Effect of Vortex Flow on Heat Transfer to Combustion Chamber Wall

2006 ◽  
Vol 129 (2) ◽  
pp. 622-624 ◽  
Author(s):  
A. Ghafourian ◽  
M. H. Saidi ◽  
S. Jahangirian ◽  
M. Abarham
Keyword(s):  
Heat Transfer ◽  
Combustion Chamber ◽  
Wall Temperature ◽  
Hot Spots ◽  
Vortex Flow ◽  
Swirl Flow ◽  
Experimental Facility ◽  
Combustion Chambers ◽  
Flow Rates ◽  
Bidirectional Flow

A new experimental facility was designed, fabricated, and tested to model and study the effect of bidirectional swirl flow on the rate of heat transfer to combustion chamber walls. Reduction of this heat transfer can result in time and cost of design and fabrication methods of combustion chambers. The experimental study was performed using propane and air with oxygen as fuel and oxidizer, respectively. For similar flow rates, in cases where bidirectional flow was present, wall temperature reductions of up to 70% were observed. In cases where only some of the oxidizer was injected from the chamber end to generate the bidirectional swirl flow, the lowest wall temperature existed. This can be due to better mixing of fuel and oxidizer and absence of hot spots in the combustion core.

Effect of Vortex Flow on Heat Transfer to Combustion Chamber Wall

2004 ◽  
Author(s):  
S. Jahangirian ◽  
M. Abarham ◽  
A. Ghafourian ◽  
M. H. Saidi
Keyword(s):  
Heat Transfer ◽  
Combustion Chamber ◽  
Wall Temperature ◽  
Wide Spectrum ◽  
Swirl Flow ◽  
Combustion Chambers ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Bidirectional Flow ◽  
Further Development

A new experimental facility was designed, fabricated and tested to model and study the effect of bidirectional swirl flow on the rate of heat transfer to combustion chamber walls in many applications. Heat transfer to combustion chamber walls is an unwanted phenomenon. Reduction of this heat transfer can result in time and cost saving methods in design and fabrication of combustion chambers. The experimental study was performed by using propane and air with oxygen as fuel and oxidizer respectively. The location of injection ports and geometry of combustion chamber are flexible and could be varied. Tests were performed with different mass flow rates of fuel and oxidizer. For the same flow rates and with the presence of bidirectional flow, a wall temperature reduction of up to 50% was observed. In cases where only some of the oxidizer was injected from the chamber end to generate the bidirectional swirl flow, highest efficiency and lowest wall temperature existed. This can be due to better mixing of fuel and oxidizer and absence of hot spots in the combusting core. Further development of this technique enables combustion chamber manufacturers in a wide spectrum of industries such as gas turbine manufacturers to use less expensive and more available material in their production of combustors.

Experimental and Theoretical Investigation of Heat Transfer in Vortex Combustion Engines

2005 ◽  
Author(s):  
E. Farvardin ◽  
M. H. Saidi ◽  
A. Ghafourian
Keyword(s):  
Heat Transfer ◽  
Wall Temperature ◽  
Radiation Heat Transfer ◽  
Flame Structure ◽  
Convection Heat Transfer ◽  
Heat Removal ◽  
Swirl Flow ◽  
Combustion Chambers ◽  
Structure Observation ◽  
Heat Transfer Phenomenon

Heat transfer phenomenon in a recently developed vortex engine has been surveyed. Cooler walls, better combustion performance and more stable relative to the other engines, make these engines very interesting. These advantages have been obtained by using a bidirectional swirl flow, containing a cool outer and a hot inner vortex, traveling upstream and downstream respectively. The most eminent benefit of these combustion chambers, having highly reduced wall temperature, is the result of convective heat release from the wall by the outer vortex. A thorough numerically and experimentally investigation has been performed on radiation and convection heat transfer to realize the exact heat transfer behavior of this engine. Results from flame structure observation indicate that flame area is much larger in vortex engine in comparison to regular engines due to vortex stretching of the flame which increases radiation heat transfer to walls. In spite of this increase, heat removal by outer swirl flow is high enough not only to compensate for increased radiation but also reduces the wall temperature substantially.

Analysis of Temperature Distribution Over a Gas Turbine Shaft Exposed to a Swirl Combustor Flue

2010 ◽  
Author(s):  
V. Aghakashi ◽  
M. H. Saidi ◽  
A. Ghafourian ◽  
A. A. Mozafari
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Equivalence Ratio ◽  
Vortex Flow ◽  
Combustion Efficiency ◽  
Swirl Flow ◽  
Axial Position ◽  
Combustion Chambers ◽  
Swirl Combustor ◽  
Turbine Shaft

Gas turbine shaft is generally exposed to high temperature gases and may seriously be affected and overheated due to temperature fluctuations in the combustion chamber. Considering vortex flow in the combustion chamber, it may increase the heat release rate and combustion efficiency and also control location of energy release. However, this may result in excess temperature on the combustor equipments and gas turbine shaft. Vortex flow in the vortex engine which is created by the geometry of combustion chamber and conditions of flow field is a bidirectional swirl flow that maintains the chamber wall cool. In this study a new gas turbine combustion chamber implementing a liner around the shaft and liquid fuel feeding system is designed and fabricated. Influence of parameters such as axial position in the combustor direction and equivalence ratio are studied. Experimental results are compared with the numerical simulation by the existing commercial software. Swirl number i.e. ratio of angular flux of angular momentum to angular flux of linear momentum multiplied by nozzle radius, in this study is assumed to be constant. In order to measure the temperature along the liner, K type thermocouples are used. Results show that the heat transfer to the liner at the inlet of combustion chamber is enough high and at the outlet of combustion chamber is relatively low. The effect of parameters such as equivalence ratio and the mass flow rate of oxidizer on the temperature of the liner is investigated and compared with the numerical solution. This type of combustion chambers can be used in gas turbine engines due to their low weight and short length of combustion chamber.

scholarly journals Numerical and Experimental Analysis of Heat Transfer for Solid Fuels Combustion in Fixed Bed Conditions

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6141
Author(s):  
Wojciech Judt
Keyword(s):  
Heat Transfer ◽  
Combustion Chamber ◽  
Transfer Process ◽  
Heat Load ◽  
Fixed Bed ◽  
Heat Transfer Process ◽  
Biomass Combustion ◽  
Solid Fuels ◽  
Hard Coal ◽  
Combustion Chambers

The paper concerns the analysis of the heat transfer process that occurred during solid fuel burning in fixed bed conditions. The subject of the analysis is a cylindrical combustion chamber with an output of 12 kW heating power equipped with a retort burner for hard coal and biomass combustion. During the research, a numerical and experimental study is performed. The analysis is prepared for various heat load of the combustion chamber, which allowed for the reconstruction of real working conditions for heating devices working with solid fuels combustion. The temperature distribution obtained by the experimental way is compared with results of the numerical modeling. Local distribution of principal heat transfer magnitudes like a heat flux density and a heat transfer coefficient that occurred on the sidewall of the combustion chamber is analyzed. The analysis showed, that the participation of convection and radiation in the overall heat transfer process has resulted from the heat load of the heating device. Research results may be used for improving an analytical approach of design process taking place for domestic and industrial combustion chambers.

Heat Transfer and Pressure Drop Correlations for Twisted-Tape Inserts in Isothermal Tubes: Part I—Laminar Flows

1993 ◽  
Vol 115 (4) ◽  
pp. 881-889 ◽  
Author(s):  
R. M. Manglik ◽  
A. E. Bergles
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Swirl Flow ◽  
Laminar Flows ◽  
Low Flow ◽  
Published Data ◽  
Twisted Tape ◽  
Flow Rates ◽  
Uniform Wall Temperature ◽  
Uniform Wall

Laminar flow correlations for f and Num are developed based on experimental data for water and ethylene glycol, with tape inserts of three different twist ratios. The uniform wall temperature condition is considered, which typifies practical heat exchangers in the chemical and process industry. These and other available data are analyzed to devise flow regime maps that characterize twisted-tape effects in terms of the dominant enhancement mechanisms. Depending upon flow rates and tape geometry, the enhancement in heat transfer is due to the tube partitioning and flow blockage, longer flow path, and secondary fluid circulation; fin effects are found to be negligible in snug- to loose-fitting tapes. The onset of swirl flow and its intensity is determined by a swirl parameter, Sw=Resw/y, that defines the interaction between viscous, convective inertia, and centrifugal forces. Buoyancy-driven free convection that comes into play at low flow rates with large y and ΔTw is shown to scale as Gr/Sw2≫ 1. These parameters, along with numerical baseline solutions for laminar flows with y = ∞, are incorporated into correlations for f and Num by matching the appropriate asymptotic behavior. The correlations describe the experimental data within ±10 to 15 percent, and their generalized applicability is verified by the comparison of predictions with previously published data.

Physical Interpretation of Flow and Heat Transfer in Pre-Swirl Systems

2006 ◽  
Author(s):  
Paul Lewis ◽  
Mike Wilson ◽  
Gary Lock ◽  
J. Michael Owen
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Turbulent Flow ◽  
Gas Turbines ◽  
Flow Parameter ◽  
Swirl Flow ◽  
Rotating Disc ◽  
Scaled Model ◽  
Flow Rates

This paper compares heat transfer measurements from a pre-swirl rotor-stator experiment with 3D steady state results from a commercial CFD code. The measured distribution of Nusselt number on the rotor surface was obtained from a scaled model of a gas turbine rotor-stator system, where the flow structure is representative of that found in an engine. Computations were carried out using a coupled multigrid RANS solver with a high-Reynolds-number k-ε/k-ω turbulence model. Previous work has identified three parameters governing heat transfer: rotational Reynolds number (Reφ), pre-swirl ratio (βp) and the turbulent flow parameter (λT). For this study rotational Reynolds numbers are in the range 0.8×106 < Reφ < 1.2×106. The turbulent flow parameter and pre-swirl ratios varied between 0.12 < λT < 0.38 and 0.5 < βp < 1.5, which are comparable to values that occur in industrial gas turbines. At high coolant flow rates, computations have predicted peaks in heat transfer at the radius of the pre-swirl nozzles. These were discovered during earlier experiments and are associated with the impingement of the pre-swirl flow on the rotor disc. At lower flow rates, the heat transfer is controlled by boundary-layer effects. The Nusselt number on the rotating disc increases as either Reφ or λT increases, and is axisymmetric except in the region of the receiver holes, where significant two-dimensional variations are observed. The computed velocity field is used to explain the heat transfer distributions observed in the experiments. The regions of peak heat transfer around the receiver holes are a consequence of the route taken by the flow. Two routes have been identified: “direct”, whereby flow forms a stream-tube between the inlet and outlet; and “indirect”, whereby flow mixes with the rotating core of fluid. Two performance parameters have been calculated: the adiabatic effectiveness for the system, Θb,ab, and the discharge coefficient for the receiver holes, CD. The computations show that, although Θb,ab increases monotonically as βp increases, there is a critical value of βp at which CD is a maximum.

Heat Transfer in Liquid-Liquid Taylor Flow in a Mini-Scale Tube With Constant Wall Temperature

2015 ◽  
Author(s):  
W. M. Adrugi ◽  
Y. S. Muzychka ◽  
K. Pope
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Wall Temperature ◽  
Silicone Oil ◽  
Transfer Enhancement ◽  
Constant Wall Temperature ◽  
Flow Rates ◽  
Taylor Flow ◽  
Low Viscosity ◽  
Wide Range

In this paper, heat transfer enhancement using liquid-liquid Taylor flow is examined. The experiments are conducted in mini-scale tubes with constant wall temperature. The segmented flow is created using several fractions of low viscosity silicone oil (1 cSt) and water for a wide range of flow rates and segment lengths. The variety of liquids and flow rates change the Prandtl, Reynolds, and capillary numbers. The dimensionless mean wall flux and the dimensionless thermal flow length are used to analyze the experimental heat transfer data. The comparison shows the heat transfer rate for Taylor flow is higher than in single-phase flow. The heat transfer enhancement occurs due to internal circulation in the fluid segments.

Heat Transfer With Insulated Combustion Chamber Walls and Its Influence on the Performance of Diesel Engines

1988 ◽  
Vol 110 (3) ◽  
pp. 482-488 ◽  
Author(s):  
G. Woschni ◽  
W. Spindler
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Combustion Chamber ◽  
Fuel Consumption ◽  
Temperature Difference ◽  
Wall Temperature ◽  
Cooling Water ◽  
Great Expectations ◽  
The Heat Transfer Coefficient

Recently great expectations were put into the insulation of combustion chamber walls. A considerable reduction in fuel consumption, a marked reduction of the heat flow to the cooling water, and a significant increase of exhaust gas energy were predicted. In the meantime there exists an increasing number of publications reporting on significant increase of fuel consumption with total or partial insulation of the combustion chamber walls. In [1] a physical explanation of this effect is given: Simultaneously with the decrease of the temperature difference between gas and wall as a result of insulation, the heat transfer coefficient between gas and wall increases rapidly due to increasing wall temperature, thus overcompensating for the decrease in temperature difference between gas and wall. Hence a modified equation for calculation of the heat transfer coefficient was presented [1]. In the paper to be presented here, recent experimental results are reported that confirm the effects demonstrated in [1], including the influence of the heat transfer coefficient, which depends on the wall temperature, on the performance of naturally aspirated and turbocharged engines.

A Mathematical Model for Heat Transfer in Combustion Chambers of Steam Generators

1981 ◽  
Vol 103 (3) ◽  
pp. 545-551
Author(s):  
M. G. Gulicˇ ◽  
D. D. Gvozdenac
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Energy Balance ◽  
Combustion Chamber ◽  
Combustion Zone ◽  
Combustion Chambers ◽  
Steam Generators ◽  
Total Heat Transfer ◽  
Hewlett Packard ◽  
Factors Influencing

This paper describes a mathematical model for determining the total heat transfer in combustion chambers of steam generators. The model is based on the energy balance of radiation in a spherical combustion chamber which is divided into a combustion zone and gaseous zone. The model was tested on a Hewlett-Packard Type 9815 A computer with 2008 program memories. Calculations were made for a number of steam generator combustion chambers of different furnace loads for which all important factors were established. The model allows a didactic analysis of factors influencing the process of combustion and heat transfer.

Heat Transfer and Pumping on a Rotating Disk With Freely Induced and Forced Cooling

1970 ◽  
Vol 92 (3) ◽  
pp. 342-348 ◽  
Author(s):  
Darryl E. Metzger
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Rotating Disk ◽  
Turbine Rotor ◽  
Experimental Facility ◽  
Heat Transfer Characteristics ◽  
Flow Rates ◽  
Transfer Rates ◽  
Small Flow ◽  
Forced Cooling

An experimental study of the heat transfer characteristics of flows between a high speed rotating disk and a parallel stationary shroud is presented. Flow and disk heat transfer rates have been determined for various combinations and rates of freely induced and forced flows supplied at both the hub and rim of the disk. The study models a practically important class of turbine rotor cooling problems where small flow rates similar in magnitude to the disk pumping flows are of interest. The experimental facility and procedures are described in detail. They have been designed to facilitate rapid and economical acquisition of rotor cooling characteristics in situations where the particular rotor-shroud geometry makes existing correlations inadequate.

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