Compliant Plate Seals: Design and Performance Simulations

2012 ◽  
Author(s):  
Hrishikesh V. Deo ◽  
Ajay Rao ◽  
Hemant Gedam
Keyword(s):  
Gas Turbines ◽  
Tip Clearance ◽  
Outer Diameter ◽  
Aircraft Engines ◽  
Steam Turbines ◽  
Flow Rates ◽  
Cfd Models ◽  
Low Leakage ◽  
And Performance ◽  
Large Rotor

Compliant Plate Seals are being developed for various turbomachinery sealing applications including gas turbines, steam turbines, aircraft engines and oil & gas compressors. These seals consist of compliant plates attached to a stator in a circumferential fashion around a rotor. The compliant plates have a slot that extends radially inwards from the seal outer diameter, and an intermediate plate extends inwards into this slot from stator. This design is capable of providing passive hydrostatic feedback forces acting on the compliant plates that balance at a small tip–clearance. Due to this self–correcting behavior, this seal is capable of providing high differential pressure capability and low leakage within a limited axial span, and non–contact operation even in the presence of large rotor transients. CFD models have been developed to predict the leakage flow rates and hydrostatic lift and blowdown forces, and a design philosophy is proposed to predict the feedback phenomenon from the CFD results.

Compliant Plate Seals: Testing and Validation

2012 ◽  
Author(s):  
Hrishikesh V. Deo
Keyword(s):  
High Frequency ◽  
Gas Turbines ◽  
Tip Clearance ◽  
Outer Diameter ◽  
Aircraft Engines ◽  
Test Results ◽  
Steam Turbines ◽  
Leakage Test ◽  
Low Leakage ◽  
Large Rotor

Compliant Plate Seals are being developed for various turbomachinery sealing applications including gas turbines, steam turbines, aircraft engines and oil & gas compressors. These seals consist of compliant plates attached to a stator in a circumferential fashion around the rotor. The compliant plates have a slot that extends radially inwards from the seal outer diameter, and an intermediate plate extends inwards into this slot from stator. This design is capable of providing passive hydrostatic feedback forces acting on the compliant plates that balance at a small tip–clearance. Due to this self–correcting behavior, this seal is capable of providing high differential pressure capability and low leakage within a limited axial span, and non-contact operation even in the presence of large rotor transients. In this paper, we have reported leakage test results for Compliant Plate Seals and visually demonstrated robust non-contact operation for different assembly clearances and interferences, stator deflections, high frequency rotor transients, different pressure conditions and rotational speeds.

Side Weld and Bend Method of Manufacturing Compliant Plate Seals

2013 ◽  
Author(s):  
William E. Adis ◽  
Michael Mack ◽  
Hrishikesh V. Deo
Keyword(s):  
Gas Turbines ◽  
Tip Clearance ◽  
Outer Diameter ◽  
Aircraft Engines ◽  
Steam Turbines ◽  
Manufacturing Method ◽  
Low Leakage ◽  
Straight Line ◽  
Differential Shrinkage ◽  
Large Rotor

Compliant Plate Seals are being developed for various turbomachinery sealing applications including gas turbines, steam turbines, aircraft engines and oil & gas compressors. These seals consist of compliant plates attached to a stator in a circumferential fashion around a rotor. The compliant plates have a slot that extends radially inwards from the seal outer diameter and an intermediate plate extends inwards into this slot from the stator. This design is capable of providing passive hydrostatic feedback forces acting on the compliant plates that balance at a small tip-clearance. Due to this self-correcting behavior, this seal is capable of providing high differential pressure capability and low leakage within a limited axial span, and robust non-contact operation even in the presence of large rotor transients. Manufacturing of Compliant Plate Seals is a challenging problem and in this paper, we describe the development of a novel manufacturing technique called Side Weld And Bend (SWAB). The compliant plates are tightly packed with alternating spacer shims in a straight line fixture and welded to a top-plate from the side along a straight line. After removal of the spacer shims, the welded assembly is bent to form an arcuate seal of a desired diameter. The Side Weld And Bend (SWAB) manufacturing method reduces distortion, deformity, differential shrinkage and other associated problems with welding across gaps between adjacent compliant plate seals as is typical in current manufacturing processes.

Side Weld and Bend Method of Manufacturing Compliant Plate Seals

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
William E. Adis ◽  
Michael Mack ◽  
Hrishikesh V. Deo
Keyword(s):  
Gas Turbines ◽  
Oil And Gas ◽  
Tip Clearance ◽  
Outer Diameter ◽  
Steam Turbines ◽  
Manufacturing Method ◽  
Low Leakage ◽  
Straight Line ◽  
Differential Shrinkage ◽  
Large Rotor

Compliant plate seals are being developed for various turbomachinery sealing applications including gas turbines, steam turbines, aircraft engines, and oil and gas compressors. These seals consist of compliant plates attached to a stator in a circumferential fashion around a rotor. The compliant plates have a slot that extends radially inward from the seal outer diameter and an intermediate plate extends inward into this slot from the stator. This design is capable of providing passive hydrostatic feedback forces acting on the compliant plates that balance at a small tip clearance. Due to this self-correcting behavior, this seal is capable of providing high differential pressure capability and low leakage within a limited axial span, and robust noncontact operation even in the presence of large rotor transients. Manufacturing of compliant plate seals is a challenging problem and in this paper we describe the development of a novel manufacturing technique called side weld and bend (SWAB). The compliant plates are tightly packed with alternating spacer shims in a straight line fixture and welded to a top plate from the side along a straight line. After removal of the spacer shims, the welded assembly is bent to form an arcuate seal of a desired diameter. The side weld and bend (SWAB) manufacturing method reduces distortion, deformity, differential shrinkage, and other associated problems with welding across gaps between adjacent compliant plate seals as is typical in current manufacturing processes.

Compliant Plate Seals for Turbomachinery Applications

2011 ◽  
Author(s):  
Hrishikesh V. Deo
Keyword(s):  
Experimental Testing ◽  
Differential Pressure ◽  
Tip Clearance ◽  
Outer Diameter ◽  
Leakage Flow ◽  
Blow Down ◽  
Flow Rates ◽  
Cfd Models ◽  
Low Leakage ◽  
Large Rotor

In this paper, a novel GE Compliant Plate Seal is proposed that consists of compliant plates attached to a stator in a circumferential fashion around a rotor. The compliant plates have a slot that extends radially inwards from the seal outer diameter, and an intermediate plate extends inwards into this slot from stator. This design is capable of providing passive hydrostatic feedback forces acting on the compliant plates that balance at a small tip-clearance. When the tip-clearance reduces below the equilibrium clearance, the hydrostatic lift forces cause the compliant plates to lift away from the rotor. Conversely when the tip-clearance increases above the equilibrium clearance, the hydrostatic blowdown forces cause the compliant plates to blow down towards the rotor. Due to this self-correcting behavior, this seal is capable of providing high differential pressure capability and low leakage within a limited axial span, and non-contact operation even in the presence of large rotor transients. Simplified CFD models have been developed to predict the leakage flow rates and hydrostatic lift and blowdown forces, and a design philosophy is proposed to predict the feedback phenomenon from the CFD models. The proposed models are validated and self-correcting behavior is demonstrated through experimental testing.

Static Testing of Compliant Plate Seals

2012 ◽  
Author(s):  
Hrishikesh V. Deo ◽  
Deepak Trivedi
Keyword(s):  
Gas Turbines ◽  
High Speed ◽  
Pressure Ratio ◽  
Differential Pressure ◽  
Tip Clearance ◽  
Design Parameters ◽  
Outer Diameter ◽  
Steam Turbines ◽  
Low Leakage ◽  
The Impact

Self–correcting Compliant Plate Seals are being developed for various turbomachinery sealing applications including gas turbines, steam turbines, aircraft engines and oil & gas compressors. These seals consist of compliant plates attached to a stator in a circumferential fashion around the rotor. The compliant plates have a slot that extends radially inwards from the seal outer diameter, and an intermediate plate extends inwards into this slot from stator. This design is capable of providing passive hydrostatic feedback forces acting on the compliant plates that balance at a small tip–clearance. Due to this self–correcting behavior, this seal is capable of providing high differential pressure capability and low leakage within a limited axial span, and robust non–contact operation even in the presence of large rotor transients. In this paper we have described the testing of Compliant Plate Seals in a static leakage test rig (“shoebox” rig) to study the impact of different design parameters on leakage and vibration. A novel high–speed visualization set–up is described and the high–speed videos demonstrate robust non–contact operation for different assembly clearances, bridge–gaps and bridge–heights, for various differential pressure and pressure ratio conditions. The reported leakage results indicate that the leakage is relatively insensitive to assembly clearances due to the self–correcting behavior.

Progressive Clearance Labyrinth Seal for Turbo-Machinery Applications

2011 ◽  
Author(s):  
Binayak Roy ◽  
Hrishikesh V. Deo ◽  
Xiaoqing Zheng
Keyword(s):  
Theoretical Models ◽  
Labyrinth Seal ◽  
Tip Clearance ◽  
Labyrinth Seals ◽  
Lower Efficiency ◽  
Thermal Transients ◽  
Low Leakage ◽  
Packing Ring ◽  
Lift Off ◽  
Large Rotor

Turbomachinery sealing is a challenging problem due to the varying clearances caused by thermal transients, vibrations, bearing lift-off etc. Leakage reduction has significant benefits in improving engine efficiency and reducing emissions. Conventional labyrinth seals have to be assembled with large clearances to avoid rubbing during large rotor transients. This results in large leakage and lower efficiency. In this paper, we propose a novel Progressive Clearance Labyrinth Seal that is capable of providing passive fluidic feedback forces that balance at a small tip-clearance. A modified packing ring is supported on flexures and employs progressively tighter teeth from the upstream to the downstream direction. When the tip-clearance reduces below the equilibrium clearance, fluidic feedback forces cause the packing ring to open. Conversely, when the tip-clearance increases above the equilibrium clearance, the fluidic feedback forces cause the packing ring to close. Due to this self-correcting behavior, the seal provides high differential pressure capability, low leakage and non-contact operation even in the presence of large rotor transients. Theoretical models for the feedback phenomenon have been developed and validated by experimental results.

scholarly journals The Inner Workings of Axial Casing Grooves in a One and a Half Stage Axial Compressor With a Large Rotor Tip Gap: Changes in Stall Margin and Efficiency

2018 ◽  
Author(s):  
Chunill Hah
Keyword(s):  
Boundary Layer ◽  
Axial Compressor ◽  
Leading Edge ◽  
Tip Clearance ◽  
Flow Rates ◽  
Stall Margin ◽  
Tip Clearance Flow ◽  
Flow Boundary ◽  
Clearance Flow ◽  
Large Rotor

Effects of axial casing grooves (ACGs) on the stall margin and efficiency of a one and a half stage low-speed axial compressor with a large rotor tip gap are investigated in detail. The primary focus of the current paper is to identify the flow mechanisms behind the changes in stall margin and on the efficiency of the compressor stage with a large rotor tip gap. Semicircular axial grooves installed in the rotor’s leading edge area are investigated. A large eddy simulation (LES) is applied to calculate the unsteady flow field in a compressor stage with ACGs. The calculated flow fields are first validated with previously reported flow visualizations and stereo PIV (SPIV) measurements. An in-depth examination of the calculated flow field indicates that the primary mechanism of the ACG is the prevention of full tip leakage vortex (TLV) formation when the rotor blade passes under the axial grooves periodically. The TLV is formed when the incoming main flow boundary layer collides with the tip clearance flow boundary layer coming from the opposite direction near the casing and rolls up around the rotor tip vortex. When the rotor passes directly under the axial groove, the tip clearance flow boundary layer on the casing moves into the ACGs and no roll-up of the incoming main flow boundary layer can occur. Consequently, the full TLV is not formed periodically as the rotor passes under the open casing of the axial grooves. Axial grooves prevent the formation of the full TLV. This periodic prevention of the full TLV generation is the main mechanism explaining how the ACGs extend the compressor stall margin by reducing the total blockage near the rotor tip area. Flows coming out from the front of the grooves affect the overall performance as it increases the flow incidence near the leading edge and the blade loading with the current ACGs. The primary flow mechanism of the ACGs is periodic prevention of the full TLV formation. Lower efficiency and reduced pressure rise at higher flow rates for the current casing groove configuration are due to additional mixing between the main passage flow and the flow from the grooves. At higher flow rates, blockage generation due to this additional mixing is larger than any removal of the flow blockage by the grooves. Furthermore, stronger double-leakage tip clearance flow is generated with this additional mixing with the ACGs at a higher flow rate than that of the smooth wall.

Bearing Housing Design for Vibration Control, Using Tilting Pad Bearings Instead of Lemon-Bore Type on a Gas Turbine

2020 ◽  
Author(s):  
Chippa Anil ◽  
Aparna Satheesh ◽  
Babu Santhanagopalakrishnan ◽  
Marcin Bielecki
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Structural Integrity ◽  
Plane Surface ◽  
Rotor Dynamics ◽  
Turbine Rotor ◽  
Outer Diameter ◽  
Housing Design ◽  
Tilting Pad ◽  
And Performance

Abstract Heavy duty gas turbines are usually equipped with hydrodynamic bearings which are either lemon-bore or tilting pad type. Baker Hughes legacy gas turbines use these two types of bearings, and its selection is based on 1) considering pros & cons from Rotor dynamics, 2) bearing performance, 3) bearing housing stiffness, 4) vibration detection & control. Non-contact probes are used to monitor the vibrations of rotor. Majority of legacy gas turbines are not equipped with these probes. Due to this fact, over the years it resulted in non-detection of dynamics & vibration issue, which caused frequent bearing replacement. As the increase in industry demand to apply and measure vibrations using non-contact probes on bearings, an effort was made by Baker Hughes to implement these on existing fleet units. Also, in order to increase rotor dynamics stability of low-pressure rotor, to improve bearing life and performance, effort was made to replace lemon-bore bearings with tilting pad. This paper demonstrates efforts made to design the titling pad which would fit within envelop of already available bearing housing. Bearing/shaft clearance, bearing performance, modification of bearing retainer clearances are the mandatory tasks which would be dealt in this study. The swap of bearing type, and its effect on whole gas turbine rotor dynamic stability, checking the frequency crossovers with Campbell diagram would also be dealt in this paper. This paper also focuses on assessment on oil passage routing, temperature & proximity probe instrumentation routing design. Re-design is performed by analyzing various configuration, assessing different sensitivity studies & validation of modified bearing housing from structural integrity, ultimate load capability, & split plane oil leakage retention and its comparison with baseline are most important aspects of finalization of this change, which will be showcased in this paper. Instrumentation routing was a critical task when the considering bearing replacement from lemon-bore to tilting pad. As lemon-bore type bearings just have an elliptical inner surface, it’s quite easy to install the thermocouples into a simple hole. But as replacement has tilting pads, the challenge is to instrument the pads without effecting their movement and functionality. Such best practices are also dealt in this paper. Comparison of tilting-pad with lemon-bore, considering the fixed shaft diameter, the retainer outer diameter of tilting pad is higher than lemon-bore. This effect has a change in bearing seat on bearing housing, thereby reducing the effective stiffness of the housing, and the reduced split plane surface. To tackle this situation, several sensitivities were executed, by re-modifying the bolts and bolt holes on the existing housing, without modifying the housing envelop.

The Inner Workings of Axial Casing Grooves in a One and a Half Stage Axial Compressor With a Large Rotor Tip Gap: Changes in Stall Margin and Efficiency

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Chunill Hah
Keyword(s):  
Boundary Layer ◽  
Axial Compressor ◽  
Leading Edge ◽  
Tip Clearance ◽  
Flow Rates ◽  
Stall Margin ◽  
Tip Clearance Flow ◽  
Flow Boundary ◽  
Clearance Flow ◽  
Large Rotor

Effects of axial casing grooves (ACGs) on the stall margin and efficiency of a one and a half stage low-speed axial compressor with a large rotor tip gap are investigated in detail. The primary focus of the current paper is to identify the flow mechanisms behind the changes in stall margin and on the efficiency of the compressor stage with a large rotor tip gap. Semicircular axial grooves installed in the rotor's leading edge area are investigated. A large eddy simulation (LES) is applied to calculate the unsteady flow field in a compressor stage with ACGs. The calculated flow fields are first validated with previously reported flow visualizations and stereo particle image velocimetry (SPIV) measurements. An in-depth examination of the calculated flow field indicates that the primary mechanism of the ACG is the prevention of full tip leakage vortex (TLV) formation when the rotor blade passes under the axial grooves periodically. The TLV is formed when the incoming main flow boundary layer collides with the tip clearance flow boundary layer coming from the opposite direction near the casing and rolls up around the rotor tip vortex. When the rotor passes directly under the axial groove, the tip clearance flow boundary layer on the casing moves into the ACGs and no roll-up of the incoming main flow boundary layer can occur. Consequently, the full TLV is not formed periodically as the rotor passes under the open casing of the axial grooves. Axial grooves prevent the formation of the full TLV. This periodic prevention of the full TLV generation is the main mechanism explaining how the ACGs extend the compressor stall margin by reducing the total blockage near the rotor tip area. Flows coming out from the front of the grooves affect the overall performance as it increases the flow incidence near the leading edge and the blade loading with the current ACGs. The primary flow mechanism of the ACGs is periodic prevention of the full TLV formation. Lower efficiency and reduced pressure rise at higher flow rates for the current casing groove configuration are due to additional mixing between the main passage flow and the flow from the grooves. At higher flow rates, blockage generation due to this additional mixing is larger than any removal of the flow blockage by the grooves. Furthermore, stronger double-leakage tip clearance flow is generated with this additional mixing with the ACGs at a higher flow rate than that of the smooth wall.

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