Improved Compressor Exit Diffuser for an Industrial Gas Turbine

2001 ◽  
Vol 124 (1) ◽  
pp. 19-26 ◽  
Author(s):  
U. Orth ◽  
H. Ebbing ◽  
H. Krain ◽  
A. Weber ◽  
B. Hoffmann

Cycle studies carried out for the medium pressure ratio gas turbine THM 1304 of 10 MW power output manufactured by MAN Turbomaschinen AG GHH BORSIG predicted that the overall efficiency of the multistage compressor, composed of a ten-stage axial and a single-stage centrifugal compressor, would improve by 0.8 percent if the efficiency of the back stage centrifugal unit could be raised by 4 percent. It was expected that this would result in a noticeable improvement of the thermal gas turbine efficiency. The paper describes the aerodynamic design process used for the stage optimization, applying today’s advanced design tools for blade generation and three-dimensional aerodynamic calculation methods. Additionally, it describes the manufacturing procedure for the resulting three-dimensional blades and the experimental verification of the design approach.

Author(s):  
U. Orth ◽  
H. Ebbing ◽  
H. Krain ◽  
A. Weber ◽  
B. Hoffmann

Cycle studies carried out for the medium pressure ratio gas turbine THM 1304 of 10 MW power output manufactured by MAN Turbomaschinen AG GHH BORSIG predicted that the overall efficiency of the multi stage compressor, composed of a 10 stage axial and a single stage centrifugal compressor, would improve by 0.8% if the efficiency of the back stage centrifugal unit could be raised by 4%. It was expected that this would result in a noticeable improvement of the thermal gas turbine efficiency. The paper describes the aerodynamical design process used for the stage optimization applying today’s advanced design tools for blade generation and three dimensional aerodynamic calculation methods. Additionally it describes the manufacturing procedure for the resulting three-dimensional blades and the experimental verification of the design approach.


Author(s):  
F. Carchedi ◽  
G. R. Wood

This paper describes the design and development of a 15-stage axial flow compressor for a −6MW industrial gas turbine. Detailed aspects of the aerodynamic design are presented together with rig test data for the complete characteristic including stage data. Predictions of spanwise flow distributions are compared with measured values for the front stages of the compressor. Variable stagger stator blading is used to control the position of the low speed surge line and the effects of the stagger changes are discussed.


Author(s):  
Mohammad R. Saadatmand

The aerodynamic design process leading to the production configuration of a 14 stage, 16:1 pressure ratio compressor for the Taurus 70 gas turbine is described. The performance of the compressor is measured and compared to the design intent. Overall compressor performance at the design condition was found to be close to design intent. Flow profiles measured by vane mounted instrumentation are presented and discussed. The flow through the first rotor blade has been modeled at different operating conditions using the Dawes (1987) three-dimensional viscous code and the results are compared to the experimental data. The CFD prediction agreed well with the experimental data across the blade span, including the pile up of the boundary layer on the corner of the hub and the suction surface. The rotor blade was also analyzed with different grid refinement and the results were compared with the test data.


1982 ◽  
Vol 104 (4) ◽  
pp. 823-831 ◽  
Author(s):  
F. Carchedi ◽  
G. R. Wood

The paper describes the design and development of a 15 stage axial flow compressor for a 6-MW industrial gas turbine. Detailed aspects of the aerodynamic design are presented together with rig test data for the complete characteristic including stage data. Predictions of spanwise flow distributions are compared with measured values for the front stages of the compressor. Variable stagger stator blading is used to control the position of the low-speed surge line and the effects of the stagger changes are discussed.


Author(s):  
Milan V. Petrovic ◽  
Alexander Wiedermann ◽  
Srecko M. Nedeljkovic ◽  
Milan Banjac

The operation under off-design conditions of a two-stage LP part of a 6.5 MW industrial gas turbine was analyzed in this work. Since the turbine is able to vary the rotation speed in a wide range from 40 to 140% of the design speed, a flow with extremely large positive and negative incidence angle appears. The flow field was calculated applying 2D through-flow code for the analysis of axial multistage turbines with cooling by air from compressor bleed. The code was developed by the authors and validated by calculation of a number of test cases with different configurations. The method is based on a stream function approach and a finite element solution procedure. In parallel, the flow in the turbine was calculated using a commercial CFD code. Based on the calculated flow field, the turbine efficiency and pressure ratio and also different stage parameters were determined for the design point and for a wide range of off-design conditions. Comparison of the predicted results and measured test data for a number of parameters showed good agreement.


Author(s):  
Takuya Ikeguchi ◽  
Akinori Matsuoka ◽  
Yusuke Sakai ◽  
Yoshinobu Sakano ◽  
Kenichiro Yoshiura

A 14-stage axial flow compressor was newly designed and tested for developing an advanced industrial gas turbine. In order to achieve a high thermal efficiency required for the new gas turbine, the compressor needed to have a significantly higher pressure ratio and higher efficiency than those of existing engines. The new design methodology used to this compressor design was based on an automated airfoil geometric optimization system combined with a 3D-CFD analysis, which resulted in arbitrary shaped airfoil design in most blade rows. A multi-stage CFD analysis was used effectively in order to adjust a loading distribution along stages and to obtain a proper stage matching. Before the full development of the gas turbine, an approximately two-thirds scaled compressor rig tests were conducted to verify the aerodynamic design and the structural reliability. The test results of the first build indicated a satisfactory level of efficiency and mass flow, but with a lack of sufficient stall margin. The second build with the re-staggered vanes was tested and its result showed improvements both in stall margin and in efficiency. The prototype test of developing an industrial gas turbine also had been conducted. The measured performance of the compressor which was scaled up from the second build rig compressor achieved the design target. Consequently, the aerodynamic design which considered the scale effects of the compressor was successful.


Author(s):  
A. R. Wadia ◽  
D. P. Wolf ◽  
F. G. Haaser

The LM2500+ gas turbine, rated between 39,000 to 40,200 shaft horsepower (shp), was introduced for field service in 1998. This growth aero-derivative gas turbine is suitable for a variety of power generation applications, such as co-generation and combined cycle, as well as mechanical drive applications. At the heart of the LM2500+ 25% power increase is an up-rated derivative 17-stage axial compressor. This paper describes the aerodynamic design and development of this high pressure ratio single spool compressor for the LM2500+ gas turbine. The compressor is derived by zero-staging the highly efficient and reliable LM2500 compressor to increase the flow by 23% at a pressure ratio of 23.3:1. The aerodynamic efficiency of the compressor is further improved by using three-dimensional, custom-tailored airfoil designs similar to those used in the CF6-80C2 high pressure compressor. The compressor achieved a peak polytropic efficiency above 91 percent, meeting all its operability objectives. The technical requirements and overall aerodynamic design features of the compressor are presented first. Next, the zero stage match point selection is described and the procedure used to set up the vector diagrams using a through-flow code with secondary flow and mixing is outlined. Detailed design results for the new transonic airfoils in the compressor using three-dimensional viscous analysis are presented. The compressor instrumentation and performance test results are discussed. The performance of the zero stage is separated from that of the baseline compressor with the CF6-80C2 airfoils to show the improvement in efficiency with the new airfoils.


2002 ◽  
Vol 124 (3) ◽  
pp. 331-340 ◽  
Author(s):  
A. R. Wadia ◽  
D. P. Wolf ◽  
F. G. Haaser

The LM2500+ gas turbine, rated between 39,000–40,200 shaft horsepower (shp), was introduced for field service in 1998. This growth aero-derivative gas turbine is suitable for a variety of power generation applications, such as co-generation and combined cycle, as well as mechanical drive applications. At the heart of the LM2500+ 25% power increase is an up-rated derivative 17-stage axial compressor. This paper describes the aerodynamic design and development of this high-pressure ratio single-spool compressor for the LM2500+ gas turbine. The compressor is derived by zero-staging the highly efficient and reliable LM2500 compressor to increase the flow by 23% at a pressure ratio of 23.3:1. The aerodynamic efficiency of the compressor is further improved by using three-dimensional, custom-tailored airfoil designs similar to those used in the CF6-80C2 high-pressure compressor. The compressor achieved a peak polytropic efficiency above 91%, meeting all its operability objectives. The technical requirements and overall aerodynamic design features of the compressor are presented first. Next, the zero stage match point selection is described and the procedure used to set up the vector diagrams using a through-flow code with secondary flow and mixing is outlined. Detailed design results for the new transonic airfoils in the compressor using three-dimensional viscous analysis are presented. The compressor instrumentation and performance test results are discussed. The performance of the zero stage is separated from that of the baseline compressor with the CF6-80C2 airfoils to show the improvement in efficiency with the new airfoils.


Author(s):  
T. L. Ragland

After industrial gas turbines have been in production for some amount of time, there is often an opportunity to improve or “uprate” the engine’s output power or cycle efficiency or both. In most cases, the manufacturer would like to provide these uprates without compromising the proven reliability and durability of the product. Further, the manufacturer would like the development of this “Uprate” to be low cost, low risk and result in an improvement in “customer value” over that of the original design. This paper describes several options available for enhancing the performance of an existing industrial gas turbine engine and discusses the implications for each option. Advantages and disadvantages of each option are given along with considerations that should be taken into account in selecting one option over another. Specific options discussed include dimensional scaling, improving component efficiencies, increasing massflow, compressor zero staging, increasing firing temperature (thermal uprate), adding a recuperator, increasing cycle pressure ratio, and converting to a single shaft design. The implications on output power, cycle efficiency, off-design performance engine life or time between overhaul (TBO), engine cost, development time and cost, auxiliary requirements and product support issues are discussed. Several examples are provided where these options have been successfully implemented in industrial gas turbine engines.


Author(s):  
Thomas Wagner ◽  
Robert J. Burke

The desire to maintain power plant profitability, combined with current market fuel gas pricing is forcing power generation companies to constantly look for ways to keep their industrial gas turbine units operating at the highest possible efficiency. Gas Turbines Operation requires the compression of very large quantities of air that is mixed with fuel, ignited and directed into a turbine to produce torque for purposes ranging from power generation to mechanical drive of pumping systems to thrust for air craft propulsion. The compression of the air for this process typically uses 60% of the required base energy. Therefore management of the compression process efficiency is very important to maintain overall cycle efficiency. Since fouling of turbine compressors is almost unavoidable, even with modern air filter treatment, and over time results in lower efficiency and output, compressor cleaning is required to maintain gas turbine efficiency.


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