Experimental Test Results for Four High-Speed, High-Pressure, Orifice-Compensated Hybrid Bearings

1994 ◽  
Vol 116 (1) ◽  
pp. 147-153 ◽  
Author(s):  
N. M. Franchek ◽  
D. W. Childs
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Pressure Ratio ◽  
Reynolds Numbers ◽  
Orifice Diameter ◽  
Test Results ◽  
Rotordynamic Coefficients ◽  
Geometric Configurations ◽  
Overall Performance ◽  
Mass Terms

In this study, four hybrid bearings having different geometric configurations were experimentally tested for their static and dynamic characteristics, including flowrate, load capacity, rotordynamic coefficients, and whirl frequency ratio. The four bearings included a square-recess, smooth-land, radial-orifice bearing (baseline), a circular-recess bearing, a triangular-recess bearing, and an angled-orifice bearing. Each bearing had the same orifice diameter rather than the same pressure ratio. Unique to these test results is the measurement of the added mass terms, which became significant in the present tests because of high operating Reynolds numbers. Comparisons of the results were made between bearings to determine which bearing had the best performance. Based on the parameters of interest, the angled-orifice bearing has the most favorable overall performance.

Theory Versus Experiment for the Effects of Pressure Ratio on the Performance of an Orifice-Compensated Hybrid Bearing

1998 ◽  
Vol 120 (4) ◽  
pp. 930-936 ◽  
Author(s):  
P. Mosher ◽  
D. W. Childs
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Load Capacity ◽  
Dynamic Stiffness ◽  
Pressure Ratio ◽  
Navier Stokes ◽  
Rotordynamic Coefficients ◽  
Wide Range ◽  
Bearing Load ◽  
Hybrid Bearing

This research investigates the effect of varying the concentric recess pressure ratio of hybrid (combination hydrostatic and hydrodynamic) bearings to be used in high-speed, high-pressure applications. Bearing flowrate, load capacity, torque, rotordynamic coefficients, and whirl frequency ratio are examined to determine the concentric, recess-pressure ratio which yields optimum bearing load capacity and dynamic stiffness. An analytical model, using two-dimensional bulk-flow Navier-Stokes equations and anchored by experimental test results, is used to examine bearing performance over a wide range of concentric recess pressure ratios. Typically, a concentric recess pressure ratio of 0.50 is used to obtain maximum bearing load capacity. This analysis reveals that theoretical optimum bearing performance occurs for a pressure ratio near 0.40, while experimental results indicate the optimum value to he somewhat higher than 0.45. This research demonstrates the ability to analytically investigate hybrid bearings and shows the need for more hybrid-bearing experimental data.

CFD Assessment of Rotordynamic Coefficients in Labyrinth Seals

2014 ◽  
Author(s):  
Sai S. Sreedharan ◽  
Giuseppe Vannini ◽  
Hiteshkumar Mistry
Keyword(s):  
High Speed ◽  
Test Results ◽  
Active Magnetic Bearings ◽  
Test Rig ◽  
Labyrinth Seals ◽  
Cfd Simulations ◽  
Flow Solver ◽  
Rotordynamic Coefficients ◽  
Pressure Test ◽  
Dynamic Seal

Seals used in high speed centrifugal compressors are prone to generate rotordynamic (RD) instabilities. To further understand their influence, a CFD based approach is developed. The objective of the current study is to numerically investigate and characterize the RD coefficients, representative of the dynamic seal forces. Experiments were carried out at high pressure test rig (up to 200 bar seal inlet pressure) which runs at 10000 RPM and has a high pre-swirl (about 0.9) along the same direction of rotor rotation. The rotor shaft in the experiment was instrumented with active magnetic bearings (AMBs) to linearly excite the rotor at three different frequencies: 28 Hz, 70 Hz and 126 Hz. Each frequency is characterized by amplitude of vibration and a phase. CFD simulations were carried out using commercial flow solver, using similar boundary conditions as that of experiments. The paper describes details of CFD model and its comparison against experiments. Numerical results show reasonable agreement of RD coefficients with test results. This job has to be considered as a first approach to CFD methodology applied to annular seals for the authors.

Design and Test Results of a Ultra High Loaded Single Stage High Pressure Turbine

2013 ◽  
Author(s):  
Harjit S. Hura ◽  
Scott Carson ◽  
Rob Saeidi ◽  
Hyoun-Woo Shin ◽  
Paul Giel
Keyword(s):  
High Pressure ◽  
Total Pressure ◽  
High Speed ◽  
Pressure Ratio ◽  
Single Stage ◽  
Test Results ◽  
High Pressure Turbine ◽  
Technology Program ◽  
High Pressure Ratio ◽  
Expected Performance

This paper describes the engine and rig design, and test results of an ultra-highly loaded single stage high pressure turbine. In service aviation single stage HPTs typically operate at a total-to-total pressure ratio of less than 4.0. At higher pressure ratios or energy extraction the nozzle and blade both have regions of supersonic flow and shock structures which, if not mitigated, can result in a large loss in efficiency both in the turbine itself and due to interaction with the downstream component which may be a turbine center frame or a low pressure turbine. Extending the viability of the single stage HPT to higher pressure ratios is attractive as it enables a compact engine with less weight, and lower initial and maintenance costs as compared to a two stage HPT. The present work was performed as part of the NASA UEET (Ultra-Efficient Engine Technology) program from 2002 through 2005. The goal of the program was to design and rig test a cooled single stage HPT with a pressure ratio of 5.5 with an efficiency at least two points higher than the state of the art. Preliminary design tools and a design of experiments approach were used to design the flow path. Stage loading and through-flow were set at appropriate levels based on prior experience on high pressure ratio single stage turbines. Appropriate choices of blade aspect ratio, count, and reaction were made based on comparison with similar HPT designs. A low shock blading design approach was used to minimize the shock strength in the blade during design iterations. CFD calculations were made to assess performance. The HPT aerodynamics and cooling design was replicated and tested in a high speed rig at design point and off-design conditions. The turbine met or exceeded the expected performance level based on both steady state and radial/circumferential traverse data. High frequency dynamic total pressure measurements were made to understand the presence of unsteadiness that persists in the exhaust of a transonic turbine.

Application of Water-Lubricated Bearings in Motorized Centrifugal Air Compressor for Fuel Cell Automotives

2014 ◽  
Vol 670-671 ◽  
pp. 920-923 ◽  
Author(s):  
Ming Feng ◽  
Tian Ming Ren
Keyword(s):  
High Speed ◽  
Proton Exchange Membrane ◽  
High Efficiency ◽  
Load Capacity ◽  
Pressure Ratio ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Air Compressor ◽  
Rotating Speed ◽  
New Energy

Proton exchange membrane (PEM) fuel cells intended for new energy automotives require a high efficiency and reliability motorized compressor to supply pressurized air. This paper presents a study and development of a motorized centrifugal air compressor using water-lubricated bearings. Comparing the performance of water-lubricated bearing with gas-lubricated bearing, we found that under the same power consumption the load capacity of water-lubricated bearings are more suitable for high speed motorized compressor system. A prototype was built and tested to verify the possibility of the developed motorized centrifugal air compressor. The results show that the system can operate at a stable rotating speed up to 80,000 rpm. The flow rate of the pressurized air is 350Kg/h and pressure ratio is 1.52 at 60,000 rpm, with a global efficiency of approximately 80%.

Test Results for Leakage and Rotordynamic Coefficients of Floating Ring Seals in a High-Pressure, High-Speed Turbopump

2005 ◽  
Vol 48 (3) ◽  
pp. 273-282 ◽  
Author(s):  
Y. B. LEE ◽  
S. K. SHIN ◽  
K. RYU ◽  
C. H. KIM ◽  
GUNHEE JANG
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Test Results ◽  
Rotordynamic Coefficients

Noise Influence of High-Speed Train Based on Air Dynamics

2014 ◽  
Vol 687-691 ◽  
pp. 265-269
Author(s):  
Xiao Qin Wang
Keyword(s):  
High Speed ◽  
Pressure Ratio ◽  
Flow Distribution ◽  
Large Change ◽  
Aerodynamic Noise ◽  
Maximum Pressure ◽  
Air Conditioner ◽  
Test Results ◽  
Train Speed ◽  
Stable Flow

How to control aerodynamic noise of high speed motor train, this paper starts from the basic theory of hydrodynamics and acoustics, it adopts method of numerical simulation and applies Fluent and VirtuaUab Acousticsand software to make study on characteristics of aerodynamic noise for high speed motor train, the test results indicates that in the stable flow distribution, the baric gradient is relatively larger when its surface pressure is in area with large change in curve curvature, when it is in the area with even curve change, the baric gradient is relatively smaller. In different gradient, the train head, the maximum pressure and the maximum negative pressure ratio of air-conditioner air deflector predicate are in proportion to the square of train speed.

Turbulent Hybrid Bearings With Fluid Inertia Effects

1990 ◽  
Vol 112 (4) ◽  
pp. 699-707 ◽  
Author(s):  
Luis San Andre´s
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Pressure Rise ◽  
Reynolds Numbers ◽  
Dynamic Force ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Friction Factors ◽  
Region Flow ◽  
The Stability

High speed hybrid bearings for cryogenic applications demand large levels of external pressurization to provide substantial load capacity. These conditions give rise to large film Reynolds numbers, and thus, cause the fluid flow within the bearing film to be turbulent and dominated by fluid inertia effects both at the recess edges and at the thin film lands. The analysis includes the effect of recess fluid compressibility and a model for the pressure rise within the recess region. Flow turbulence is simulated by friction factors dependent on the local Reynolds numbers and surface conditions. A perturbation method is used to calculate the zeroth and first flow fields and determine the bearing steady-state and dynamic force response. Comparison of results with existing experimental data shows the accuracy of the present full inertial-turbulent analysis. A roughened bearing surface is shown to improve considerably the stability characteristics of hybrid bearings operating at high speeds.

Theory Versus Experiment for the Effects of Pressure Ratio on the Performance of an Orifice-Compensated Hybrid Bearing

1995 ◽  
Author(s):  
Phillip Mosher ◽  
Dara W. Childs
Keyword(s):  
Stokes Equations ◽  
Load Capacity ◽  
Dynamic Stiffness ◽  
Pressure Ratio ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Rotordynamic Coefficients ◽  
Wide Range ◽  
Bearing Load ◽  
Hybrid Bearing

Abstract This research investigates the effect of varying the concentric recess pressure ratio of hybrid (combination hydrostatic and hydrodynamic) bearings to be used in highspeed, high-pressure applications. Bearing flowrate, load capacity, torque, rotordynamic coefficients, and whirl frequency ratio are examined to determine the concentric, recess-pressure ratio which yields optimum bearing load capacity and dynamic stiffness. An analytical model, using two-dimensional bulk-flow Navier-Stokes equations and anchored by experimental test results, is used to examine bearing performance over a wide range of concentric recess pressure ratios. Typically, a concentric recess pressure ratio of 0.50 is used to obtain maximum bearing load capacity. This analysis reveals that theoretical optimum bearing performance occurs for a pressure ratio near 0.40, while experimental results indicate the optimum value to be somewhat higher than 0.45. This research demonstrates the ability to analytically investigate hybrid bearings and shows the need for more hybrid-bearing experimental data.

Off-Design Performance of a Single Stage Transonic Turbine

1998 ◽  
Author(s):  
M. Woinowsky-Krieger ◽  
J.-P. Lavoie ◽  
E. P. Vlasic ◽  
S. H. Moustapha
Keyword(s):  
Pressure Ratio ◽  
Reynolds Numbers ◽  
Single Stage ◽  
Lapse Rate ◽  
Test Results ◽  
Efficiency Change ◽  
Transonic Turbine ◽  
Design Speed ◽  
Design Pressure ◽  
Good Agreement

This paper presents results of rig testing of a transonic, single stage turbine at off-design conditions. Mapping of the 3.4 pressure ratio, 1.9 stage loading turbine ranged from 70% through 120% of design speed and 75% to 125% of design pressure ratio. Results show expansion efficiency dropping over 4% from 100% to 80% of design speed at design pressure ratio, while remaining within half a percent from 90% to 110% of design pressure ratio at design speed. Efficiency lapse rate from equivalent sea-level to cruise altitude Reynolds numbers at the design point was measured and found to be worth over 1.5%. Analyses of test results using a viscous 3D solver showed very good agreement for the efficiency change with speed.

scholarly journals Measurements Versus Predictions for a Hybrid (Hydrostatic Plus Hydrodynamic) Thrust Bearing for a Range of Orifice Diameters

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Dara W. Childs ◽  
Paul Esser
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Fluid Film ◽  
Orifice Diameter ◽  
Axial Stiffness ◽  
Test Results ◽  
Flow Rates ◽  
Face To Face ◽  
Thrust Bearings ◽  
Inner Radius

A fixed-geometry hybrid thrust bearing is investigated with three different supply orifice diameters, (1.63, 1.80, and 1.93 mm). The test rig uses a face-to-face thrust-bearing design, with the test bearing acting as the rotor loading mechanism. A hydraulic shaker applies the static axial load, which is reacted by a second (slave) thrust bearing. The rotor is supported radially by two water-lubricated fluid-film journal bearings and is attached to a 30.6 krpm motor via a high-speed coupling with very low axial stiffness. Thrust bearings are tested for a range of supply pressures (5.17, 10.34, and 17.34 bars), fluid film thicknesses, and speeds (7.5, 12.5, and 17.5 krpm). The water-lubricated test bearings have eight pockets, with feed orifices located centrally in each pocket. Experimental results are compared to predictions from a bulk-flow model, showing generally good agreement. Thrust-bearing inlet supply and inner radius flow rates all decreased with decreasing orifice diameters and bearing axial clearances. In most cases, the bearings with larger orifice diameters exhibit higher recess pressure ratios, operating clearances, and flow rates. An optimum hybrid thrust-bearing orifice diameter will depend on the conditions of individual applications. Larger orifices generally provide larger operating clearances and higher stiffnesses, but also require higher flow rates. For most applications, a compromise of bearing performance parameters will be desired. The test results and comparisons presented will aid in sizing orifice diameters for future hybrid thrust-bearing designs and in validating and improving models and predictions.

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