Experimental Investigation of an Innovative Cooling System (ICS) for High Temperature Transonic Turbine Stages

2002 ◽  
Author(s):  
E. Go¨ttlich ◽  
H. Lang ◽  
W. Sanz ◽  
J. Woisetschla¨ger
Keyword(s):  
Cooling System ◽  
Flow Behavior ◽  
Leading Edge ◽  
Optical Methods ◽  
Blade Surface ◽  
Camera System ◽  
Flow Measurements ◽  
Cooling Effectiveness ◽  
Ir Camera ◽  
Transonic Turbine

Gas turbine design technology requires the development of transonic turbine stages capable of carrying high stage load and of handling hot gas temperatures at turbine inlet. A reliable cooling system is necessary to cope with the shock system in the main flow field especially in the leading edge region of the rotor blades. These requirements are fulfilled by the Innovative Cooling System (ICS) developed at the Institute for Thermal Turbomachinery and Machine Dynamics, Graz University of Technology. The ICS is also able to cover large areas of the blade surface with an effective cooling film and to reduce the metal temperature. In this paper the authors present results on the flow measurements giving the aerodynamic behavior of these cooling films and on the investigation of their cooling effectiveness. The measurements were done on an industrial turbine blade in a linear cascade arrangement. In addition to conventional measurement methods optical methods (Schlieren visualization, Laser Doppler Velocimetry) were employed to investigate and visualize the transonic flow through the linear blade cascade. An infrared (IR) camera system was used to determine the effectiveness of this newly designed cooling system by measuring the temperature distribution on the blade surface. Experimental results concerning aerodynamic flow behavior and cooling effectiveness are presented.

Cooling of Turbine Blades With Expanded Exit Holes: Computational Analyses of Leading Edge and Pressure-Side of a Turbine Blade

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Fariborz Forghan ◽  
Omid Askari ◽  
Uichiro Narusawa ◽  
Hameed Metghalchi
Keyword(s):  
High Speed ◽  
Turbine Blades ◽  
Leading Edge ◽  
Weak Shock ◽  
Suction Side ◽  
Pressure Side ◽  
Blade Surface ◽  
Cooling Effectiveness ◽  
Hot Gas ◽  
Computational Analyses

Turbine blades are cooled by a jet flow from expanded exit holes (EEH) forming a low-temperature film over the blade surface. Subsequent to our report on the suction-side (low-pressure, high-speed region), computational analyses are performed to examine the cooling effectiveness of the flow from EEH located at the leading edge as well as at the pressure-side (high-pressure, low-speed region). Unlike the case of the suction-side, the flow through EEH on the pressure-side is either subsonic or transonic with a weak shock front. The cooling effectiveness, η (defined as the temperature difference between the hot gas and the blade surface as a fraction of that between the hot gas and the cooling jet), is higher than the suction-side along the surface near the exit of EEH. However, its magnitude declines sharply with an increase in the distance from EEH. Significant effects on the magnitude of η are observed and discussed in detail of (1) the coolant mass flow rate (0.001, 0.002, and 0.004 (kg/s)), (2) EEH configurations at the leading edge (vertical EEH at the stagnation point, 50 deg into the leading-edge suction-side, and 50 deg into the leading-edge pressure-side), (3) EEH configurations in the midregion of the pressure-side (90 deg (perpendicular to the mainstream flow), 30 deg EEH tilt toward upstream, and 30 deg tilt toward downstream), and (4) the inclination angle of EEH.

An Experimental Study of Mist/Air Film Cooling On a Flat Plate With Application to Gas Turbine Airfoils—Part II: Two-Phase Flow Measurements and Droplet Dynamics

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Lei Zhao ◽  
Ting Wang
Keyword(s):  
Film Cooling ◽  
Flow Behavior ◽  
Droplet Size Distribution ◽  
Main Flow ◽  
Reynolds Stresses ◽  
Two Phase ◽  
Flow Measurements ◽  
Cooling Effectiveness ◽  
Droplet Dynamics ◽  
Air Film

A phase Doppler particle analyzer (PDPA) system is employed to measure the two-phase mist flow behavior including flow velocity field, droplet size distribution, droplet dynamics, and turbulence characteristics. Based on the droplet measurements made through PDPA, a projected profile describing how the air-mist coolant jet flow spreads and eventually blends into the hot main flow is proposed. This proposed profile is found to be well supported by the measurement results of the turbulent Reynolds stresses. The coolant film envelope is identified with shear layers characterized by higher magnitudes of turbulent Reynolds stresses. In addition, the separation between the mist droplet layer and the coolant air film is identified through the droplet measurements—large droplets penetrate through the air coolant film layer and travel further into the main flow. With the proposed air-mist film profile, the heat transfer results on the wall presented in Part I are re-examined and more in-depth physics is revealed. It is found that the location of the optimum cooling effectiveness coincides with the point where the air-mist coolant stream starts to bend back towards the surface. Thus, the data suggests that the “bending back” film pattern is critical in keeping the mist droplets close to the surface, which improves the cooling effectiveness for mist cooling.

Measurement and Simulation of a Transonic Innovative Cooling System (ICS) for High-Temperature Transonic Gas Turbine Stages

2004 ◽  
Author(s):  
E. Go¨ttlich ◽  
L. Innocenti ◽  
A. Vacca ◽  
W. Sanz ◽  
J. Woisetschla¨ger ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Cooling System ◽  
Leading Edge ◽  
Numerical Comparison ◽  
Blade Surface ◽  
Trailing Edge ◽  
Advantages And Disadvantages

Gas turbine design technology requires the development of transonic turbine stages capable of carrying high stage load and of handling hot gas temperatures at turbine inlet. A reliable cooling system is necessary to cope with shocks emanating from preceding blade rows and impinging on the blade especially in the leading edge region. In order to fulfill these requirements researchers at Graz University of Technology have been working on an Innovative Cooling System (ICS) since 1995. The ICS is able to cover large areas of the blade surface with an effective cooling film and to reduce the metal temperature without a shower head cooling arrangement at the leading edge and any trailing edge cooling air ejection. In this paper the authors present a numerical comparison of the ICS to a conventional modern film cooling system both implemented in the same industrial transonic gas turbine blade. An experimental determination of the adiabatic film cooling effectiveness distribution around the blades surface was necessary for the ICS because of its uncommon design. The measurements were done on a cylindrical blade in a linear cascade arrangement. An infrared camera system was used to determine the effectiveness of this newly designed cooling system by measuring the temperature distribution on the blade surface. Then a numerical simulation of heat transfer and of internal and external cooling for the turbine blade at test rig conditions was performed. The ICS showed a lower outer wall temperature distribution of the blade compared to a standard film cooling system. The heavily loaded leading edge as well as the trailing edge are well cooled. Further conclusions on the advantages and disadvantages of the ICS are drawn.

Aero-Thermal Performance of a Nozzle Vane Cascade With a Generic Non Uniform Inlet Flow Condition: Part II — Influence of Purge and Film Cooling Injection

2016 ◽  
Author(s):  
G. Barigozzi ◽  
H. Abdeh ◽  
A. Perdichizzi ◽  
M. Henze ◽  
J. Krueckels
Keyword(s):  
Thermal Performance ◽  
Film Cooling ◽  
Cooling System ◽  
Leading Edge ◽  
Axial Position ◽  
Intensity Level ◽  
Cooling Effectiveness ◽  
Inlet Flow ◽  
Film Cooling Effectiveness ◽  
Nozzle Vane

In the present paper, the influence of the presence of an inlet flow non uniformity on the aerodynamic and thermal performance of a film cooled linear nozzle vane cascade is fully assessed. Tests have been carried out with platform cooling, with coolant ejected through a slot located upstream of the leading edge. Cooling air is also ejected through a row of cylindrical holes located upstream of the slot, simulating a combustor cooling system. An obstruction was installed upstream of the cascade at variable tangential and axial position to generate a flow non uniformity. The cascade was tested at a high inlet turbulence intensity level (Tu1 = 9%) and at a constant inlet Mach number of 0.12 and nominal cooling condition. Aero-thermal characterization of vane platform was obtained through 5-hole probe and end wall adiabatic film cooling effectiveness measurements. Results show a relevant negative impact of inlet flow non uniformity on the cooled cascade aerodynamic and thermal performance. Higher film cooling effectiveness and lower aerodynamic losses are obtained when the inlet flow non uniformity is located at mid pitch, while lower effectiveness and higher losses are obtained when it is aligned to the vane leading edge. Moving the non uniformity axially or changing its blockage only marginally influences the platform thermal protection.

Experiment Study of Simulated Effect of Rotor Stator Interaction: Effect of Axial Spacing and Rotor Blade Film Cooling Air Injection Ratio

2011 ◽  
Author(s):  
Murari Sridhar ◽  
B. V. S. S. S. Prasad ◽  
N. Sitaram
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Density Ratio ◽  
Leading Edge ◽  
Main Flow ◽  
Air Injection ◽  
Blade Surface ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness

The effect of inlet wake and air injection on blade surface temperature distribution is experimentally determined in the present paper. A flat plate with smoothly curved leading edge and a symmetric beveled trailing edge is used to produce inlet wake. Experiments are performed on a seven-airfoil linear cascade in a low speed wind tunnel at the chord Reynolds number of 5.3×105. Three blades in the middle of the cascade are provided with multiple rows of air injection holes on both pressure surface and suction surface. The distance between the trailing edge of the wake plate and leading edge of the cascade blade is kept at three axial locations, i.e. 0.25, 0.35 and 0.5 (all measured in terms of percent blade chord), at seven transverse locations for each axial location. The detailed temperature distributions on the blade surface are measured using “T-Type” thermocouples connected to a data logger. The results are obtained in terms of film cooling effectiveness for a density ratio (between the hot fluid through air injection holes and cold main flow fluid) of 1.1 and injection mass flow rates of 1.1, 2.5, 3.0 and 5.0 percent of main flow. A significant change in the film cooling effectiveness is observed with increase in the injection mass flow rate and change in the axial spacing.

An Experimental Study of Mist/Air Film Cooling on a Flat Plate With Application to Gas Turbine Airfoils: Part 2 — Two-Phase Flow Measurements and Droplet Dynamics

2013 ◽  
Author(s):  
Lei Zhao ◽  
Ting Wang
Keyword(s):  
Film Cooling ◽  
Flow Behavior ◽  
Droplet Size Distribution ◽  
Main Flow ◽  
Reynolds Stresses ◽  
Two Phase ◽  
Flow Measurements ◽  
Cooling Effectiveness ◽  
Droplet Dynamics ◽  
Air Film

A Phase Doppler Particle Analyzer (PDPA) system is employed to measure the two-phase mist flow behavior including flow velocity field, droplet size distribution, droplet dynamics, and turbulence characteristics. Based on the droplet measurements made through PDPA, a projected profile describing how the air-mist coolant jet flow spreads and eventually blends into the hot main flow is proposed. This proposed profile is found to be well supported by the measurement results of the turbulent Reynolds stresses. The coolant film envelope is identified with shear layers characterized by higher magnitudes of turbulent Reynolds stresses. In addition, the separation between the mist droplet layer and the coolant air film is identified through the droplet measurements — large droplets penetrate through the air coolant film layer and travel further into the main flow. With the proposed air-mist film profile, the heat transfer results on the wall presented in Part 1 are re-examined and more in-depth physics is revealed. It is found that the location of optimum cooling effectiveness is coincided with the point where the air-mist coolant stream starts to bend back towards the surface. Thus, the data suggests that the “bending back” film pattern is critical in keeping the mist droplets close to the surface, which improves the cooling effectiveness for mist cooling.

An Infrared Microscope for Use on a Focused Ion Beam for Circuit Edit and Backside Edit Applications

2015 ◽  
Author(s):  
Alexander Richards ◽  
Matthew Weschler ◽  
Michael Durller
Keyword(s):  
Focused Ion Beam ◽  
Near Infrared ◽  
Ion Beam ◽  
Visible Spectrum ◽  
Camera System ◽  
Buried Structures ◽  
Ir Camera ◽  
Area Of Interest ◽  
Near Ultraviolet ◽  
Infrared Microscope

Abstract To help solve the navigational problem, i.e., being able to successfully locate a circuit for probing or editing without destroying chip functionality, a near-infrared (NIR), near-ultraviolet (NUV), and visible spectrum camera system was developed that attaches to most focused ion beam (FIB) or scanning electron microscope vacuum chambers. This paper reviews the details of the design and implementation of the NIR/NUV camera system, as instantiated upon the FEI FIB 200, with a particular focus on its use for the visualization of buried structures, and also for non-destructive real time area of interest location and end point detection. It specifically considers the use of the micro-optical camera system for its benefit in assisting with frontside and backside circuit edit, as well as other typical FIB milling activities. The quality of the image obtained by the IR camera rivals or exceeds traditional optical based imaging microscopy techniques.

Numerical simulation of swirling flow effect on the first stage vane film cooling distribution

2016 ◽  
Vol 07 (03) ◽  
pp. 1650031
Author(s):  
Hong Yin
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Swirling Flow ◽  
Cooling System ◽  
Leading Edge ◽  
Suction Side ◽  
Local Area ◽  
Swirl Flow ◽  
Flow Effect ◽  
Recirculation Flow

In advanced gas turbine technology, lean premixed combustion is an effective strategy to reduce peak temperature and thus, NO[Formula: see text] emissions. The swirler is adopted to establish recirculation flow zone, enhancing mixing and stabilizing the flame. Therefore, the swirling flow is dominant in the combustor flow field and has impact on the vane. This paper mainly investigates the swirling flow effect on the turbine first stage vane cooling system by conducting a group of numerical simulations. Firstly, the numerical methods of turbulence modeling using RANS and LES are compared. The computational model of one single swirl flow field is considered. Both the RANS and LES results give reasonable recirculation zone shape. When comparing the velocity distribution, the RANS results generally match the experimental data but fail to at some local area. The LES modeling gives better results and more detailed unsteady flow field. In the second step, the RANS modeling is incorporated to investigate the vane film cooling performance under the swirling inflow boundary condition. According to the numerical results, the leading edge film cooling is largely altered by the swirling flow, especially for the swirl core-leading edge aligned case. Compared to the pressure side, the suction side film cooling is more sensitive to the swirling flow. Locally, the film cooling jet is lifted and turned by the strong swirling flow.

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