Carlos Ha¨rtel ◽  
Peter Pfeiffer
Keyword(s):  
Mass Transfer ◽  
Gaseous Phase ◽  
Gas Turbines ◽  
Pressure Rise ◽  
Droplet Model ◽  
Ideal Model ◽  
Lower Efficiency ◽  
Saturated Mixture ◽  
Evaporation Of Droplets ◽  
Cost Efficient

In recent years, high fogging has received increasing attention as a comparatively simple and cost-efficient means of gas turbine power augmentation. The effects of high fogging on the work of compression are studied in this paper from a fundamental perspective. Considered is a prototype configuration, namely the evaporation of droplets in an initially saturated mixture of air and water, which is exposed to a prescribed pressure rise. Two different approaches are applied: The first approach (‘ideal model’) assumes that thermodynamic equilibrium prevails. In the second approach (‘droplet model’) the finite time of evaporation is taken into account by introducing discrete droplets and modeling explicitly the heat and mass transfer between liquid and gaseous phase. For compression speeds representative of modern gas turbines, it is found that droplets of 1μm in diameter are small enough to allow for approximate equilibrium during compression. The influence of polytropic efficiency on the gains of high fogging is addressed, and it is shown that high fogging is more effective for compressors of lower efficiency.

scholarly journals Numerical Investigation of Pressure Influence on the Confined Turbulent Boundary Layer Flashback Process

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 146 ◽  
Author(s):  
Aaron Endres ◽  
Thomas Sattelmayer
Keyword(s):  
Boundary Layer ◽  
Gas Turbines ◽  
Separation Zone ◽  
Turbulent Flame ◽  
Pressure Rise ◽  
Flame Speed ◽  
Zone Size ◽  
Detailed Chemical Kinetics ◽  
Turbulent Flame Speed ◽  
Quenching Distance

Boundary layer flashback from the combustion chamber into the premixing section is a threat associated with the premixed combustion of hydrogen-containing fuels in gas turbines. In this study, the effect of pressure on the confined flashback behaviour of hydrogen-air flames was investigated numerically. This was done by means of large eddy simulations with finite rate chemistry as well as detailed chemical kinetics and diffusion models at pressures between 0 . 5 and 3 . It was found that the flashback propensity increases with increasing pressure. The separation zone size and the turbulent flame speed at flashback conditions decrease with increasing pressure, which decreases flashback propensity. At the same time the quenching distance decreases with increasing pressure, which increases flashback propensity. It is not possible to predict the occurrence of boundary layer flashback based on the turbulent flame speed or the ratio of separation zone size to quenching distance alone. Instead the interaction of all effects has to be accounted for when modelling boundary layer flashback. It was further found that the pressure rise ahead of the flame cannot be approximated by one-dimensional analyses and that the assumptions of the boundary layer theory are not satisfied during confined boundary layer flashback.

Influence of an inclined magnetic field on heat and mass transfer of the peristaltic flow of a couple stress fluid in an inclined channel

2017 ◽  
Vol 14 (1) ◽  
pp. 7-18 ◽  
Author(s):  
Ajaz Ahmad Dar ◽  
K. Elangovan
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Pressure Gradient ◽  
Couple Stress ◽  
Pressure Rise ◽  
Peristaltic Flow ◽  
Inclined Magnetic Field ◽  
Content Type ◽  
Inclined Channel ◽  
Velocity Pressure

Purpose This paper aims to intend for investigating the influence of an inclined magnetic field on the peristaltic flow of a couple stress fluid through an inclined channel with heat and mass transfer. Design/methodology/approach Long wavelength and low Reynolds number methodology is actualized for simplifying the highly nonlinear equations. Mathematical expressions of axial velocity, pressure gradient and volume flow rate are obtained. Pressure rise, frictional force and pumping phenomenon are portrayed and symbolized graphically. Exact and numerical solutions have been carried out. The computed results are presented graphically for various embedded parameters. Temperature and concentration profile are also scrutinized and sketched. Findings Results from the current study concluded that the fluid motion can be enhanced by increasing the inclination of both the magnetic field and the channel. Originality/value The elemental characteristics of this analysis is a complete interpretation of the influence of couple stress parameter and inclination of magnetic field on the velocity, pressure gradient, pressure rise and frictional forces.

Analysis of Mixed Convective Heat and Mass Transfer on Peristaltic Flow of Fene-P Fluid with Chemical Reaction

2015 ◽  
Vol 32 (1) ◽  
pp. 83-92 ◽  
Author(s):  
Z. Asghar ◽  
N. Ali
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Chemical Reaction ◽  
Wave Length ◽  
Linear Equations ◽  
Pressure Rise ◽  
Boussinesq Approximation ◽  
Flow Equations ◽  
Highly Nonlinear ◽  
Concentration Changes

AbstractThis study presents the influence of heat and mass transfer on peristaltic transport of Finitely Extensible Nonlinear Elastic Peterlin (FENE-P) fluid in the presence of chemical reaction. It is assumed that all the fluid properties, except the density are constant. The Boussinesq approximation which relates density change to temperature and concentration changes is used in formulating buoyancy force terms in the momentum equation. Moreover, we neglect viscous dissipation and include diffusion-thermal (Dufour) and thermal-diffusion (Soret) effects in the present analysis. By the consideration of such important aspects the flow equations become highly nonlinear and coupled. In order to make the problem tractable we have adopted widely used assumptions of long wave length and low Reynolds number. An exact solution of the simplified coupled linear equations for the temperature and concentration has been obtained whereas numerical solution is obtained for dimensionless stream function and pressure gradient. The effects of different parameters on velocity field, temperature and concentration fields and trapping phenomenon are highlighted through various graphs. Numerical integration has been performed to analyze pressure rise per wavelength.

Gas Turbine Efficiency (GTE) Benefits of GTE Water Wash Systems

2008 ◽  
Author(s):  
Thomas Wagner ◽  
Robert J. Burke
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Process Efficiency ◽  
Compression Process ◽  
Lower Efficiency ◽  
Fuel Gas ◽  
Air Filter ◽  
Turbine Efficiency ◽  
Industrial Gas Turbine

The desire to maintain power plant profitability, combined with current market fuel gas pricing is forcing power generation companies to constantly look for ways to keep their industrial gas turbine units operating at the highest possible efficiency. Gas Turbines Operation requires the compression of very large quantities of air that is mixed with fuel, ignited and directed into a turbine to produce torque for purposes ranging from power generation to mechanical drive of pumping systems to thrust for air craft propulsion. The compression of the air for this process typically uses 60% of the required base energy. Therefore management of the compression process efficiency is very important to maintain overall cycle efficiency. Since fouling of turbine compressors is almost unavoidable, even with modern air filter treatment, and over time results in lower efficiency and output, compressor cleaning is required to maintain gas turbine efficiency.

scholarly journals Peristaltic Motion of Non-Newtonian Fluid with Heat and Mass Transfer through a Porous Medium in Channel under Uniform Magnetic Field

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Nabil T. M. Eldabe ◽  
Bothaina M. Agoor ◽  
Heba Alame
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Porous Medium ◽  
Heat And Mass Transfer ◽  
Newtonian Fluid ◽  
Pressure Rise ◽  
Perturbation Series ◽  
Peristaltic Motion ◽  
Method Of Solution ◽  
Permeability Parameter

This paper is devoted to the study of the peristaltic motion of non-Newtonian fluid with heat and mass transfer through a porous medium in the channel under the effect of magnetic field. A modified Casson non-Newtonian constitutive model is employed for the transport fluid. A perturbation series’ method of solution of the stream function is discussed. The effects of various parameters of interest such as the magnetic parameter, Casson parameter, and permeability parameter on the velocity, pressure rise, temperature, and concentration are discussed and illustrated graphically through a set of figures.

Automatized 3D-Scanning Application for the Virtualization of Large Components

2019 ◽  
Author(s):  
Stephan Mönchinger ◽  
Marvin M. Schmidt ◽  
Sebastian Dreßen ◽  
Patrick Wissmann ◽  
Rainer Stark
Keyword(s):  
Gas Turbines ◽  
Software Tool ◽  
Low Complexity ◽  
3D Scanning ◽  
Shop Floor ◽  
Final State ◽  
Scanning Procedure ◽  
Cost Efficient ◽  
Easy Integration ◽  
Automated Scanning

Abstract Many of the large components of modern gas turbines are cast, resulting in rough surface profiles, which have to be machined to achieve the component’s final state. As there are high deviations in casting components, the real geometry does not meet the ideal model dimensions and is known neither to the supplier nor to the customer. While manual 3D-scanning processes, heavily depending on the operator’s qualification, get more attention, conventional means are still the basis for quality assurance of such parts. Although significant time reduction can be reached by automated scanning, there is still a low variety of corresponding applications for large components on the market. Flexible systems are an approach for further development as most of the manufacturers handling large components already have and use machine tools for the processing of their components. The designed and implemented prototypical system allows the acquisition of a large component’s surface with only a few manual inputs prior to the actual scanning procedure. It can be used with existing machining tools, allowing an easy implementation for different use cases of a pre-manufacturing scan, e.g. for CAM planning. The application is implemented in a small software tool that can be adapted to other machines with low effort. The implementation has been demonstrated in a real manufacturing environment with typical environmental conditions in the shop floor. The prototypical application has been built mainly with existing components. Following the V-Model, each domain has been investigated individually followed by a complete system investigation. With a system price below 100.000€ the price is below 10% of most automated systems on the market. The presented cost efficient, low complexity prototypical system can provide early information about the product for a digital process chain in industry 4.0, enabling flexible, intuitive and easy integration.

Modeling of Simultaneous Gas Absorption and Evaporation of Large Droplet

2005 ◽  
Author(s):  
Tov Elperin ◽  
Andrew Fominykh ◽  
Boris Krasovitov
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Gaseous Phase ◽  
Method Of Lines ◽  
Material Balance ◽  
Liquid Interface ◽  
Rate Of Change ◽  
Gas Absorption ◽  
Gaseous Species ◽  
Essential Change

In this study we investigated numerically simultaneous heat and mass transfer during evaporation/condensation on the surface of a stagnant droplet in the presence of inert admixtures containing non-condensable solvable gas. The performed analysis is pertinent to slow droplet evaporation/condensation when Mach number is small (M≪1). The system of transient conjugate nonlinear energy and mass conservation equations was solved using anelastic approximation. Transport coefficients of the gaseous phase were calculated as functions of temperature and concentrations of gaseous species. Thermophysical properties of the liquid phase are assumed to be constant. Using the material balance at the droplet surface we obtained equations for Stefan velocity and the rate of change of the droplet radius taking into account the effect of solvable gas absorption at the gas-liquid interface. We derived also boundary conditions at gas-liquid interface taking into account the effect of gas absorption. The governing equations were solved using a method of lines. Numerical calculations showed essential change of the rates of heat and mass transfer in water droplet-air-water vapor system under the influence of solvable species in a gaseous phase. Consequently, the use of additives of solvable noncondensable gases to enhance the rate of heat and mass transfer in dispersed systems allows to increase the efficiency and reduce the size of gas-liquid contactors.

Effects of Droplet Size on Transient Behavior of after Fogging Process

2012 ◽  
Vol 249-250 ◽  
pp. 493-497
Author(s):  
Kyoung Hoon Kim ◽  
Chul Ho Han ◽  
Young Guan Jung
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Droplet Size ◽  
Water Injection ◽  
Transient Behavior ◽  
Analytic Expressions ◽  
Evaporation Of Droplets ◽  
System Variables ◽  
Important System ◽  
Injection Ratio

Gas turbine cycles with after fogging where water is injected after compressor could offer enhanced efficiency compared to inlet fogging system due to higher water injection ratio. In this work the after fogging process is modeled based on the evaporation of droplets. Transient behaviors of the process are investigated with analytic expressions obtained by considering heat and mass transfer and thermodynamic relations. Effects of droplet size on the transient behaviors of important system variables are thoroughly investigated including diameter and mass of droplets, temperature and density of air, and mass flux and heat transfer from the droplets.

The Mass Transfer Analogy to Heat Transfer in Fluids With Temperature-Dependent Properties

1991 ◽  
Vol 113 (1) ◽  
pp. 27-33 ◽  
Author(s):  
J. N. Shadid ◽  
E. R. G. Eckert
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Film Cooling ◽  
Gas Turbines ◽  
Transport Processes ◽  
Constant Property ◽  
Impingement Cooling ◽  
Fluid Properties ◽  
Temperature Dependent Properties ◽  
Isothermal Mass

The analogy between heat transfer in a single-component fluid and isothermal mass transfer of a two-component fluid without chemical reaction is presented. The analogy is well established and frequently used for fluids with constant properties. However, in various applications such as in the cooling of hot components in gas turbines, the temperature varies widely, causing significant fluid property variations. The present paper reviews the constant-property situation and considers in detail the conditions necessary to ensure similarity of the two transport processes with temperature and concentration-dependent fluid properties. An application of the variable property analogy to mass transfer in binary mixtures is presented along with specific recommendations for the CO2–air and Freon-air systems. It is demonstrated that the essential similarity conditions of the analogy are very well fulfilled for film cooling, total coverage film cooling, and impingement cooling when the heat (mass) flux into the wall in the transport process is zero. The heat/mass transfer analogy can, therefore, be used with confidence for these processes.

Modeling Particle Deposition Effects in Aircraft Engine Compressors

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Felix Döring ◽  
Stephan Staudacher ◽  
Christian Koch ◽  
Matthias Weißschuh
Keyword(s):  
Gas Turbines ◽  
Particle Deposition ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Engine Performance ◽  
Aircraft Engine ◽  
Deposition Process ◽  
Aircraft Engines ◽  
Blade Row ◽  
Performance Deterioration

Airborne particles ingested in aircraft engines deposit on compressor blading and end walls. Aerodynamic surfaces degrade on a microscopic and macroscopic scale. Blade row, compressor, and engine performance deteriorate. Optimization of maintenance scheduling to mitigate these effects requires modeling of the deterioration process. This work provides a deterioration model on blade row level and the experimental validation of this model in a newly designed deposition test rig. When reviewing previously published work, a clear focus on deposition effects in industrial gas turbines becomes evident. The present work focuses on quantifying magnitudes and timescales of deposition effects in aircraft engines and the adaptation of the generalized Kern and Seaton deposition model for application in axial compressor blade rows. The test rig's cascade was designed to be representative of aircraft engine compressor blading. The cascade was exposed to an accelerated deposition process. Reproducible deposition patterns were identified. Results showed an asymptotic progression of blade row performance deterioration. A significant increase in total pressure loss and decrease in static pressure rise were measured. Application of the validated model using existing particle concentration and flight cycle data showed that more than 95% of the performance deterioration due to deposition occurs within the first 1000 flight cycles.

Sign in / Sign up

Export Citation Format

Share Document