Mechanisms of Gas Turbine Regenerator Fouling

1967 ◽  
Author(s):  
James A. Miller
Keyword(s):  
Heat Transfer ◽  
Particulate Matter ◽  
Theoretical Model ◽  
Gas Turbine ◽  
Two Phase ◽  
Degradation Data ◽  
Proposed Model ◽  
Controlling Mechanism ◽  
Adhesive Coating ◽  
Phase Process

Possible mechanisms of gas turbine regenerator fouling are examined and compared with extant experimental evidence. A theoretical model of fouling which encompasses a two-phase process is proposed. It is shown that the controlling mechanism is the condensation of heavy hydrocarbon isomers which form an adhesive coating in which particulate matter subsequently become entrapped. Typical overall heat transfer and pressure drop degradation data are presented which tend to support the proposed model.

Study of Oil Film Heat Transfer in Gas Turbine Engine Bearing Chamber

2021 ◽  
Author(s):  
Illia Petukhov ◽  
Taras Mykhailenko ◽  
Oleksii Lysytsia ◽  
Artem Kovalov
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Gas Turbine ◽  
Gas Turbine Engine ◽  
Flow Core ◽  
Two Phase ◽  
Turbine Engine ◽  
Oil Film ◽  
Phase Medium ◽  
Engine Bearing

Abstract A clear understanding of the heat transfer processes in a gas turbine engine bearing chamber at the design stage makes it possible to properly design the lubrication and sealing systems and ensure the future bearing safe operation. The heat transfer coefficient (HTC) calculated based on the classical Newton-Richman equation is widely used to represent the heat transfer data and useful for the thermal resistance analysis. However, this approach is only formally applicable in the case of a two-phase medium. While there is a need to model a two-phase medium, setting the flow core temperature correctly in the Newton-Richman equation is an issue that is analyzed in this study. The heat from the flow core is transferred to the boundary of the oil film on the bearing chamber walls by an adjacent air and precipitating droplets. The analysis showed that droplet deposition plays a decisive role in this process and significantly intensifies the heat transfer. The main contribution to the thermal resistance of internal heat transfer is provided by the oil film. In this regard, the study considers the issues of the bearing chamber workflow modeling allowing to determine the hydrodynamic parameters of the oil film taking into account air and oil flow rates and shaft revolutions. The study also considers a possibility to apply the thermohydraulic analogy methods for the oil film thermal resistance determination. The study presents practical recommendations for process modeling in the bearing chamber.

Two-Phase Flow Simulation of Mist Film Cooling on Turbine Blades With Conjugate Internal Cooling

2008 ◽  
Vol 130 (10) ◽  
Author(s):  
Xianchang Li ◽  
Ting Wang
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Film Cooling ◽  
Turbine Blades ◽  
Flow Simulation ◽  
Solid Base ◽  
Internal Cooling ◽  
Adiabatic Wall ◽  
Two Phase ◽  
Air Film

Effective cooling of gas turbine combustor liners, combustor transition pieces, turbine vanes (nozzles), and blades (buckets) is a critical task to protect these components from the flue gas at extremely high temperature. Air film cooling has been successfully used to cool these hot sections for the past half century. However, the net benefits from the traditional methods seem to be incremental, but the temperature of working gas is continuously increasing to achieve high thermal efficiency. Therefore, new cooling techniques need to be developed. One of the promising techniques is to enhance film cooling with mist injection. While the previous study reported the effect of mist on the cooling effectiveness with an adiabatic wall, this paper focuses on the effect of mist injection on heat transfer of film cooling with a nonadiabatic flat wall, using the commercial computational fluid dynamics software package FLUENT. Both 2D and 3D cases are considered with a 2D slot and diffusive compound-angle holes. Modeling of the interaction of a droplet with a uniformly cooled wall as well as conjugate heat conduction inside the solid base are conducted. Different mist droplet sizes and mist concentrations are adopted. Conditions both in a gas turbine operating environment (15 atm and 1561 K) and in a laboratory environment (1 atm and 450 K) are considered. Results show that injecting 2–10% mist reduces the heat transfer coefficient and the wall temperature. Especially, mist has the prolonged effect of cooling the region downstream for 15 jet hole diameters, where conventional air film cooling is not effective.

Heat Transfer With Vaporization of a Liquid by Direct Contact in Another Immiscible Liquid: Experimental and Numerical Study

1991 ◽  
Vol 113 (3) ◽  
pp. 705-713 ◽  
Author(s):  
L. Tadrist ◽  
J. Sun ◽  
R. Santini ◽  
J. Pantaloni
Keyword(s):  
Heat Transfer ◽  
Theoretical Model ◽  
Void Fraction ◽  
Direct Contact ◽  
Numerical Study ◽  
Water System ◽  
Immiscible Liquid ◽  
Transfer Model ◽  
Two Phase ◽  
Spray Column

An experimental setup was designed to study direct-contact evaporators using a liquid dispersed in another immiscible liquid. The study was carried out on an n-pentane–water system to determine the influence of different parameters on these systems, and consequently to construct a model for this type of evaporator. An optical probe was used to measure the local void fraction. At different column abscissas along a selected diameter, the local void fraction variations were determined. The shape of the curves can be attributed to the different processes occurring in the spray column. A one-dimensional heat transfer model in the spray column was established. Simplifying assumptions were used to establish and resolve the set of equations governing heat transfer and two-phase flow. The vaporization process induces a volumetric expansion of the two-phase mixture. A theoretical model was used, in which the coalescence between the spherical fluid particles is taken into account. Different coalescence laws dependent on particle density were introduced into the theoretical model and then tested. The numerical results are discussed and compared with the experimental data obtained for the n-pentane–water system.

scholarly journals Simulation of Impinging Cooling Performance with Pin Fins and Mist Cooling Adopted in a Simplified Gas Turbine Transition Piece

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Tao Xu ◽  
Hang Xiu ◽  
Junlou Li ◽  
Haichao Ge ◽  
Qing Shao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Weighted Average ◽  
Two Phase ◽  
Cooling Performance ◽  
Pin Fin ◽  
Pin Fins ◽  
Mist Cooling ◽  
Transition Piece ◽  
Impinging Cooling

The gas turbine transition piece was simplified to a one-four cylinder double chamber model with a single row of impinging holes in the outer wall. Heat transfer augmentation in the coolant chamber was achieved through the use of pin fin structure and mist cooling, which could increase the turbulence and heat transfer efficiency. The present research is focused on heat transfer and pressure characteristics of the impinging cooling in the coolant chamber using FLUENT software. With the given diameter of impinging hole, pin fin diameter ratiosD/dhave been numerically studied in ranges from 1 to 2. Three different detachedLwere simulated. The impinging cooling performance in all cases was compared between single-phase and two-phase (imported appropriate mist) flow in the coolant chamber. All the simulation results reveal that the factors ofLandD/dhave significant effects on the convective heat transfer. After the pin fin structure was taken, the resulting temperature decrease of 38.77 K at most compared with the result of structure without pin fins. And with the mist injecting into the cooling chamber, the area weighted average temperature got a lower value without excess pressure loss, which could satisfy the more stringent requirements in engineering.

scholarly journals CFD Model for Aircraft Ground Deicing: Verification and Validation of an Extended Enthalpy-Porosity Technique in Particulate Two Phase Flows

Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 210
Author(s):  
Sami Ernez ◽  
François Morency
Keyword(s):  
Heat Transfer ◽  
Melting Process ◽  
Transient Temperature ◽  
Ice Melting ◽  
Two Phase ◽  
Transient Temperature Field ◽  
Proposed Model ◽  
Deicing Fluid ◽  
Cfd Method ◽  
Surface Ice

Researchers have focused in the last five years on modelling the aircraft ground deicing process using CFD (computational fluid dynamics) in order to reduce its costs and pollution. As preliminary efforts, those studies did not model the ice melting nor the diffusion between deicing fluids and water resulting from the melting process. This paper proposes a CFD method to simulate this process filling these gaps. A particulate two-phase flow approach is used to model the spray impact on ice near the contaminated surface. Ice melting is modelled using an extended version of the enthalpy-porosity technique. The water resulting from the melting process is diffused into the deicing fluid forming a single-phase film. This paper presents a new model of the process. The model is verified and validated through three steps. (i) verification of the species transport. (ii) validation of the transient temperature field of a mixture. (iii) validation of the convective heat transfer of an impinging spray. The permeability coefficient of the enthalpy-porosity technique is then calibrated. The proposed model proved to be a suitable candidate for a parametric study of the aircraft ground deicing process. On the validation test cases, the precision of heat transfer prediction exceeds 88%. The model has the ability of predicting the deicing time and the deicing fluid quantities needed to decontaminate a surface.

scholarly journals Modelling of Transient CO2/Water Flow in Wellbore considering Multiple Mass and Heat Transfer

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xinxin Zhao ◽  
Xiangzhen Yan ◽  
Xiaohui Sun ◽  
Qing Zhao ◽  
Hongwei Jiang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Two Phase Flow ◽  
Coupled Model ◽  
Mass Conservation ◽  
Phase Flow ◽  
Co2 Solubility ◽  
Two Phase ◽  
Gas Kick ◽  
Proposed Model ◽  
Mass And Heat Transfer

A transient fully coupled model is proposed to investigate the two-phase flow of CO2 and water-based fluid in a wellbore, considering the complex mass and heat transfer in different flow patterns and dynamic coupling between the wellbore and reservoir. Based on mass conservation, momentum, and energy balance, the model employs a state-of-the-art equation of state and transport models to analyze the variations of multiphase flow behaviors and CO2 properties in a wellbore. Applied in the scenario of a drilled gas kick, the proposed model is used to simulate the processes of gas migration and two-phase flow in the wellbore. The results indicate that the CO2 solubility increases gradually with the increment of depth, the trend of which shows an abrupt change in 500-1000 m due to the phase transition of CO2. During kick development, the fronts of free gas and dissolved gas increase almost linearly with time. Through a comparison of CO2 and CH4 kicks, gas dissolution is found to significantly suppress the development process of CO2 kick. The error in kick prediction can reach 42% if the effect of gas dissolution is neglected. However, it can be neglected for CH4 kick.

Theoretical Model of the Mixture-Vapor Transition Point Oscillations Associated With Two-Phase Evaporating Flow Instabilities

1974 ◽  
Vol 96 (2) ◽  
pp. 138-144 ◽  
Author(s):  
G. L. Wedekind ◽  
B. T. Beck
Keyword(s):  
Theoretical Model ◽  
Transition Point ◽  
Horizontal Tube ◽  
Rayleigh Distribution ◽  
Flow Instabilities ◽  
Statistical Characteristics ◽  
Two Phase ◽  
Proposed Model ◽  
Complete Vaporization ◽  
Liquid Film Dryout

A horizontal tube evaporator in which complete vaporization takes place can be divided into three distinct regions—a subcooled, a two-phase, and a superheat region. The mixture-vapor transition point corresponds to the liquid film dryout point, and when entrainment is negligible, it represents the boundary between the two-phase and superheat regions. Experimental evidence indicates that during what is conventionally accepted as steady flow conditions, the motion of the mixture-vapor transition point is of an oscillatory nature. Furthermore, not only are the oscillations random, but their statistical characteristics can be represented by a modified Rayleigh distribution. This paper presents the formulation of a theoretical model which incorporates various deterministic mechanisms, while at the same time includes the existence of a random phenomenon. The model has the capability of predicting the influence of evaporator heat flux and inlet flow quality on the statistical characteristics of the transition point oscillations. Perhaps, the most significant potential of the proposed model is that it represents a first step toward the formulation of some of the fundamental mechanisms associated with two-phase evaporating flow instabilities on a statistical basis; a basis which appears to be consistent with many of the experimental observations currently available.

Blading Heat Transfer Considerations in a Reheat-Gas-Turbine Combined Cycle

1981 ◽  
Author(s):  
P. E. Jenkins ◽  
I. G. Rice
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Steam Injection ◽  
Combined Cycle ◽  
Future Research ◽  
Air Cooling ◽  
Two Phase ◽  
Cooling Fluid ◽  
Cycle System ◽  
Transfer Equations

A brief presentation of the basic heat transfer equations for blade cooling is presented. Various cooling schemes have been developed over the past twenty years utilizing air as the cooling fluid. The mathematical models have subsequently predicted cooling schemes for the air cooling with little consideration for two phase fluids. This paper is written to describe the research needs for utilizing steam as a cooling fluid in a reheat-gas-turbine combined cycle system. The basic heat transfer equations are derived and discussed with regard to implementing the steam blanket cooling mechanism. The steam injection and dispersion problem is discussed, along with the need for future research in using steam as a viable cooling technique.

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