An All-Metal Compliant Seal Versus a Labyrinth Seal: A Comparison of Gas Leakage at High Temperatures

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Luis San Andrés ◽  
Alain Anderson
Keyword(s):  
High Pressure ◽  
Pressure Ratio ◽  
High Surface ◽  
Secondary Flows ◽  
Effect Of Temperature ◽  
Maximum Speed ◽  
The Novel ◽  
Steam Turbines ◽  
Flow Factor ◽  
Metal Seal

Parasitic secondary flows (seals' leakage) in centrifugal compressors and gas and steam turbines represent a substantial loss in efficiency and power delivery with an increase in specific fuel consumption. Labyrinth seals (LS) are the most common and inexpensive means of reducing secondary leakage, albeit wearing out with operation and thereby penalizing performance and even affecting rotordynamic stability. The novel hydrostatic advanced low leakage (HALO) seal is an all-metal seal with flexibly supported shoes that enable clearance self-control to effectively reduce leakage, in particular for operation with high pressure ratios and at high surface rotor speeds. This paper presents leakage tests with hot air (max. 300 °C) conducted in a test rig holding a LS and a HALO seal, both of similar diameter, axial length, and clearance. The novel seal leaks much less than the LS as the supply/discharge pressure ratio (Ps/Pa) increases. The leakage reduction is ∼50% for (Ps/Pa) < 2 and continuously dropping to 70% for (Ps/Pa) > 3.0. Thus, the savings in leakage are maximized for operation with a high pressure differential. Leakage measurements with a rotor spinning to a maximum speed of 2700 rpm (surface speed ∼24 m/s) produce a slight decrease in leakage for both seals. Characterization of seal leakage in terms of a flow factor removes the effect of temperature and supply pressure; the LS showing a constant flow factor for (Ps/Pa) > 2. Application of the novel seal technology will aid to increase system efficiency by reducing leakage and will extend maintenance intervals since it eliminates wear of components.

An All-Metal Compliant Seal Versus a Labyrinth Seal: A Comparison of Gas Leakage at High Temperatures

2014 ◽  
Author(s):  
Luis San Andrés ◽  
Alain Anderson
Keyword(s):  
High Pressure ◽  
Pressure Ratio ◽  
High Surface ◽  
Labyrinth Seal ◽  
Secondary Flows ◽  
Effect Of Temperature ◽  
Maximum Speed ◽  
The Novel ◽  
Flow Factor ◽  
Metal Seal

Parasitic secondary flows (seals’ leakage) in centrifugal compressors and gas and steam turbines represent a substantial loss in efficiency and power delivery with an increase in specific fuel consumption. Labyrinth seals are the most common and inexpensive means of reducing secondary leakage, albeit wearing out with operation and thereby penalizing performance and even affecting rotordynamic stability. The novel Hydrostatic Advanced Low Leakage (HALO) seal is an all-metal seal with flexibly supported shoes that enable clearance self-control to effectively reduce leakage, in particular for operation with high pressure ratios and at high surface rotor speeds. This paper presents leakage tests with hot air (max. 300°C) conducted in a test rig holding a labyrinth seal and a HALO seal, both of similar diameter, axial length and clearance. The novel seal leaks much less than the labyrinth seal as the supply/discharge pressure ratio (Ps/Pa) increases. The leakage reduction is ∼50% for (Ps/Pa) < 2 and continuously dropping to 70% for (Ps/Pa) > 3.0. Thus, the savings in leakage are maximized for operation with a high pressure differential. Leakage measurements with a rotor spinning to a maximum speed of 2,700 rpm (surface speed ∼ 24 m/s) produce a slight decrease in leakage for both seals. Characterization of seal leakage in terms of a flow factor removes the effect of temperature and supply pressure; the labyrinth seal showing a constant flow factor for (Ps/Pa) > 2. Application of the novel seal technology will aid to increase system efficiency by reducing leakage and will extend maintenance intervals since it eliminates wear of components.

Development of New Single and High-Density Heat-Flux Gauges for Unsteady Heat Transfer Measurements for a Rotating Transonic Turbine

2020 ◽  
Author(s):  
Richard Celestina ◽  
Spencer Sperling ◽  
Louis Christensen ◽  
Randall Mathison ◽  
Hakan Aksoy ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
High Pressure ◽  
Pressure Ratio ◽  
High Density ◽  
Secondary Flows ◽  
Single Stage ◽  
High Pressure Turbine ◽  
Transonic Turbine ◽  
New Generation

Abstract This paper presents the development and implementation of a new generation of double-sided heat-flux gauges at The Ohio State University Gas Turbine Laboratory (GTL) along with heat transfer measurements for film-cooled airfoils in a single-stage high-pressure transonic turbine operating at design corrected conditions. Double-sided heat flux gauges are a critical part of turbine cooling studies, and the new generation improves upon the durability and stability of previous designs while also introducing high-density layouts that provide better spatial resolution. These new customizable high-density double-sided heat flux gauges allow for multiple heat transfer measurements in a small geometric area such as immediately downstream of a row of cooling holes on an airfoil. Two high-density designs are utilized: Type A consists of 9 gauges laid out within a 5 mm by 2.6 mm (0.20 inch by 0.10 inch) area on the pressure surface of an airfoil, and Type B consists of 7 gauges located at points of predicted interest on the suction surface. Both individual and high-density heat flux gauges are installed on the blades of a transonic turbine experiment for the second build of the High-Pressure Turbine Innovative Cooling program (HPTIC2). Run in a short duration facility, the single-stage high-pressure turbine operated at design-corrected conditions (matching corrected speed, flow function, and pressure ratio) with forward and aft purge flow and film-cooled blades. Gauges are placed at repeated locations across different cooling schemes in a rainbow rotor configuration. Airfoil film-cooling schemes include round, fan, and advanced shaped cooling holes in addition to uncooled airfoils. Both the pressure and suction surfaces of the airfoils are instrumented at multiple wetted distance locations and percent spans from roughly 10% to 90%. Results from these tests are presented as both time-average values and time-accurate ensemble averages in order to capture unsteady motion and heat transfer distribution created by strong secondary flows and cooling flows.

Leakage and Cavity Pressures in an Interlocking Labyrinth Gas Seal: Measurements vs. Predictions

2019 ◽  
Author(s):  
Luis San Andrés ◽  
Tingcheng Wu ◽  
Jose Barajas-Rivera ◽  
Jiaxin Zhang ◽  
Rimpei Kawashita
Keyword(s):  
Mass Flow ◽  
Pressure Ratio ◽  
Labyrinth Seal ◽  
Secondary Flows ◽  
Tip Clearance ◽  
Inlet Pressure ◽  
Steam Turbines ◽  
Rotor Speed ◽  
Labyrinth Seals ◽  
Gas Seals

Abstract Gas labyrinth seals (LS) restrict secondary flows (leakage) in turbomachinery and their impact on the efficiency and rotordynamic stability of high-pressure compressors and steam turbines can hardly be overstated. Amongst seal types, the interlocking labyrinth seal (ILS), having teeth on both the rotor and on the stator, is able to reduce leakage up to 30% compared to other LSs with either all teeth on the rotor or all teeth on the stator. This paper introduces a revamped facility to test gas seals for their rotordynamic performance and presents measurements of the leakage and cavity pressures in a five teeth ILS. The seal with overall length/diameter L/D = 0.3 and small tip clearance Cr/D = 0.00133 is supplied with air at T = 298 K and increasing inlet pressure Pin = 0.3 MPa ∼ 1.3 MPa, while the exit pressure/inlet pressure ratio PR = Pout/Pin is set to range from 0.3 to 0.8. The rotor speed varies from null to 10 krpm (79 m/s max. surface speed). During the tests, instrumentation records the seal mass flow (ṁ) and static pressure in each cavity. In parallel, a bulk-flow model (BFM) and a computational fluid dynamics (CFD) analysis predict the flow field and deliver the same performance characteristics, namely leakage and cavity pressures. Both measurements and predictions agree closely (within 5%) and demonstrate the seal mass flow rate is independent of rotor speed. A modified flow factor Φ¯=m.T/PinD1-PR2 characterizes best the seal mass flow with a unique magnitude for all pressure conditions, Pin and PR.

Experimental Investigation of Purge Flow Effects on a High Pressure Turbine Stage

2014 ◽  
Vol 137 (4) ◽  
Author(s):  
K. Regina ◽  
A. I. Kalfas ◽  
R. S. Abhari
Keyword(s):  
Experimental Investigation ◽  
High Pressure ◽  
Gas Turbines ◽  
Radial Displacement ◽  
Secondary Flows ◽  
Turbine Stage ◽  
Flow Factor ◽  
Purge Flow ◽  
The Impact ◽  
Stage Efficiency

In the present paper, an experimental investigation of the effects of rim seal purge flow on the performance of a highly loaded axial turbine stage is presented. The test configuration consists of a one-and-a-half stage, unshrouded, turbine, with a blading representative of high pressure (HP) gas turbines. Efficiency measurements for various purge flow injection levels have been carried out with pneumatic probes at the exit of the rotor and show a reduction of isentropic total-to-total efficiency of 0.8% per percent of injected mass flow. For three purge flow conditions, the unsteady aerodynamic flow field at rotor inlet and rotor exit has been measured with the in-house developed fast response aerodynamic probe (FRAP). The time-resolved data show the unsteady interaction of the purge flow with the secondary flows of the main flow and the impact on the radial displacement of the rotor hub passage vortex (HPV). Steady measurements at off-design conditions show the impact of the rotor incidence and of the stage flow factor on the resulting stage efficiency and the radial displacement of the rotor HPV. A comparison of the effect of purge flow and of the off-design conditions on the rotor incidence and stage flow factor shows that the detrimental effect of the purge flow on the stage efficiency caused by the radial displacement of the rotor HPV is dominated by the increase of stage flow factor in the hub region rather than by the increase of negative rotor incidence.

Effect of temperature on the strength of a centrifugal compressor impeller for a turbocharger

2012 ◽  
Vol 227 (5) ◽  
pp. 896-904 ◽  
Author(s):  
Xinqian Zheng ◽  
Lei Jin ◽  
Tao Du ◽  
Binlin Gan ◽  
Fenghu Liu ◽  
...  
Keyword(s):  
High Pressure ◽  
Tensile Strength ◽  
Temperature Distribution ◽  
Ultimate Tensile Strength ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Critical Role ◽  
Effect Of Temperature ◽  
High Pressure Ratio ◽  
Compressor Impeller

High pressure ratio turbocharger technology is used to decrease fuel consumption, reduce emissions and improve power density of an internal combustion engine. The centrifugal compressor is the turbocharger’s core component. The reliability of its impeller becomes critical as the pressure ratio gets higher and the temperature starts playing an important role. In order to study the effect of the flow temperature on the reliability of a centrifugal compressor impeller, solid–fluid coupling is used to calculate the temperature distribution on the impeller surface. This temperature distribution is then applied as boundary condition in three-dimensional finite element analysis to analyze impeller stress. The results show that the percentage of impeller stress caused by thermal load remains approximately constant (about 2%) at different pressure ratios, which does not increase with increasing pressure ratio. Centrifugal load plays an absolutely critical role in the impeller stress at different pressure ratios. High pressure ratio also leads to an increase of air temperature, which causes higher material temperature and consequently the lower ultimate tensile strength of the impeller material. The maximum compressor pressure ratio which the impeller can bear decreases from 4.6 to 4.2 for the researched compressor if the effect of temperature on the ultimate tensile strength was considered. That means the effect of the temperature on compressor impeller strength and reliability at high pressure ratio should be considered while it can be ignored at low pressure ratio.

Numerical Study on the Effects of Blade Lean on High-Pressure Centrifugal Impeller Performance

2011 ◽  
Author(s):  
JongSik Oh ◽  
Charles W. Buckley ◽  
Giri L. Agrawal
Keyword(s):  
High Pressure ◽  
Degrees Of Freedom ◽  
Numerical Solutions ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Internal Flow ◽  
Secondary Flows ◽  
Centrifugal Impeller ◽  
High Pressure Ratio

Blade lean and sweep are additional degrees of freedom for the three dimensional blade design. When compared to blade sweep, the influence of blade lean on the performance is not extensively described in the public literature. The effects of blade lean on the aerodynamic performance of a high-pressure ratio centrifugal impeller were investigated using a CFD (Computational Fluid Dynamics) approach. For total of 15 variations of blade lean given at the impeller inlet and outlet, while blade angles at the impeller inlet and outlet were unchanged, numerical solutions of the impeller with a vaneless diffuser were obtained at the design speed from a maximum choke flow to a minimum flow available. Compressor performance maps were generated to compare overall characteristics, and details of internal flow structure at 5 different quasi-orthogonal planes were investigated to see the effects of blade lean on the development of secondary flows. It was found that a positive lean at the impeller exit shroud helps mitigate the wake region to contribute to more uniform flows, resulting in an increase of the impeller pressure and efficiency. A negative lean at the impeller exit causes a limited head rise due to a reduced blade loading on the shroud. A negative inlet lean at the shroud provided the worst performance.

Leakage and Cavity Pressures in an Interlocking Labyrinth Gas Seal: Measurements Versus Predictions

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Luis San Andrés ◽  
Tingcheng Wu ◽  
Jose Barajas-Rivera ◽  
Jiaxin Zhang ◽  
Rimpei Kawashita
Keyword(s):  
Mass Flow ◽  
Pressure Ratio ◽  
Labyrinth Seal ◽  
Secondary Flows ◽  
Tip Clearance ◽  
Inlet Pressure ◽  
Steam Turbines ◽  
Rotor Speed ◽  
Labyrinth Seals ◽  
Gas Seals

Gas labyrinth seals (LS) restrict secondary flows (leakage) in turbomachinery and their impact on the efficiency and rotordynamic stability of high-pressure compressors and steam turbines can hardly be overstated. Among seal types, the interlocking labyrinth seal (ILS), having teeth on both the rotor and the stator, is able to reduce leakage up to 30% compared to other LSs with either all teeth on the rotor (TOR) or all teeth on the stator. This paper introduces a revamped facility to test gas seals for their rotordynamic performance and presents measurements of the leakage and cavity pressures in a five teeth ILS. The seal with overall length/diameter L/D = 0.3 and small tip clearance Cr/D = 0.00133 is supplied with air at T = 298 K and increasing inlet pressure Pin = 0.3–1.3 MPa, while the exit pressure/inlet pressure ratio PR = Pout/Pin is set to range from 0.3 to 0.8. The rotor speed varies from null to 10 krpm (79 m/s max. surface speed). During the tests, instrumentation records the seal mass flow (m˙) and static pressure in each cavity. In parallel, a bulk-flow model (BFM) and a computational fluid dynamics (CFD) analysis predict the flow field and deliver the same performance characteristics, namely leakage and cavity pressures. Both measurements and predictions agree closely (within 5%) and demonstrate that the seal mass flow rate is independent of rotor speed. A modified flow factor Φ¯=m˙T/(PinD1−PR2) characterizes best the seal mass flow with a unique magnitude for all pressure conditions, Pin and PR.

Dealing with hot rocky environments: Critical thermal maxima and locomotor performance in Leptodactylus lithonaetes (Anura: Leptodactylidae)

2019 ◽  
pp. 155-161 ◽  
Author(s):  
Ivan Beltran
Keyword(s):  
Environmental Temperature ◽  
Extreme Temperature ◽  
Effect Of Temperature ◽  
Maximum Speed ◽  
Locomotor Performance ◽  
Extreme Temperatures ◽  
Physiological Limits ◽  
Fitness Consequences ◽  
Thermal Maximum ◽  
Environmental Temperatures

Environmental temperature has fitness consequences on ectotherm development, ecology and behaviour. Amphibians are especially vulnerable because thermoregulation often trades with appropriate water balance. Although substantial research has evaluated the effect of temperature in amphibian locomotion and physiological limits, there is little information about amphibians living under extreme temperature conditions. Leptodactylus lithonaetes is a frog allegedly specialised to forage and breed on dark granitic outcrops and associated puddles, which reach environmental temperatures well above 40 ˚C. Adults can select thermally favourable microhabitats during the day while tadpoles are constrained to rock puddles and associated temperature fluctuations; we thus established microhabitat temperatures and tested whether the critical thermal maximum (CTmax) of L. lithonaetes is higher in tadpoles compared to adults. In addition, we evaluated the effect of water temperature on locomotor performance of tadpoles. Contrary to our expectations, puddle temperatures were comparable and even lower than those temperatures measured in the microhabitats used by adults in the daytime. Nonetheless, the CTmax was 42.3 ˚C for tadpoles and 39.7 ˚C for adults. Regarding locomotor performance, maximum speed and maximum distance travelled by tadpoles peaked around 34 ˚C, approximately 1 ˚C below the maximum puddle temperatures registered in the puddles. In conclusion, L. lithonaetes tadpoles have a higher CTmax compared to adults, suggesting a longer exposure to extreme temperatures that lead to maintain their physiological performance at high temperatures. We suggest that these conditions are adaptations to face the strong selection forces driven by this granitic habitat.

Improving of quality of gate assembly contact surfaces of high-pressure fi ttings by diamond burnishing

2020 ◽  
pp. 99-104
Author(s):  
S.A. Zaydes ◽  
A.N. Mashukov ◽  
T.Ya. Druzhinina
Keyword(s):  
Surface Roughness ◽  
High Pressure ◽  
Main Part ◽  
Conical Surface ◽  
The Real ◽  
Metal Seal ◽  
Diamond Burnishing ◽  
Air Tightness ◽  
Contact Surfaces

The contact belt of the gate assembly is the main part of high pressure fittings. The serviceability of the fittings assembly as whole depends on the air-tightness and quality of the mating surfaces. The technology of diamond burnishing allows to increase the interface of the nodes by red ucing the surface roughness of the metal-to-metal seal. The real experience for improving of the fittings contact belt due to the use of diamond burnishing of the nozzles seats and the conical surface of the rods.

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