Additively Manufactured Compliant Hybrid Gas Thrust Bearing for SCO2 Turbomachinery: Experimental Evaluation & Fluid-Structure Model Predictions

2021 ◽  
Author(s):  
Bugra Ertas ◽  
Keith Gary ◽  
Adolfo Delgado
Keyword(s):  
Thrust Bearing ◽  
Load Capacity ◽  
Ideal Gas ◽  
Squeeze Film ◽  
Outer Diameter ◽  
Structure Model ◽  
Unit Load ◽  
Free System ◽  
Fluid Structure ◽  
Process Gas

Abstract The following paper presents test results and advances an analytical predictive fluid-structure model for a new type of gas lubricated thrust bearing fabricated using direct metal laser melting (DMLM). The concept in the present study is a compliant hybrid gas thrust bearing using external pressurization to increase load carrying capacity, where the testing in the present study only focused on steady state static performance. The need for the bearing concept comes from enabling highly efficient supercritical carbon dioxide (sCO2) turbomachinery by replacing oil-lubricated bearings with process gas lubrication. Leveraging the process gas for bearing lubrication results in lowered bearing power loss [1], simplified mechanical design, and allows for novel oil-free hermetic drivetrains resulting in an efficient emission-free system [2,3]. The new concept utilizes hydrostatic pressurization on individual tilting pads flexibly mounted with hermetic squeeze film dampers (HSFD). The paper focuses on tests of a 173mm outer diameter gas thrust bearing in air up to 10krpm and hydrostatic inlet pressures to 365psi (2.52MPa). The present work advances a fluid-structure thrust bearing model using an isothermal ideal-gas based Reynolds flow equation coupled to a lumped stiffness element possessing axial and rotational degrees of freedom. The rotating testing demonstrated load capability of 1,816 lbs (8.1KN), which equates to a thrust bearing unit load of 67psi (0.46 MPa). Load capability was shown to increase with increasing hydrostatic inlet pressure while the increase in thrust runner speed revealed a small decrease in load capacity.

Additively Manufactured Compliant Hybrid Gas Thrust Bearing for sCO2 Turbomachinery: Experimental Evaluation and Fluid-Structure Model Predictions

2020 ◽  
Author(s):  
Bugra Ertas ◽  
Keith Gary ◽  
Adolfo Delgado
Keyword(s):  
Thrust Bearing ◽  
Load Capacity ◽  
Inlet Pressure ◽  
Squeeze Film ◽  
Outer Diameter ◽  
Structure Model ◽  
Free System ◽  
Fluid Structure ◽  
Process Gas ◽  
Load Carrying

Abstract The following paper presents rotating test results and advances an analytical predictive fluid-structure model for a new type of gas lubricated thrust bearing fabricated using direct metal laser melting (DMLM). The bearing concept in the present study is a compliant hybrid gas thrust bearing that uses external pressurization to increase load carrying capacity, where the testing campaign in the present study was only focused on steady state static performance. The need for the bearing concept comes from enabling highly efficient supercritical carbon dioxide (sCO2) turbomachinery by replacing oil-lubricated bearings with process gas lubrication. Leveraging the process gas of the turbomachine for bearing lubrication results in lowered bearing power loss [1], simplified mechanical design, and allows for novel oil-free hermetic drivetrains resulting in an efficient emission-free system [2,3]. The new concept utilizes hydrostatic pressurization on individual tilting pads flexibly mounted with hermetic squeeze film dampers (HSFD). The paper focuses on rotating tests of a 173mm outer diameter gas thrust bearing in air up to 10krpm and hydrostatic inlet pressures to 365psi (2.52MPa). The influence of thrust runner speed and bearing inlet pressure on force deflection characteristics and load carrying capability of the gas film were experimentally evaluated. The present work also advances a predictive fluid-structure thrust bearing model using an isothermal ideal-gas based compressible Reynolds flow equation directly coupled to a lumped stiffness element possessing axial and rotational degrees of freedom. The rotating testing demonstrated load capability of 1,816 lbs (8.1KN), which equates to a thrust bearing unit load of 67psi (0.46 MPa). Gas film force-deflection curves reveal a nonlinear relationship between thrust load and film clearance. Comparison of film thickness values with the predictive model show good agreement under high load and inlet pressure, however deviate as load and pressure decrease. Load capability was shown to increase with increasing hydrostatic inlet pressure while the increase in thrust runner speed revealed a small decrease in load capacity.

Additively Manufactured Compliant Hybrid Gas Thrust Bearing for SCO2 Turbomachinery: Design and Proof of Concept Testing

2021 ◽  
Author(s):  
Bugra Ertas
Keyword(s):  
Thrust Bearing ◽  
Nonlinear Behavior ◽  
Squeeze Film ◽  
Outer Diameter ◽  
Proof Of Concept ◽  
Unit Load ◽  
Rotating Speed ◽  
Load Carrying ◽  
New Type ◽  
Turbomachinery Design

Abstract The following paper presents a new type of gas lubricated thrust bearing fabricated using additive manufacturing or direct metal laser melting (DMLM). The motivation for the new bearing concept is derived from the need for highly efficient supercritical carbon dioxide turbomachinery in the mega-watt power range. The paper provides a review of existing gas thrust bearing technologies, outlines the need for the new DMLM concept, and discusses proof of concept testing results. The new concept combines hydrostatic pressurization with individual flexibly mounted pads using hermetic squeeze film dampers in the bearing-pad support. Proof-of-concept testing in air for a 6.8" (173mm) outer diameter thrust bearing was performed; with loads up to 1,500 lbs (6.67kN) and a rotating speed of 10krpm (91 m/s tip speed). The experiments were performed with a bent shaft resulting in thrust runner axial vibration magnitudes of 2.9mils (74microns) p-p and dynamic thrust loads of 270 lbs (1.2kN) p-p. In addition, force deflection characteristics of the bearing system are presented for an inlet hydrostatic pressure of 380psi (2.62MPa). Results at 10krpm show that the pad support architecture was able to sustain high levels of dynamic misalignment equaling 6 times the nominal film clearance while demonstrating a unit load carrying capacity of 55psi (0.34Mpa). Gas-film force-deflection tests portrayed nonlinear behavior like a hardening spring, while the pad support stiffness was measured to be linear and independent of film thickness.

Additively Manufactured Compliant Hybrid Gas Thrust Bearing for sCO2 Turbomachinery: Design and Proof of Concept Testing

2020 ◽  
Author(s):  
Bugra Ertas
Keyword(s):  
Thrust Bearing ◽  
Nonlinear Behavior ◽  
Squeeze Film ◽  
Outer Diameter ◽  
Proof Of Concept ◽  
Unit Load ◽  
Load Carrying ◽  
Final Design ◽  
New Type ◽  
Turbomachinery Design

Abstract The following paper presents a new type of gas lubricated thrust bearing that utilizes additive manufacturing or also known as direct metal laser melting (DMLM) to fabricate the bearing. The motivation for the new bearing concept is derived from the need for highly efficient supercritical carbon dioxide (sCO2) turbomachinery in the mega-watt power range. The paper provides a review of existing gas thrust bearing technology, outlines the need for the new DMLM concept, and discusses proof of concept testing results. The new concept combines hydrostatic pressurization with individual tilting pads that are flexibly mounted using hermetic squeeze film dampers (HSFD) in the bearing-pad support. This paper describes the thrust bearing concept and discusses the final design approach. Proof-of-concept testing in air for a 6.8” (173mm) outer diameter thrust gas bearing was performed; with thrust loading, up to 1,500 lbs (6.67kN) and a thrust runner speed of 10krpm (91 m/s tip speed). The experiments were performed with a bent shaft resulting in thrust runner axial vibration magnitudes of 2.9mils (74microns) p-p and dynamic thrust loads of 270 lbs (1.2kN) p-p. In addition, force deflection characteristics and stiffness coefficients of the bearing system are presented for an inlet hydrostatic pressure of 380psi (2.62MPa). Results at 10krpm show that the pad support architecture was able to sustain high levels of dynamic misalignment equaling 6 times the nominal film clearance while demonstrating a unit load carrying capacity of 55psi (0.34Mpa). Gas-film force deflection tests portrayed nonlinear behavior like a hardening spring, while the bearing pad support stiffness was measured to be linear and independent of gas film thickness.

scholarly journals Design Charts for Arbitrarily Pivoted, Liquid-Lubricated, Flat-Sector-Pad Thrust Bearing

1978 ◽  
Vol 100 (2) ◽  
pp. 279-284 ◽  
Author(s):  
I. Etsion
Keyword(s):  
Thrust Bearing ◽  
Center Of Pressure ◽  
Load Capacity ◽  
Loss Coefficient ◽  
Performance Characteristics ◽  
Direct Approach ◽  
Friction Loss ◽  
Unit Load ◽  
Design Charts

A flat sector-shaped geometry for a liquid-lubricated thrust bearing is analyzed considering both the pitch and roll of the pad. Performance characteristics such as center of pressure location, unit load, and friction loss coefficient, are presented in design charts. These charts enable a direct approach to the design of both point and line pivoted pads and also provide the necessary procedure for the design of nontilting flat pads. The various features of point and line pivoted configurations are discussed, and a comparison is made with the Michell bearing approximation. It is found that this approximation always overestimates load capacity.

Analysis of an Aerodynamic Compliant Foil Thrust Bearing: Method for a Rapid Design

1999 ◽  
Vol 121 (4) ◽  
pp. 816-822 ◽  
Author(s):  
I. Iordanoff
Keyword(s):  
Reynolds Equation ◽  
Thrust Bearing ◽  
Design Method ◽  
Load Capacity ◽  
Direct Calculation ◽  
Outer Diameter ◽  
Performance Parameters ◽  
Inner Diameter ◽  
Foil Thrust Bearing ◽  
High Load Capacity

A very simple design method for an aerodynamic compliant foil thrust bearing is presented in this paper. It is based on 3D modeling (called: complete direct calculation) of the elastoaerodynamic problem. In this approach, the structural analysis has been simplified. This enables the calculation to be carried out faster. However this model, based on the resolution of the Reynolds equation, only gives the performance of a thrust bearing for a given geometric profile. An efficient method for solving the inverse problem for predicting the desired bearing performance parameters is presented. The complete direct calculation is only used to improve the profile geometry thus found. Finally, the proposed method has been applied for the design of a 80 mm outer diameter 40 mm inner diameter thrust bearing operating between 20,000 and 50,000 rpm. It is shown that the thrust bearing designed by this approach has a high load capacity (300 kPa) at a speed of 50,000 rpm. It is also shown that the predicted performance of the bearing agrees well with the complete direct calculation.

Numerical and experimental studies on the thermal and static characteristics of multi-leaf foil thrust bearing

2021 ◽  
pp. 135065012110110
Author(s):  
Yu Guo ◽  
Yu Hou ◽  
Qi Zhao ◽  
Xionghao Ren ◽  
Shuangtao Chen ◽  
...  
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Failure Process ◽  
Experimental Studies ◽  
Elastic Model ◽  
Static Characteristics ◽  
Bearing Load ◽  
Foil Thrust Bearing ◽  
Cooling Air

Foil bearing is considered to be a promising supporting technology in high-speed centrifugal machinery. Due to the high-speed shearing effect in the viscous lubricant film, heat generation could not be ignored. In this paper, a thermo-elastic model of the multi-leaf foil thrust bearing is proposed to predict its thermal and static characteristics. In the model, modified Reynolds equation, energy equation, and Kirchhoff equation are solved in a coupling way. The contact area between the foil and welding plate is taken into account. Besides, the effect of cooling air on the bearing temperature is investigated. The ultimate load capacity and transient overload failure process of the bearing is analyzed and discussed. The effect of rotation speed on the bearing temperature is more obvious than that of the bearing load. The bearing temperature drops obviously by introducing the cooling air, and the cooling effect is improved with the supply pressure. The transient overload failure of the bearing occurs when the bearing load exceeds the ultimate value.

An Accurate Solution of the Gas Lubricated, Flat Sector Thrust Bearing

1977 ◽  
Vol 99 (1) ◽  
pp. 82-88 ◽  
Author(s):  
I. Etsion ◽  
D. P. Fleming
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Thickness Distribution ◽  
Maximum Load ◽  
Accurate Solution ◽  
Operating Conditions ◽  
Thrust Bearings ◽  
Practical Design ◽  
Minimum Film Thickness

A flat sector shaped pad geometry for gas lubricated thrust bearings is analyzed considering both pitch and roll angles of the pad and the true film thickness distribution. Maximum load capacity is achieved when the pad is tilted so as to create a uniform minimum film thickness along the pad trailing edge. Performance characteristics for various geometries and operating conditions of gas thrust bearings are presented in the form of design curves. A comparison is made with the rectangular slider approximation. It is found that this approximation is unsafe for practical design, since it always overestimates load capacity.

Static Performance of a Hydrostatic Thrust Foil Bearing for Large Scale Oil-Free Turbomachines

2020 ◽  
Author(s):  
Nguyen LaTray ◽  
Daejong Kim ◽  
Myongsok Song
Keyword(s):  
Large Scale ◽  
Load Capacity ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Outer Diameter ◽  
Frictional Loss ◽  
Foil Bearing ◽  
Foundation Model ◽  
Static Performance ◽  
High Load Capacity

Abstract This work presents a novel design of a hydrostatic thrust foil bearing (HSTFB) with an outer diameter of 154mm along with simulation and test results up to specific load capacity of 223kPa (32.3psi). The HSTFB incorporates a high pressure air/gas injection to the thrust foil bearing with a uniform clearance. This bearing has high load capacity, low power loss, and no friction/wear during startup and shutdown. In addition, the HSTFB allows for bidirectional operation. The paper also presents an advanced simulation model which adopts the exact locations of a tangentially arranged bumps to a cylindrical two-dimensional plate model of the top foil. This method predicts top foil deflection with better accuracy than the traditional independent elastic foundation model which distributes the bump locations over the nodal points in the cylindrical coordinates, and with less computational resource than the finite element method applied to the entire bump/top foils. The presented HSTFB, was designed for Organic Rankine Cycle (ORC) generators, but its performance was predicted and measured using air in this paper. The bearing static performance is compared analytically against the rigid counterpart, and presented at different supply pressures, speeds, and minimum film thicknesses. Experimental verification is conducted at 10, 15 and 20krpm. The measured load capacity and frictional loss agree well with the prediction. The measured film thickness also agrees with the prediction after the structural deflection of the thrust runner disc is compensated. Overall, the novel HSTFB demonstrates an excellent static performance and shows good potential for adoption to the intended ORC generators and other large oil-free turbomachines.

Influence of different flow regimes on the performance characteristics of a four-pad hydrostatic squeeze film damper loaded between pads

2019 ◽  
Vol 71 (3) ◽  
pp. 440-446
Author(s):  
Amina Nemchi ◽  
Ahmed Bouzidane ◽  
Aboubakeur Benariba ◽  
Hicham Aboshighiba
Keyword(s):  
Turbulent Flow ◽  
Load Capacity ◽  
Flow Regimes ◽  
Performance Characteristics ◽  
Squeeze Film ◽  
Eccentricity Ratio ◽  
Flow Conditions ◽  
Content Type ◽  
Turbulent Flow Regime ◽  
Squeeze Film Dampers

Purpose The purpose of this paper is to study the influence of different flow regimes on the dynamic characteristics of four-pad hydrostatic squeeze film dampers (SFDs) loaded between pads. Design/methodology/approach A numerical model based on Constantinescu’s turbulent lubrication theory using the finite difference method has been developed and presented to study the effect of eccentricity ratio on the performance characteristics of four-pad hydrostatic SFDs under different flow regimes. Findings It was found that the influence of turbulent flow on the dimensionless damping of four-pad hydrostatic SFDs appears to be essentially controlled by the eccentricity ratio. It was also found that the laminar flow presents higher values of load capacity compared to bearings operating under turbulent flow conditions. Originality/value In fact, the results obtained show that the journal bearing performances are significantly influenced by the turbulent flow regime. The study is expected to be useful to bearing designers.

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