Oil-free Turbomachinery Research Articles

Theoretical and Experimental Study on the Performance of Hermetic Diaphragm Squeeze Film Dampers for Gas-Lubricated Bearings

Low damping characteristics have always been a key sticking points in the development of gas bearings. The application of squeeze film dampers can significantly improve the damping performance of gas lubricated bearings. This paper proposed a novel hermetic diaphragm squeeze film damper (HDSFD) for oil-free turbomachinery supported by gas lubricated bearings. Several types of HDSFDs with symmetrical structure were proposed for good damping performance. By considering the compressibility of the damper fluid, based on hydraulic fluid mechanics theory, a dynamic model of HDSFDs under medium is proposed, which successfully reflects the frequency dependence of force coefficients. Based on the dynamic model, the effects of damper fluid viscosity, bulk modulus of damper fluid, thickness of damper fluid film and plunger thickness on the dynamic stiffness and damping of HDSFDs were analyzed. An experimental test rig was assembled and series of experimental studies on HDSFDs were conducted. The damper fluid transverse flow is added to the existing HDSFD concept, which aims to make the dynamic force coefficients independent of frequency. Although the force coefficient is still frequency dependent, the damping coefficient at high frequency excitation with damper fluid supply twice as that without damper fluid supply. The results serve as a benchmark for the calibration of analytical tools under development.

The application of the bilinear foil model to three-pad foil air bearings in rotordynamic analysis including reduced order modelling

Foil air bearings (FABs) are the mainstay of oil-free turbomachinery technology which is undergoing rapid expansion. A rotor system using such bearings is a nonlinear multi-domain dynamical system comprising the rotor, the air films and the foil structures. Multi-pad (segmented) FABs offer opportunity for enhanced stability performance but are naturally more computationally challenging than single (360°) pad FABs. Their analysis has been limited to a simple model that ignores the detachment of the top foil from the underlying foil. Although a correction can be applied for the rotor vibration, the actual top foil deflection cannot be predicted. Additionally, reduced order modelling techniques have so far not been applied to such bearings. This paper presents the nonlinear and linearised dynamic analyses of three-pad FAB rotor systems considering foil detachment and using both Galerkin Reduction (GR) and Finite Difference (FD) to model the air film. Various models for the force distribution on the top foil are considered for use within a bilinear foil model, focusing on the ability to achieve numerical convergence. GR halved the computation time for a waterfall graph, without compromising the accuracy of the prediction of the nonlinear response. The results are validated against results from the literature.

Theoretical analysis and experimental tests of tilting pad journal bearings with shoes made of polymer material and low-boiling liquid lubrication

Selecting the appropriate bearing system for the rotor requires a good knowledge of the available solutions and the operating conditions of the machine. For newly designed machinery operating in adverse conditions, selecting bearings that ensure correct and long-lasting operation can be extremely challenging. Difficulties increase when the machine's operating parameters are beyond the technical capabilities of available technical solutions. This article presents the course of the design process and results of numerical and experimental research of a prototype microturbine that uses an innovative rotor-bearing system. Due to the adverse operating conditions, new tilting pad journal bearings were designed, in which the sliding surfaces of the tilting pads were made of polymeric material and a low-viscosity medium in liquid form was used as the lubricating medium. The basic bearing parameters were selected and pre-checked by numerical calculations. The oil-free turbomachinery design thus developed was subjected to experimental testing under near-real conditions. The results of these tests confirmed that the developed bearings performed very well, ensuring stable operation of the high-speed rotor of the microturbine over a wide speed range. Despite the unfavourable lubrication conditions, no signs of bearing wear were observed. The results obtained indicate a new, promising direction for the development of bearing systems for turbomachinery, in which, with a suitable design of the bearings, a low-boiling working medium in liquid form can be used as a lubricating medium.

Experimental investigation on stiffness and damping characteristics of hybrid foil magnetic bearings

Hybrid Foil Magnetic Bearings (HFMBs) are a promising bearing technology for high-speed, oil-free turbomachinery that structurally embeds a gas foil bearing (GFB) into the inner diameter of an active magnetic bearing (AMB). The flexible foil structure provides sufficient support stiffness for the rotor, while closed-loop control allows real-time adjustment of the dynamic performance of the bearing. In this paper, the static and dynamic performance of the HFMB is measured experimentally. The effect of the control gain on the static and dynamic performance of the HFMB is highlighted. The proportional gain increases the stiffness but weakens the stability of the system, while the differential gain increases the damping but unexpectedly increases the stiffness. The static and dynamic performance of the HFMB is compared with that of the GFB. At low excitation frequencies, the stability of the GFB is higher than that of the HFMB, while as the excitation frequency is increased, the stability of the HFMB exceeds that of the GFB.

Theoretical and Experimental Investigation of Porous Tilting Pad Gas Bearings with Hermetic Squeeze Film Dampers Based on Multilayer Diaphragm Structure

A novel porous tilting pad gas bearing (PTPGB) with hermetic squeeze film dampers based on multilayer diaphragm structure (MLD-HSFD) is proposed for oil-free turbomachinery. A dynamic model of MLD-HSFDs including the frequency dependence effect is presented by considering the compressibility of the damper fluid. An experimental test rig was assembled to measure the performance of MLD-HSFDs. The model predicts well the test data, including the frequency dependence of force coefficients. A comprehensive theoretical model of PTPGBs with MLD-HSFDs is proposed based on the implementation of the isothermal compressible Reynolds equation coupled to a flexible support and porous models. The effects of thickness of diaphragms thickness, bearing clearance, and supply pressure on bearing performance are discussed.

A new Galerkin Reduction approach for the analysis of a fully coupled foil air bearing rotor system with bilinear foil model

The foil air bearing (FAB) is a key enabler of the rapidly expanding technology of oil-free turbomachinery. However, it presents a formidable computational challenge due to the intricacy of the mathematical modelling of the nonlinear interaction between the foil structure, air film, and rotor. Galerkin Reduction (GR) allows the integration of the compressible Reynolds Equation within a FAB-rotor model without the need for spatial discretisation, resulting in a considerable gain in computational efficiency relative to grid/mesh-based methods like Finite Difference (FD) and Finite Element (FE). GR has so far been limited to a simple model that ignores the detachment of the top foil from the underlying foil. A new GR approach is developed to overcome this limitation. Following transient and static equilibrium analyses of the nonlinear system, Jacobian-based linearization is used to extract the full mode set, Campbell diagram and linear stability map. The use of GR instead of FD reduced the computational time by over 50% and required 20-60 times less memory for saving the results, without compromising accuracy and reliability. In particular, Jacobian-based linearization using GR retains the ability to detect instabilities (like top foil flutter) that are beyond the capability of the traditional linear force coefficients method.

Modelling, analysis and optimization of design parameter of bump-type gas foil journal bearing

The bump-type gas foil bearing (GFB) is widely used in various high-speed oil-free turbomachinery due to its extra features such as high-speed capability without any external oil lubricant. Under the high-speed condition, the performance characteristics of GFB are majorly dependent on its design parameter. Thus, this paper briefly analyzes and optimizes the design parameters of bump-type GFB to improve its performance characteristic. The numerical simulation of bump-type GFB is performed in ANSYS software. The effect of various design parameters such as foil thickness, bump half-length, bump pitch, and bump angle on the output responses are analyzed using a response surface methodology based CCD design matrix. Here, the output responses are structural stiffness and the equivalent stress in foil bearing. To optimize it, the multi-objective GRA technique is used. These results show that the foil thickness is the most influencing and the bump angle is the least influencing design parameter. The optimal value of foil thickness, bump angle, bump half-length and bump pitch are 0.14 mm, 63.75 deg., 1.55 mm and 4.6 mm respectively. At these optimal design parameters, the deviation between the predicted regression model and the numerical results are within 3.5%. Moreover, with these optimal design parameters, the structural stiffness of foil bearings increases by 68.4% and stress distribution reduces by 44.22% compared to the general configuration of foil bearings.

On the Application of Small-Scale Turbines in Industrial Steam Networks

This study investigates the technical and economic feasibility of replacing throttling valves with smale-scale, oil-free turbomachinery in industrial steam networks. This is done from the perspective of the turbomachine, which has to be integrated into a new or existing process. The considered machines have a power range of P=[0.5,…,250 kW] and have been designed using real industrial data from existing processes. Design guidelines are developed, which take into account the thermodynamic process as well as engineering aspects of such a turbomachine. The results suggest that steam conditioning prior to heat exchange could be completed by small expanders to produce mechanical work, reducing exergy destruction and improving site-wide energy efficiency compared to throttling valves. Cost estimates for such machines are presented, which serve as a basis for case-specific investment calculations. The resulting payback times of less than 18 months highlight the economic potential such solutions.

Numerical analyzes and experimental investigations on the fully-coupled thermo-elasto-gasdynamic behavior of air foil journal bearings

Air foil journal bearings are an important component in high-speed, oil-free turbomachinery applications. In order to optimize the performance of rotor systems supported by air foil journal bearings, detailed numerical models are needed. In this paper, a fully-coupled thermo-elasto-gasdynamic bearing model is presented. Using this model, the thermo-elasto-gasdynamic behavior of a mechanically preloaded three-pad air foil journal bearing is investigated numerically. Furthermore, experiments are accomplished in order to validate the results obtained with the numerical model. The 3D thermo-elasto-gasdynamic bearing model comprises the description of bump and top foil deflection and the calculation of the pressure and temperature distribution in the air film as well as the temperature distributions in the surrounding structure, namely in the rotor, in the bearing sleeve and in the top and bump foil. The bump and top foil deflection are described by a nonlinear beamshell theory according to Reissner. The model accounts for the contact between the bump and the top foil and between the bump foil and the bearing sleeve. The pressure distribution is calculated by solving the generalized Reynolds equation according to Dowson. Temperature distributions in the air film and in the surrounding structure are obtained from the 3D energy equation and appropriate heat equations. In order to reduce the computational effort of the thermo-elasto-gasdynamic problem, the 3D energy equation and the generalized Reynolds equation are reduced by an averaging approach. The governing equations are solved by a finite element method.

Pressure Profile Measurements Within the Gas Film of Journal Foil Bearings Using an Instrumented Rotor With Telemetry

Abstract Foil bearings are strong candidates to support oil-free turbomachinery. Although foil bearings are a widely used technology, models describing their behavior are not validated using the film pressure, which is the fundamental variable of any fluid film bearing. This paper presents pressure profiles measured within the gas film of a journal foil bearing. The pressure is measured using an instrumented rotor with embedded pressure probes and wireless telemetry. The measurements yield the simultaneous circumferential pressure profiles at two axial positions inside the bearing. Proximity probes on the bearing allowed the measurement of the corresponding rotor orbits. The bearing under investigation is a bump-type compliant journal bearing, with a nominal diameter of 40 mm, an L/D = 1, and was tested up to 37.5 krpm. Load-displacement and break-away tests were performed on the test bearing in order to identify bearing parameters necessary for reproducibility. The pressure profiles are compared to a frequency domain foil bearing model. This paper is a step toward further fundamental understanding of the foil bearing behavior and the validation of the rich modeling literature.

Effect of Circumferential Location of Radial Injection on Rotordynamic Performance of Hybrid Air Foil Bearings

Air foil bearings (AFBs) are introduced as promising bearings for oil-free turbomachinery applications. AFBs provide reliable operation at high speed and high temperature with negligible power loss. Hybrid air foil bearing (HAFB) technology utilizes the radial injection of externally pressurized air into the traditional hydrodynamic AFB's film thickness through orifices attached to the top foil. Previous studies have reported enhancement in the rotordynamic stability of HAFBs compared to traditional hydrodynamic AFBs. HAFBs have several orifices distributed in the circumferential direction. In this study, the effect of the circumferential location of radial injection on the rotordynamic performance of the rotor-HAFB is studied. Analytical and experimental evaluations of the rotordynamic performance of a rotor supported by two single-pad HAFBs are presented. Parametric studies are conducted using three sets of single-pad HAFBs. The circumferential locations of orifices are different for each set. The presented simulation analyses consist of time-domain orbit simulation and frequency-domain modal analysis. Imbalance responses of rotor-HAFB were measured with various orifice locations and the results agree well with predictions. Comparison of the rotordynamic performance of HAFBs with different orifice configurations demonstrates substantial improvement in rotordynamic stability as well as enhancement in the stiffness and damping coefficients of HAFBs by choosing the best circumferential location for radial injection to control rotor eccentricity and attitude angle.

Identification of Dynamic Characteristics of Hybrid Bump-Metal Mesh Foil Bearings

The stability of oil-free high-speed turbo-machinery can be effectively improved by increasing the damping characteristic of the gas foil bearing (GFB). Novel hybrid bump-metal mesh foil bearings (HB-MFBs) have been previously developed. Prior experimental results show that the parallel combination of bump structure and metal mesh not only can improve the structure stiffness but also provide better damping property compared with the bump-type foil structure. To investigate the dynamic behavior of floating HB-MFBs and promote its application, this study measured the dynamic force coefficients of HB-MFBs on a rotating test rig. The vibrations of HB-MFBs with different mesh densities (40%, 32.5%, and 25%) and a generation І bump-type foil bearing (BFB) with similar size are measured under static and impact loads to estimate the bearing characteristics. Static load test results show that the linear stiffness decreases when the air film is generated (from 0 rpm to 20 krpm) but increases gradually with speed (from 20 krpm to 30 krpm, and 40 krpm). Moreover, the dynamic force coefficients of HB-MFBs indicate the significant influence of metal mesh density on bearing dynamic characteristics. The growth in block density increases the dynamic stiffness and damping coefficients of bearing. The comparison of HB-MFB (32.5% and 40%) and BFB emphasizes the good damping characteristics of HB-MFB.

Performance of Thrust Airfoil Bearing for Oil-Free Turbomachinery

IntroductionDuring operation of any turbomachinery, the pressure distribution on rotor parts, i.e., impellers, causes an occurrence of radial and thrust forces. These forces must be transferred by the bearings to the machine casing. One of the most promising bearing types that can be applied in modern high-speed turbomachinery is the airfoil bearings. They have low losses, they can operate at relative high rotational speed, and they usually are lubricated with machine working medium. On the other hand, they have relative low bearing load capacity (DellaCorte and Valco in Tribol Trans 43:795–801, 2000; Radil and DellaCorte in Tribol Trans 53, 771–778, 2010). This problem especially concerns the airfoil thrust bearing.ObjectiveThe article describes the performance and operational properties of a thrust airfoil bearing on the test stand.MethodThe test stand consisted of vertical axis electric motor with thrust plate attached to the shaft. The test covered a wide range of loads and rotational speeds. At these various conditions, the bearing frictional torque was measured. Indirectly, the power loses were calculated depending on the applied load and the shaft rotational speed. At last, after the test, the wear of top foil coating was inspected visually.

On the performance of foil thrust bearing with misaligned bearing runner

PurposeCompliant foil thrust bearings are promising bearings for high-speed oil-free turbomachinery. However, most previous experimental and numerical approaches to investigate the performance of these bearings have ignored the effect of bearing runner misalignment. Therefore, this paper aims to evaluate the effects of static and dynamic angular misalignments of the bearing runner on the performance of a gas-lubricated foil thrust bearing.Design/methodology/approachThe bearing runner is allowed a maximum angular misalignment that produces a minimum gas film thickness as low as 20 per cent of the nominal clearance. Then, the variations of bearing load carrying capacity, viscous power loss and stiffness and damping coefficients of the gas film with runner misalignment are thoroughly analyzed. The flow in the gas film is modeled with compressible Reynolds equation along with the Couette approximation technique, and the deformation of the compliant bearing is calculated with a robust analytical model. Small perturbations method is used to calculate the force and moment dynamic coefficients of the gas film.FindingsThe results show that misaligned foil thrust bearings are capable of developing a restoring moment sufficient enough to withstand the imposed misalignments. Furthermore, the enhanced hydrodynamic effect ensures a stable operation of the misaligned bearing, and the results highlighted the role of the compliant bearing structure to maintain foil bearing prominent features even at misaligned conditions.Originality/valueThe value of this study is the evaluation of the effects of runner angular misalignments on the static and dynamic characteristics of Generation II bump-type foil thrust bearing.

Thermal Behavior of Radial Foil Bearings Supporting an Oil-Free Gas Turbine: Design of the Cooling Flow Passage and Modeling of the Thermal System

Gas foil bearings (GFBs) have many noticeable advantages over the conventional rigid gas bearings, such as frictional damping of the compliance structure and tolerance to the rotor misalignment, so they have been successfully adopted as the key element that makes possible oil-free turbomachinery. As the adoption of the GFB increases, one of the critical elements for its successful implementation is thermal management. Even though heat generation inside the GFB is small due to the low viscosity of the lubricant, many researchers have reported that the system might fail without an appropriate cooling mechanism. The objective of the current research is to demonstrate the reliability of GFBs installed in the hot section of a micro-gas turbine (MGT). For the cooling of the GFBs, we designed a secondary flow passage and thermohydrodynamic (THD) analysis has been done for temperature prediction. In the analysis, the 3D THD model for the radial GFB extended to include the surrounding structure, such as the plenum, chamber, and the rotor in the solution domain by solving global mass and energy balance equations. In the MGT, the pressurized air discharged from the compressor wheel was used as the cooling air source, and it was injected into the plenum between two radial GFBs. We monitored the pressure and temperature of the cooling air along the secondary flow passage during the MGT operation. No thermal instability occurred up to the maximum operation speed of 43,000 rpm. The test results also showed that the pressure drop between the main reservoir and the plenum increases with an increasing operation speed, which indicated an increased cooling air flow into the plenum. The plenum and bearing sleeve temperature was maintained close to the cooling air source temperature for the entire speed due to a sufficient cooling air flow into the bearing. In addition, the direct injection of the cooling air from the main stream lowered the bearing sleeve temperature by 5–20 °C over the injection through the reservoirs. The predicted plenum and bearing sleeve temperatures with the developed THD model show good agreement with the test data.

Rigid Mode Vibration Control and Dynamic Behavior of Hybrid Foil–Magnetic Bearing Turbo Blower

In this study, experimental and analytical analyses of the vibration stability of a 225 kW class turbo blower with a hybrid foil–magnetic bearing (HFMB) were performed. First, critical speed and unbalance vibration responses were examined as part of the rotordynamic research. Its shaft diameter was 71.5 mm, its total length was 693 mm, and the weight of the rotor was 17.8 kg. The air foil bearing (AFB) utilized was 50 mm long and had a 0.7 aspect ratio. In the experiments conducted, excessive vibration and rotor motion instability occurred in the range 12,000–15,000 rpm, which resulted from insufficient dynamic pressure caused by the length of the foil bearing being too short. Consequently, as the rotor speed increased, excessive rotor motion attributable to aerodynamic and bearing instability became evident. This study therefore focused on improving rotordynamic performance by rectifying rigid mode unstable vibration at low speed, 20,000 rpm, and asynchronous vibration due to aerodynamic instability by using HFMB with vibration control. The experimental results obtained were compared for each bearing type (AFB and HFMB) to improve the performance of the vibration in the low-speed region. The experimental results show that the HFMB technology results in superior vibration stability for unbalance vibration and aerodynamic instability in the range 12,000–15,000 rpm (200–250 Hz). The remarkable vibration reduction achieved from vibration control of the HFMB–rotor system shows that oil-free turbomachinery can achieve excellent performance.

Parametric study on static and dynamic characteristics of bump-type gas foil thrust bearing for oil-free turbomachinery

Gas foil bearings have bright application prospects in oil-free turbomachinery such as aircraft air cycle machines, compressors and gas turbines. To extend the applicability of foil bearings to high-speed and heavy-load systems, the axial force produced primarily by the pressure difference between the turbine and compressor sides must be taken into consideration. The thrust disc of the rotor is typically used to sustain the axial force and maintain the attitude of the rotor in a rotor-bearing system. In an analytical model used to predict the performance of gas foil thrust bearings (GFTBs), fluid–structure interaction must be considered because of the coupling effects of hydrodynamic lubrication and the compliance of bearing surface. In this study, a link-spring structural model was employed to calculate the equivalent vertical stiffness of the bump foil. This model exhaustively considered the effect of three factors: flexibility of the bump foil, interactions between bumps, and frictional forces at the contact surfaces. In addition, top foil deflection that directly affects film thickness is calculated using a finite-element shell model. The static and dynamic characteristics of GFTBs were predicted after solving the steady-state Reynolds equation and two linearized dynamic coefficient equations which were obtained with perturbation method by using finite-difference method. The structural deformation equation was substituted into the Reynolds equations in the calculation process. The calculated static load was compared with the published experimental data, and the results validated the theoretical analysis. Thereafter, the static and dynamic characteristics including impact of rotational speed, initial minimum film thickness and the ratio of the inlet to outlet film thicknesses were analyzed. Parametric studies were also conducted to evaluate the effect of different structural parameters of the bump foil and journal tilting on the static characteristics of GFTBs. Because the proposed analytical model is completely algebraic, it can be easily programmed for accurately and effectively investigating the performance of GFTBs.

가스 포일 스러스트 베어링의 하중지지 성능 및 구동 토크에 관한 실험적 연구

Gas foil thrust bearings (GFTBs) have attractive advantages over rolling element bearings and oil film thrust bearings, such as oil-free operation, high speed stability, and high-temperature operation. However, GFTBs have lower load carrying capacity than the other two types of bearings owing to the inherent low gas viscosity. The load carrying capacity of GFTBs depends mainly on the compliance of the foil structure and the formed hydrodynamic wedge, where the gas pressure field is generated between the top foil and the thrust runner. The load carrying capacity of the GFTBs is very important for the suitable design of oil-free turbomachinery with high performance. The aim of the present study is to identify the characteristics of the load carrying performance of GFTBs. A new test rig for the experimental measurements is designed to provide static loads up to 800 N using a pneumatic cylinder. The maximum operating speed of the driving motor is 30,000 rpm. A series of experimental tests—lift-off test, static load performance test, and maximum load capacity test—estimate the performance of a six-pad GFTB, in terms of the static load, driving torque, and temperature. The maximum load capacity is determined by increasing the static load until the driving torque rises suddenly with a sharp peak. The test results show that the torque and temperature increase linearly with the static load. The estimated maximum load capacity per unit area is approximately 80.5 kPa at a rotor speed of 25,000 rpm. The test results can be used as a design guideline for GFTBs for realizing oil-free turbomachinery.

Effects of misalignment on the structure characteristics of bump-type foil bearings: a comparison between experimental and theoretical results

Purpose – The purpose of this paper is to investigate the effects of misalignment on the static and dynamics characteristics of bump-type foil bearings (BFBs). High-speed and high-temperature oil-free turbomachinery can be realized with the use of gas foil bearings (GFBs). GFBs have a flexible supporting structure; thus, they can tolerate a higher degree of misalignment compared with rolling element bearings. Design/methodology/approach – A test rig for GFBs has been developed to measure the effects of misalignment on the structure characteristics of bump-type foil bearings. The link-spring model, which is the foil structure model presented previously by the authors, is used as a basis in the present study to predict the static and dynamic performances of the foil structure. In general, predictions of the dynamic characteristics exhibit good agreement with the measurements acquired from the dynamic load tests. Findings – Results from the static tests show that GFBs develop high stiffness when the misalignment angle increases. Moreover, the dynamic characteristics of GFBs are identified by considering the test bearing supported by a non-rotating shaft as a one-degree-of-freedom system. The results indicate that the dynamic characteristics of GFBs strongly depend on excitation frequency and excitation amplitude because of the variation in the dynamic friction force within the foil structure. The structural stiffness and equivalent viscous damping increase with an increase in the misalignment angle. Originality/value – The present study focuses on the misalignment of GFBs and investigates experimentally the effects of misalignment on the structure characteristics of GFBs.

Parametric study on static and dynamic characteristics of bump-type gas foil thrust bearing for oil-free turbomachinery

Gas foil bearings have bright application prospects in oil-free turbomachinery such as aircraft air cycle machines, compressors, and gas turbines. To extend the applicability of foil bearings to high-speed and heavy-load systems, the axial force produced primarily by the pressure difference between the turbine and compressor sides must be taken into consideration. The thrust disc of the rotor is typically used to sustain the axial force and maintain the attitude of the rotor in a rotor-bearing system. In an analytical model used to predict the performance of gas foil thrust bearings, fluid–structure interaction must be considered because of the coupling effects of hydrodynamic lubrication and the compliance of bearing surface. In this study, a link-spring structural model was employed to calculate the equivalent vertical stiffness of the bump foil. This model exhaustively considered the effect of three factors: flexibility of the bump foil, interactions between bumps and frictional forces at the contact surfaces. In addition, top foil deflection that directly affects film thickness is calculated using a finite-element shell model. The static and dynamic characteristics of gas foil thrust bearings were predicted after solving the steady-state Reynolds equation and two linearized dynamic coefficient equations which were obtained with perturbation method by using finite-difference method. The structural deformation equation was substituted into the Reynolds equations in the calculation process. The calculated static load was compared with the published experimental data, and the results validated the theoretical analysis. Thereafter, the static and dynamic characteristics including impact of rotational speed, initial minimum film thickness and the ratio of the inlet to outlet film thicknesses were analyzed. Parametric studies were also conducted to evaluate the effect of different structural parameters of the bump foil and journal tilting on the static characteristics of gas foil thrust bearings. Because the proposed analytical model is completely algebraic, it can be easily programmed for accurately and effectively investigating the performance of gas foil thrust bearings.