Egress Interaction Through Turbine Rim Seals

2017 ◽  
Author(s):  
James A. Scobie ◽  
Fabian P. Hualca ◽  
Carl M. Sangan ◽  
Gary D. Lock
Keyword(s):  
Film Cooling ◽  
Outer Region ◽  
Co2 Concentration ◽  
Flow Coefficient ◽  
Cfd Validation ◽  
Engine Efficiency ◽  
Purge Flow ◽  
Cooling Air ◽  
End Wall ◽  
First Time

Engine designers require accurate predictions of ingestion (or ingress) principally caused by circumferential pressure asymmetry in the mainstream annulus. Cooling air systems provide purge flow designed to limit metal temperatures and protect vulnerable components from the hot gases which would otherwise be entrained into disc cavities through clearances between rotating and static discs. Rim seals are fitted at the periphery of these discs to minimise purge. The mixing between the efflux of purge (or egress) and the mainstream gases near the hub end-wall results in a deterioration of aerodynamic performance. This paper presents experimental results using a turbine test rig with wheel-spaces upstream and downstream of a rotor disc. Ingress and egress was quantified using a CO2 concentration probe, with seeding injected into the upstream and downstream sealing flows. The probe measurements have identified an outer region in the wheel-space and confirmed the expected flow structure. For the first time, asymmetric variations of concentration have been shown to penetrate through the seal clearance and the outer portion of the wheel-space between the discs. For a given flow coefficient in the annulus, the concentration profiles were invariant with rotational Reynolds number. The measurements also reveal that the egress provides a film-cooling benefit on the vane and rotor platforms. Further, these measurements provide unprecedented insight into the flow interaction, and provide quantitative data for CFD validation, which should help reduce the use of purge and improve engine efficiency.

Egress Interaction Through Turbine Rim Seals

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
James A. Scobie ◽  
Fabian P. Hualca ◽  
Carl M. Sangan ◽  
Gary D. Lock
Keyword(s):  
Film Cooling ◽  
Outer Region ◽  
Co2 Concentration ◽  
Flow Coefficient ◽  
Cfd Validation ◽  
Engine Efficiency ◽  
Purge Flow ◽  
Rotor Disk ◽  
Computational Fluid Dynamics Cfd ◽  
Cooling Air

Engine designers require accurate predictions of ingestion (or ingress) principally caused by circumferential pressure asymmetry in the mainstream annulus. Cooling air systems provide purge flow designed to limit metal temperatures and protect vulnerable components from the hot gases which would otherwise be entrained into disk cavities through clearances between rotating and static disks. Rim seals are fitted at the periphery of these disks to minimize purge. The mixing between the efflux of purge (or egress) and the mainstream gases near the hub end-wall results in a deterioration of aerodynamic performance. This paper presents experimental results using a turbine test rig with wheel-spaces upstream and downstream of a rotor disk. Ingress and egress was quantified using a CO2 concentration probe, with seeding injected into the upstream and downstream sealing flows. The probe measurements have identified an outer region in the wheel-space and confirmed the expected flow structure. For the first time, asymmetric variations of concentration have been shown to penetrate through the seal clearance and the outer portion of the wheel-space between the disks. For a given flow coefficient in the annulus, the concentration profiles were invariant with rotational Reynolds number. The measurements also reveal that the egress provides a film-cooling benefit on the vane and rotor platforms. Further, these measurements provide unprecedented insight into the flow interaction and provide quantitative data for computational fluid dynamics (CFD) validation, which should help to reduce the use of purge and improve engine efficiency.

Investigations of Dust Separation in a Gasturbine Pre-Swirl Cooling Air System Using New, Enhanced Simulation Methods

2005 ◽  
Author(s):  
O. Schneider ◽  
H. J. Dohmen ◽  
F. K. Benra ◽  
K. Jarzombek
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Navier Stokes ◽  
Flow Conditions ◽  
System A ◽  
Air System ◽  
Physical Effects ◽  
Film Cooling Holes ◽  
Cooling Air ◽  
First Time

In the last years the leading manufacturers enhanced the performance of heavy-duty gas turbines rapidly. With the increasing amount of cooling air passing the internal air system, a rising amount of air borne particles are transported to the film cooling holes at the turbine blade surface. Due to the size, these holes are critical for blockage. Experience with gas turbines during operation showed a complex interaction of cooling air under different flow conditions and its particle load. In this paper the results of a new Lagrange-Tracking simulation algorithm based on 3D-Navier-Stokes flow solution are shown for the first time. Compared to previously shown simulations the algorithm is enhanced by models, taking additional, relevant physical effects into account. The new simulation results are compared to experimental results and former simulations.

Re-Ingestion of Upstream Egress in a 1.5-Stage Gas Turbine Rig

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
James A. Scobie ◽  
Fabian P. Hualca ◽  
Marios Patinios ◽  
Carl M. Sangan ◽  
J. Michael Owen ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Co2 Concentration ◽  
Test Facility ◽  
Operating Life ◽  
Annulus Flow ◽  
Purge Flow ◽  
Rotor Disk ◽  
First Time ◽  
Measured Mass ◽  
Insight Into

In gas turbines, rim seals are fitted at the periphery of stator and rotor discs to minimize the purge flow required to seal the wheel-space between the discs. Ingestion (or ingress) of hot mainstream gases through rim seals is a threat to the operating life and integrity of highly stressed components, particularly in the first-stage turbine. Egress of sealing flow from the first-stage can be re-ingested in downstream stages. This paper presents experimental results using a 1.5-stage test facility designed to investigate ingress into the wheel-spaces upstream and downstream of a rotor disk. Re-ingestion was quantified using measurements of CO2 concentration, with seeding injected into the upstream and downstream sealing flows. Here, a theoretical mixing model has been developed from first principles and validated by the experimental measurements. For the first time, a method to quantify the mass fraction of the fluid carried over from upstream egress into downstream ingress has been presented and measured; it was shown that this fraction increased as the downstream sealing flow rate increased. The upstream purge was shown to not significantly disturb the fluid dynamics but only partially mixes with the annulus flow near the downstream seal, with the ingested fluid emanating from the boundary layer on the blade platform. From the analogy between heat and mass transfer, the measured mass-concentration flux is equivalent to an enthalpy flux, and this re-ingestion could significantly reduce the adverse effect of ingress in the downstream wheel-space. Radial traverses using a concentration probe in and around the rim seal clearances provide insight into the complex interaction between the egress, ingress and mainstream flows.

Re-Ingestion of Upstream Egress in a 1.5-Stage Gas Turbine Rig

2017 ◽  
Author(s):  
James A. Scobie ◽  
Fabian P. Hualca ◽  
Marios Patinios ◽  
Carl M. Sangan ◽  
J. Michael Owen ◽  
...  
Keyword(s):  
First Principles ◽  
Gas Turbines ◽  
Co2 Concentration ◽  
Test Facility ◽  
Operating Life ◽  
Annulus Flow ◽  
Purge Flow ◽  
First Time ◽  
Measured Mass ◽  
Insight Into

In gas turbines, rim seals are fitted at the periphery of stator and rotor discs to minimise the purge flow required to seal the wheel-space between the discs. Ingestion (or ingress) of hot mainstream gases through rim seals is a threat to the operating life and integrity of highly-stressed components, particularly in the first-stage turbine. Egress of sealing flow from the first-stage can be re-ingested in downstream stages. This paper presents experimental results using a 1.5-stage test facility designed to investigate ingress into the wheel-spaces upstream and downstream of a rotor disc. Re-ingestion was quantified using measurements of CO2 concentration, with seeding injected into the upstream and downstream sealing flows. Here a theoretical mixing model has been developed from first principles and validated by the experimental measurements. For the first time, a method to quantify the mass fraction of the fluid carried over from upstream egress into downstream ingress has been presented and measured; it was shown that this fraction increased as the downstream sealing flow rate increased. The upstream purge was shown to not significantly disturb the fluid dynamics but only partially mixes with the annulus flow near the downstream seal, with the ingested fluid emanating from the boundary layer on the blade platform. From the analogy between heat and mass transfer, the measured mass-concentration flux is equivalent to an enthalpy flux and this re-ingestion could significantly reduce the adverse effect of ingress in the downstream wheel-space. Radial traverses using a concentration probe in and around the rim seal clearances provide insight into the complex interaction between the egress, ingress and mainstream flows.

Experimental Investigation of the Effect of Purge Flow on Film Cooling Effectiveness on a Rotating Turbine With Nonaxisymmetric End Wall Contouring

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
M. Rezasoltani ◽  
M. T. Schobeiri ◽  
J. C. Han
Keyword(s):  
Experimental Investigation ◽  
Film Cooling ◽  
Density Ratio ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive ◽  
Purge Flow ◽  
Cooling Loops ◽  
End Wall ◽  
The Impact

The impact of the purge flow injection on aerodynamics and film cooling effectiveness of a three-stage, high-pressure turbine with nonaxisymmetric end wall contouring has been experimentally investigated. As a continuation of the previously published work involving stator-rotor gap purge cooling, this study investigates film cooling effectiveness on the first-stage rotor contoured platform due to a coolant gas injection. Film cooling effectiveness measurements are performed on the rotor blade platform using a pressure-sensitive paint (PSP) technique. The present study examines, in particular, the film cooling effectiveness due to injection of coolant from the rotor cavity through the circumferential gap between the first stator followed by the first rotor. Effects of the presence of contouring, blowing ratios, rotational speeds, and coolant density ratio are studied and compared to a noncontouring platform. The experimental investigation is carried out in a three-stage turbine facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL) at Texas A&M University. Its rotor includes nonaxisymmetric end wall contouring on the first and second rotor row. The turbine has two independent cooling loops. Film cooling effectiveness measurements are performed for three coolant-to-mainstream mass flow ratios of 0.5%, 1.0%, and 1.5%. Film cooling data is obtained for three rotational speeds, 3000 rpm (reference condition), 2550 rpm, and 2400 rpm, and compared with noncontoured end wall data. Effect of density ratio for coolant-to-mainstream density ratio (DR) = 1.0 and DR = 1.5 is also investigated. The comparisons of film effectiveness results show that contoured cases have a noticeable quantitative improvement compared to those of noncontoured ones.

The Effect of Freestream Turbulence on Film Cooling Adiabatic Effectiveness

2002 ◽  
Author(s):  
James E. Mayhew ◽  
James W. Baughn ◽  
Aaron R. Byerley
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Density Ratio ◽  
Main Flow ◽  
Freestream Turbulence ◽  
Coverage Area ◽  
Liquid Crystal Thermography ◽  
Blowing Ratio ◽  
Adiabatic Effectiveness ◽  
Cooling Air

The film-cooling performance of a flat plate in the presence of low and high freestream turbulence is investigated using liquid crystal thermography. High-resolution distributions of the adiabatic effectiveness are determined over the film-cooled surface of the flat plate using the hue method and image processing. Three blowing rates are investigated for a model with three straight holes spaced three diameters apart, with density ratio near unity. High freestream turbulence is shown to increase the area-averaged effectiveness at high blowing rates, but decrease it at low blowing rates. At low blowing ratio, freestream turbulence clearly reduces the coverage area of the cooling air due to increased mixing with the main flow. However, at high blowing ratio, when much of the jet has lifted off in the low turbulence case, high freestream turbulence turns its increased mixing into an asset, entraining some of the coolant that penetrates into the main flow and mixing it with the air near the surface.

End-Wall Film Cooling Through Fan-Shaped Holes With Different Area Ratios

2006 ◽  
Vol 129 (2) ◽  
pp. 212-220 ◽  
Author(s):  
Giovanna Barigozzi ◽  
Giuseppe Franchini ◽  
Antonio Perdichizzi
Keyword(s):  
Secondary Flow ◽  
Mass Flow ◽  
Film Cooling ◽  
Three Dimensional ◽  
Wide Band ◽  
Lateral Spreading ◽  
Area Ratio ◽  
Adiabatic Effectiveness ◽  
Flow Effects ◽  
End Wall

The present paper reports on the aerothermal performance of a nozzle vane cascade, with film-cooled end walls. The coolant is injected through four rows of cylindrical holes with conical expanded exits. Two end-wall geometries with different area ratios have been compared. Tests have been carried out at low speed (M=0.2), with coolant to mainstream mass flow ratio varied in the range 0.5–2.5%. Secondary flow assessment has been performed through three-dimensional (3D) aerodynamic measurements, by means of a miniaturized five-hole probe. Adiabatic effectiveness distributions have been determined by using the wide-band thermochromic liquid crystals technique. For both configurations and for all the blowing conditions, the coolant share among the four rows has been determined. The aerothermal performances of the cooled vane have been analyzed on the basis of secondary flow effects and laterally averaged effectiveness distributions; this analysis was carried out for different coolant mass flow ratios. It was found that the smaller area ratio provides better results in terms of 3D losses and secondary flow effects; the reason is that the higher momentum of the coolant flow is going to better reduce the secondary flow development. The increase of the fan-shaped hole area ratio gives rise to a better coolant lateral spreading, but appreciable improvements of the adiabatic effectiveness were detected only in some regions and for large injection rates.

scholarly journals Performance of Turbulence Models and Near-Wall Treatments in Discrete Jet Film Cooling Simulations

1998 ◽  
Author(s):  
Jeffrey D. Ferguson ◽  
Dibbon K. Walters ◽  
James H. Leylek
Keyword(s):  
Experimental Data ◽  
Film Cooling ◽  
Turbulence Models ◽  
Viscous Sublayer ◽  
Reynolds Stress Model ◽  
Quality Data ◽  
Wall Functions ◽  
First Time ◽  
Near Wall ◽  
Non Equilibrium

For the first time in the open literature, code validation quality data and a well-tested, highly reliable computational methodology are employed to isolate the true performance of seven turbulence treatments in discrete jet film cooling. The present research examines both computational and high quality experimental data for two length-to-diameter ratios of a row of streamwise injected, cylindrical film holes. These two cases are used to document the performance of the following turbulence treatments: 1) standard k-ε model with generalized wall functions; 2) standard k-ε model with non-equilibrium wall functions: 3) Renormalization Group k-ε (RNG) model with generalized wall functions; 4) RNG model with non-equilibrium wall functions: 51 standard k-ε model with two-layer turbulence wall treatment; 6) Reynolds Stress Model (RSM) with generalized wall functions; and 7) RSM with non-equilibrium wall functions. Overall, the standard k-ε turbulence model with the two-layer near-wall treatment, which resolves the viscous sublayer, produces results that are more consistent with experimental data.

Influence of Coolant Density on Turbine Platform Film-Cooling With Stator–Rotor Purge Flow and Compound-Angle Holes

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Kevin Liu ◽  
Shang-Feng Yang ◽  
Je-Chin Han
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Fundamental Parameters ◽  
Blowing Ratio ◽  
Purge Flow ◽  
Cylindrical Holes ◽  
Exit Mach Number ◽  
Compound Angle

A detailed parametric study of film-cooling effectiveness was carried out on a turbine blade platform. The platform was cooled by purge flow from a simulated stator–rotor seal combined with discrete hole film-cooling. The cylindrical holes and laidback fan-shaped holes were accessed in terms of film-cooling effectiveness. This paper focuses on the effect of coolant-to-mainstream density ratio on platform film-cooling (DR = 1 to 2). Other fundamental parameters were also examined in this study—a fixed purge flow of 0.5%, three discrete-hole film-cooling blowing ratios between 1.0 and 2.0, and two freestream turbulence intensities of 4.2% and 10.5%. Experiments were done in a five-blade linear cascade with inlet and exit Mach number of 0.27 and 0.44, respectively. Reynolds number of the mainstream flow was 750,000 and was based on the exit velocity and chord length of the blade. The measurement technique adopted was the conduction-free pressure sensitive paint (PSP) technique. Results indicated that with the same density ratio, shaped holes present higher film-cooling effectiveness and wider film coverage than the cylindrical holes, particularly at higher blowing ratios. The optimum blowing ratio of 1.5 exists for the cylindrical holes, whereas the effectiveness for the shaped holes increases with an increase of blowing ratio. Results also indicate that the platform film-cooling effectiveness increases with density ratio but decreases with turbulence intensity.

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