Rapid Transients Research Articles

Modelling and simulation of a single slit micro packed bed reactor for methanol synthesis

Simulation results from methanol synthesis kinetic module at 80bar, 528K. • Single slit packed bed microstructured heat exchanger. • Methanol synthesis on Cu/ZnO/Al 2 O 3 commercial catalyst. • Development of a mathematical pseudo-homogeneous reactor model. • Simulation and experiments validated the concept of isothermal operation. • Promising benefits of micro processing technology for process intensification. A mathematical model for a single slit packed microstructured reactor-heat exchanger in the synthesis of methanol from syngas was developed. The model constitutes a simplified 3D-pseudo homogeneous approach for a reaction slit with integrated pillar geometry. Literature kinetic rate expressions for methanol synthesis over commercial Cu/ZnO/support type catalysts were applied at 80 bar total pressure, temperature range of 473-558 K, and syngas composition of H 2 /CO/CO 2 /N 2 :65/25/5/5 mol%. The model is found capable of predicting experimental CO conversion data with acceptable accuracy. Superior thermal stability of the microchannel upon variation of different parameters such as contact time, feed gas temperature and reaction temperature were shown. The simulation results also reveal that the microchannel reactor can operate free of performance loss due to concentrations field that may arise from overlaid temperature fields. Simulations have also been used to calculate the rapid temperature transients at the inlet. The agreement between simulation results and experimental data signifies the applicability of the developed model for further design and performance optimization of microstructured reactors for methanol synthesis and other exothermic processes.

Synthesis and Application of Nano structured Bi layer YSZ LZ Thermal Barrier Coating

Present work is on synthesis of high purity Nano-structured TBC materials, Lanthanum Zirconate and YSZ. They were prepared via wet chemical routes, starting from the indigenous source minerals such as zircon and monazite available in the beach sand. This is first time that the results of TBC materials synthesis from these base minerals, their purification and a high end application being presented comprehensively. Their characterisation and thermal barrier application on aeroengine components have been presented. The total oxide impurities being critical to the life of the coating, could be controlled within 0.03 per cent by weight. On comparison with other powders it was found that the indigenously synthesised YSZ powder had practically 100 per cent tetragonal prime phase and no monoclinic phase; whereas others had significant amounts of monoclinic phases present in them. Both YSZ and LZ powders were sinter agglomerated at 850 °C to preclude the possibility of any contamination and sieved. APS process was used to realise nano-structured bi-layer coating on the exhaust nozzle parts of an aeroengine. The components were subjected to rapid thermal transients during long accelerated endurance testing, equivalent to 1000 h of engine operations. The coatings also withstood the gas erosion of supersonic combustion products, vibratory loads of 4 g and more than 30000 nozzle actuations similar to aircraft maneuver. The paper also presents a brief review of implications of a nano-structured thermal barrier coating and certain nuances of chemical synthesis which forms the backbone of the strategies for durable coatings.

In situ pPy-modification of chitosan porous membrane from mussel shell as a cardiac patch to repair myocardial infarction

Polypyrrole (pPy), a widely-used conductive material, can create an electrophysiological condition for the exogenous cardiomyocytes (CMs) via its conductivity, biocompatibility and available processing method. Our previously developed flexible scaffold from the mussel-derived chitosan shell possessed multiscale, interconnected-porous structure and proper stiffness, which was a promising tissue substitute for wound healing. Here, a 3D pristine hybrid scaffold was fabricated by incorporating polypyrrole into the mussel shell-derived membrane (shell-pPy). The pyrrole monomers were grafted onto to the shell membrane and then in situ polymerized to form conjugated pPy-chitosan shell using FeCl3. The developed pPy-chitosan shell was used to produce an engineered cardiac patch (ECP). The shell-pPy ECP maintained subtle spatial structure and was granted well cellular viability, aligned morphology, abundant striation and organized CX43, robust contraction and rapid calcium transients in vitro. When transplanted into the infarcted hearts, the developed shell-pPy ECP could also mimic the mechano-electronic function for cardiomyocytes maturation and integrity. Notably, obvious angiogenesis was triggered, and cardiac pumping performance was promoted in the infarcted area by the shell-pPy ECP. The study highlighted a functional pPy-modified cardiac patch with suitable conductivity, subtle 3D structure, and mechanical property can serve as an ideal ECP to mimic cardiac niche for myocardial repair.

An Advanced Surge Dynamic Model for Simulating Emergency Shutdown Events and Comparing Different Antisurge Strategies

The compressor surge is a phenomenon which has to be avoided since it implies the deterioration of performance and leads to mechanical damage to the compressor and system components. As a consequence, compression system models have a crucial role in predicting the phenomena which can occur in the compressor and pipelines during operation. In this paper, a dynamic model, developed in the matlab/simulink environment, is further implemented to allow the study of surge events caused by rapid transients, such as emergency shutdown events (ESD). The aim is to validate the model using the experimental data obtained in a single-stage centrifugal compressor installed in the test facility at Southwest Research Institute. The test facility consists of a closed loop system and is characterized by a recycling circuit, and thus a recycling valve, which is opened in case of surge or driver shutdown. Simulations were carried out at 17,800 and 19,800 rpm; the comparison with experimental data showed the accuracy of the model in simulating different opening rates and different sizes of the recycle valve, at both low and high suction pressure (HSP). Moreover, different actions for recovering/preventing surge were simulated by controlling different valves along the piping system and by adding a check valve immediately downstream the compressor. The results demonstrated the fidelity of the model and its capability of simulating piping systems with different configurations and components, also showing, qualitatively, the different effects of some alternative actions which can be taken after surge onset.

Ultrafast Rectifier for Variable-Frequency Applications

In this paper, an ultrafast active rectifier is presented for variable-frequency applications. Three-phase ac-dc converters (rectifiers) are extensively implemented in motor-drives, wind turbines, electric vehicles, and aircraft's power systems. In some technologies, e.g., more electric aircraft and drones, power systems may employ variable-frequency generators for higher efficiency and reliability indices. The proposed ultrafast rectifier is equipped by a step-ahead predictive control scheme, an instantaneous phase-locked loop (PLL), and a module of six SiC MOSFETs. The control scheme regulates the dc voltage and maintains unity power factor with an extremely low total harmonic distortion in the input currents. The instantaneous PLL, applicable only for three-phase systems, is integrated to the proposed variable-frequency control scheme in order to minimize the error in the power factor. The step-ahead predictive scheme and instantaneous PLL combination provides fast and smooth dynamic responses under rapid frequency transients. Experimental results are presented using a laboratory-scale SiC-based MOSFET 115VLL/270Vdc rectifier, and the performance of the proposed controller is compared with a classical power factor correction controller in the presence of frequency ramp and step changes. The experimental results demonstrate a superior dynamic performance of the proposed ultrafast active rectifier.

AnT²COK, an analytical model for cyclic oxidation kinetics of hot-work tool steels in transient thermal cycling conditions

In hot forming processes, steel tools are subjected to rapid temperature transients and cyclic oxidation. AnT²COK, a new analytical model based on diffusion-controlled oxide growth in cyclic conditions, is proposed to predict the parabolic oxidation kinetics in spallation-free conditions. Compared to cyclic oxidation models of the literature (COREST, COSP, DICOSM, etc.), it is applicable for any shape of thermal cycle, fully transient or with dwell time. The model is applied to thermal fatigue tests on X38CrMoV5 steel, for Tmax between 500 and 685 °C. Its validity is demonstrated above 550 °C, using frequency factor and activation energy calculated from isothermal tests.

Liquid redistribution in sheared wet granular media

Shearing wet granular systems causes a redistribution of the interstitial liquid, which can affect the material's bulk behavior. Using the discrete-element method, we study the early rapid transients, the intermediate states, and the slow long-term evolution of liquid redistribution for various material parameters and different initial wetting conditions in an inhomogeneous split-bottom ring-shear cell featuring a wide shear band away from the system walls. In our model, liquid exists in two states, either in liquid bridges between particles or in liquid films on the particle surfaces. Under deformations like shear, the liquid is redistributed due to the rupture of existing and formation of new liquid bridges. Since we assume the immediate redistribution limit as a new model parameter, a liquid bridge limit volume is imposed to avoid extensive clustering of liquid. Studying the effect of the local shear rate on the liquid redistribution, two distinct effects are observed: For small amounts of shear, i.e., small strain amplitude, the interstitial liquid is randomly redistributed locally, and for larger amounts of shear, liquid is transported away from the shear zone. The local redistribution quickly results in a characteristic probability distribution of liquid bridge volumes, independent of the initial wetting conditions, but the mean and the shape of the distribution are dependent on the limit volume. Although the shear-driven diffusion-like liquid transport is active from the beginning, it dominates the transport in the long term, when the liquid moves out of the shear band, making the shear band dry. Ongoing theoretical analysis suggests a competition of drift and diffusive mechanisms in a different set of coordinates that can explain all our observations by defining a local P\'eclet number that quantifies the relative strength of the two transport mechanisms.

Optical follow-up observation of Fast Radio Burst 151230

Abstract The origin of fast radio bursts (FRBs), bright millisecond radio transients, is still somewhat of a mystery. Several theoretical models expect that the FRB accompanies an optical afterglow (e.g., Totani et al., 2013, PASJ, 65, L12; Kashiyama 2013, ApJ, 776, L39). In order to investigate the origin of FRBs, we perform gri-band follow-up observations of FRB 151230 (estimated $z$ ≲ 0.8) with Subaru/Hyper Suprime-Cam at 8, 11, and 14 days after discovery. The follow-up observation reaches a 50% completeness magnitude of 26.5 mag for point sources, which is the deepest optical follow-up of FRBs to-date. We find 13 counterpart candidates with variabilities during the observation. We investigate their properties with multi-color and multi-wavelength observations and archival catalogs. Two candidates are excluded by the non-detection of FRB 151230 in the other radio feed horns that operated simultaneously to the detection, as well as the inconsistency between the photometric redshift and that derived from the dispersion measure of FRB 151230. Eight further candidates are consistent with optical variability seen in active galactic nuclei (AGNs). Two more candidates are well fitted with transient templates (Type IIn supernovae), and the final candidate is poorly fitted with all of our transient templates and is located off-center of an extended source. It can only be reproduced with rapid transients with a faint peak and rapid decline, and the probability of chance coincidence is ∼3.6%. We also find that none of our candidates are consistent with Type Ia supernovae, which rules out the association of Type Ia supernovae to FRB 151230 at $z$ ≤ 0.6 and limits the dispersion measure of the host galaxy to ≲300 pc cm−3 in a Type Ia supernova scenario.

A New Index to Evaluate the Potential Damage of a Surge Event: The Surge Severity Coefficient

Industrial compressors suffer from strong aerodynamic instability that arises when low ranges of flow rate are achieved; this instability is called surge. This phenomenon creates strong vibrations and forces acting on the compressor and system components due to the fact that it produces variable time-averaged mass flow and pressure. Therefore, surge is dangerous not only for aerodynamic structures but also for mechanical parts. Surge is usually prevented in industrial plants by means of anti-surge systems, which act as soon as surge occurs; however, some rapid transients or system upsets can lead the compressor to surge anyway. Despite the fact that surge can be classified as mild, classic, or deep, depending on the amplitudes and frequency of the fluctuations, operators are used to simply referring to surge, without making a distinction between the three main classes. This is one of the reasons why, when surge occurs in industrial plants, it is a common practice to stop the machine to perform inspections and check if any damage occurred. Obviously, this implies maintenance costs and time, during which the machine does not operate. On the other hand, not all surge events are dangerous in terms of damage, and they can be tolerated by the mechanical structures of the compressor; thus, in these cases, inspections would not be required. Unfortunately, a method for establishing the potential damage of a surge event is not available in literature. In order to fill this gap, this paper proposes a final formulation of a surge severity index, which was only preliminarily formulated by the authors in a previous work. The preliminary form of this coefficient demonstrated some limitations, which are overcome in this paper. The surge severity index derives from an energy-force based analysis. The coefficient demonstration is carried out in this paper by means of (i) the application of the Buckingham's Pi-theorem, and (ii) a careful analysis of the causative and restorative factors of surge. Finally, some simple practical evaluations are shown by means of a sensitivity analysis, using simulation results of an existing model, to effectively further highlight the consistency of this coefficient for industry.

Rapidly evolving transients in the Dark Energy Survey

We present the results of a search for rapidly evolving transients in the Dark Energy Survey Supernova Programme. These events are characterized by fast light curve evolution (rise to peak in $\lesssim 10$ d and exponential decline in $\lesssim30$ d after peak). We discovered 72 events, including 37 transients with a spectroscopic redshift from host galaxy spectral features. The 37 events increase the total number of rapid optical transients by more than factor of two. They are found at a wide range of redshifts ($0.05<z<1.56$) and peak brightnesses ($-15.75>M_\mathrm{g}>-22.25$). The multiband photometry is well fit by a blackbody up to few weeks after peak. The events appear to be hot ($T\approx10000-30000$ K) and large ($R\approx 10^{14}-2\cdot10^{15}$ cm) at peak, and generally expand and cool in time, though some events show evidence for a receding photosphere with roughly constant temperature. Spectra taken around peak are dominated by a blue featureless continuum consistent with hot, optically thick ejecta. We compare our events with a previously suggested physical scenario involving shock breakout in an optically thick wind surrounding a core-collapse supernova (CCSNe), we conclude that current models for such a scenario might need an additional power source to describe the exponential decline. We find these transients tend to favor star-forming host galaxies, which could be consistent with a core-collapse origin. However, more detailed modeling of the light curves is necessary to determine their physical origin.

An effective numerical algorithm for intra-granular fission gas release during non-equilibrium trapping and resolution

Fission gas release and gaseous swelling in nuclear fuel are driven by the transport of fission gas from within the fuel grains to grain boundaries (intra-granular fission gas release). The process involves gas atom diffusion in conjunction with trapping in and resolution from intra-granular bubbles, and is described mathematically by a system of two partial differential equations (PDE). Under the assumption of equilibrium between trapping and resolution (quasi-stationary approximation) the system can be reduced to a single diffusion equation with an effective diffusion coefficient. Numerical solutions used in engineering fuel performance calculations invariably rely on this simplification. First, we investigate the validity of the quasi-stationary approximation compared to the solution of the general system of PDEs. Results demonstrate that the approximation is valid under most conditions of practical interest, but is inadequate to describe intra-granular fission gas release during rapid transients to relatively high temperatures such as postulated reactivity-initiated accidents (RIA). Then, we develop a novel numerical algorithm for the solution of the general PDE system in time-varying conditions. We verify the PolyPole-2 algorithm against a reference finite difference solution for a large number of randomly generated operation histories including prototypical RIA transients. Results demonstrate that PolyPole-2 captures the solution of the general system with a high accuracy and a low computational cost. The PolyPole-2 algorithm overcomes the quasi-stationary approximation and the concept of an effective diffusion coefficient for the solution of the intra-granular fission gas release problem in nuclear fuel analysis.

Photometric calibration of a wide‐field sky survey data from Mini‐MegaTORTORA

Mini‐MegaTORTORA is a nine‐channel wide‐field camera that continuously monitors the sky looking for rapid optical transients since mid‐2014. It is also performing a regular sky survey, and has already acquired nearly half a million images covering every point of Northern Sky hundreds to thousands of times. Photometric analysis of these data may provide a huge amount of information useful for the detection and characterization of different types of variable objects. Here we present a brief description of our activities related to the acquisition, processing, and calibration of these data, as well as examples of uncataloged variable stars of various types detected during the analysis.

Development of Reliable NARX Models of Gas Turbine Cold, Warm, and Hot Start-Up

This paper documents the setup and validation of nonlinear autoregressive network with exogenous inputs (NARX) models of a heavy-duty single-shaft gas turbine (GT). The data used for model training are time series datasets of several different maneuvers taken experimentally on a GT General Electric PG 9351FA during the start-up procedure and refer to cold, warm, and hot start-up. The trained NARX models are used to predict other experimental datasets, and comparisons are made among the outputs of the models and the corresponding measured data. Therefore, this paper addresses the challenge of setting up robust and reliable NARX models, by means of a sound selection of training datasets and a sensitivity analysis on the number of neurons. Moreover, a new performance function for the training process is defined to weigh more the most rapid transients. The final aim of this paper is the setup of a powerful, easy-to-build and very accurate simulation tool, which can be used for both control logic tuning and GT diagnostics, characterized by good generalization capability.

A Four-Phase Buck Converter With Capacitor-Current-Sensor Calibration for Load-Transient-Response Optimization That Reduces Undershoot/Overshoot and Shortens Settling Time to Near Their Theoretical Limits

This paper presents a four-phase buck converter with capacitor-current-sensor (CCS) calibration for load-transient-response optimization that targets the theoretically minimal output-voltage undershoot $\Delta V_{\mathrm {US}}$ , overshoot $\Delta V_{\mathrm {OS}}$ , and settling time $t_{S}$ when large and rapid load-current transients $\Delta I_{\mathrm {load}}$ occur. The proposed CCS calibration calibrates the CCS’ equivalent impedance to emulate a scaled replica of the output capacitor’s impedance $Z_{\mathrm {Co}}$ . Thus, the CCS can accurately sense the output-capacitor current $I_{\mathrm {Co}}$ despite $Z_{\mathrm {Co}}$ variations due to different output voltages, fabrication variations, and printed-circuit-board parasitics. Moreover, a load-transient optimizer is proposed to utilize the accurately sensed $I_{\mathrm {Co}}$ to instantly detect the large and rapid $\Delta I_{\mathrm {load}}$ , and synchronously control the charging and discharging durations of the output inductors in all four phases, resulting in small $\Delta V_{\mathrm {US}}/\Delta V_{\mathrm {OS}}$ and short $\text{t}_{S}$ . The converter is implemented in a 0.18- $\mu \text{m}$ CMOS process with 1.93-mm2 chip area. For a 1.8-A/5-ns step-up (step-down) $\Delta I_{\mathrm {load}}$ , the measured $\Delta V_{\mathrm {US}}$ ( $\Delta V_{\mathrm {OS}})$ and $\text{t}_{S}$ are 92 mV (75 mV) and 133 ns (110 ns), respectively. Compared with other state-of-the-arts, both the measured $\Delta {V}_{\mathrm {US}}$ ( $\Delta V_{\mathrm {OS}})$ and $\text{t}_{S}$ in this paper are the closest to their respective theoretical limits, i.e., the fastest load-transient response with the smallest $\Delta V_{\mathrm {US}}$ ( $\Delta V_{\mathrm {OS}})$ and the shortest $t_{S}$ under the same input voltage, output voltage, output inductance, and output capacitance.

Perspectives of intellectual processing of large volumes of astronomical data using neural networks

In the process of astronomical observations vast amounts of data are collected. BSA (Big Scanning Antenna) LPI used in the study of impulse phenomena, daily logs 87.5 GB of data (32 TB per year). This data has important implications for both short-and long-term monitoring of various classes of radio sources (including radio transients of different nature), monitoring the Earth’s ionosphere, the interplanetary and the interstellar plasma, the search and monitoring of different classes of radio sources. In the framework of the studies discovered 83096 individual pulse events (in the interval of the study highlighted July 2012 - October 2013), which may correspond to pulsars, twinkling springs, and a rapid radio transients. Detected impulse events are supposed to be used to filter subsequent observations. The study suggests approach, using the creation of the multilayered artificial neural network, which processes the input raw data and after processing, by the hidden layer, the output layer produces a class of impulsive phenomena.

IPTF 16asu: A Luminous, Rapidly Evolving, and High-velocity Supernova

Abstract Wide-field surveys are discovering a growing number of rare transients whose physical origin is not yet well understood. Here we present optical and UV data and analysis of intermediate Palomar Transient Factory (iPTF) 16asu, a luminous, rapidly evolving, high-velocity, stripped-envelope supernova (SN). With a rest-frame rise time of just four days and a peak absolute magnitude of mag, the light curve of iPTF 16asu is faster and more luminous than that of previous rapid transients. The spectra of iPTF 16asu show a featureless blue continuum near peak that develops into an SN Ic-BL spectrum on the decline. We show that while the late-time light curve could plausibly be powered by 56Ni decay, the early emission requires a different energy source. Nondetections in the X-ray and radio strongly constrain the energy coupled to relativistic ejecta to be at most comparable to the class of low-luminosity gamma-ray bursts (GRBs). We suggest that the early emission may have been powered by either a rapidly spinning-down magnetar or by shock breakout in an extended envelope of a very energetic explosion. In either scenario a central engine is required, making iPTF 16asu an intriguing transition object between superluminous SNe, SNe Ic-BL, and low-luminosity GRBs.

Effects of gas–wall partitioning in Teflon tubing and instrumentation on time-resolved measurements of gas-phase organic compounds

Abstract. Recent studies have demonstrated that organic compounds can partition from the gas phase to the walls in Teflon environmental chambers and that the process can be modeled as absorptive partitioning. Here these studies were extended to investigate gas–wall partitioning of organic compounds in Teflon tubing and inside a proton-transfer-reaction mass spectrometer (PTR-MS) used to monitor compound concentrations. Rapid partitioning of C8–C14 2-ketones and C11–C16 1-alkenes was observed for compounds with saturation concentrations (c∗) in the range of 3 × 104 to 1 × 107 µg m−3, causing delays in instrument response to step-function changes in the concentration of compounds being measured. These delays vary proportionally with tubing length and diameter and inversely with flow rate and c∗. The gas–wall partitioning process that occurs in tubing is similar to what occurs in a gas chromatography column, and the measured delay times (analogous to retention times) were accurately described using a linear chromatography model where the walls were treated as an equivalent absorbing mass that is consistent with values determined for Teflon environmental chambers. The effect of PTR-MS surfaces on delay times was also quantified and incorporated into the model. The model predicts delays of an hour or more for semivolatile compounds measured under commonly employed conditions. These results and the model can enable better quantitative design of sampling systems, in particular when fast response is needed, such as for rapid transients, aircraft, or eddy covariance measurements. They may also allow estimation of c∗ values for unidentified organic compounds detected by mass spectrometry and could be employed to introduce differences in time series of compounds for use with factor analysis methods. Best practices are suggested for sampling organic compounds through Teflon tubing.

PolyHWG: 3D Printed Substrate-Integrated Hollow Waveguides for Mid-Infrared Gas Sensing.

Gas analysis via mid-infrared (MIR) spectroscopic techniques has gained significance due to its inherent molecular selectivity and sensitivity probing pronounced vibrational, rotational, and roto-vibrational modes. In addition, MIR gas sensors are suitable for real-time monitoring in a wide variety of sensing scenarios. Our research team has recently introduced so-called substrate-integrated hollow waveguides (iHWGs) fabricated by precision milling, which have been demonstrated to be useful in online process monitoring, environmental sensing, and exhaled breath analysis especially if low sample volumes (i.e., few hundreds of microliters) are probed with rapid signal transients. A logical next step is to establish ultralightweight, potentially disposable, and low-cost substrate-integrated hollow waveguides, which may be readily customized and tailored to specific applications using 3D printing techniques. 3D printing provides access to an unprecedented variety of thermoplastic materials including biocompatible polylactides, readily etchable styrene copolymers, and magnetic or conductive materials. Thus, the properties of the waveguide may be adapted to suit its designated application, e.g., drone-mounted ultralightweight waveguides for environmental monitoring or biocompatible disposable sensor interfaces in medical/clinical applications.

Analyzing temperature fluctuations to predict boiling regime

Determination of forthcoming boiling regime is one of the challenging problems in diagnostics of industrial systems where rapid thermal transients exist. Taking into account intensive temperature oscillations met there, a conventional, boiling-curve based forecast becomes inaccurate. In the present paper we demonstrate the technique to cope temperature instabilities and predict the regime employing them. The method is validated against two experimental datasets, considering liquid nitrogen at 1–4 bars and water at normal conditions.

Measurement and Prediction of Centrifugal Compressor Axial Forces During Surge—Part II: Dynamic Surge Model

The force acting on centrifugal compressors is an important parameter to be considered throughout the operating life of these turbomachines. When the compressor is operating in surge conditions, these forces can become highly dangerous for the mechanical and aerodynamic structures. This instability is usually avoided in industrial applications, but the antisurge system may not react in time when emergency shutdowns or power failures take place. During these rapid transients, surge can develop, generating unsteady forces which can harm the close clearance components of the compressor. Therefore, the capability to predict the characteristics and the dynamics of these surge forces would allow the estimation of the off-design fatigue cycles produced on these components by surge. Currently, no validated method exists to predict the frequency and amplitude of the surge forces and determine the potential damage of these components. In this paper, a lumped parameter model, developed by using the bond graph approach to predict the dynamic surge fluid-dynamic oscillations, is presented. The model requires the geometry and the steady-state performance maps of the compressor as inputs, together with the piping system configuration characteristics. The simulator is provided with a supplementary tool to estimate the axial force frequency and amplitude, taking into consideration all the contributions to the axial fluid-dynamic thrust, the stiffness-damping of the thrust bearing, and the mass of the rotor. The model was tuned and validated using the test case axial force data from the Southwest Research Institute (SWRI) facility. The model has shown good agreement with the experimental results which implies that it can offer significant information about the severity of a surge event and the quantification of the machine performance losses together with possible damage to the close clearance components. This study is a first important step that can lead to schedule optimization for maintenance and repair activities.