Full-scale Test Rig Research Articles

Crack propagation retardation behavior of shattered rim in the railway wheel

Shattered rim, known as “wheel cancer”, is a century-old problem that restricts the reliability of railway wheels. Crack propagation retardation of shattered rim in the railway wheel was investigated in this paper. First, a full-scale wheel-rail bench test rig was used to conduct wheel-rail tests on a wheelset with an interior rim crack taken from service. The interior rim crack did not propagate over the entire 50000 km distance. Cracks initiated from the two through-rim defects and propagated at a slow speed. Then, equivalent tests were conducted to investigate crack propagation behavior of the shattered rim. The crack growth rate increased with the increase of crack length for the specimen under tension–torsion loading, while that decreased with the increase of crack length for the specimens under pure-torsion and compression-tension loading. The crack propagation retardation is attributed to the compression and friction of the crack surfaces. Finally, a model was developed to describe crack propagation retardation in shattered rims. The effective stress intensity factor predicted by the model initially increases and then gradually decreases. The shattered rim has a critical size at different depths from the tread under constant amplitude load. The predicted critical size decreases with the increase of the depth.

Investigation of the performance of a newly designed solar chimney for enhancing natural ventilation and mitigation of summer overheating

The significant challenge encountered in utilizing Trombe walls for winter heating is summer overheating, which limits the overall feasibility of the system. In response to this issue, the present study introduces a novel model of a Trombe wall-solar chimney system designed to enhance natural ventilation and address the problem of summer overheating. To assess the performance of the proposed model, a full-scale experimental test rig is constructed in Kirkuk, Iraq. This rig comprises a test room integrated with a Trombe wall-solar chimney system. Additionally, a numerical simulation based on the CFD approach along with a computer code is developed to investigate the behavior of the system. System analysis is conducted for the period August 14th–15th. The parameters studied include chimney height (ranging from 0.0m to 2.0m in 0.5m increments), chimney width (0.2m, 0.3m, 0.4m, and 0.5m), room inlet vent height (ranging from 0.2m to 0.4m with 0.05m increments), and chimney inlet vent height (ranging from 0.2m to 0.4m with 0.05m increments). The results highlight the crucial role of the massive storage wall in sustaining nighttime ventilation in the absence of solar energy by utilizing stored heat to warm the air and maintain the ventilation process. The study establishes that chimney height and width significantly influence airflow rate, while other factors have marginal effects. An empirical equation is formulated to predict the 24-h averaged air changes per hour (ACH), which is a critical measure of system performance in ventilation. This equation is developed using artificial neural network (ANN) techniques. Finally, the findings indicate that the suggested model effectively reduces summertime overheating while generating a satisfactory ventilation rate. This enhances the overall versatility and year-round usability of Trombe wall systems, making them more adaptive and efficient in regions with diverse climatic conditions.

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.

Prediction of slab track settlement using an innovative 3D train-track numerical tool: Full-Scale laboratory validation

The growth of slab track construction in recent years is mainly due to its high stability performance and low deterioration rates when subjected to high-demand railway traffic. Nevertheless, when required, slab track maintenance, such as track geometry correction, can be extensively expensive, time consuming and may involve rail service interruptions. Therefore, the development of tools that are able to analyse the performance and predict the behaviour of slab tracks over time can bring significant economic benefits to the railway industry. This work presents slab track settlement studies using a novel hybrid 3D finite-element tool (HI-Track), which is coupled with mechanistic empirical design, that is able to analyse the track behaviour over millions of train passages. The paper presents a case study of long-term experimental measurements conducted in a full scale test rig using the Bögl slab track system subjected to over 3 million load cycles emulating train operation over a long period of time. The HI-Track tool is used to investigate the long-term performance of the slab track laboratory test case, where simulations are compared and checked in a validation process. The main findings substantiate the reliability of the numerical tool to accurately predict track settlement within specified soil compressive strength of 70–100 kPa and a soil stiffness ranging between 100 and 400 MPa.

A robotized 6-DOF dry test rig for wave power

Wave power has the potential to contribute significantly to sustainability by reducing our global dependence on fossil fuels. Due to harsh conditions and high costs associated with offshore testing, lab experiments are favourable for resource-efficient validation and optimization in developing Wave Energy Converter (WEC) technologies. The limited scale and availability of existing wave tanks, and the limited flexibility of existing dry test rigs does however put significant restraints on such experiments. In this paper we introduce an alternative novel robotized dry test rig concept for wave power, evaluate its performance and discuss its potential. A full-scale robotized dry test rig demonstrator is constructed and used for experiments with a WEC prototype device. High motion flexibility and accuracy is thereby validated, also for repeating recorded wave and buoy motions. Compared to other dry test rigs, no special components were used and the motion trajectories were defined in full 6-Degrees-Of-Freedom. Two real-time hydrodynamic motion response methods are also demonstrated in the test rig, enabling emulation of actual offshore operation as well as development of advanced WEC control strategies. With a larger industrial robot manipulator, the introduced test rig concept could achieve realistic scaled force and power experiments with most point absorber WECs.

Experimental and Numerical Visualisation of Subsurface Rail Deformation in a Full-Scale Wheel–Rail Test Rig

To tackle the problem of various types of rail damage, such as rolling contact fatigue (RCF) or wear, a profound knowledge of the occurring mechanisms is necessary. This paper presents a newly developed full-scale test rig experiment that involves inserting softer pins into the rail head. These tests help deepen our understanding of shear deformation in rail steels. Furthermore, a finite element (FE) simulation approach is introduced that can be related to the test rig experiments. With these experiments, in combination with the FE simulation, valuable information regarding the plastic deformation can be obtained. This methodology allows predictions regarding a rail’s material behaviour during cyclic wheel loading. Moreover, it enables an effective and rapid qualitative material assessment, reducing the costs of expensive and time-consuming experiments.

Test Rig Design Considerations to Detect Volatile Organic Compounds in Aircraft Cabins

A numerical investigation for simulating the aircraft cabin as an environmental chamber is set to assist a test rig design assimilating passenger comfort, considering their exposure to high concentrations of Volatile Organic Compounds. Computational Fluid Dynamics is used to evaluate the flow inside the cabin for 800 sec of actual flow time, where the mixing and transport of chemical species are also evaluated. Measurements close to the passengers’ noses are used to create a Boruta feature selection-based dataset that trains four machine learning classifiers, namely, Support Vector Machine, Random Forest, Naive Bayes, and Logistic Regression, and compares their performance. Furthermore, the evaluation of molecular weight impact on residence time is explored, with an additional simulation including cabin filters. The model is proven to be insensitive to inlet air mass flow variation, indicating that the air-conditioning system mass flow has a minor impact on chemical species mass measurements. The Naive Bayes classifier shows the greatest performance with 96 % accuracy and is being selected to create a digital nose model. Moreover, when comparing simulation results between the models with and without cabin filters, results indicate that the residence time is independent of each compound’s molecular weight, with all showing equivalent residence time reduction. Finally, the observed cabin flow irregularities indicate that passengers may share different comfort experiences during the flight. This dictates the need to manufacture a full-scale test rig to quantify the impact of the flow asymmetry on the comfort of frequent travelers and aviation professionals.

A numerical study for coating of ventilation ducts using jet injection

In this study, the performance of a novel method where an antibacterial solution is pressurized and sprayed into recirculated air through nozzles, is investigated numerically. This resembles a jet in a cross-flow problem where the antibacterial solution mixes with ventilation air and further adheres to the inner surfaces of the duct. The motion of particles dispersed in antibacterial solution is described as the advection of a passive scalar, i.e., temperature, allowing for a single-phase flow solution. The effectiveness of the coating is evaluated by the temperature distribution on the inner surfaces of the duct. Single phase 3-D turbulent flow of air at two different temperatures is modeled and the velocity and temperature fields in the ventilation duct were calculated using the commercial code ANSYS FLUENT. The numerical model is validated by experiments conducted on a full-scale test rig, in terms of temperature. The numerical calculations were conducted in four series: where the effect of the nozzle arrangement, the jet injection angle, the jet-to-cross-flow velocity ratio, and a time-dependent jet velocity profile of a sinusoidal wave form are investigated. The numerical solutions show that the coating is highly inefficient for velocity ratios less than 3.3, and the period of time-varying jet stream has little effect on the coating performance.

Full-scale dynamometer tests of composite railway brake shoes including latxa sheep wool fibers

The main target of the present work is to characterize the effect of the inclusion of natural sheep wool (SW) into a railway brake block composition and then to compare it to that of a set of three organic fibers commonly used in the friction material industry: aramid fiber (AF), cellulose fiber (CF) and polyacrylonitrile fiber (PAN). In order to achieve this, 4 versions of the same friction material with a fixed amount of each organic fiber were produced and one more sample was manufactured including no organic fibers. The characterization work consisted of friction tests on a full-scale railway test rig. Then, the samples were SEM analyzed in order to characterize the tested surface microstructure. It was found that all organic fibers helped achieve a more stable bedding, and showed lower friction in wet conditions. They also affected the recovery %. Pictures of the blocks were taken after certain phases of the test and, although the failure sequence remained the same for all samples, the organic fibers very much influenced the magnitude of the wear rates. Sheep wool led to better results than cellulose. No final conclusions could be drawn with respect to metal pick-up. SEM analysis evidenced primary and secondary plateaus, but no significant differences were observed depending on the fiber nature. Finally, a Life Cycle Assessment with a “from cradle to gate” perspective was carried out. Ecoinvent v3.5 database and CML and ReCiPe Endpoint methodologies were used to evaluate the environmental impact create by the five brake block materials. Overall, cellulose, PAN and sheep wool brake blocks show slightly lower environmental impacts that the base material or than aramid fibers. Therefore, Latxa sheep wool offers a good balance between low cost, adequate wear rates and environmental impact, making it a compelling substitute for cellulose fibers.

Theoretical and experimental study on vibration reduction and frequency tuning of a new damped-sleeper track

• A new elastic side-supporting long sleeper damping track (ESSDT) is proposed. • A vibration reduction and frequency modulation device (VRFMD) is applied to the ESSDT. • The vehicle-track coupled dynamics analysis is achieved by co-simulation. • The VRFMD can adjust natural frequency and improve dynamics performance of the ESSDT. In urban rail transit, it is important to reduce the train-induced vibration on ambient environment. To achieve this goal, a new elastic side-supporting long sleeper damping track (ESSDT) is proposed in this study. Besides, a novel vibration reduction and frequency modulation device (VRFMD) is also proposed to improve the vibration damping performance as well as structural stability of ESSDT. Based on the vehicle-track coupled dynamics model and the finite element model of ESSDT, dynamic characteristics of ESSDT are investigated theoretically. The influence of key dynamic parameters of VRFMD on the damping effect and stability of the track system are studied in detail. Further, a hammer test was conducted on a full-scale test rig of ESSDT with VRFMD. Test results validate the theoretical research results, which proves that both the vibration of track and the vibration transmitted to the foundation can be attenuated effectively due to the installation of VRFMD. The results show that the spring stiffness of VRFMD has great influence on the dynamic response to ESSDT. The natural frequency of ESSDT could be adjusted by modifying the parameters of VRFMD, which may provide a new approach to avoid wheel-rail contact resonance. Moreover, VRFMD may also be introduced to other types of track for the purpose of vibration reduction and frequency adjustment, such as floating slab track and ladder sleeper track.

Analysis on the Performances of Misaligned Journal Bearings using Full-Scale Test Rig and Conjugate Heat Transfer Method

Misalignment effects increase the risk of scratch or seizure failure for the journal bearings-rotor system. To investigate the performances of misaligned journal bearings, a full-scale journal bearings-rotor system test rig is designed and journal orbits are tested under different speeds. Then, a THD lubrication model is established to simulate lubrication performances under different misalignment conditions. The results show that for a misaligned journal bearings-rotor system, the center of the orbits of the bearing closing to coupling is fixed around the coupling. The orbits center of the bearing far away coupling is floating gradually with an increasing speed. The vibration amplitude of bearing closing to coupling is larger than that of bearing far away from the coupling. When the minimum oil film thickness is decreasing, the maximum film temperature is increasing except for the bearing closing to coupling. For different misalignment directions, maximum film temperature is determined by the position of the high pressure zone and high temperature zone.

An experimental study of the summer and winter thermal performance of an opaque ventilated facade in cold zone of China

As a promising envelope technology for energy saving, opaque ventilated facades (OVFs) have spread to various climates and regions. Nevertheless, few reports have been published on their application in a typical continental climate zone with hot summers and cold winters, especially in China. Within the framework of a Chinese nationally funded project, comparative experiments were conducted on two full-scale test rigs to assess the thermal and energy performance of an OVF in cold zone of China. By comparing the conductive heat flux across the internal wall, the facade design features, including joint opening ratio, external cladding color, air vents openness and cavity width, showed substantial impacts on the thermal behaviors of the OVFs. It was highlighted that the surface solar radiation control features most affected the summer performance, while those restricting the cavity ventilation dominated winter. By integrating the optimal solutions for each design feature, the summer- and winter-optimal OVF configurations were proposed, bringing 11.4% and 6.5% energy use reductions compared to a conventional monolithic facade, respectively. Moreover, the daytime energy-saving effects of the OVFs were proved more significant, meaning that they were more suitable for daytime use buildings. However, considering the highly differed structures for these optimal OVFs, an integrated configuration was further qualitatively proposed through a normalized analysis of all tested facades, aiming for the optimal annual performance with minimal construction and operation complexities. These results provide general guidelines for designing performance-optimized OVFs while demonstrating a climatically representative sample from cold zone of China.

Oxidation behaviour of C/C–SiC brake discs tested on full-scale bench rig

C/C–SiC composites are considered to be strong candidates for the new generation of high-speed train brake discs. To achieve a better application, it is necessary to improve understanding of the oxidation behaviour of C/C–SiC brake discs after a full-scale bench test rig. In this study, full-scale braking bench tests for C/C–SiC self-mated brake pairs were conducted under a braking speed of 350–420 km/h and a braking pressure of 17–28 kN. Moreover, the oxidation behaviour and mechanisms of the C/C–SiC brake discs during the practical braking process were investigated. The results indicate that the oxidation behaviour is highly dependent on the friction surface region of the C/C–SiC brake disc owing to the distribution of microcracks, the formation of friction films, the difference in temperature, and the contact content with O 2 . Specifically, the oxidation depths of the friction layer on the inner circumferential surface, middle friction surface, and outer circumferential surface were 278.3, 252.1, and 359.9 μm, respectively. Furthermore, the oxidation reaction preferentially occurs in the active area of the C fibre and pyrolytic carbon (PyC) during the braking process.

Cryptosporidium surrogate removal in five commonly used point-of-use domestic filters

Point-of-use filters are the major means of treating household drinking-water from non-reticulated water supplies, especially in developing communities, but their effectiveness at removing protozoa varies greatly. We custom built a full-scale filter test rig to simulate typical household use conditions (40 psi, 21.6 L water/day treated, intermittent operation), and assessed the efficiencies of five commonly used low-cost household filter cartridges at removing glycoprotein-coated 4.5 μm polystyrene microspheres that had been validated as a surrogate for Cryptosporidium oocysts. The filter cartridges included 1 μm nominal activated carbon, 1 μm nominal polypropylene, 1 μm nominal polyester, 1 μm absolute pleated-paper and 2 μm nominal silver-impregnated carbon. The data from 120 test runs (duplicate filters, 24 replicate runs per filter type) indicated that the surrogate particles' log10 reduction values (LRVs) were 3.93–4.54 in the 1 μm activated carbon filters, 1.95–2.94 in the 2 μm silver-impregnated carbon filters, and <1.0 in the 1 μm polypropylene, 1 μm polyester and 1 μm pleated-paper filters. To achieve an LRV >3, which is a requirement of domestic drinking-water treatment units for protozoan reduction, 1 μm activated carbon filters are recommended. To satisfy protozoan removal requirements when using the other four filter types tested, additional treatment, for example, water boiling or ultraviolet disinfection, is necessary.

Wheel wear performance assessment and model validation using Harold full scale test rig

The railway industry has focused on the improvement of maintenance through the use of novel technologies. Recently, the utilisation of repair welding to restore the worn area on wheels has been investigated, as it can bring significant savings in wheelset maintenance. Under an Innovate UK AURORA project, a worn wheel that previously operated on London Underground (LUL) was restored using this process. To test its performance and compare with a new standard steel grade wheel, the HAROLD full scale test rig was used in which an LUL vehicle bogie equipped with both the restored and R9 grade wheels was operated under the representative lateral and yaw displacements computed from vehicle dynamics simulations. The wear measurements carried out at the end of test cycles showed that although the restored wheel suffered from initial higher wear, the levels reduced and became similar to the R9 grade wheel. Furthermore, the full-scale testing provided an opportunity to validate the wear model predictions which were conducted using the vehicle dynamics simulations utilised in testing inputs. It was found that while the flange wear predictions were higher, the tread wear estimations were smaller than the measurements on the R9 grade wheel.

An experimental investigation on the passive ventilation and cooling performance of an integrated solar chimney and earth–air heat exchanger

Earth–air heat exchangers (EAHEs) and solar chimneys (SCs) can be used to improve indoor air quality and thermal comfort, and reduce the energy consumption of buildings. The ventilation and cooling performance of an SC integrated with an EAHE system (SCEAHE) on a typical sunny summer day is investigated herein, using a full-scale experimental test rig. The SC provides the driving force required to draw airflow through the EAHE pipe, and the air is cooled by the surrounding soil. The experimental results indicate that the buoyant driving force induced by the SC can drive the EAHE during the daytime. The maximum airflow rate achieved during the day was 252 m3/h. Furthermore, an airflow rate of 50–70 m3/h was achieved when the solar radiation intensity was low or zero due to the building thermal mass. Therefore, the combined effects of the building thermal mass and the SC provided 24 h of natural ventilation. The maximum reduction in the temperature of the outlet air compared to that of the inlet air was 12.5 °C. The maximum total cooling capacity, sensible cooling capacity, and latent cooling capacity of the EAHE were approximately 1398.0 W, 892.0 W, and 611.7 W, respectively.

Experimental and Numerical Characterization of a Novel Natural Gas Low NOx Burner in Gas Turbine Realistic Environment

Abstract A fundamental milestone in the development of a low NOx burner technology is the demonstration of its capabilities in realistic environment. This is especially true for the novel burner subject of this paper, which has been extensively characterized throughout single burner scale experiments. An exhaustive description of the early development phases of the novel burner has been provided by authors in recently published works. The most promising geometry was selected for the assessment in real combustor arrangement, consisting of a full-scale annular combustor test rig. This paper reports the main results of such an assessment. Pollutant emissions and pressure pulsations have been measured at gas turbine relevant operating conditions. Moreover, dedicated blow-out tests have been performed to obtain the extinction equivalence ratio at both ambient and pressurized conditions, as done during the past single burner rig campaign. Basically, an adequate set of data has been gathered, allowing a direct comparison between full-annular and reduced-scale tests. A general alignment of behavior has been observed, as both low NOx capability and blow-out characteristics of full-annular arrangement turned out to be substantially unchanged with respect to the single burner. Nevertheless, some discrepancies in magnitude have been highlighted and discussed. Details have been given involving deeper numerical analysis by means of a dedicated model developed by the authors in previous works. Indeed, improvement to the model has been introduced in the context of this paper to overcome some limitations arisen in predicting emissions. Finally, a preliminary stability analysis has been carried out, with the aim to describe the onset of thermoacoustic instability tendency as observed in the full-annular tests.

Calibration and validation of the dynamic response of two slab track models using data from a full-scale test rig

For the development of accurate and reliable simulation models, the procedure of calibration and validation against measurement data is essential. In this paper, a finite element model and a waveguide finite element model of a slab track are calibrated and validated against hammer impact measurement data from a full-scale test rig. The finite element model is three-dimensional, where the rails are modelled as Rayleigh–Timoshenko beams and the concrete slab and support layer are modelled using linear shell elements. In the waveguide finite element model, a constant track cross-section described by two-dimensional finite elements is assumed, and the vibration in the direction perpendicular to the cross-section is described by propagating waves that are decaying exponentially. Measured frequency response functions (FRFs) are compared with the corresponding calculated FRFs from the two modelling approaches. The calibration is conducted in two steps using (i) a parameter study and (ii) a genetic algorithm. For multiple excitation positions and sensor locations, both calibrated models capture the trend of the Single-Input Multiple-Output measurements with rather small deviations compared to the overall dynamic range. This implies that both models can successfully represent the dynamic response of the test rig and can be considered as validated.

Identification of a dynamic friction model for railway disc brakes

Braking forces occurring during emergency brake applications of passenger trains are generated by disc brake units. The acting friction forces depend on the frictional properties between disc and brake pad and are influenced by relative velocity, temperatures and normal pressure of the contacting surfaces. In this work a mathematical model is developed which aims to link these influencing variables to the instantaneous acting friction coefficient in order to include the characteristic behavior of friction forces in the calculation of longitudinal dynamics of railway vehicles. The model is identified by the use of data recorded on a full-scale dynamometer test rig and verified regarding the estimation of the brake distance.

Unraveling the Causes of Excess Lead in Drinking Water Supply Systems of Densely Populated High-Rise Buildings in Hong Kong.

Excess concentrations of lead (Pb) were found in tap water from drinking water supply systems of high-rise buildings in 11 public rental housing (PRH) estates in Hong Kong, posing threats to public health. The copper supply lines are fitted with lead-soldered connections and brass fixtures and faucets. The causes of excess lead are studied through field sampling on occupied households, experiments on prototype supply chains, and 3D numerical modeling. The tap water lead concentration of 129 households in the PRH estates was sampled using a specially designed protocol, revealing the highly variable lead concentration variations induced by sources along the supply chain. Lead concentration variation at consumer tap and its relation with various lead sources are studied in a full-scale test rig. A 3D computational fluid dynamics (CFD) model is successfully developed to interpret the time variation of lead concentrations at the consumer tap. Model predictions of the complex variation of dissolved lead are in good agreement with data and confirm lead solder in copper pipe connections as a major cause of the "lead water" episode in Hong Kong. The CFD calculations demonstrate the importance of turbulent diffusion and shear flow dispersion in the modeling of lead; the use of a "plug flow" approximation can result in significant overestimation of lead concentration. The findings provide a basis for lead risk assessment of different water sampling strategies in densely populated high-rise buildings in Megacities.