The Influence of the Total Pressure Profile on the Performance of Axial Gas Turbine Diffusers

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
A. Hirschmann ◽  
S. Volkmer ◽  
M. Schatz ◽  
C. Finzel ◽  
M. Casey ◽  
...  
Keyword(s):  
Flow Separation ◽  
Gas Turbines ◽  
Total Pressure ◽  
Pressure Profile ◽  
Cfd Simulations ◽  
Pressure Profiles ◽  
Industrial Gas Turbines ◽  
Sst Turbulence Model ◽  
Computational Fluid Dynamics Cfd ◽  
Highly Loaded

Large industrial gas turbines for combined heat and power generation normally have axial diffusers leading to the heat recovery steam generator. The diffusers operate with high inlet axial Mach number (0.6) and with a nonuniform inlet total pressure profile from the turbine. Tests have been carried out on a generic highly loaded axial diffuser in a scaled axial diffuser test rig, with different inlet total pressure profiles including those that might be met in practice. The results show that the inlet total pressure profile has a strong effect on the position of flow separation, whereby a hub-strong profile tends to separate at the casing and the tip-strong profile on the hub. Steady computational fluid dynamics (CFD) simulations using the shear stress transport (SST) turbulence model have been carried out based on extensive studies of the best way to model the inlet boundary conditions. These simulations provide good agreement with the prediction of separation in the diffuser but the separated regions often persist too long so that, in this highly loaded case with flow separation, the calculated diffuser pressure recovery can be in error by up to 30%.

The Influence of the Total Pressure Profile on the Performance of Axial Gas Turbine Diffusers

2010 ◽  
Author(s):  
A. Hirschmann ◽  
S. Volkmer ◽  
M. Schatz ◽  
C. Finzel ◽  
M. Casey ◽  
...  
Keyword(s):  
Flow Separation ◽  
Gas Turbines ◽  
Total Pressure ◽  
Pressure Profile ◽  
Cfd Simulations ◽  
Pressure Profiles ◽  
Industrial Gas Turbines ◽  
Sst Turbulence Model ◽  
Highly Loaded ◽  
Good Agreement

Large industrial gas turbines for combined heat and power generation normally have axial diffusers leading to the heat recovery steam generator. The diffusers operate with high inlet axial Mach number (0.6) and with a non-uniform inlet total pressure profile from the turbine. Tests have been carried out on a generic highly loaded axial diffuser in a scaled axial diffuser test rig, with different inlet total pressure profiles including those that might be met in practice. The results show that the inlet total pressure profile has a strong effect on the position of flow separation, whereby a hub-strong profile tends to separate at the casing and the tip-strong profile on the hub. Steady CFD simulations using the SST turbulence model have been carried out based on extensive studies of the best way to model the inlet boundary conditions. These simulations provide good agreement with the prediction of separation in the diffuser but the separated regions often persist too long so that, in this highly loaded case with flow separation, the calculated diffuser pressure recovery can be in error by up to 30%.

Influence of Tip Jet Mass Flow and Blowing Rate on the Performance of an Axial Diffuser at Different Inlet Total Pressure Profiles

2015 ◽  
Author(s):  
Rojas Thomas ◽  
Markus Schatz ◽  
Benjamin Kuschel ◽  
Silke Brouwer ◽  
A. M. Pradeep ◽  
...  
Keyword(s):  
Mass Flow ◽  
Total Pressure ◽  
Pressure Recovery ◽  
Jet Flows ◽  
Cfd Simulations ◽  
Blowing Ratio ◽  
Pressure Profiles ◽  
Mass Flow Rates ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact

The present paper evaluates the impact of casing energized jet flow on the performance of an annular-conical exhaust diffuser. Two different inflow profiles, namely a uniform total pressure and a hub-strong total pressure inlet profile were studied. For both profiles, the flow is observed to separate at the casing. Experiments were performed at different tip jet mass flow rates and two different tip gap heights to understand their effect on the diffuser performance. Apart from wall pressure readings, probe measurements have been done at various locations within the diffuser to study the flow behaviour in more detail. The results show that at the diffuser inlet already small tip jet flows help to prevent casing separation and hence improve pressure recovery noticeably, especially in the front section of the diffuser. On the other hand, higher tip jet flows tend to weaken the core flow at the diffuser exit, thus generating an inhomogeneous outflow velocity profile. To enhance the interpretation of the experimental data, results from Computational Fluid Dynamics (CFD) simulations are used. Interestingly, the experimental results indicate that while the blowing ratio seems to be the major parameter for the improvement of pressure recovery for a hub-strong inlet profile, the pressure recovery for a uniform profile appears to be more sensitive to the tip jet mass flow rate. However, the numerical results do not show this trend.

scholarly journals Comparison of Blade Element Method and CFD Simulations of a 10 MW Wind Turbine

Fluids ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 73 ◽  
Author(s):  
Galih Bangga
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Separation ◽  
Spatial Interpolation ◽  
Flow Conditions ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Correction Terms ◽  
Selection Of ◽  
Blade Element

The present studies deliver the computational investigations of a 10 MW turbine with a diameter of 205.8 m developed within the framework of the AVATAR (Advanced Aerodynamic Tools for Large Rotors) project. The simulations were carried out using two methods with different fidelity levels, namely the computational fluid dynamics (CFD) and blade element and momentum (BEM) approaches. For this purpose, a new BEM code namely B-GO was developed employing several correction terms and three different polar and spatial interpolation options. Several flow conditions were considered in the simulations, ranging from the design condition to the off-design condition where massive flow separation takes place, challenging the validity of the BEM approach. An excellent agreement is obtained between the BEM computations and the 3D CFD results for all blade regions, even when massive flow separation occurs on the blade inboard area. The results demonstrate that the selection of the polar data can influence the accuracy of the BEM results significantly, where the 3D polar datasets extracted from the CFD simulations are considered the best. The BEM prediction depends on the interpolation order and the blade segment discretization.

Computational Study of Multiple Hydrokinetic Turbines: The Effect of Wake

2015 ◽  
Author(s):  
Cosan Daskiran ◽  
Jacob Riglin ◽  
Alparslan Oztekin
Keyword(s):  
Computational Study ◽  
Relative Power ◽  
Cfd Simulations ◽  
Significant Drop ◽  
Hydrokinetic Turbines ◽  
Hydrokinetic Turbine ◽  
Wake Interactions ◽  
Sst Turbulence Model ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Design

Computational Fluid Dynamics (CFD) simulations have been conducted to investigate the performance of a predetermined propeller-based hydrokinetic turbine design in staggered and non-staggered placements for river applications. Actual turbine models were used instead of low fidelity actuator line or actuator disks for CFD simulations to achieve more reliable results. The k-ω Shear Stress Transport (SST) turbulence model was employed to resolve wall effects on turbine surface and to determine wake interactions behind the turbines. The wake interaction behind the upstream turbine causes significant drop on downstream turbine performance within non-staggered configuration. The upstream turbines in both staggered and non-staggered placement offers the same relative power of 0.96, while the relative power for downstream turbine is 0.98 for staggered installment and 0.16 for inline placement.

Analysis of Turbofan Performance Under Total Pressure Distortion at Various Operating Points

2015 ◽  
Author(s):  
David B. Weston ◽  
Steven E. Gorrell ◽  
Matthew L. Marshall ◽  
Carol V. Wallis
Keyword(s):  
Total Pressure ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Cfd Simulations ◽  
Blade Loading ◽  
Distortion Analysis ◽  
Work Input ◽  
Total Temperature ◽  
Computational Fluid Dynamics Cfd ◽  
Operating Points

Inlet distortion is an important consideration in fan performance. The focus of this paper is a series of high-fidelity time accurate Computational Fluid Dynamics (CFD) simulations of a multistage fan at choke, design, and near stall operating conditions. These investigate distortion transfer and generation as well as the underlying flow physics of these phenomena under different operating conditions. The simulations are performed on the full annulus of a 3 stage fan and are analyzed. The code used to carry out these simulations is a modified version of OVERFLOW 2.2. The inlet is specified as a 1/rev total pressure distortion. Analysis includes the phase and amplitude of total temperature and pressure distortion through each stage of the fan and blade loading. The total pressure distortion does not change in severity through the fan, but the peak pressure distortion rotates by as much as 45° at the near stall point. This is due to a variation in the work input around the blades of the rotor. This variation is also responsible for the generation of total temperature distortion in the fan. The rotation of the total temperature distortion becomes more pronounced as the fan approaches stall, and the total temperature distortion levels increase. The amount of work performed by a single blade can vary by as much as 25% in the first stage at near stall. The variation in work becomes more pronounced as the fan approaches stall. The passage shock in the rotor blades moves nearly 20% of the blade chord in both the peak efficiency and near stall cases.

Partial Stall Effects on the Failure of an Axial Compressor Blade

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
E. Poursaeidi ◽  
M. R. Mohammadi Arhani ◽  
S. Hosseini ◽  
M. Darayi ◽  
M. Arablu
Keyword(s):  
Stress Concentration ◽  
Gas Turbines ◽  
Natural Frequencies ◽  
Cfd Simulation ◽  
Flow Instability ◽  
Axial Compressor ◽  
Cfd Simulations ◽  
Rotating Blades ◽  
History Of ◽  
Computational Fluid Dynamics Cfd

This paper is aimed to show the effects of partial stall on the fracture of the first stage rotating blades of the gas turbine compressors of an onshore gas refinery. The first part of the paper deals with the results of finite element modeling (FEM) of stress distribution and stress concentration areas on the blades under its first to third natural frequencies. Comparison of the stress concentration areas with the fractured blades shows that the blades have been fractured due to resonance under the first and second natural frequencies. The second part of the paper deals with the computational fluid dynamics (CFD) simulation of air flowing through the blades to determine the most probable sources of vibrational loads as the aerodynamic forces. Results of CFD simulations show that the operation of the gas turbines under 40–50% of their nominal output power—which has been very regular in the history of operation of the turbines—increases the possibility of stall at the tip side of the first stages rotating blades. The vortices shedding due to downwash flow at the tip side of the blades causes flow instability and increases the aerodynamic vibrational forces on the blades, which finally makes them to experience a kind of high cycle fatigue (HCF).

scholarly journals Comparison of Blade Element Method and CFD Simulations of a 10 MW Wind Turbine

2018 ◽  
Author(s):  
Galih Bangga
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Separation ◽  
Spatial Interpolation ◽  
Flow Conditions ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Correction Terms ◽  
Selection Of ◽  
Blade Element

The present studies deliver the computational investigations of a 10 MW turbine with a diameter of 205.8 m developed within the framework of the AVATAR (Advanced Aerodynamic Tools for Large Rotors) project. The simulations were carried out using two methods with different fidelity levels, namely the computational fluid dynamics (CFD) and blade element and momentum (BEM) approaches. For this purpose, a new BEM code namely B-GO was developed employing several correction terms and three different polar and spatial interpolation options. Several flow conditions were considered in the simulations, ranging from the design condition to the off-design condition where massive flow separation takes place, challenging the validity of the BEM approach. An excellent agreement is obtained between the BEM computations and the 3D CFD results for all blade regions, even when massive flow separation occurs on the blade inboard area. The results demonstrate that the selection of the polar data can influence the accuracy of the BEM results significantly, where the 3D polar datasets extracted from the CFD simulations are considered the best. The BEM prediction depends on the interpolation order and the blade segment discretization.

scholarly journals Investigation of Wash Fluid Preheating on the Effectiveness of Online Compressor Washing in Industrial Gas Turbines

2020 ◽  
Author(s):  
Roupa Agbadede ◽  
Biweri Kainga
Keyword(s):  
Gas Turbines ◽  
Pressure Loss ◽  
Total Pressure ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Compressor Cascade ◽  
Flow Angle ◽  
Pressure Loss Coefficient ◽  
Industrial Gas Turbines ◽  
Total Pressure Loss Coefficient

Abstract This study presents an investigation of wash fluid preheating on the effectiveness of online compressor washing in industrial gas turbines. Crude oil was uniformly applied on the compressor cascade blades surfaces using a roller brush, and carborundum particles were ingested into the tunnel to create accelerated fouled blades. Demineralized water was preheated to 500C using the heat coil provided in the tank. When fouled blades washed with preheated demineralized and the one without preheating were compared, it was observed that there was little or no difference in terms of total pressure loss coefficient and exit flow angle. However, when the fouled and washed cases were compared, there was a significant different in total pressure loss coefficient and exit flow angle.

Numerical Investigation of Crosswind Effect on Different Rear Mounted Engine Installations

2014 ◽  
Author(s):  
Hairun Xie ◽  
Yadong Wu ◽  
Anjenq Wang ◽  
Hua Ouyang
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Pressure Profile ◽  
Operating Conditions ◽  
Operating Characteristics ◽  
Close Coupling ◽  
Pressure Profiles ◽  
Air Intake ◽  
A Minor ◽  
Condition Assessments

The rear-mounted engine is widely used in business and regional jets. It is a “clean wing” design. The engine is mounted behind the wing, so that the inlet/outlet of the nacelle has a minor influence on the flow over the wing. The engine thrust line is close to the fuselage axis. As a result, the asymmetric yaw moment will be smaller when single engine stall occurs. Strict regulations and requirements were set by certification agencies to assess aircraft maneuver capability as well as engine operating characteristics. These regulations are mainly defined to evaluate structural strength, aerodynamics, & engine/aircraft performance. However, due to the nature of the complexity of the flow field at the air intake, the inlet compatibility of fuselage mounted engines becomes one of the most complicated & challenging items to meet FAR33 as well as FAR25 certification requirements, especially during cross wind operating conditions. This research paper discusses the inlet compatibility of rear-mounted aircraft engines with respect to the installed configuration and crosswind operating conditions. Models of two installed configurations, set by the relative position of engine to the fuselage and the wing were created. In each case, the engine inlet flow field was calculated at various ambient wind conditions. Comparisons of the total pressure profile at the air intake were made to assess the likelihood of flow separation at the inlet of engine. Inlet distortion levels of corresponding total pressure profiles were calculated for each operating and installed condition. Assessments are made based on intensive usage of CFD analysis of different engine installations and operating conditions. The flow field information obtained by CFD calculation reveals a close coupling phenomenon exists among engine installations, cross wind, and inlet capability.

scholarly journals The Effect of Hub Leakage Flow on Two High Speed Axial Flow Compressor Rotors

1997 ◽  
Author(s):  
A. Shabbir ◽  
M. L. Celestina ◽  
J. J. Adamczyk ◽  
A. J. Strazisar
Keyword(s):  
Numerical Simulations ◽  
Total Pressure ◽  
High Speed ◽  
Axial Flow ◽  
Pressure Rise ◽  
Pressure Profile ◽  
Leakage Flow ◽  
Cfd Simulations ◽  
Significant Deficit ◽  
Flow Compressor

The effect of hub leakage flow on the performance of two high speed transonic rotors is investigated through numerical simulations and experiments. The leakage flow emanates from a small gap between the stationary and rotating parts of the hub flow path upstream of the rotor. Results of both the experiments and CFD simulations show that the introduction of a small leakage flow (0–25% of the main passage flow) can reduce the total pressure rise produced by the rotor across the entire span and generate a significant deficit in the total pressure profile near the hub. Numerical simulations done with a sinusoidal distribution of the leakage flow across the rotor pitch show that this deficit is present even when there is zero net leakage. Particle tracer studies of CFD simulations show that this deficit is due to the flow blockage produced by the radial migration of the low momentum leakage fluid. The performance degradation trends predicted by the simulations are qualitatively confirmed in the experimental investigation.

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