Aerodynamic Model Study of Marine Gas Turbine Exhaust Cooling

1978 ◽  
Vol 22 (02) ◽  
pp. 123-129
Author(s):  
C. J. Marquand
Keyword(s):  
Gas Turbine ◽  
Air Entrainment ◽  
Ambient Air ◽  
Royal Navy ◽  
Model Study ◽  
Plume Temperature ◽  
Gas Turbine Exhaust ◽  
New Generation ◽  
Exhaust Jet ◽  
Cooling Air

Problems such as the overheating of aerials by hot exhaust gas have been experienced by the Royal Navy on their new generation of gas turbine powered ships. Model tests indicate that the temperature trajectories from square, rectangular and clusters of circular exhausts may be correlated on the same basis as single circular exhausts, by substitution of a characteristic dimension in a simple temperature-decay equation. Plume temperature measurements show that lower temperatures can be obtained by enhancing the vortex activity in the plume, thereby causing more ambient air to be entrained, and that this can be achieved by using exhausts other than circular, where the plume drag is increased. Plume temperatures may also be reduced by introducing air entrainment into the uptake itself. Here it is important to ensure that the low-momentum entrained cooling air surrounds the hot exhaust jet as it leaves the uptake. It is then easily deflected into twin vortices in the downstream plume and these entrain ambient air. Air-entraining exhausts produce at least 20 percent lower % CTmax values in the downstream hot gas plume than more conventional exhausts.

scholarly journals Combined Gas Turbine and Diesel Generator Cooling Air Intake System

1998 ◽  
Author(s):  
Roger Yee ◽  
Alan Oswald
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Lessons Learned ◽  
Aviation Fuel ◽  
Diesel Generator ◽  
Intake System ◽  
Air Intake ◽  
New Generation ◽  
Cooling Air ◽  
The U.S

A new generation of auxiliary ships to enter the U.S. Navy (USN) fleet is the AOE-6 SUPPLY CLASS. These fast combat support ships conduct operations at sea as part of a Carrier Battle group to provide oil, aviation fuel, and ammunition to the carrier and her escorts. The SUPPLY CLASS is the first ship in the entire USN fleet to use a combined gas turbine and diesel generator cooling air intake system to cool its respective engine modules. The cooling air intake was designed this way to save on costs. As the ships in this class continued with operations and problems of insufficient supply of cooling air for the gas turbines modules started surfacing, the entire intake system required investigation and analysis. Since the gas turbines and diesel generators share a common cooling air trunk, they were competing for air. This paper will outline the tests that were performed to determine the problems, the recommended solutions, and the lessons learned from the investigations.

Gas Turbine Exhaust Expansion Joints, Diverter and Damper Designs for the New Generation of Higher Temperature, High Efficiency Gas Turbines

1989 ◽  
Author(s):  
Lothar Bachmann ◽  
W. Fred Koch
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Combined Cycle ◽  
Operating Conditions ◽  
High Mass ◽  
Expansion Joints ◽  
Gas Turbine Exhaust ◽  
New Generation ◽  
Turbine Exhaust

The purpose of this paper is to update the industry on the evolutionary steps that have been taken to address higher requirements imposed on the new generation combined cycle gas turbine exhaust ducting expansion joints, diverter and damper systems. Since the more challenging applications are in the larger systems, we shall concentrate on sizes from nine (9) square meters up to forty (40) square meters in ducting cross sections. (Reference: General Electric Frame 5 through Frame 9 sizes.) Severe problems encountered in gas turbine applications for the subject equipment are mostly traceable to stress buckling caused by differential expansion of components, improper insulation, unsuitable or incompatible mechanical design of features, components or materials, or poor workmanship. Conventional power plant expansion joints or dampers are designed for entirely different operating conditions and should not be applied in gas turbine applications. The sharp transients during gas turbine start-up as well as the very high temperature and high mass-flow operation conditions require specific designs for gas turbine application.

Performance of a Longitudinal Circular-to-Slot Gas Turbine Exhaust Duct With a 90 Degree Bend

2004 ◽  
Author(s):  
S. Bottenheim ◽  
A. M. Birk ◽  
D. J. Poirier
Keyword(s):  
Gas Turbine ◽  
Structural Integrity ◽  
Ambient Air ◽  
Effective Area ◽  
Loss Coefficient ◽  
Flow Distortion ◽  
Rectangular Slot ◽  
High Loss ◽  
Numerical Predictions ◽  
Gas Turbine Exhaust

In some gas turbine applications, it is desirable to redirect the exhaust flow through 90 degrees and mix this flow with the ambient air for the purposes of structural integrity and heat signature suppression. A method to achieve this is to transform the flow from a circular profile to a rectangular slot of high aspect ratio. The increase in wetted perimeter allows for greater mixing with the ambient air; however the shape of such a duct causes significant amounts of flow distortion and poor pressure recovery. This paper presents preliminary experimental results of the performance of such a duct and discusses the ability of a commercial CFD software package to numerically predict this performance. Significant crossflows and reversed flows were observed at the duct outlet leading to inefficient use of the outlet area, high back pressure and consequently a high loss coefficient. These trends are exacerbated with an increasing inlet swirl angle. The preliminary numerical predictions captured the general trends of the flow but could not capture the extent of the reversed flow, leading to over-prediction of the effective area ratio, E, and under-prediction of the loss coefficient, k.

Numerical and Experimental Study on the Suppression for the Infrared Signatures of a Marine Gas Turbine Exhaust System

2000 ◽  
Author(s):  
Shaorong Zhou ◽  
Zhaohui Du ◽  
Hanping Chen ◽  
Fangyuan Zhong
Keyword(s):  
Gas Turbine ◽  
Exhaust System ◽  
Scale Model ◽  
Ir Radiation ◽  
Exhaust Duct ◽  
Ir Signature ◽  
Gas Turbine Exhaust ◽  
Control Volumes ◽  
Cooling Air ◽  
Turbine Exhaust

The flow and thermal fields within the cooling air injection device which is widely used to suppress the infrared (IR) signatures of a marine gas turbine exhaust system were studied numerically and experimentally. A turbulence near-wall model based on the wall function method was adopted. The discretization equations were derived for the control volumes when conjugate heat transfer exists at their interfaces, with the radiation heat flux at the interfaces appearing as an additional source term. The solution method of entrained velocities at the entrance of secondary flow was introduced. The distributions of temperature and static pressure on the diffuser surface, and the temperature of gas at the outlet of the exhaust duct were simulated numerically. The numerical calculated results agreed well with corresponding scale model experimental data. Lastly, the measured IR radiation distributions by scale model experiments at different view angles and various engine power settings, with and without IR signature suppression (IRSS) devices were presented.

Marine Gas Turbine Infra-Red Signature Suppression: Aerothermal Design Considerations

1989 ◽  
Author(s):  
A. M. Birk ◽  
D. Vandam
Keyword(s):  
Gas Turbine ◽  
Ambient Air ◽  
Ir Radiation ◽  
Engine Exhaust ◽  
Design Considerations ◽  
Quantitative Performance ◽  
The Subject ◽  
Ir Signature ◽  
Gas Turbine Exhaust ◽  
System Selection

In recent years it has become evident that the Infrared (IR) Radiation given off by marine gas turbine exhaust systems is highly undesirable for naval vessels and commercial vessels traveling in areas of conflict. As a result, great interest has surfaced in the ways that IR signatures can be reduced. This paper presents an overview of some of the methods that can be used for engine exhaust IR signature suppression (IRSS). The methods considered here involve only ambient air addition for metal and plume cooling. The present paper describes various IRSS systems and discusses the basic technical criteria for system selection. Basic operating principles are also described. Aerothermal design considerations are discussed and areas requiring special care during the design are highlighted. Because of the confidential nature of the subject, direct quantitative performance comparisons cannot be made.

Gas Turbine Training in the Royal Navy

1988 ◽  
Author(s):  
T. J. Meadows
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Royal Navy ◽  
Career Training ◽  
Enlisted Men ◽  
Marine Engineering ◽  
New Generation

This paper discusses the training given to the personnel of the Marine Engineering Branch of the Royal Navy to enable them to maintain and operate the main propulsion gas turbines fitted in the new generation of warships. Concentrating on the aspects appertaining to gas turbines, the paper describes the training given to both officers and enlisted men during their initial career training both ashore and at sea, and also outlines the training undertaken by personnel to prepare them for appointments to specific ships. Finally, the methods of validating this training to ensure that it meets the requirements of the Fleet are described.

Grid Connected Electrical-Thermal (Cogeneration) Energy System for University of California, Davis, California

1978 ◽  
Author(s):  
C. Martineau ◽  
J. L. Boyen
Keyword(s):  
Gas Turbine ◽  
Heat Recovery ◽  
Electrical Power ◽  
Energy System ◽  
Heat Recovery Boiler ◽  
Utility System ◽  
Fuel Rate ◽  
Gas Turbine Exhaust ◽  
Continuous Blowdown ◽  
Cooling Air

The energy system described represents the latest technology in on-site grid-connected systems for the power range used. The electrical portion of the system consists of a liquid fuel fired gas turbine driving a 3-MW alternator which is connected into the utility system. The gas turbine is supercharged to 12 in. w.c. It is planned to operate the turbine-generator at full load continuously, thereby securing operation at the optimum fuel rate. Heat is recovered from the gas turbine exhaust by a novel heat recovery boiler utilizing a controlled economizer. Steam is generated at 150 psig and is fed into the campus steam system for heating, air conditioning, and other uses. Steam rate is 20,300 lb/hr to a final stack temperature of 308 F. Additional heat is recovered from the turbine oil cooler, the alternator cooling air, and the boiler’s continuous blowdown. The combination of electrical power generation and heat recovery from the above sources produces an overall plant efficiency of 83 percent.

Influence of Non-Equilibrium Fluid Properties During Fogging on Intake Duct and Compressor Characteristics

2017 ◽  
Author(s):  
Christoph Günther ◽  
Franz Joos
Keyword(s):  
Relative Humidity ◽  
Gas Turbine ◽  
Thermophysical Properties ◽  
Ambient Air ◽  
Compressor Stage ◽  
Compression Process ◽  
Fluid Properties ◽  
Temperature And Pressure ◽  
Gas Turbine Compressor ◽  
Non Equilibrium

This study reports on numerically calculated thermophysical properties of air passing through a gas turbine compressor after passage through an intake duct affected by wet compression. Case of reference is unaffected ambient air (referenced to as dry scenario) passing through intake duct and compressor. Furthermore, ambient air cooled down by (overspray) fogging (referenced to as wet scenarios) was considered. Acceleration at the end of intake duct causing reduction of static temperature and pressure results in supersaturated fluid properties at inlet to gas turbine compressor. These supersaturated fluid properties are non-equilibrium with saturation level above relative humidity of φ = 1. Entrance of supersaturated fluid into gas turbine compressor can result in condensation within first compressor stage. At the same time delayed impact of evaporative cooling influences compression process.

Dynamic Simulation of a HRSG System for a Given Start-Up/Shut Down Curve

2011 ◽  
Author(s):  
Hun Cha ◽  
Yoo Seok Song ◽  
Kyu Jong Kim ◽  
Jung Rae Kim ◽  
Sung Min KIM
Keyword(s):  
Dynamic Analysis ◽  
Gas Turbine ◽  
Flow Rate ◽  
Exhaust Gas ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Start Up ◽  
Gas Turbine Exhaust ◽  
Main Steam ◽  
Duct Burner

An inappropriate design of HRSG (Heat Recovery Steam Generator) may lead to mechanical problems including the fatigue failure caused by rapid load change such as operating trip, start-up or shut down. The performance of HRSG with dynamic analysis should be investigated in case of start-up or shutdown. In this study, dynamic analysis for the HRSG system was carried out by commercial software. The HRSG system was modeled with HP, IP, LP evaporator, duct burner, superheater, reheater and economizer. The main variables for the analysis were the temperature and mass flow rate from gas turbine and fuel flow rate of duct burner for given start-up (cold/warm/hot) and shutdown curve. The results showed that the exhaust gas condition of gas turbine and fuel flow rate of duct burner were main factors controlling the performance of HRSG such as flow rate and temperature of main steam from final superheater and pressure of HP drum. The time delay at the change of steam temperature between gas turbine exhaust gas and HP steam was within 2 minutes at any analysis cases.

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