Flow Guiding and Distributing Devices on the Exhaust Side of Stationary Gas Turbines

1990 ◽  
Vol 112 (1) ◽  
pp. 80-85
Author(s):  
F. Fleischer ◽  
C. Koerner ◽  
J. Mann

Following repeated cases of damage caused to exhaust silencers located directly beyond gas turbine diffusers, this paper reports on investigations carried out to determine possible remedies. In all instances, an uneven exhaust gas flow distribution was found. The company’s innovative approach to the problem involved constructing a scale model of a complete gas turbine exhaust system and using it for flow simulation purposes. It was established for the first time that, subject to certain conditions, the results of tests conducted on a model can be applied to the actual turbine exhaust system. It is shown that when an unfavorable duct arrangement might produce an uneven exhaust flow, scale models are useful in the development of suitable flow-distributing devices.

Author(s):  
Friedrich Fleischer ◽  
Christian Koerner ◽  
Juergen Mann

Following repeated cases of damage caused to exhaust silencers located directly beyond gas turbine diffusers, this paper reports on investigations carried out to determine possible remedies. In all instances, an uneven exhaust gas flow distribution was found to be present. The company’s innovative approach to the problem involved constructing a scale model of a complete gas turbine exhaust system and using it for flow simulation purposes. It was established for the first time that, subject to certain conditions, the results of tests conducted on a model can be applied to the actual turbine exhaust system. It is shown that when an unfavourable duct arrangement might produce an uneven exhaust flow, scale models are useful in the development of suitable flow-distributing devices.


Author(s):  
Fangyuan Zhong ◽  
Yu Dai

On the basis of scale model tests in two different dimensions of marine gas turbine exhaust system with infrared signature suppression device, and in the light of similarity analysis and simplified numerical calculation, this paper discusses the effects of scale factor on the flow (flow resistance), temperature (of air-flow and tube wall), and infrared radiant (of exhaust plumes and exhaust uptake inner wall) fields of the exhaust system, and accordingly estimates the corresponding parameters of real ship exhaust systems as well as presents the magnitude of scale factor impacts and the recommended values for selecting the scale factor.


Author(s):  
Shaorong Zhou ◽  
Zhaohui Du ◽  
Hanping Chen ◽  
Fangyuan Zhong

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.


Author(s):  
Bijay K. Sultanian ◽  
Shinichiro Nagao ◽  
Taro Sakamoto

Both experimental and 3D CFD investigations are carried out in a scale model of an industrial gas turbine exhaust system to better understand its complex flow field and to validate CFD prediction capabilities for improved design applications. The model consists of an annular diffuser passage with struts, followed by turning vanes and a rectangular plenum with side exhaust. Precise measurements of total/static pressure and flow velocity distributions at the model inlet, strut outlet and model outlet are made using aerodynamic probes and locally a Laser Doppler Velocimeter (LDV). Numerical analyses of the model internal flow field are performed utilizing a three-dimensional Navier-Stokes (N-S) calculation method with the industry standard k-ε turbulence model. Both the experiments and computations are carried out for three load conditions: full speed no load (FSNL), full speed mid load (FSML, 57% load), and full speed full load (FSFL). Based on the overall comparison between the measurements and CFD predictions, this study concludes that the applied N-S method is capable of predicting complicated gas turbine exhaust system flows for design applications.


1999 ◽  
Vol 121 (2) ◽  
pp. 364-374 ◽  
Author(s):  
B. K. Sultanian ◽  
S. Nagao ◽  
T. Sakamoto

Both experimental and three-dimensional CFD investigations are carried out in a scale model of an industrial gas turbine exhaust system to better understand its complex flow field and to validate CFD prediction capabilities for improved design applications. The model consists of an annular diffuser passage with struts, followed by turning vanes and a rectangular plenum with side exhaust. Precise measurements of total/static pressure and flow velocity distributions at the model inlet, strut outlet and model outlet are made using aerodynamic probes and locally a Laser Doppler Velocimeter (LDV). Numerical analyses of the model internal flow field are performed utilizing a three-dimensional Navier-Stokes (N-S) calculation method with the industry standard k-ε turbulence model. Both the experiments and computations are carried out for three load conditions: full speed no load (FSNL), full speed mid load (FSML, 57 percent load), and full speed full load (FSFL). Based on the overall comparison between the measurements and CFD predictions, this study concludes that the applied N-S method is capable of predicting complicated gas turbine exhaust system flows for design applications.


Author(s):  
L. Itter ◽  
M. Cagna ◽  
A. Wiedermann ◽  
M. Boehle

Today’s market for gas turbines is getting bigger since there is a huge demand for power generation and mechanical drive applications. To meet the market requirements gas turbine components have to be very efficient to play a leading role. In order to accelerate component improvement the introduction of integrated CAx Technology is a key to achieve a less time-consuming and therefore cheaper design. This paper will describe a procedure which can be used to design an exhaust system for gas turbines with hot-end drive. It shows how to combine various technologies like CAD and CFD and make them work together rapidly. Firstly a 1D design is done and compared with a performance chart of conventional use. Then, a 2D parametric study of a 90 degree bend will be performed by the combination of a CAD-system and a CFD-solver. Thirdly a full 3D-simulation of the entire exhaust will be performed with a calibrated solver. Different complex geometry modifications are applied and their influence on the performance of the exhaust will be discussed.


1974 ◽  
Vol 96 (3) ◽  
pp. 181-184 ◽  
Author(s):  
J. R. Cummins

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.


Author(s):  
Jie Gao ◽  
Feng Lin ◽  
Xiying Niu ◽  
Qun Zheng ◽  
Guoqiang Yue ◽  
...  

The marine gas turbine exhaust volute is an important component that connects a power turbine and an exhaust system, and it is of great importance to the overall performance of the gas turbine. Gases exhausted from the power turbine are expanded and deflected 90 degrees in the exhaust volute, and then discharge radially into the exhaust system. The flows in the power turbine and the nonaxisymmetric exhaust volute are closely coupled and inherently unsteady. The flow interactions between the power turbine and the exhaust volute have a significant influence on the shrouded rotor blade aerodynamic forces. However, the interactions have not been taken into account properly in current power turbine design approaches. The present study aims to investigate the flow interactions between the last stage of a shrouded power turbine and the nonaxisymmetric exhaust volute with struts. Special attention is given to the coupled aerodynamics and pressure response studies. This work was carried out using coupled computational fluid dynamics (CFD) simulations with the computational domain including a stator vane, 76 shrouded rotor blades, 9 struts and an exhaust volute. Three-dimensional (3D) unsteady and steady Reynolds-averaged Navier-Stokes (RANS) solutions in conjunction with a Spalart-Allmaras turbulence model are utilized to investigate the aerodynamic characteristics of shrouded rotors and an exhaust volute using a commercial CFD software ANSYS Fluent 14.0. The asymmetric flow fields are analyzed in detail; as are the unsteady pressures on the shrouded rotor blade. In addition, the unsteady total pressures at the volute outlet is also analyzed without consideration of the upstream turbine effects. Results show that the flows in the nonaxisymmetric exhaust volute are inherently unsteady; for the studied turbine-exhaust configuration the nonaxisymmetric back-pressure induced by the downstream volute leads to the local flow varying for each shrouded blade and low frequency fluctuations in the blade force. Detailed results from this investigation are presented and discussed in this paper.


1974 ◽  
Author(s):  
Marv Weiss

A unique method for silencing heavy-duty gas turbines is described. The Switchback exhaust silencer which utilizes no conventional parallel baffles has at operating conditions measured attenuation values from 20 dB at 63 Hz to 45 dB at higher frequencies. Acoustic testing and analyses at both ambient and operating conditions are discussed.


Author(s):  
David T. Ryan ◽  
Judith A. Veatch ◽  
Akber Pasha

‘Soft’ start flow distribution, control capability, sealing performance, and safety, were four reasons Oklahoma Municipal Power Authority (OMPA), in cooperation with Black & Veatch and Vogt, installed Dual BiPlane Heat Recovery Steam Generator (HRSG) Isolation and Bypass Dampers from Damper Design, Inc. on the gas turbine outlet at this facility. The DDI BiPlane damper is truly a unique damper for this application. This design allowed OMPA to have the safety and isolation of a flap diverter white providing the even gas distribution and accurate flow control to the HRSG under startup conditions available from a louver style damper. The arrangement consists of two DDI BiPlane dampers, one on the inlet to the HRSG and one isolating the stack. Since safety is highest priority, Damper Design utilized an independent lockout type linkage that allows control of the dampers while positively preventing the closure of both gas paths at the same time. By installing the DDI BiPlane damper, OMPA has the ability to throttle the gas turbine exhaust flow independently to the HRSG and stack. This allows the gases to enter the HRSG with a much more evenly distributed flow pattern and at lower controlled flow rates than with competing designs. This paper will address the benefits, design, and operating advantages of the use of the DDI BiPlane Damper specifically in HRSG isolation and bypass installations. It is also applicable to other systems where control and isolation with one damper is desirable.


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