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.

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.

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 Enhancing scour protection in river bends: a novel slotted bank-attached vane

2020 ◽  
Vol 20 (6) ◽  
pp. 2175-2184
Author(s):  
Mohamad Azizipour ◽  
Farshid Amirsalari Meymani ◽  
Mohammad Mahmoodian Shooshtari
Keyword(s):  
Effective Area ◽  
Local Scour ◽  
Flume Experiments ◽  
Rectangular Slot ◽  
Outer Bank ◽  
Scour Hole ◽  
Submerged Vane ◽  
River Bends ◽  
Scour Protection ◽  
Control Erosion

Abstract One of the most effective approaches for bank control erosion is using bank-attached vanes. In spite of the superiority of the bank-attached vanes to spur dikes, the vanes' tips are still vulnerable to local scour caused by flow–structure interaction. In this study, slotted bank-attached vanes are proposed to reduce local scour at the tip of the triangular submerged vane. For this, a rectangular slot is created parallel to the chord of the vane with an area of ten percent of the effective area of the vane surface. Two types of conventional vanes and slotted vanes were installed at different angles of attack of 23, 30, 40 and 60 degrees in an arch flume. Experiments were carried out in clear water conditions with different flow regimes with Froude numbers of Fr = 0.287, 0.304 and 0.322. The results show that the slotted vane outperforms the conventional vane by reducing maximum scour depth by about 70, 20, 17 and 54 percent for different angles of attack of 23, 30, 40 and 60 degrees, respectively. The proposed slotted vane also resulted in reduction of scour hole volume around the vane and formed the scour hole away from the outer bank.

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.

Acoustic Characteristics of a Gas Turbine Exhaust Model

1974 ◽  
Vol 96 (3) ◽  
pp. 181-184 ◽  
Author(s):  
J. R. Cummins
Keyword(s):  
Gas Turbine ◽  
Acoustic Radiation ◽  
Flow Path ◽  
Scale Model ◽  
Temperature Ratio ◽  
Acoustic Characteristics ◽  
Gas Turbine Exhaust ◽  
Acoustical Data ◽  
Turbine Exhaust

To investigate the sources of acoustic radiation from a gas turbine exhaust, a one-seventh scale model has been constructed. The model geometrically scales the flow path downstream of the rotating parts including support struts and turning vanes. A discussion and comparison of different kinds of aerodynamic and acoustic scaling techniques are given. The effect of the temperature ratio between model and prototype is found to be an important parameter in comparing acoustical data.

A New Calculation Approach to the Energy Balance of a Gas Turbine Including a Study of the Impact of the Uncertainty of Measured Parameters

2005 ◽  
Author(s):  
Helmer G. Andersen ◽  
Pen-Chung Chen
Keyword(s):  
Energy Balance ◽  
Gas Turbine ◽  
Control Volume ◽  
Ambient Air ◽  
Energy Balance Equation ◽  
Inlet Temperature ◽  
Exhaust Gas ◽  
Gas Composition ◽  
Intake Flow ◽  
The Impact

Computing the solution to the energy balance around a gas turbine in order to calculate the intake mass flow and the turbine inlet temperature requires several iterations. This makes hand calculations very difficult and, depending on the software used, even causes significant calculation times on PCs. While this may not seem all that important considering the power of today’s personal computers, the approach described in this paper presents a new way of looking at the gas turbine process and the resulting simplifications in the calculations. This paper offers a new approach to compute the energy balance around a gas turbine. The energy balance requires that all energy flows going into and out of the control volume be accounted for. The difficulty of the energy balance equation around a gas turbine lies in the fact that the exhaust gas composition is unknown as long as the intake flow is unknown. Thus, a composition needs to be assumed when computing the exhaust gas enthalpy. This allows the calculation of the intake flow, which in turn provides a new exhaust gas composition, and so forth. By viewing the exhaust gas as a flow consisting of ambient air and combusted fuel, the described iteration can be avoided. The study presents the formulation of the energy balance applying this approach and looks at the accuracy of the result as a function of the inaccuracy of the input parameters. Furthermore, solutions of the energy balance are presented for various process scenarios, and the impact of the uncertainty of key process parameter is analyzed.

Prediction of Pressure Rise in a Gas Turbine Exhaust Duct Under Flameout Scenarios While Operating On Hydrogen and Natural Gas Blends

2021 ◽  
Author(s):  
Orlando Ugarte ◽  
Suresh Menon ◽  
Wayne Rattigan ◽  
Paul Winstanley ◽  
Priyank Saxena ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Combustion Process ◽  
Pressure Rise ◽  
Combustion Model ◽  
Computational Domain ◽  
Cfd Model ◽  
Exhaust Duct ◽  
Gas Turbine Exhaust ◽  
Turbine Exhaust

Abstract In recent years, there is a growing interest in blending hydrogen with natural gas fuels to produce low carbon electricity. It is important to evaluate the safety of gas turbine packages under these conditions, such as late-light off and flameout scenarios. However, the assessment of the safety risks by performing experiments in full-scale exhaust ducts is a very expensive and, potentially, risky endeavor. Computational simulations using a high fidelity CFD model provide a cost-effective way of assessing the safety risk. In this study, a computational model is implemented to perform three dimensional, compressible and unsteady simulations of reacting flows in a gas turbine exhaust duct. Computational results were validated against data obtained at the simulated conditions in a representative geometry. Due to the enormous size of the geometry, special attention was given to the discretization of the computational domain and the combustion model. Results show that CFD model predicts main features of the pressure rise driven by the combustion process. The peak pressures obtained computationally and experimentally differed in 20%. This difference increased up to 45% by reducing the preheated inflow conditions. The effects of rig geometry and flow conditions on the accuracy of the CFD model are discussed.

scholarly journals General Design Considerations for Gas Turbine Waste Heat Steam Generators

1968 ◽  
Author(s):  
W. V. Hambleton
Keyword(s):  
Gas Turbine ◽  
Heat Recovery ◽  
Waste Heat ◽  
Steam Generation ◽  
Steam Generators ◽  
Design Considerations ◽  
Exhaust Heat ◽  
Gas Turbine Exhaust ◽  
Exhaust Heat Recovery ◽  
Turbine Exhaust

This paper represents a study of the overall problems encountered in large gas turbine exhaust heat recovery systems. A number of specific installations are described, including systems recovering heat in other than the conventional form of steam generation.

scholarly journals Gas Turbine Heat Recovery Steam Generators for Combined Cycles Natural or Forced Circulation Considerations

1988 ◽  
Author(s):  
Akber Pasha
Keyword(s):  
Gas Turbine ◽  
Steam Generator ◽  
Heat Recovery ◽  
Power Plants ◽  
Natural Circulation ◽  
Combined Cycle ◽  
Heat Recovery Steam Generator ◽  
Steam Generators ◽  
Forced Circulation ◽  
Gas Turbine Exhaust

In recent years the combined cycle has become a very attractive power plant arrangement because of its high cycle efficiency, short order-to-on-line time and flexibility in the sizing when compared to conventional steam power plants. However, optimization of the cycle and selection of combined cycle equipment has become more complex because the three major components, Gas Turbine, Heat Recovery Steam Generator and Steam Turbine, are often designed and built by different manufacturers. Heat Recovery Steam Generators are classified into two major categories — 1) Natural Circulation and 2) Forced Circulation. Both circulation designs have certain advantages, disadvantages and limitations. This paper analyzes various factors including; availability, start-up, gas turbine exhaust conditions, reliability, space requirements, etc., which are affected by the type of circulation and which in turn affect the design, price and performance of the Heat Recovery Steam Generator. Modern trends around the world are discussed and conclusions are drawn as to the best type of circulation for a Heat Recovery Steam Generator for combined cycle application.

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