Experimental and Analytical Leakage Characterization of Annular Gas Seals: Honeycomb, Labyrinth and Pocket Damper Seals

2011 ◽  
Author(s):  
Nuo Sheng ◽  
Eric J. Ruggiero ◽  
Ravindra Devi ◽  
Jianping Guo ◽  
Massimiliano Cirri
Keyword(s):  
New York ◽  
High Pressure ◽  
High Speed ◽  
System Level ◽  
Operating Pressure ◽  
Test Rig ◽  
Flow Mechanisms ◽  
Successful Design ◽  
Gas Seals ◽  
Analytical Tools

Modern day turbomachinery requires the use of annular gas seals to provide flow restriction from high pressure to low pressure regions within the machine. These flow restrictions are critical design points in the overall performance of the machine and directly impact the system-level efficiency. Consequently, understanding the leakage performance of a given seal element as a function of operating pressure, rotor speed, and rotor offset is critical to the successful design of the turbomachine. In the present work, three annular gas seals are experimentally tested on a leakage test rig at GE Global Research (Niskayuna, New York). The test rig is capable of high-speed, high-pressure flow testing and has a radial degree of freedom that enables non-concentric leakage characterization. The leakage performances of a labyrinth, honeycomb and pocket damper seals are compared over a range of inlet pressures and pressure ratios. Analytical tools, including a CFD model and a Bulk Flow Code, are developed to provide leakage prediction and to establish understanding of underlying flow mechanisms. Predictions of the seal leakage are found to be in good agreement with experimental data.

scholarly journals A New Analysis Tool Assessment for Rotordynamic Modeling of Gas Foil Bearings

2010 ◽  
Author(s):  
Samuel A. Howard ◽  
Luis San Andre´s
Keyword(s):  
Power Loss ◽  
High Speed ◽  
Structural Deformation ◽  
Analysis Tool ◽  
Test Rig ◽  
Contributing Factors ◽  
Foil Bearings ◽  
Rotordynamic Coefficients ◽  
Foil Bearing ◽  
Analytical Tools

Gas foil bearings offer several advantages over traditional bearing types that make them attractive for use in high-speed turbomachinery. They can operate at very high temperatures, require no lubrication supply (oil pumps, seals, etc), exhibit very long life with no maintenance, and once operating airborne, have very low power loss. The use of gas foil bearings in high-speed turbomachinery has been accelerating in recent years, although the pace has been slow. One of the contributing factors to the slow growth has been a lack of analysis tools, benchmarked to measurements, to predict gas foil bearing behavior in rotating machinery. To address this shortcoming, NASA Glenn Research Center (GRC) has supported the development of analytical tools to predict gas foil bearing performance. One of the codes has the capability to predict rotordynamic coefficients, power loss, film thickness, structural deformation, and more. The current paper presents an assessment of the predictive capability of the code, named XLGFBTH©. A test rig at GRC is used as a simulated case study to compare rotordynamic analysis using output from the code to actual rotor response as measured in the test rig. The test rig rotor is supported on two gas foil journal bearings manufactured at GRC, with all pertinent geometry disclosed. The resulting comparison shows that the rotordynamic coefficients calculated using XLGFBTH© represent the dynamics of the system reasonably well, especially as they pertain to predicting critical speeds.

High Pressure Amplifying Framework Materials for Programmable Pneumatics Systems

2020 ◽  
Author(s):  
Volodymyr Bon ◽  
Simon Krause ◽  
Irena Senkovska ◽  
Nico Grimm ◽  
Dirk Wallacher ◽  
...  
Keyword(s):  
High Pressure ◽  
Pressure Range ◽  
Gas Adsorption ◽  
System Level ◽  
Operating Pressure ◽  
Framework Materials ◽  
Pressure Amplification ◽  
University Of Technology ◽  
Theoretical Pressure

Negative Gas Adsorption (NGA), discovered in a series of mesoporous switchable MOFs, was hitherto regarded as a curios phenomenon occurring only at pressures well below or close to atmospheric merit. Herein we demonstrate mesoporous frameworks interacting with carbon dioxide, to show stimulated breathing transitions well above 100 kPa. Reversible CO<sub>2</sub> adsorption-induced switching was observed in DUT-46 (DUT = Dresden University of Technology), in contrast to irreversible transitions for DUT-49 and DUT-50, as demonstrated via synchrotron in situ PXRD/adsorption experiments. Systematic physisorption experiments reveal the best conditions for high pressure NGA transitions in the pressure range of 350 - 680 kPa. The stimulated framework contraction expells CO<sub>2</sub> in the range of 1.1 to 2.4 mmol g<sup>-1</sup> leading to autonomous pressure amplification in a closed system. In a pneumatic demonstrator system we achieved pressure amplification of 90 kPa at a high operating pressure of 340 kPa. According to system level estimations even higher theoretical pressure amplification may be achieved between 535 kPa and 1011 kPa for DUT-49 using CO<sub>2</sub> as a non-toxic and non-flammable working gas. Operable pressure ranges exceeding 100 kPa render pressure amplifying framework materials as realistic candidates for the integration into energy autonomous responsive pneumatic systems.

Design of a High-Speed Rotating Test Rig for Adaptive Seal Systems

2015 ◽  
Author(s):  
Laura S. Beermann ◽  
Corina Höfler ◽  
Hans-Jörg Bauer
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
High Speed ◽  
Operating Conditions ◽  
Turbine Engines ◽  
Parameter Study ◽  
Test Rig ◽  
Swirl Chamber ◽  
Mass Flows ◽  
Gap Width

Gas turbine engines are subject to increased performance and improved efficiency, which leads to rising core temperatures with additional cooling needs. Reducing the parasitic leakage in the secondary flow system is important to meet the challenging requirements. New seal designs have to be tested and optimized at engine like conditions, like high pressure of up to 9 bar and surface speed of up to 280 m/s as well as an adjusted flow field. Flexible seal designs are an innovative approach to reduce leakage mass flows significantly. Axial and radial movements during transient operating conditions can be compensated easily, thus allowing a smaller gap width and minimizing rub and heat load. This paper describes the design and construction of a new rotating test rig facility. To the knowledge of the authors, this is the only test rig with an adjustable gap width and flow field in a high pressure and speed range. The facility is capable of up to 8 bar differential pressure across the seal and up to 4 bar back pressure. The high revolution engine facilitates a surface speed of up to 280 m/s. A traversable casing allows a quick change of the gap width during operation and simulates radial and axial rotor/stator movements in the engine. The seal movement as well as the resulting gap width are measured during operation to fully understand the seal behavior. An important feature of the new test rig is the continuously adjustable pre-swirl system. It has been designed to cover the different flow conditions in the real engine. Therefore, a RANS parameter study of the pre-swirl chamber has been conducted, which shows the adjustability of different pre-swirl ratios for constant and changing inlet mass flows.

Numerical Simulation of Aerodynamic Instabilities in a Multistage High-Speed High-Pressure Compressor on Its Test-Rig—Part I: Rotating Stall

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Flore Crevel ◽  
Nicolas Gourdain ◽  
Stéphane Moreau
Keyword(s):  
High Pressure ◽  
Numerical Simulations ◽  
Rotational Speed ◽  
High Speed ◽  
Low Frequency ◽  
Flow Patterns ◽  
Rotating Stall ◽  
Implicit Time ◽  
Test Rig ◽  
The Third

Aerodynamic instabilities such as stall and surge may lead to mechanical failures. They can be avoided by better understanding and accurate prediction of the associated flow phenomena. Numerical simulations of rotating stall do not often match well the experiments as the number of cells and/or their rotational speed are not correctly predicted. The volumes surrounding the compressor have known effects on rotating stall flow patterns; therefore, an increased need for more realistic simulations has emerged. In that context, this paper addresses a comparison of numerical stall simulation in a compressor alone with a numerical stall simulation including the additional compressor rig. This study investigates the influence of the upstream and downstream volumes of the compressor rig on the rotating stall flow patterns and the consequences on surge inception in a high-pressure, high-speed research compressor. The numerical simulations were conducted using an implicit, time-accurate, 3D compressible Reynolds-averaged Navier–Stokes (URANS) solver. First, rotating stall is simulated in both configurations, and then the outlet nozzles are further closed to bring the compressors to surge. The numerical results show that when the compressor rig is accounted for, fewer cells develop in the third stage and their rotational speed is slightly higher. The major difference linked to the presence of the rig lays in the existence of a 1D low frequency oscillation of the static pressure, which affects the entire flow and modifies surge inception. The analysis of the results leads to a calculation of the thermo-acoustic modes in the whole configuration, which shows that this low frequency corresponds to the third thermo-acoustic mode of the complete test-rig.

Numerical Simulation of Aerodynamic Instabilities in a Multistage High-Speed High-Pressure Compressor on Its Test Rig—Part II: Deep Surge

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Flore Crevel ◽  
Nicolas Gourdain ◽  
Xavier Ottavy
Keyword(s):  
Numerical Simulation ◽  
High Pressure ◽  
High Speed ◽  
Aircraft Engine ◽  
Recovery Phase ◽  
Implicit Time ◽  
Test Rig ◽  
Reversed Flow ◽  
Mechanical Integrity ◽  
Flow Phase

Aerodynamic instabilities such as stall and surge may occur in compressors, possibly leading to mechanical failures so their avoidance is crucial. A better understanding of those phenomena and an accurate prediction are necessary to improve both the performance and the safety. A surge event in a compressor threatens the mechanical integrity of the aircraft engine, and this remains true for a research compressor on a test rig. As a result, few experimental data on surge are available. Moreover, there are technological, restrictive constraints that exist on test rigs and limit severely the type of data obtainable experimentally. This partially explains why numerical simulation has become a usual, complementary and convenient tool to collect data in a compressor, as it does not disturb the flow nor does it encounter technological limits. Despite the inherent difficulties, an entire surge cycle has been simulated in a high-speed, high-pressure, multistage research compressor, using an implicit, time-accurate, 3D compressible unsteady Reynolds-averaged Navier–Stokes solver. First, the paper presents the main features of the surge cycle obtained, along with those from the experimental cycle, for a validation purpose. Four phases compose the surge cycle: surge inception, the reversed-flow phase, the recovery phase, and the repressurization of the compressor flow. All of them are described, and focus is put on surge inception and the reversed-flow phase, as they induce greater risk for the mechanical integrity of the machine.

scholarly journals Rotordynamic Stability Case Studies

2004 ◽  
Vol 10 (3) ◽  
pp. 203-211 ◽  
Author(s):  
Pranabesh De Choudhury
Keyword(s):  
High Pressure ◽  
Case Studies ◽  
Analytical Methods ◽  
High Speed ◽  
Field Data ◽  
Cross Coupling ◽  
Related Field ◽  
Hydrodynamic Bearing ◽  
Problem Resolution ◽  
Analytical Tools

In this article case studies are presented involving rotordynamic instability of modern high-speed turbomachinery relating the field data to analytical methods. The studies include oil seal related field problems, instability caused by aerodynamic cross-coupling in high-pressure, high-speed compressors, and hydrodynamic bearing instability resulting in subsynchronous vibration of a high-speed turbocharger. It has been shown that the analytical tools not only help in problem diagnostics, but also aid in problem resolution. Examples are presented showing how analytical methods, when appropriately applied, can solve rotordynamic instability and result in stable rotor system.

Pressure Influence on the Flame Transfer Function of a Premixed Swirling Flame

2006 ◽  
Author(s):  
E. Freitag ◽  
H. Konle ◽  
M. Lauer ◽  
C. Hirsch ◽  
T. Sattelmayer
Keyword(s):  
High Pressure ◽  
Transfer Function ◽  
High Speed ◽  
Transfer Functions ◽  
Ambient Pressure ◽  
Operating Conditions ◽  
Phase Lag ◽  
Operating Pressure ◽  
Common Procedure ◽  
Wide Range

In order to assess the stability of gas turbine combustors measured flame transfer functions are frequently used in thermoacoustic network models. Although many combustion systems operate at high pressure, the measurement of flame transfer functions was essentially limited to atmospheric conditions in the past. With the test rig employed in the study presented in the paper transfer function measurements were made for a wide range of combustor pressures. The results show similarities of the amplitude response in the entire pressure range investigated. However, the increase of the pressure leads to a considerable amplitude gain at higher frequencies. In the low frequency regime the phase is also independent of pressure, whereas above this region the pressure increase results in a considerably smaller phase lag. These observations are particularly important when evaluating Rayleigh’s criterion: Interestingly, the choice of the operating pressure can render a system stable or unstable, so that the common procedure of applying flame transfer functions measured at ambient pressure for the high pressure engine case may not always be appropriate. The detailed analysis of high speed camera images, which were recorded to get locally resolved information on the flame response reveal different regions of activity within the flame that change in strength, size and location with changing operating conditions. The observed transfer function phase behavior is explained by the interaction of those regions and it is shown that the region of highest dynamic activity dominates the phase.

High Pressure Amplifying Framework Materials for Programmable Pneumatics Systems

2020 ◽  
Author(s):  
Volodymyr Bon ◽  
Simon Krause ◽  
Irena Senkovska ◽  
Nico Grimm ◽  
Dirk Wallacher ◽  
...  
Keyword(s):  
High Pressure ◽  
Pressure Range ◽  
Gas Adsorption ◽  
System Level ◽  
Operating Pressure ◽  
Framework Materials ◽  
Pressure Amplification ◽  
University Of Technology ◽  
Theoretical Pressure

Negative Gas Adsorption (NGA), discovered in a series of mesoporous switchable MOFs, was hitherto regarded as a curios phenomenon occurring only at pressures well below or close to atmospheric merit. Herein we demonstrate mesoporous frameworks interacting with carbon dioxide, to show stimulated breathing transitions well above 100 kPa. Reversible CO<sub>2</sub> adsorption-induced switching was observed in DUT-46 (DUT = Dresden University of Technology), in contrast to irreversible transitions for DUT-49 and DUT-50, as demonstrated via synchrotron in situ PXRD/adsorption experiments. Systematic physisorption experiments reveal the best conditions for high pressure NGA transitions in the pressure range of 350 - 680 kPa. The stimulated framework contraction expells CO<sub>2</sub> in the range of 1.1 to 2.4 mmol g<sup>-1</sup> leading to autonomous pressure amplification in a closed system. In a pneumatic demonstrator system we achieved pressure amplification of 90 kPa at a high operating pressure of 340 kPa. According to system level estimations even higher theoretical pressure amplification may be achieved between 535 kPa and 1011 kPa for DUT-49 using CO<sub>2</sub> as a non-toxic and non-flammable working gas. Operable pressure ranges exceeding 100 kPa render pressure amplifying framework materials as realistic candidates for the integration into energy autonomous responsive pneumatic systems.

Design and analysis of a synthetic jet actuator-based fluid atomization device

2017 ◽  
Vol 28 (17) ◽  
pp. 2307-2316 ◽  
Author(s):  
Paul Gilmore ◽  
Vishnu-Baba Sundaresan ◽  
Jeremy Seidt ◽  
Jarrod Smith
Keyword(s):  
High Pressure ◽  
Flow Rate ◽  
High Speed ◽  
Fluid Management ◽  
Synthetic Jet ◽  
System Level ◽  
Substrate Thickness ◽  
High Speed Imaging ◽  
Peak Displacement ◽  
Synthetic Jet Actuator

High-pressure nozzles and ultrasonic atomizers are the two most common devices used to generate sprays. Each of these has some disadvantages, such as controllability in high-pressure nozzles and fluid management challenges in ultrasonic devices. To overcome these limitations, a new atomization technology using a synthetic jet actuator was developed and is presented here. The work includes design and experimental analysis of both the stand-alone synthetic jet actuator and the synthetic jet-based atomization device. The synthetic jet actuator is designed using a model-based approach and characterized by measuring dynamic orifice pressure, diaphragm peak-to-peak displacement, flow rate, and power consumption. Orifice pressure reaches 296 Pa at a flow rate of 16 mL/s and 186 Pa at a flow rate of 37 mL/s for two possible synthetic jet actuator geometries, respectively. Piezoelectric diaphragm displacement reaches 50 µm with a brass substrate thickness of 0.20 mm. The synthetic jet-based atomization device is characterized with high-speed imaging and measurement of water atomization rate. It produces droplets with average sizes of 92–116 µm at maximum rates of 19–28 µL/s, depending on the geometry of the synthetic jet actuator. The outcomes of this work are principles for designing effective synthetic jet-based atomization devices, as well as system-level implementation concepts and control schemes.

scholarly journals A New Analysis Tool Assessment for Rotordynamic Modeling of Gas Foil Bearings

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Samuel A. Howard ◽  
Luis San Andrés
Keyword(s):  
Power Loss ◽  
High Speed ◽  
Structural Deformation ◽  
Analysis Tool ◽  
Test Rig ◽  
Contributing Factors ◽  
Foil Bearings ◽  
Rotordynamic Coefficients ◽  
Foil Bearing ◽  
Analytical Tools

Gas foil bearings offer several advantages over traditional bearing types that make them attractive for use in high-speed turbomachinery. They can operate at very high temperatures, require no lubrication supply (oil pumps, seals, etc.), exhibit very long life with no maintenance, and once operating airborne, have very low power loss. The use of gas foil bearings in high-speed turbomachinery has been accelerating in recent years although the pace has been slow. One of the contributing factors to the slow growth has been a lack of analysis tools, benchmarked to measurements, to predict gas foil bearing behavior in rotating machinery. To address this shortcoming, NASA Glenn Research Center (GRC) has supported the development of analytical tools to predict gas foil bearing performance. One of the codes has the capability to predict rotordynamic coefficients, power loss, film thickness, structural deformation, and more. The current paper presents an assessment of the predictive capability of the code named XLGFBTH©. A test rig at GRC is used as a simulated case study to compare rotordynamic analysis using output from the code to actual rotor response as measured in the test rig. The test rig rotor is supported on two gas foil journal bearings manufactured at GRC with all pertinent geometry disclosed. The resulting comparison shows that the rotordynamic coefficients calculated using XLGFBTH© represent the dynamics of the system reasonably well especially as they pertain to predicting critical speeds.

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