Experimental Facility Research Articles

Realization of a standing normal detonation for hypersonic propulsion

A standing normal detonation mode of combustion consisting of a normal shock coupled with heat release is realized in an experimental high-speed reacting-flow facility. The normal detonation is stabilized using a 2D ramp where the high-enthalpy freestream Mach number and reactant composition is equivalently matched to the Chapman-Jouguet (CJ) consumption speed of the detonation, at M∞/MCJ = 1.06. High resolution optical measurements of OH* chemiluminescence and density gradients from schlieren clearly show the close-coupling between the normal shock and the heat release of the standing detonation. A ZND analysis have been conducted using the boundary conditions where the induction length is found to closely matches the experimentally measured induction length. The agreement between the induction length scales and the freestream Mach number to detonation CJ Mach number confirm the realization of a standing detonation mode of combustion.

Astrochemistry: The study of chemical processes in space

The formation of our solar system occurred approximately 4.6 billion years ago as a result of the gravitational collapse of a small portion of a giant molecular cloud. The origin of life on Earth is yet to be fully understood. Astrochemistry plays a crucial role in unraveling this mystery. It is an interdisciplinary field that mainly encompasses astronomy and astrophysics, focusing on studying molecules in the universe and their interactions with radiation. A substantial portion of the universe can be called the “Molecular Universe.” These molecules serve as valuable diagnostic tracers in the regions where they are observed. Recent progress in observational, experimental, and computational facilities has significantly enhanced our understanding of the molecular universe. This review aims to delve into this captivating field’s current state of the art.

Measurement of muon flux behind the beam dump of the J-PARC Hadron Experimental Facility

A muon-flux measurement behind the beam dump of the J-PARC Hadron Experimental Facility was performed with a compact muon detector that can be inserted into a vertical observing hole with 81 mm in diameter which was dug underground. The detector consists of 12 plastic scintillation strips with a length of 80 mm each, which are arranged with cylindrical shape and contained inside an aluminum housing with an outer diameter of 75 mm. A silicon photomultiplier is coupled to the end of each strip to collect the scintillating light. The flux of the muons penetrating the beam dump was scanned vertically at intervals of 0.5 m, showing a wide distribution with a maximum at the beam level. The muon flux was consistent with the expectation from a Monte-Carlo simulation at more than 1 m away from the beam axis, which is expected to be used for signal-loss evaluation in the future KOTO II experiment for measuring rare kaon decays. The data can also be used in improving the accuracy of shielding calculations in the radiation protection.

Emulation tests of dynamics and control for a turbocharged SOFC system

This work regards experimental emulation activities for a Solid Oxide Fuel Cell (SOFC) pressurized by a turbocharger, focusing attention on the control system validation. The SOFC-based plant considered here was developed to couple high efficiency (due to pressurization) with reasonable capital costs. In detail, significant cost decrease (against SOFC hybrid plants including a microturbine) can be obtained with a turbocharger, due to large mass manufacturing process for these machines. Moreover, to pursue the zero emission target, the system was sized to operate with a renewable source fuel (biogas).Since this system has integration problems due to critical dynamic and control aspects, the University of Genoa designed and installed an experimental facility based on the coupling between a pressure vessel with a commercial turbocharger. The fuel cell is emulated equipping the vessel with a burner (to obtain the SOFC temperature range) and with inert ceramic material (to generate the same dynamic response).The tests presented in this work were obtained with this emulation rig operated in cyber-physical mode: the hardware interacted in real-time mode with previously validated software for components not physically included in the rig. The results demonstrated the system feasibility for load changes and validated the proposed control system, showing robustness and good prevention of critical conditions, such as SOFC thermal stress.

Experimental study on mechanical behavior and countermeasures of mountain tunnels under strike-slip fault movement

In the seismic mountainous regions such as western China, it is usuallly inevitable to construct tunnels near active fault zones. Those fault-crossing tunnel structures can be extremely vulnerable during earthquakes. Extensive experimental studies have been conducted on the response of continuous mountain tunnels under reverse and normal fault movements, limited experimental investigations are available in the literatures on mountain tunnels with special structural measures crossing strike-slip faults. In this study, a new experimental facility for simulating the movement of strike-slip fault was developed, accounting for the spatial deformation characteristics of large active fault zones. Two groups of sandbox experiment were performed on the scaled tunnel models to investigate the evolution of ground deformation and surface rupture subjected to strike-slip fault motion and its impact on a water conveyance tunnel. The nonlinear response and damage mechanism of continuous tunnels and tunnels incorporated with specially designed articulated system were examined. The test results show that most of slip between stationary block and moving block occurred within the fault core, and significant surface ruptures are observed along the fault strike direction at the fault damage zone. The continuous tunnel undergoes significant shrinkage deformation and diagonal-shear failure near the slip surface and resulted in localized collapse of tunnel lining. The segments of articulated system tunnel suffer a significant horizontal deflection of about 5°, which results in opening and misalignment at the flexible joint. The width of the damaged zone of the articulated system tunnel is about 0.44 to 0.57 times that of the continuous tunnel. Compared to continuous tunnels, the articulated design significantly reduces the axial strain response of the tunnel lining, but increases the circumferential tensile strain at the tunnel crown and invert. It is concluded that articulated design provides an effective measure to reduce the extent of damage in mountain tunnel.

Performance compensation model of turbine flowmeter under vibration conditions

Vibration conditions will affect the performance of the turbine flowmeters, resulting in inaccurate or unstable measurement results. A DN10 turbine flowmeter is taken as an example to study the influence rule of vibration conditions on the turbine flowmeter performance. An experimental facility is built to simulate the vibration conditions with amplitude ranging from 35 mm to 90 mm and frequency ranging from 0 Hz to 4 Hz. A simulation method for simulating a turbine flowmeter under vibration conditions based on a dynamic coordinate system and 6DOF (Six Degrees of Freedom) is proposed. Based on the experiments and CFD (Computational Fluid Dynamics) simulation, the results show that the average meter factor of the turbine flowmeter under vibration conditions is larger than that under non-vibration conditions. The average meter factor increases with vibration amplitude and vibration frequency. The maximum relative error of the measured flow rate is 9.73 %. To reduce the measurement error, a performance compensation model of the turbine flowmeter applied to vibration conditions is proposed. The meter factor increment is taken as the dependent variable, and the frequency, amplitude, and flow rate are taken as independent variables. The results show that compared to the original model, the relative error of the turbine flowmeter with the compensation model shows an average reduction of 76.61 %.

Impact of key parameters on the numerical modelling of Phase-Changing phenomena in horizontal latent heat thermal energy storage

Numerous studies have focused on numerical investigations of the performance of the shell-and-tube Latent Heat Thermal Energy Storage (LHTES). However, many studies have often overlooked rigorous assessment of key parameters’ impact on the numerical simulation accuracy relative to experimental results. Therefore, this paper aims to develop a numerical model to track the solid–liquid interface during phase-changing phenomena in a horizontal LHTES system and investigate the effects of key parameters on the simulation accuracy. For this purpose, an experimental facility was built, and the numerical model was developed in ANSYS using the enthalpy-porosity method. During the simulation of the computational model, consideration was given to thermophysical properties (constant versus variable) of phase change material, contact resistance (zero versus nonzero), and the mushy zone constant (105, 5 × 105, and 106). The simulation results were compared with experimental data obtained from the in-house studies. The results showed that, compared to using constant thermophysical properties, employing variable thermophysical properties more accurately tracked the solid–liquid interface during melting. It substantially improved the simulation accuracy with a Root Mean Square (RMS) error less than 5 % for most of the temperature-measuring locations. Conversely, variable properties did not make a significant difference in the solidification process. The contact resistance due to the air gap was determined to be 0.035 m2·K/W for the current study. Furthermore, incorporating this resistance resulted in a more accurate approximation of the solid–liquid interface during melting, with RMS errors below 5 % across all locations. The study comparing different mushy zone constants recommended utilizing a slightly higher value of 106 for melting, whereas its impact on solidification was found to be insignificant.

Studying the Effects of Inhaled Environmental Pollutants on Olfactory Function in Mice.

Olfactory impairment is a significant public health problem and independently predicts the risk of neurodegenerative diseases. Inhaled environmental pollutants exposure may impair olfaction; thereby, there is an urgent need for methods to evaluate the effects of inhaled environmental pollutants exposure on olfaction. Mice are ideal models for olfactory experiments because of their highly developed olfactory system and behavioral characteristics. To assess the effects of inhaled environmental pollutants exposure on olfactory function in mice, a detailed buried food test and social odor discrimination experiment is provided, including the experiment preparation, the selection and construction of experimental facilities, the testing process, and indexes of time. Meanwhile, timekeeping equipment, operational details, and the experimental environment are discussed to ensure the success of the assay. Zinc sulfate is used as the treatment to demonstrate the feasibility of the experimental approach. The protocol provides a simple and clear operational process for assessing the effects of inhaled environmental pollutants on olfactory function in mice.

Design and construction of GaInSn experimental facility for studies of mixed-convection MHD flows

A multifunctional liquid metal loop named MaTHE-XJTU (Magneto-Thermo-Hydrodynamic Experiments-Xi'an Jiaotong University) that utilizes eutectic alloy GaInSn as a working fluid has been designed and constructed. The function of the MaTHE-XJTU facility is to study the magnetohydrodynamic (MHD) flow and mixed convection characteristics under the coupling effect. The main operating parameters of the loop are: the maximum magnetic field intensity is 3T, the effective magnetic field region is 300 mm × 800 mm × 1000 mm, the maximum flow rate of electromagnetic pump (EM pump) is 8 m3/h, the maximum pressure head of EM pump is 0.5 MPa. The paper describes the major components and basic operation procedures of the loop, the related flow diagnostics method, and near-future experiments. This loop could provide a high-parameter experimental platform (Ha∼104, Gr∼109, Re∼104) for investigations that improve the present understanding of magnetohydrodynamic and heat transfer performance in liquid metal blankets.

Photoproduction of the X(3872) beyond vector meson dominance: the open-charm coupled-channel mechanism

Hidden-charm exotic hadrons will be searched for and investigated at future electron–ion colliders. For instance, the X(3872) can be produced through the exclusive process γ p → X(3872)p. The vector meson dominance model has been commonly employed in estimating the cross sections of such processes. However, the coupled-channel production mechanism through open-charm meson-baryon intermediate states may play a crucial role. To assess the significance of such contributions, we estimate the cross section of the γ p → X(3872)p reaction assuming the coupled-channel mechanism. For energies near the threshold, the total cross section is predicted to be of tens of nanobarns for γ p → X(3872)p, which can be measured at future experimental facilities. Furthermore, the open-charm coupled-channel mechanism leads to a distinct line shape of the total cross section that can be utilized to reveal the production dynamics.

Experimental study on the thermal performance of a high-temperature finned latent heat storage system

The primary objective of this study is to develop and evaluate the performance of a latent heat storage (LHS) system. A tube-in-tube heat exchanger configuration was used to design the LHS system. Sodium nitrate and air were employed as the phase change material (PCM) and heat transfer fluid (HTF), respectively. To mitigate the low thermal conductivity of the PCM, six circular fins were integrated on the HTF tube surface and experiments were conducted in an in-house experimental facility. Temperature plots from the charging-discharging experiments revealed that the HTF flow direction governs the heat transfer along the axis of the system. The sensible heat gain by the PCM in the range of 270–330 °C, led to an additional ⁓0.4 MJ of heat storage beyond the storage capacity of 1 MJ. Furthermore, increasing the inlet temperature from 400 °C to 440 °C reduced the charging time by 39.6 %, while reducing the inlet temperature from 210 °C to 170 °C decreased the discharging time by 18.2 %. Despite improved heat transfer, higher inlet temperatures adversely affected the thermal uniformity whereas, the increase in inlet air velocity enhanced both the dynamics of heat transfer and the thermal uniformity within the storage system.

Dynamic model of the UC San Diego NHERI six‐degree‐of‐freedom large high‐performance outdoor shake table

AbstractThe UC San Diego large high‐performance outdoor shake table (LHPOST), which was commissioned on October 1, 2004 as a shared‐use experimental facility of the National Science Foundation (NSF) Network for Earthquake Engineering Simulation (NEES) program, was upgraded from its original one degree‐of‐freedom (LHPOST) to a six‐degree‐of‐freedom configuration (LHPOST6) between October 2019 and April 2022. A mechanics‐based numerical model of the LHPOST6 able to capture the dynamics of the upgraded 6‐DOF shake table system under bare table condition is presented in this paper. The model includes: (i) a rigid body kinematic model that relates the platen motion to the motions of the components attached to the platen, (ii) a hydraulic dynamic model that calculates the hydraulic actuator forces based on all fourth‐stage servovalve spool positions, (iii) a hold‐down strut model that determines the pull‐down forces produced by the three hold‐down struts, (iv) Bouc‐Wen models utilized to represent the dissipative forces in the shake table system, and (v) a rigid body dynamic model borrowed from robotic analysis governing the translational and rotational motions of the platen subjected to the forces from the various components attached to the platen. Extensive validation against experimental data shows excellent agreement for tri‐axial and six‐axial earthquake shake table tests. This validated model can be coupled with finite element models of test specimens to study the interaction between the shake table system and the specimens, and it offers potential for enhancing motion tracking performance through off‐line controller tuning or advanced control algorithm development.

Progress of Experimental Studies on Oblique Detonation Waves Induced by Hyper-Velocity Projectiles

Oblique detonation waves (ODWs) are hypersonic combustion phenomena induced by oblique shock waves. When applied to air-breathing engines, ODWs offer high thermal cycle efficiency, adaptability to a wide range of flight Mach numbers, and the advantage of a short combustion chamber, making them highly promising for hypersonic propulsion applications. Despite numerous numerical studies on the heat release and multi-wave flow mechanisms of ODWs, practical applications of oblique detonation engines (ODEs) remain limited due to several technical challenges. These challenges include generating the required high-velocity test environments, achieving effective fuel and oxidant mixing, and measuring the flow field structure in hyper-velocity and high-temperature flows. These limitations hinder the development of ODEs, underscoring the importance of experimental research, particularly for understanding the initiation and propagation mechanisms of ODWs. One of the primary experimental techniques involves inducing oblique detonation using high-velocity models. This method is extensively used to study the initiation process, shock structure, initiation criteria, and ODW propagation. It is advantageous because the state of the experimental mixture is controllable, and the model state can be precisely measured. This paper reviews studies on oblique detonation induced by hyper-velocity projectiles, presenting advances in experimental methods, detonation wave structures, unsteady processes, and initiation characteristics. Additionally, we discuss the deficiencies in existing studies, noting that the current measurement methods fall short of the requirements for observing the ODW initiation process, propagation process, and fine structure. The application of advanced combustion diagnostic techniques and the exploration of the relationship between initiation processes and criteria are crucial for advancing our understanding of ODW initiation and stabilization mechanisms. Finally, we summarize the current state of experimental facilities and measurement techniques, providing suggestions for future research on the measurement of shock waves and chemical reaction zones.

Aerodynamic Optimization Design of a Supergravity Centrifuge: A Low-Resistance Strategy

Wind resistance optimization is crucial for enhancing the rotational speed of supergravity centrifuges. We conducted a study using computational fluid dynamics on the Centrifugal Hypergravity and Interdisciplinary Experiment Facility (CHIEF) under construction at Zhejiang University and validated it experimentally using a ZJU400gt centrifuge. Our findings indicate significant reductions in wind resistance through structural modifications of the CHIEF. Reducing the outer radius from 4650 to 4150 mm decreased wind resistance by 16%, primarily due to reduced effective viscosity in the wake region’s gases. More substantial reductions were achieved by lowering the height of the outer wall from 2200 to 1400 mm, which cut wind resistance by 25%. This height reduction suppressed vortex shedding and Kármán vortex street development via the Venturi effect. Adjustments to the roughness height of wall surfaces further decreased wind resistance, with minimal impact from arm roughness. A critical roughness height was identified, below which no further reductions in wind resistance could be attained. Notably, using disc-shaped arms reduced wind resistance by approximately 73% because of their minimal pressure–resistance components and predominant frictional resistance, highlighting their potential in future high-speed centrifuge designs.

Optimization of Material Utilization by Developing a Reliable Design Criterion for Tool Construction in Cross-Wedge Rolling

The massive forming industry in Germany produces around 1.4 million parts every year, which are mainly used in safety-relevant areas such as the automotive industry. The production of these parts requires a considerable amount of energy, much of which remains unused and causes high CO2 emissions. An efficient approach to reduce these emissions and improve material utilization is cross-wedge rolling, which enables efficient material utilization but is limited by the so-called Mannesmann effect, which leads to unwanted material defects. This paper describes the development and validation of a safe design criterion for cross-wedge rolling tools in order to avoid material damage caused by the Mannesmann effect and thus increase resource efficiency in forging. Based on simulation-supported investigations and experimental tests, process maps are created for various materials. The validation is carried out both in an experimental test facility with real tools and in an industrial production facility, which leads to a significant reduction in excess material and CO2 emissions. The results show that the full resource potential of cross-wedge rolling can be exploited by optimizing process parameters and tool geometries.

Missing-Mass Measurement of the 12C(K-, K+) Reaction at 1.8 GeV/c with the Superconducting Kaon Spectrometer

Abstract We performed a measurement of the inclusive missing-mass spectrum of the $^{12}$C$(K^-, K^+)$ reaction at an incident beam momentum of 1.8 GeV/c. This measurement was carried out by using the Superconducting Kaon Spectrometer (SKS) and the K1.8 beamline spectrometer at the Hadron Experimental Facility in J-PARC. From the missing-mass of the $^{12}$C$(K^-, K^+)$ reaction, the binding energy of a $\Xi ^-$ hyperon in a core $^{11}$B nucleus, $B_{\Xi ^-}$, can be calculated. Our experimental setup yielded a good energy resolution of 8.2 MeV (full width at half maximum), which allowed us to observe significant enhancements in the proximity of the $^{12}_{\Xi }$Be production threshold region. In order to extract information from the missing-mass spectrum, we employed several fitting parameters assumptions. A good agreement with the spectrum shape was obtained by adding two Gaussian functions, with the constant experimental resolution for the $\Xi$-hypernuclear states, to the background distribution. The peak positions were obtained to be $B_{\Xi ^-} = 8.9 \pm 1.4$ (stat.) $^{+3.8}_{-3.1}$ (syst.) MeV and $B_{\Xi ^-} = -2.4 \pm 1.3$ (stat.) $^{+2.8}_{-1.2}$ (syst.) MeV. Another model assumption, one Breit–Wigner function with $B_{\Xi ^-} = -2.7 \pm 2.2$ (stat.) $^{+0.5}_{-0.7}$ (syst.) MeV and $\Gamma = 4.1 \pm 2.1$ (stat.) $^{+1.2}_{-0.7}$ (syst.) MeV, also yielded a similar $\chi ^2$ value.

High-Fidelity Simulation of the Light-to-Dense Stratification Transient in the HiRJET Facility

Density stratification in a large enclosure is a crucial phenomenon to heat transfer and sustainable passive heat removal of a sodium fast reactor during reactivity transients. However, engineering turbulence models were identified to have unsatisfactory performance in predicting propagation of a stratified front. Yet, the scarcity of high-resolution data for stratification hampers the development of models. To explor e applications of leveraging direct numerical simulation (DNS) data to support turbulence model development, this work conducted DNS using NekRS to study a long stratification transient in the High-Resolution Jet (HiRJET) experimental facility. This work considers an experiment run where light fluid is injected into a tank containing a denser fluid with a relative density difference of 1.5%. Formation of the stratified layer is identified as impingement of the buoyant jet promoting mixing of the two fluids. Based on the transient statistics, transport of the concentration can be characterized by regions with dominating effects of turbulent mixing, buoyant dissipation, and molecular diffusion, respectively, as moving away from the elevation of jet impingement. Concentration near the stratified front also exhibits oscillation at Brunt-Väisälä frequency. Preliminary validation of the simulation showed encouraging agreement of the concentration distribution with the reference experiment.

Molecular Hydrogen Formation via Vibrational Excitation of Partially Superhydrogenated Pyrenes

While polycyclic aromatic hydrocarbons (PAHs) are now accepted to be abundant in interstellar space, the abundance and influence of superhydrogenated PAHs (HPAHs) in the interstellar medium (ISM) are still under investigation. HPAHs may act as catalysts for or reactants in small-molecule formation via hydrogen abstraction reactions, H2 evaporation, and carbon skeleton fragmentation. Here, we present a gas-phase infrared (IR) action spectroscopy study of the HPAH 4, 5, 9, 10-tetrahydropyrene (THP; C16H14), performed at the Free Electron Lasers for Infrared eXperiments facility. IR action spectroscopy was performed on the THP cation, protonated THP, and their fragments produced by collision-induced dissociation in the range from 600 to 1800 cm−1. Calculated IR spectra, at the density functional theory level, agree with experimental IR spectra to a high degree and were utilized to determine molecular structures of the HPAH fragments. Molecular dynamics simulations compared with experimental mass spectra reveal favorable HPAH fragmentation pathways. Molecular hydrogen (H2) is observed to be a primary fragment of [THP+H]+ with superhydrogenated duo groups. This contrasts the notion that HPAHs typically undergo carbon skeleton fragmentation leading to C x H y formation. These observations show that lowered symmetry and duo or trio aliphatic groups on HPAHs uniquely change their IR spectra, stability, and fragmentation patterns. As a result, these species may contribute to H2 formation in the ISM.

Performance evaluation and multi-objective optimization of a tubular indirect evaporative cooler integrated with moisture-conducting fibers

Indirect evaporative cooling (IEC) technology is an energy-efficient approach for regulating the indoor thermal environment of buildings. The conventional tubular indirect evaporative cooler (TIEC) may have a relatively low cooling efficiency due to poor wettability issues. The application of moisture-conducting fibers provides a feasible way to solve the above problem. However, the integration of moisture-conducting fibers with TIEC is still in the exploratory stage. This study proposed a novel moisture-conducting fiber-assisted TIEC and conducted a multi-objective optimization. An experimental facility and theoretical model of the proposed moisture-conducting fiber-assisted TIEC were developed. Based on the numerical model validated by experiments and response surface methodology (RSM), the regression models for performance prediction of the cooler were established. Eight input parameters including inlet air parameters, operating parameters and geometric parameters were selected, and four performance evaluation indicators were chosen as output responses. The parameter sensitivity of the regression models was analyzed. The multi-objective optimization was performed by considering the influence of different relative weights assigned to the output responses. Furthermore, the performance of the optimized cooler applied in different climate zones was predicted. The results showed that the product air temperature drop could achieve 8.8–11.3 °C after cooling by the cooler. The established regression models can predict the performance of the moisture-conducting fiber-assisted TIEC conveniently and effectively, which is expected to guide the design and optimization of engineering practices.

Efficacy of organic acids, lactic and formic acid, and peracetic acid in decontaminating process water and carcasses in chicken slaughter

AbstractFoodborne pathogens pose a persistent threat in broiler chicken production, particularly during the slaughter process, where contamination with zoonotic pathogens remains a concern. This study focuses on the potential of organic acids, such as formic and lactic acid, and the oxidizing agent peracetic acid, to decontaminate scalding water and enhance the hygiene of chicken carcasses. We conducted suspension tests introducing various organic loads to mirror the conditions of practical scalding water. Additionally, the surface tests were performed on chicken skin. Both methods were further tested in an experimental slaughtering facility. In suspension tests, the organic acids achieved impressive decontamination, with a 5‐log10 reduction of the test organisms Enterococcus hirae, Salmonella Typhimurium and Campylobacter jejuni at minimal concentrations (between 0.04% and 2% for formic acid; between 0.1% and 4.5% for lactic acid). Peracetic acid also effectively sanitized model water and chicken skin, even when used in low concentrations (between 0.001% and 0.1%), both in the laboratory‐based testing and in the experimental slaughtering facility. These results suggest that the tested disinfectants can effectively sanitize process water, even under conditions mimicking practical scalding water with organic matter. Peracetic acid, in particular, proved highly effective in improving chicken skin hygiene even at low concentrations.