Laboratory Test Rig Research Articles

Integrated analysis of additive and multiplicative internal excitation parameters in misaligned-bowed-internally damped rotor systems with active magnetic bearings: Numerical and experimental identification

Precisely identifying internal excitation parameters within rotor-bearing systems is imperative for ensuring reliability and optimal performance. This paper meticulously addresses various issues, such as coupling misalignment, residual bow, internal damping, and imbalance. However, the novelty of the work lies in its detailed exploration of the interplay between these parameters, particularly emphasizing the multiplicative effect resulting from residual bow and misalignment. Introducing an innovative approach, the paper employs an active magnetic bearing (AMB) near the output rotor's disc to mitigate vibrations and enhance system stability. A robust identification algorithm is developed, leveraging least-squares fitting in the frequency domain to accurately estimate multiple internal excitation parameters and system characteristics. These parameters encompass viscous damping, internal damping, unbalance, residual bow, static and dynamic coupling misalignment, multiplicative force, and various AMB constants. The algorithm's resilience is demonstrated through rigorous testing against noise percentage errors. Furthermore, practical experimentation using a laboratory test rig validates its efficacy. Response data from proximity probes are inputted into the algorithm, successfully identifying parameters. Experimental validation is achieved by comparing irregularities in orbit plots and full spectra with numerical simulations based on the identified parameters, affirming the algorithm's reliability in real-world scenarios. This comprehensive approach offers a dependable solution for internal excitation identification in complex rotor systems.

Experimental investigations of hydrogen iodide (HI) decomposition process for different catalysts and various temperature conditions

This article presents the results of experimental work carried out at the Institute of Power Engineering on the process of thermal decomposition of hydrogen iodide. This process is one of the three key steps taking place in sulfur-iodine (S-I) thermochemical hydrogen production technology. For this purpose, a laboratory test rig equipped with an electrically heated chemical reactor was constructed, enabling the study of hydrogen iodide decomposition under controlled conditions. The research was carried out using various catalytic substances, as well as different temperature conditions. The process of hydrogen iodide decomposition required keeping the temperature of the reactor above 300°C and continuous analysis of the concentration of hydrogen formed over time. The results of the study will make it possible to determine the kinetics of the hydrogen iodide decomposition reaction under selected conditions of the process, allowing for future optimization of the process with the use of numerical methods.

Hydrogen permeability testing of fibre reinforced thermoplastics under cryogenic conditions – validation of a test rig concept

The need to decrease the gross weight of cryogenic hydrogen fuel systems in future zero emission mobility leads to increasing activities in the field of cryogenic lightweight engineering. Fibre reinforced thermoplastic composite materials (FRT) are considered for cryogenic applications despite their bias towards permeation. However, permeation through plastic materials is of major concern in cryogenic applications. Even tiny fluxes can very much compromise the insulating power of high vacuum spaces required for insulation of cryogenic systems such as tank structures or transfer lines. Hence, it is essential to qualify those FRT in terms of their hydrogen permeability for future usage in mobile cryogenic applications. The conventional concepts for measuring permeability in plastic materials are not sufficient for cryogenic measurements of FRT as shown in a previous paper. For that, a novel laboratory test rig concept was proposed. In this paper, we validate this concept and show its eligibility for measuring permeation of hydrogen through thermoplastic materials. Therefore, we report results of helium permeation through polytetrafluoroethylene (PTFE) at room temperature and compare those results to literature permeability data.

RANQUE-HILSCH VORTEX TUBE AS AN EDUCATIONAL TOOL FOR CLASSICAL THERMODYNAMICS TEACHING

A vortex or Ranque-Hilsch tube is a moving parts-free device that splits a compressed air stream into a cold and a hot stream at its two extremities. Although there exist some theoretical approaches based on internal shock and expansion waves as well as Maxwell velocity distribution, a final word on the phenomenon to explain the thermal energy splitting has not been reached yet. Nevertheless, from the classical Thermodynamics point-of-view, the conservation laws of mass and energy along with the Second Law validation applied to a control volume enveloping the vortex must be fulfilled. Consequently, such a simple device may be an outstanding tool for hands-on laboratory teaching of engineering Thermodynamics. In accordance with that, an educational laboratory test rig was conceived to carry out experiments to demonstrate the fundamental laws: mass and energy conservations, and the Second Law constraint. As a secondary goal, students can be acquainted with flow, pressure, and temperature measuring techniques, along with obtaining thermodynamic properties, computing, and data-reducing procedure as part of the testing as well. In addition, the coefficient of performance in refrigeration and heat pump operation modes can be obtained and a proper discussion of the vortex tube working principle can be fostered.

Empirical study of robust/developed PID control for nonlinear time-delayed dynamical system in discrete time domain

In addition to the high nonlinearity of liquid dynamics inside a tank, a study was conducted to overcome loading/unloading liquid storage tank control problems. In this study, the author developed a nonlinear control system to conquer both nonlinearity and the significant time delay arising from using a pressure-difference-based level sensor. To this end, this study proposes the implementation of nonlinear state dependent (SDP-PID+) control using the SDP transfer function model as a class of nonlinear descriptions of dynamical systems. By incorporating additional robust (plus) compensators alongside the traditional P-, I-, and D-compensators, the robust SDP-PID controller utilizes the complete state feedback to create a time-varying state variable feedback (SDP-SVF) control law. This approach effectively mitigates the effects of the discrete-time SDP-TF. It introduces the pole placement tuning approach, which renders significant performance using the laboratory test rig TPS8.2.2.4, for automatic liquid level control.

Diagnosing simultaneous bearing and misalignment faults in an induction motor using sensor fusion

A monitoring system for induction motors (IMs) is essential for most industrial plants. Bearing faults and shaft misalignment are common mechanical defects in induction motors. Since one fault could cause another fault in the system, multiple faults can occur simultaneously and change the vibration (electrical) behaviour of the induction motors from that of a single fault condition. This paper aims to identify two common faults (shaft misalignment and defective bearing) simultaneously in IMs using data fusion of vibration and current measurements. Sensor fusion of accelerometer and Hall-effect sensor signals is used to combine the vibration and current signals. The proposed method is applied via a laboratory test-rig based on data fusion to detect multiple defects simultaneously in induction motors. Then, by extracting the important features using a principal component analysis (PCA) algorithm, the K-nearest neighbours (KNN) classification algorithm is used to detect defects and make decisions. The results show that the fusion of both current and vibration signal analyses significantly improves the efficiency and reliability of multiple fault detection. Also, bispectrum analysis of the current signal is highly sensitive to misalignment and can be an effective method for detecting such faults.

A hybrid rotordynamic modeling method for a rotor system with flexible foundation and nonlinear support force: Numerical and experimental investigation

The dynamic characteristics of a flexible foundation would greatly affect the dynamic behavior of the rotor system. In this paper, a hybrid dynamic model method in time domain combines the finite element (FE) method and the subspace-based identification method to model a rotor system with the consideration of a flexible foundation and nonlinear support forces. The state-space model of flexible foundation is identified by the subspace state-space system identification algorithm with measured frequency response functions (FRFs). To solve the calculation problem of the hybrid dynamic model in time domain, a general algorithm named the hybrid model fusion solution (HMFS) method is proposed, which combines the linear and nonlinear nodes separation method used in the FE model and the trapezoidal rule used in the state-space model, improving the calculation efficiency of solving transient response with nonlinear forces. Simulations for the hybrid dynamic model under constant speed and speed-up cases were carried out, resulting that the dynamic characteristics of the entire system can be represented when the nonlinear factors of rolling bearings and gravity were also taken into consideration. Additionally, owe to the consideration of tested dynamic behaviors of flexible base, experimental results in the laboratory test rig are well agreed with the numerical ones under two different test configurations. The investigation provides a complete modeling and highly efficient solution framework for the rotor system with a flexible foundation and nonlinear rolling bearings, with the abilities of further consideration of more nonlinear components such as squeeze film dampers and rubbing forces.

Measurement, Modeling, and Analysis of the Dynamic Properties of Resilient Elements Used for Vibration Isolation

Abstract Resilient elements are widely applied for vibration and noise control in many areas of engineering. Their complex dynamic stiffness gives fundamental information to describe their dynamic performance and is required for predicting structure-borne sound and vibration using dynamic modeling. Many laboratory measurement methods have been developed to determine the dynamic properties of resilient elements. This paper presents a review of recent developments in the measurement methods from the perspective of force–displacement relations of the resilient element assembly rather than of their material properties. To provide context, the review begins with an introduction to modeling methods for resilient elements, especially for rubber and rubber-like isolators, and three standardized measurement methods are introduced. Recent developments are then discussed including methods to extend the frequency range, which are mainly developments of the indirect method. Mobility methods, modal-based methods, recent active frequency-based substructuring (FBS), and inverse substructuring (IS) methods to study the dynamic properties of resilient elements are also described. Laboratory test rigs and the corresponding identification methods are outlined. Methods to evaluate nonlinear dynamic properties of resilient elements by laboratory measurements are also discussed. Finally, the review is concluded by discussing the advantages and limitations of the existing methods and giving suggestions for future research.

Laboratory Experiments Qualify Bit Influence on High-Frequency Torsional Oscillations

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 212566, “Qualifying Bit Influence on High-Frequency Torsional Oscillations Based on Full-Scale Laboratory Experiments,” by Armin Kueck, Eliah Everhard, and Xu Huang, Baker Hughes, et al. The paper has not been peer reviewed. _ High-frequency torsional oscillations (HFTOs) generate dynamic loads that can damage drilling tools, resulting in cracks, twistoffs, or broken electronics. Recently, a full-scale drilling test rig was proven to generate verified HFTO behavior under laboratory conditions. This rig allows for a comprehensive study of the influences of bit characteristics on HFTO. The complete paper presents methods to qualify bit features to suppress HFTO. Laboratory Rig Setup Test-Rig Design. The full-scale laboratory test rig drills rocks in a pressurized rock chamber. Rate of penetration (ROP), weight on bit (WOB), rotational speed, pressure, bit type, and rock type can be varied. The simulator consists of an open-loop mud-circulation system with capacity for 200 bbl of fluid, two 1,000-hp triplex pumps capable of up to 500 gal/min, a hoisting mechanism for raising and loading the drillstring up to 10,000 lbf, a 1,000-hp rotary drive capable of up to 10,000 ft-lbf, and a pressure vessel rated to 10,000 psi. High-frequency measurement instrumentation, including in-bit vibration sensors, records the tangential accelerations and dynamic torque at various positions in the BHA. The mounted device can be seen in the top left photo in Fig. 1. Measurement. To initially characterize the frequency response of the system, an impact test was performed on the system in a suspended nonoperating state with roving accelerometers (sensors) positioned as indicated by the blue lines in Fig. 1. Also indicated are the free-end and fixed-end boundary conditions at the bit (left) and drive (right), respectively, as well as the point of reference impact. The data from each pair of sensors are then processed to separate the torsional motions from lateral. Because HFTO is a self-excited vibration, it must be validated that this type of vibration is actually excited in the laboratory setup. To demonstrate that the excitation mechanism is representative for the field, one of the test results was used as a reference. A laboratory investigation showed that the measured vibration matches characteristics of self-excited vibrations. Investigations in the laboratory will, therefore, lead to valid solutions in the field.

Influence of noise masking on leak pinpointing: Experimental analysis on a laboratory test rig for leak noise correlation.

The efficient management of water distribution networks requires the detection and mitigation of leaks that result in significant water losses, economic costs, and potential health hazards. This experimental study focuses on the optimal frequency range for accurately locating a water leak in a distribution network using the noise correlation approach while mitigating the influence of background noise associated with water consumption from users. Through laboratory experimental tests, a digital bandpass filter was defined in order to pre-process signals and to improve cross-correlation analysis within the pertinent frequency range. This was done by characterising the frequency content of leak-induced noise, noise masking resulting from water consumption, and background noise. The analysed signals were recorded using hydrophones installed within the pipes of a laboratory test rig under different conditions of water flow rate. The spectra analysis assessed the influence of varying water flow rates on the acoustic sound field within the pipeline system. Additionally, the results of the analysis made it possible to discriminate clearly between noise generated by leaks and noise attributed to water consumption. This distinction is useful for implementing suitable filters, and also to establish a threshold ratio of leak flow rate to water consumption flow rate for effective pre-filtering. This study aims to establish a methodological framework that can effectively differentiate between acoustic signals stemming from leaks and noise generated by other sources within the system, to improve leak location accuracy through the noise correlation approach.

SEM and EDX analysis of erosion products formed on steam turbine blade

ABSTRACT Water droplet erosion (WDE), which is brought on by the high-energy impact of liquid water droplets, is a serious problem for steam turbine blades. Nevertheless, rather than addressing the WDE of actual steam turbine blades, the majority of the published research on this issue uses laboratory test rigs. In this study, scanning electron microscopy and energy-dispersive X-ray analysis are used to examine how the surface of low-pressure steam turbine blades that had been in service eroded over time. The results of this study provide valuable insights into the microstructural features and elemental composition of X20Cr13 steel in steam turbine blades, as well as the factors that can contribute to damage and failure.

Test rig for submerged transmissions in wave energy converters as a development tool for dynamic sealing systems

A submerged transmission, fitted with a dynamic sealing system, in a wave energy converter (WEC) serves the purpose of transmitting the force, absorbed by a wave activated body, to an encapsulated power take-off (PTO) system, while preventing seawater from entering the capsule. Dry generator operation is generally a prerequisite for attaining long technical service life. Little attention seems to be devoted in publications to the study of dynamic sealing systems in WECs, and to test rigs for experimental verification and/or evaluation of the ability/performance of existing dynamic sealing systems in a controlled laboratory environment. This paper begins by presenting some of our earlier research within the focus area of dynamic sealing systems, incl. design considerations and typical operating conditions. This part also presents the 1st laboratory test rig, used for verifying the sealing ability of the piston rod mechanical lead-through design in the 1st and 2nd full-scale experimental WEC prototype from Uppsala University. In 2021 project DynSSWE (Dynamic Sealing Systems for Wave Energy) was initiated. Drawing from experience, the project includes development of a new test rig, representing a tool for further development of dynamic sealing systems. This paper introduces steps in the design and development process of that new test rig, enabling accelerated long-term test runs with a setup of multiple piston rod specimens. The test specimens’ will be surface treated differently with the aim of improving the prospects of a long maintenance free service life. Since the new test rig is in the design stage, seal testing results are not yet reported. The presented work is funded by the Swedish energy agency with the aim of improving subsystem performance in wave energy devices.

Development of annular pump to enhance drilling distance and cuttings return in horizontal directional drilling

In many shallow horizontal directional drilling (HDD) projects, the annulus fluid pressure soon reaches the blowout or frac-out pressure of the soil formation. The pressure at single-source pump therefore must be limited. This limits the maximum drilling distance (borehole length), maximum attainable rate of penetration (ROP), and maximum distance over which cuttings can be returned. A novel concept involving a series of annular pumps distributed along the borehole length to aid in generation of distributed annulus pressure boost and cuttings transport in HDD was conceived. The success of the above concept, designated as distributed pumping system (DPS), relies on the ability to design and power an annular pump that can fit in the constricted annulus geometry of HDD boreholes while satisfying the performance requirements. We present the laboratory-scale development of three annular pumps based on the turbomachinery design principle of axial blade propellers. The pump prototypes were 3D printed and tested in the laboratory test rig flow loop built to simulate the annular flow configuration of HDD boreholes. The annular pump was powered using the axial propeller turbine housed inside the hub of each annular pump. The turbine converts hydraulic energy from the inner flow (analogous to drilling fluid flow within drill rod) to power the integrated setup of the axial inner turbine and annular pump, in short, designated as integrated turbine-pump (ITP). Results from the tests on three preliminary prototypes of the annular pump using water as the medium in the test rig yielded a maximum pressure boost of 44 kPa–enough to space the annular pumps 80 m apart when designed for a typical annular pressure drop rate of 0.54 kPa/m. The performance index (i) of the ITP, defined as the ratio of pressure boost provided by the annular pump in the outer (annular) flow to the pressure drop created by an inner turbine in the inner flow, reached a maximum value of 0.6. The results from the study promise a technology that can enable long-distance HDD cuttings return without the risk of blowout or the need for an external power source.

Analysis of cyclic frosting and defrosting of a vehicle heat pump

Heat pumps are used for energy-efficient heating in electric vehicles. If ambient air is used as a heat source, frost may form on the surface of the exterior heat exchanger at low ambient temperatures. If significant amounts of frost accumulate, the heat exchanger performance degrades and it must be defrosted. The aim of this work is the energy analysis of a heat-release-controlled vehicle heat pump with a direct flat tube evaporator in cyclic frosting and defrosting operation. The effects of fan speed and number of refrosting phases on the heat quantity released per frosting phase are analyzed on a laboratory test rig. The experiments show that the heat quantity released decreases with lower fan speed and increasing number of frosting phases. Defrosting operation parameters are also examined using the test rig and it is found that shorter defrosting times can be achieved at higher compressor speeds and larger expansion valve openings. A numerical model of the heat pump in cyclic frosting and defrosting operation is developed and validated using test rig data. An average relative deviation of less than 7% is determined between the model and experimental data. The heat pump is then integrated in a prototypical vehicle and the model is calibrated with experimental data from test drives. A numerical study of the validated vehicle heat pump model in cyclic frosting and defrosting operation shows a maximum increase of the mean total electric power consumption of 33% between dry air and saturated moist air at an ambient temperature of 0 °C. At an ambient temperature of -10 °C the mean total electric power consumption increases by 17% from dry air to saturated moist air conditions.

Waste Recycling: Waste to Energy System

The current economic growth trend of increased urbanization has resulted in huge amounts of municipal waste and energy consumption. Many emerging countries, such as Iraq, suffer from the worsening of such a problem. Thus, an adequate municipal waste management system and the innovation of renewable energy alternatives are the fundamental issues that need to be addressed. Two test rigs were used in this study: the first separates waste based on the principle of gravity and the difference in density between the constituent elements of the waste, The test rig consists of a conveyor belt (0.5 meter) width and (1.5 meter) length with variable height and speed that throws the waste into special containers to separate the waste. The study suggested taking samples of equal size (1 cm3) for all elements and showing the effect of the sampling process on the separation methods approved by the test rig. The second is a laboratory test rig that analyzes waste and produces combustible gas, thus producing thermal energy. The main components of the rig are a digester (0.4 meter diameter - 0.64 meter height), a calorimeter, and several other components. The data analysis method developed by Japanese scientist Takeuchi was used to analyze the results of the first test rig's experimental work. The main results of this analysis showed that the height is (0.67 meter), the speed is (1.9 meter/second), and the distance of the samples falling ranges from about (0.53 meter) to (0.58 meter). The significant findings of the current study for the second test rig are obtained for the amount of thermal energy and measured using a calorimeter, and it was found that the highest value of energy was obtained on the 23 day of the start of the fermentation process; the amount was (10752.88 Jules) in the second experimental test.

Experimental investigation on a Jeffcott rotor with combined coupling misalignment using time-frequency analysis

Abstract Rotating machinery, such as turbo-jet engines, operate at a high rotational speed and passes through critical zones. The dynamic response of high-speed machines is critical for long-term stability and functioning. In this work, a fast and effective method for detecting coupling misalignment utilising time-frequency analysis (TFA) based on both the adaptive noise added complete ensemble empirical mode decomposition and wavelet-based denoising is presented. This novel and innovative method detect the coupling misalignment feature via the amplitude modulation aspect in the envelope analysis of the fault-containing intrinsic mode function. The Hilbert spectrum analysis provides spontaneous frequency and spectral energy in the time-frequency domain. The experiments were performed for various rotor accelerations and combined parallel and angular coupling misalignments using a laboratory test rig. The suggested approach gives excellent denoising efficiency and can improve misalignment identification accuracy. Additionally, it may be highly helpful for machinery that starts and stops often.

Application of the Methods of Monitoring and Detecting the Belt Mistracking in Laboratory Conditions

Belt mistracking is one of the most dangerous and costly failures of belt conveyors. This phenomenon can lead to complete damage to the conveyor belt, increased demand for electricity from the drive, accelerated wear of route elements, and poses a fire hazard. The article presents the most important causes and ways to detect belt mistracking. Based on the tests carried out at the laboratory test rig, the mechanical and operating parameters of the electric drive of conveyor operation burdened with the problem of lateral running off for the tested belt were compared. The mistracking causes a sudden, differentiated increase in the resistance to movement of the machine, which directly affects the recorded values of forces in the drive system and tensioning mechanism and increases the electrical energy consumption of the drive motor. Belt run monioring based on these parameters is not precise, because there are many other factors on the conveyor route, potentially responsible for the increase in recorded currents and forces. The paper presents an analysis of the possibility of using three, non-contact methods directly monitoring the lateral run-off of the belt, based on vibration measurements of conveyor pulley bearing, RGB images, thermal imaging and measuring the compressive force on the tensioning device.

Variable displacement axial-piston pump control by genetic algorithm tuned PID controller

The article present design, optimal tuning and experimental investigation of a multivariable PID controller intended for variable displacement axial-piston pump. The pump is designed for open circuit hydraulic drive systems. The regulation of the displacement volume of the pump is carried out through a proportional spool valve intended for its model. Unlike classic systems in which the valve receives control electrical signals from an analogue electronic amplifier, in this system the proportional valve receives a control signal generated by a specially developed embedded PID control system. The controller is designed on the base of a model obtained by means of system identification. The set of the controller is performed through an optimization procedure based on a genetic algorithm. Experimental studies were carried out with the designed controller on a laboratory test rig. А comparison between the experimental and simulation results is done.

Measurement of Cross-Sectional Velocity Distribution of Pneumatically Conveyed Particles in a Square-Shaped Pipe Through Gaussian Process Regression-Assisted Nonrestrictive Electrostatic Sensing

Online continuous measurement of the cross-sectional velocity distribution of pneumatically conveyed solids in a square-shaped pipe is desirable in monitoring and optimizing circulating fluidized beds, coal-fired power plants, and exhaust pipes. Due to the limitation of nonrestrictive electrostatic sensors in spatial sensitivity, it is difficult to accurately measure the velocity of particles in large-diameter pipes. In this article, a novel approach is presented for the measurement of cross-sectional particle velocity distribution in a square-shaped pipe using sensors and Gaussian process regression (GPR). The electrostatic sensor includes 12 pairs of strip-shaped electrodes. Experimental tests were conducted on a laboratory test rig to measure the cross-sectional particle velocities in a vertical square-shaped pipe under various experimental conditions. The GPR model is developed to infer the relationship between the input variables of velocities and the cross-sectional velocity distribution of particles in nine areas of the pipe cross section, and the performance of the built models was compared with other machine learning models. The relative error of velocities predicted under all the experimental conditions is within ±3%. When the training dataset is not comprehensive enough, the performance of the model is negatively affected, and the relative error range is −9% to +15%. With fewer measurement electrodes (input variables), the relative error of the predicted velocities in each area increases slightly but remains within ±5%. Results obtained suggest that the electrostatic sensor in conjunction with the GPR model is a feasible approach to obtain the cross-sectional velocity distribution of pneumatically conveyed particles in a square-shaped pipe.

Novel Joint Transfer Network for Unsupervised Bearing Fault Diagnosis From Simulation Domain to Experimental Domain

Unsupervised cross-domain fault diagnosis of bearings has practical significance; however, the existing studies still face some problems. For example, transfer diagnosis scenarios are limited to the experimental domain, cross-domain marginal distribution and conditional distribution are difficult to align simultaneously, and each source-domain sample is assigned with equal importance during the domain adaptation process. Aiming at the above-mentioned challenges, this article proposes a novel joint transfer network for unsupervised bearing fault diagnosis from the simulation domain to the experimental domain. The sufficient bearing simulation data containing rich fault label information are used to construct the source domain to reduce the dependence on the resources of laboratory test rigs. An improved loss function embedded with joint maximum mean discrepancy is designed to achieve simultaneous alignments of marginal and conditional distributions across domains in unsupervised scenarios. A weight allocation mechanism for each source-domain sample is developed to suppress negative transfer. Two experimental datasets collected from laboratory test rigs are used as the target domains to validate the effectiveness of the proposed method. The results show that the proposed method is superior to other popular unsupervised cross-domain fault diagnosis methods.