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%.

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%.

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.

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 Correlation between total pressure losses of highly loaded annular diffusers and integral stage design parameters

2018 ◽  
Vol 2 ◽  
pp. I9AB30 ◽  
Author(s):  
Dajan Mimic ◽  
Christoph Jätz ◽  
Florian Herbst
Keyword(s):  
Boundary Layer ◽  
Gas Turbines ◽  
Pressure Loss ◽  
Total Pressure ◽  
Total Pressure Loss ◽  
Pressure Recovery ◽  
Design Parameters ◽  
Pressure Losses ◽  
Tip Leakage ◽  
Highly Loaded

Diffusers convert kinetic flow energy into a rise in static pressure. This pressure recovery is the primary aerodynamic design objective for exhaust gas diffusers in power-generating steam and gas turbines. The total pressure loss is an equally important diffuser design parameter. It is strongly linked to the pressure recovery and the residual kinetic energy of the diffuser outlet flow. A reduction benefits the overall thermodynamic cycle, which requires the adjacent components of a diffuser to be included in the design process. This paper focuses on the total pressure losses in the boundary layer of a highly loaded annular diffuser. Due to its large opening angle the diffuser is susceptible to flow separation under uniform inlet conditions, which is a major source for total pressure losses. However, the unsteady tip leakage vortices of the upstream rotor, which are a source of losses, stabilise the boundary layer and prevent separation. Experiments and unsteady numerical simulation conducted show that the total pressure loss reduction caused by the delayed boundary layer separation exceed the vortex-induced losses by far. This flow interaction between the rotor and diffuser consequently decreases the overall total pressure losses. The intensity of the tip leakage vortex is linked to three rotor design parameters, namely work coefficient, flow coefficient and reduced blade-passing frequency. Based on these parameters, we propose a semi-empiric correlation to predict and evaluate the change in total pressure losses with regards to design operating conditions.

Study on Film Cooling Performance Improvement of NGV Leading Edge Subject to Distortion Profiles of Low NOx Combustor

2020 ◽  
Author(s):  
Wenhao Zhang ◽  
Zhihao Wang ◽  
Zhiduo Wang ◽  
Zhenping Feng
Keyword(s):  
Film Cooling ◽  
Total Pressure ◽  
Swirling Flow ◽  
Leading Edge ◽  
Pressure Profile ◽  
Flow Angle ◽  
Cooling Performance ◽  
Positive Effects ◽  
Inlet Distortion ◽  
Pressure Profiles

Abstract Under the effect of inlet distortion profiles (including hot-streaks, total pressure profiles, and swirling flow angle patterns), the film cooling performance on the leading edge (LE) region of GE-E3 nozzle guide vanes (NGVs) has been numerically investigated in this paper. Firstly, the complicated inlet distortion profiles of a low NOx combustor chamber has been decoupled to single factors to explore the individual and the coupling effects on the film cooling performance of the NGV LE region (Case 1 to Case 4). Then the original and three modified film-hole configurations are compared and discussed under the quasi-real environment (Case 5 to Case 8). The results indicate that total pressure profile tends to draw more coolant toward the midspan and the residual swirl promotes turnover of the cooling film to the other side of NGVs near the enwalls of LE region. Under the combined effects of different distortion profiles, the cooling film is redistributed on the LE region with some area near the stagnation lines with poor coverage. The upwash or downwash of boundary layer fluid caused by the complicated vortex in passages draws the cooling film on NGV surfaces. And this effect will be strengthened or weakened by the injection angles of holes. Finally, the filmhole configuration in Case 8 with counter-inclined film-hole rows arranged along the stagnation lines shows the best film cooling performance, which has positive effects on the decrease of high temperature region induced by hot streak (HS), and results in more uniform temperature distribution.

A Conceptual Design Study for a New High Temperature Fast Response Cooled Total Pressure Probe

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Jean-François Brouckaert ◽  
Mehmet Mersinligil ◽  
Marco Pau
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Total Pressure ◽  
Fast Response ◽  
Pressure Probe ◽  
Piezoresistive Pressure Sensor ◽  
Industrial Gas Turbines ◽  
Aero Engines ◽  
Harsh Conditions

The present paper proposes a concept for a water-cooled high temperature unsteady total pressure probe intended for measurements in the hot sections of industrial gas turbines or aero-engines. This concept is based on the use of a conventional miniature piezoresistive pressure sensor, which is located at the probe tip to achieve a bandwidth of at least 40 kHz. Due to extremely harsh conditions and the intention to immerse the probe continuously into the hot gas stream, the probe and sensor must be heavily cooled. The short term objective of this design is to gain the capability of performing measurements at the temperature conditions typically found at high pressure turbine exit (1100–1400 K) and in the long term at combustor exit (2000 K or higher).

A Conceptual Design Study for a New High Temperature Fast Response Cooled Total Pressure Probe

2008 ◽  
Author(s):  
Jean-Franc¸ois Brouckaert ◽  
Mehmet Mersinligil ◽  
Marco Pau
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Total Pressure ◽  
Fast Response ◽  
Pressure Probe ◽  
Industrial Gas Turbines ◽  
Aero Engines ◽  
Harsh Conditions ◽  
Term Objective

The present paper proposes a concept for a water cooled high temperature unsteady total pressure probe, intended for measurements in the hot sections of industrial gas turbines or aero-engines. This concept is based on the use of a conventional miniature piezo-resistive pressure sensor, located at the probe tip to achieve a bandwidth of at least 40kHz. Due to extremely harsh conditions and the intention to immerse the probe continuously into the hot gas stream, the probe and sensor must be heavily cooled. The short term objective of this design is to gain the capability of performing measurements at the temperature conditions typically found at high pressure turbine exit (1100–1400K) and in the long term at combustor exit (2000K or higher).

Pressure Losses for Jet Array Impingement With Crossflow

2012 ◽  
Author(s):  
Yeshayahou Levy ◽  
Arvind G. Rao ◽  
V. Erenburg ◽  
V. Sherbaum ◽  
I. Gaissinski ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Numerical Simulations ◽  
Gas Turbines ◽  
Total Pressure ◽  
Turbine Blades ◽  
Jet Impingement ◽  
Solar Panels ◽  
Cfd Simulations ◽  
Pressure Losses

Jet impingement is an efficient heat transfer method and has been used successfully in cooling of turbine blades in gas turbine engines. Although many studies have been conducted on the heat transfer characteristics of jet impingement array, there is a lack of knowledge in pressure drop characteristics of large jet impingement arrays. The pressure losses encountered are becoming increasingly important when applied to micro gas turbines, cooling concentrated solar panels and high density electronic chips. The present work focuses on experimental and theoretical investigation of pressure losses in low Re impingement arrays, 200< Re <3000. Experiments were carried out on jet impingement array with nozzle diameters of 200 to 800 μm. Numerical simulations were also performed with available commercial CFD tools. Reasonable comparisons between experimental results and numerical simulations were obtained. Detailed flow structure, mass flow rate distribution, jet velocity profiles, and pressure drop within the array in the streamwise direction were obtained from the CFD simulations. These simulations enhance the understanding of the physics within multiple jet impingement system. Additionally a semi empirical–analytical method is developed for calculating the total pressure loss within a multi jet impingement system. This simple methodology can provide a quick estimate of the total pressure drop and hence is suited for first order optimization. The methodology is validated by results obtained from experiments and from CFD simulations.

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