Chamber Shell Research Articles

Development of High-Voltage Electrodes for Neutron Scattering Sample Environment Devices

The sample environment is essential to neutron scattering experiments as it induces the sample under study into a phase or state of particular interest. Various sample environments have been developed, yet the high-voltage electric field has rarely been documented. In this study, Bruce electrodes with various sectional geometries and chamber sizes were examined by using simulation modeling based on ANSYS Maxwell. A large uniform field region where samples would sit could be achieved in the planar region for all specifications, but the size of the region and the field strength varied with the gap distance between electrodes. The edging effect was inherently observed even for bare electrodes, about 1.7% higher in the sinusoidal region than the planar region, and was significantly deteriorated when a chamber was applied. This effect, however, presented an exponential decrease as the minimum distance between the electrode edge and the chamber shell increased. A compromise between the spatial confinement and the achievable field (strength and uniform region) could be reached according to the unique applicability of neutron instruments. This research provides a theoretical basis for the subsequent design and manufacturing of high-voltage sample environment devices.

Mode-matching technique for analyzing scattering in elastic shell chambers: Applications in trifurcated waveguide systems

This study presents a comprehensive investigation into the behavior of elastic shell chambers used for noise control and vibration mitigation in engineering applications. The study focuses on the analysis of fluid–structure coupled waves in a cylindrical waveguide system with trifurcated structures and membrane discs. The mode-matching technique is employed to analyze the scattering characteristics of the elastic chamber shell. Numerical simulations and analytical techniques are used to explore the interplay between material properties, geometric configurations, and loading conditions. The Galerkin formulation is utilized to model the response of membrane bridging discs and elastic shell regions. Linear algebraic systems are solved numerically to obtain the scattering amplitudes, and the convergence of the obtained solution is assessed. The energy conservation law and transmission loss are analyzed to evaluate the accuracy and convergence behavior of the system. The numerical results provide insights into the scattering behavior of the structure, showing the influence of frequency, chamber radius, and edge conditions. The findings highlight the importance of parameter selection and boundary conditions in guiding structures and provide a basis for design optimization.

Optimal Sensor Deployment for Parameter Estimation Precision by Integrating Bayesian Networks in Wet-Grinding Systems

Accurately and efficiently determining a system’s physical variables is crucial for precise product-quality control. This study proposes a novel method for optimal sensor deployment to increase the accuracy of sensing data for physical variables and ensure the timely detection of the product’s particle size in a wet-grinding system. This approach involves three steps. First, a Bayesian network (BN) is designed to model the cause–effect relationship between the physical variables by applying the path model. The detectability is determined to confirm that the mean shifts of all the physical variables are identifiable using sensor sets in the wet-grinding system. Second, the sensing location of accelerometers mounted on the chamber shell is determined according to the coupled computational fluid dynamics–discrete element method simulations. Third, the shuffled frog leaping algorithm is developed by combining the BN to minimize the maximum data output deviation index among all sensor sets and sensory costs; this is achieved under the constraints of the mean shift detectability, achieving optimum sensor allocation. Subsequently, a case study is performed on a zirconia powder production process to demonstrate that the proposed approach minimizes the requirements of the data output deviation index, sensory costs, and detectability. The proposed approach is systematic and universal; it can be integrated into monitor architecture for parameter estimation in other complex production systems.

Experimenting and Optimizing Design Parameters for a Pneumatic Hill-Drop Rapeseed Metering Device

The planter plate is the most important component of the pneumatic hill-drop seed metering system for rapeseed. The structural parameters of the planter plate are the primary determinants of rape planting. The key structural and operational parameters, such as the layout of the suction hole, its diameter, and its shape, were determined through theoretical analysis. Fluent is used to simulate the flow field of various types of suction holes, and the effect of suction hole shape on the change in the flow field of the suction chamber shell is analyzed. Under the same boundary conditions, the results indicate that the maximum velocity of the end face of the horn hole and the average pressure of the section are the highest. Using a high-speed camera, the effects of suction hole diameter and shape on seed filling performance were studied, and the results of Fluent simulation analysis were validated. The optimal seed metering device operating parameters were as follows: planter plate speed of 30–70 r/min and negative pressure of −2.5–−1.5 kPa. The influence of working negative pressure and the rotational speed of the planter plate on seed arrangement performance was studied within the optimal operating parameter range. In order to improve the performance of rational close planting in the seed planter, the multi-objective optimization design of working parameters and the verification test were also conducted. The results showed that with the best combination of working parameters, the empty broadcast rate does not go above 3%, the hole number qualified rate does not go below 96%, and the difference between them and the theoretical optimization result does not go above 5.5%.

Technology for Obtaining Tangential Holes in the Shell of the Combustion Chamber of a Liquid Propellant Rocket Engine

Method of obtaining tangential holes in the shell of a combustion chamber of liquid-propellant rocket engine is presented in this article. Advantages and disadvantages of technologies for making small diameter holes are consired. The developed technology and tooling made it possible to obtain small diameter holes designed to swirl the coolant flow in the veil belt of the combustion chamber shell. As a result, material and labor costs were reduced in the manufacture of engine components.

Horizontal Distribution and Carbon Biomass of Planktonic Foraminifera in the Eastern Indian Ocean

Distribution and carbon biomass of planktonic foraminifera were investigated from the euphotic zone of the Eastern Indian Ocean during a two-month cruise, ‘Shiyan I’ (10 April–13 May 2014). Foraminifera species were collected through plankton net sampling at 44 locations (80.00°–96.10° E, 10.08° N–6.00° S). The temperature (°C) ranged between 12.82 and 31.8 °C, the salinity ranged between 32.5 and 35.5, and chlorophyll-a concentrations ranged between 0.005 µg/L and 0.89 µg/L. A total of 20 taxa were identified based on the spherical chamber shell, spines, and a final whorl which were examined under light microscopy and scanning electron microscopy. Dominant species that were characterized by the high dominant index Y > 0.14–0.46 were Globigerina bulloides, Globigerinoides ruber white, Globigerinella siphonifera, Turborotalita quinqueloba, and Globigerinella calida, contributing to the community up to 86%. The shell size of collected taxa was from 51 to 508 μm and the total carbon biomass was estimated to be between 0.062 µg C m–3 and 26.52 µg C m–3. The high carbon biomass was recorded at two stations in the equator zone. Due to its large size, Globorotalia menardii had total carbon biomass of 3.9 µg C m–3, followed by G. calida 0.68 µg C m−3, Trilobatus sacculifer 0.38 µg C m–3, Orbulina universa 0.56 µg C m–3, and G. ruber white 0.22 µg C m–3, respectively. The Pearson correlation analysis showed that the temperature and chlorophyll-a were two explanatory environmental variables that were found to be highly significant (p < 0.05) and that triggered the distribution and abundance of dominant foraminifera species in the study region. Overall, high abundances and carbon biomass were derived from the euphotic zone and equatorial region of the Eastern Indian Ocean.

Assessment of thrust chamber stability margins to high-frequency oscillations based on mathematical modeling of coupled ‘injector – rocket combustion chamber’ dynamic system

High-frequency instability of a liquid-propellant rocket engine (LRE) during static firing tests is often accompanied by a significant increase in dynamic loads on the combustion chamber structure, often leading to a chamber destruction. This dynamic phenomenon can also be extremely dangerous for the dynamic strength of a liquid-propellant rocket engine. The calculation of acoustic combustion product oscillation parameters is important in the design and static firing tests of such rocket engines. The determination of the oscillation parameters (natural frequencies and stability margins such as oscillation decrement) is one of the problems solved in the LRE design period as part of the development of measures to ensure the engine stability. The main aim of the paper is to develop a numerical approach to determining the parameters of acoustic oscillations of combustion products in liquid-propellant rocket engines combustion chambers taking into account the features of combustion space configuration and the variability of gaseous medium physical properties depending on the axial length of the chamber, acoustic impedance in critical throat and dissipation effects (damping experimental values) in the shell structure and the gas media in the chamber. The approach is based on mathematical modeling of the coupled ‘chamber shell structure – gas’ dynamic system by using the finite element method and the CAE (Computer Aided Engineering) system. The developed approach testing and further analysis of the results for the RD 253 engine using nitrogen tetroxide and unsymmetrical dimethylhydrazine as a propellant pair were carried out. The dynamic system shapes and frequencies of longitudinal, tangential and radial modes are determined. The results of mathematical modeling of the dynamic system indicate a satisfactory agreement of the calculated decrements of the first longitudinal oscillation mode and third tangential oscillation mode with the experimental decrements obtained by hot-fire tests data. From system harmonic analysis of the thrust chamber, it follows that the dynamic pressure gain factor of the gas media in the chamber at the first longitudinal mode frequency is 1.6 times greater than the system dynamic gain in the tangential mode. At the same time, the oscillation decrement for the system tangential mode is 2 times smaller than that of the first longitudinal mode. This means that the thrust chamber tangential mode is more dangerous and can lead to rocket engine combustion instability. The effect of the injector on the high-frequency stability of the combustion chamber and the possibility of partial suppression of combustion chamber thermoacoustic oscillations by adjusting the high-frequency dynamics of the injector are shown theoretically.

ТЕРМО-ПРОЧНОСТНОЙ АНАЛИЗ НЕОХЛАЖДАЕМОГО КОМПОЗИТНОГО СОПЛА ЖИДКОСТНОГО РАКЕТНОГО ДВИГАТЕЛЯ

In order to improve the power characteristics of liquid propulsion systems used in rocket technology by accelerating charged particles, the authors performed a thermal and strength analysis of the liquid rocket engine design using an uncooled nozzle. A model of a nozzle made with the use of composite materials was considered and the conditions of real thermal stress and force loading on the combustion chamber shell with the use of a composite nozzle were simulated.

Relationship between individual chamber and whole shell Mg/Ca ratios in Trilobatus sacculifer and implications for individual foraminifera palaeoceanographic reconstructions

Precisely targeted measurements of trace elements using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) reveal inter-chamber heterogeneities in specimens of the planktic foraminifer Trilobatus (Globigerinoides) sacculifer. We find that Mg/Ca ratios in the final growth chamber are generally lower compared to previous growth chambers, but final chamber Mg/Ca is elevated in one of thirteen sample intervals. Differences in distributions of Mg/Ca values from separate growth chambers are observed, occurring most often at lower Mg/Ca values, suggesting that single-chamber measurements may not be reflective of the specimen’s integrated Mg/Ca. We compared LA-ICPMS Mg/Ca values to paired, same-individual Mg/Ca measured via inductively coupled plasma optical emission spectrometry (ICP-OES) to assess their correspondence. Paired LA-ICPMS and ICP-OES Mg/Ca show a maximum correlation coefficient of R = 0.92 (p < 0.05) achieved by applying a weighted average of the last and penultimate growth chambers. Population distributions of paired Mg/Ca values are identical under this weighting. These findings demonstrate that multi-chamber LA-ICPMS measurements can approximate entire specimen Mg/Ca, and is thus representative of the integrated conditions experienced during the specimen’s lifespan. This correspondence between LA-ICPMS and ICP-OES data links these methods and demonstrates that both generate Mg/Ca values suitable for individual foraminifera palaeoceanographic reconstructions.

Numerical simulation of air arc impinging to chamber shell with multi-physical coupling method of fluid-thermal-structure

The air arc impinging to chamber shell during interruption current process were studied by experiments and numerical simulation. Firstly, strain characteristics of chamber shell were measured by the strain gauge, and the strain changing with times were lagging behind the pressure in arc chamber. Experiment strain results 0.0035 and 0.0025 were slightly smaller than the calculation results 0.0055 and 0.0035. Furthermore, the thermal field mathematics model of chamber shell was proposed, and it was found that there was a large temperature gradient in the thickness of the chamber shell. Lastly, stresses-strains of three kinds of coupling methods, which were the fluid-structure coupling, the thermal-structure coupling and the fluid-thermal-structure coupling were compared. It was confirmed that the mechanical stress was concentrated in the middle of the side wall, while the maximum thermal stress was distributed on the vent area. Total stress and total strain were not equal to the algebraic sum of mechanical field and thermal field. The effect of different fixed supports on the thermal field was greater than the effect on the fluid field, and outer side wall fixed support had minimal displacement.

Development of a plug-type IMS-MS instrument and its applications in resolving problems existing in in-situ detection of illicit drugs and explosives by IMS

Ion mobility spectrometry (IMS) which acts as a rapid analysis technique is widely used in the field detection of illicit drugs and explosives. Due to limited separation abilities of the pint-sized IMS challenges and problems still exist regarding high false positive and false negative responses due to the interference of the matrix. In addition, the gas-phase ion chemistry and special phenomena in the IMS spectra, such one substance showing two peaks, were not identified unambiguously. In order to explain or resolve these questions, in this paper, an ion mobility spectrometry was coupled to a mass spectrometry (IMS-MS). A commercial IMS is embedded in a custom-built ion chamber shell was attached to the mass spectrometer. The faraday plate of IMS was fabricated with a hole for the ions to passing through to the mass spectrometer. The ion transmission efficiency of IMS-MS was optimized by optimizing the various parameters, especially the distance between the faraday plate and the cone of mass spectrum. This design keeps the integrity of the two original instruments and the mass spectrometry still works with multimode ionization source (i.e., IMS-MS, ESI-MS, APCI-MS modes). The illicit drugs and explosive samples were analyzed by the IMS-MS with 63Ni source. The results showed that the IMS-MS is of high sensitivity. The ionization mechanism of the illicit drug and explosive samples with 63Ni source were systematically studied. In addition, the interferent which interfered the detection of cocaine was identified as dibutyl phthalate (DBP) by this platform. The reason why the acetone solution of amphetamine showed two peaks was explained.

Collaborative Simulation Optimization Analysis of Family Refuge Chamber Shell Structure Based on ANSYS Workbench

In order to improve the structural anti-impact strength for family refuge chamber, an arched transition capsule is designed. The structural static analysis for the shell structure under the pressure of 0.1MPa and the modal analysis of structural dynamic are calculated, then goal driven optimization analysis is used for main parameters affected the shell strength which is designed by the collaborative optimization function of Pro/E and Workbench, the parameters sensitivity curve and the candidate optimum design point are obtained. The optimization results show that under the minimum change of the module’s mass, shell’s maximum equivalent stress and total deformation decreases by 32.56% and 44.23% respectively, provide theory support for the capsule manufacturer.

Study of Impact Process of Air Arc on the Chamber Shell Based on the Interaction of Fluid–Structure Method

Based on the commercial ANSYS workbench simulation software, the fluid–structure interaction method is used to calculate the air arc pressure distribution in arc chamber, and its impact effect on the shell during interrupting the high current is simulated and analyzed. The stress and deformation distributions of the arc chamber shell with different materials and thicknesses are obtained. It is confirmed that the maximum stress of the shell with 6-mm thickness decreases by ~25% compared with that of 3-mm thickness shell, and the maximum deformation decreases by ~20%. Four models for thickening different local regions are proposed to optimize the shell structure based on the above analysis, including thickened middle regions of the wall inside/outside and corresponding edge regions of the wall. The simulations results indicate that the structure of the arc chamber shell could be optimized very well to achieve the most uniform stress/deformation distribution using the model with thickening the middle region of the outside wall.

A novel fast response and radiation-resistant scintillator detector for beam loss monitor

At high luminosity area, beam loss monitor with fast response and high radiation resistance is crucial for accelerator operation. In this article, we report the design and test results of a fast response and radiation-resistant scintillator detector as the beam loss monitor for high luminosity collider, especially at low energy region such as RFQ. The detector is consisted of a 2 cm× 2 cm× 0.5 cm LYSO crystal readout by a 6 mm × 6 mm Silicon photomultiplier. Test results from various radioactive sources show that the detector has good sensitivity to photons from tens of keV to several MeV with good linearity and energy resolution (23% for 60 keV γ-ray). For field test, two such detectors are installed outside of the vacuum chamber shell of an 800 MeV electron storage ring. The details of the test and results are introduced.

An Approximate Analysis of the Inner Wall Loading of a Bimetallic Camera Shell of Reusable Rocket Engine

В различных технических устройствах в качестве конструктивных элементов достаточно широко используют биметаллические оболочки. Характерным примером применения биметаллических оболочек является конструкция камеры сгорания жидкостного ракетного двигателя (ЖРД). В процессе работы ЖРД оболочка камеры сгорания подвержена интенсивным тепловым и механическим воздействиям, что приводит к необходимости ее охлаждения. Охлаждающий тракт оболочки образован зазором между ее внутренней и наружной стенками, скрепленными между собой гофрированными проставками или фрезерованными ребрами. Наружная стенка выполняет роль силового элемента оболочки, а внутренняя стенка непосредственно контактирует с высокотемпературными продуктами сгорания и подвержена интенсивному нагреву. Различие функций стенок оболочки вызывает необходимость их изготовления из разных материалов с различающимися теплофизическими и механическими характеристиками.

Analysis of Heat Stress and the Indoor Climate Control Requirements for Movable Refuge Chambers.

Movable refuge chambers are a new kind of rescue device for underground mining, which is believed to have a potential positive impact on reducing the rate of fatalities. It is likely to be hot and humid inside a movable refuge chamber due to the metabolism of trapped miners, heat generated by equipment and heat transferred from outside. To investigate the heat stress experienced by miners trapped in a movable refuge chamber, the predicted heat strain (PHS) model was used to simulate the heat transfer process between the person and the thermal environment. The variations of heat stress with the temperature and humidity inside the refuge chamber were analyzed. The effects of air temperature outside the refuge chamber and the overall heat transfer coefficient of the refuge chamber shell on the heat stress inside the refuge chamber was also investigated. The relationship between the limit of exposure duration and the air temperature and humidity was numerically analyzed to determine the upper limits of temperature and humidity inside a refuge chamber. Air temperature of 32 °C and relative humidity of 70% are recommended as the design standard for internal thermal environment control of movable refuge chambers.

Thermal properties and energetic characteristics of a combustion system

In this paper, the thermal decomposition characteristics and the energy characteristics were studied to select a suitable propellant formulation. The temperature distribution of micro-thruster array was calculated to study the effect of heat loss on the combustion chamber shell. The monopropellant micro motor model was established, and the effect of heat loss on the micro-thruster performance was studied. Results indicated that 5:5 Lead Styphnate (LS)/Nitrocellulose (NC) was suitable as micro-motor formulation, and the highest temperature appeared at the boundary of the combustion chamber, where the thermal stress and deformation were the maximum. Furthermore, the thermal stress and deformation of silicon material was smaller than steel and the thermal stress was the main reason for the destruction of micro-thruster stability. In addition, the heat loss had great effects on micro-thruster performance: the thrust decreased by 21.7%, and the specific impulse also decreased by 11.8%.

Influences of Heat Loss on Micro-Thruster Performance

ABSTRACTThe thermal conductivity of high temperature gas to the wall can significantly affect the performance of a micro-rocket motor. In this article, the thermal decomposition characteristics and the energy characteristics were studied to select a suitable propellant formulation, which meets the requirements of a micro motor. The heat distribution of a micro-thruster array was calculated to study the effect of heat loss on the combustion chamber shell. The monopropellant micro-motor model was established, and the effect of heat loss on the micro-thruster performance was investigated. Results indicated that 5:5 Lead Styphnate/Nitrocellulose was suitable as the micro-motor formulation; the highest temperature appeared at the boundary of the combustion chamber where the thermal stress and deformation were the maximum. The thermal stress and deformation of silicon material was smaller than steel and the thermal stress was the main reason for the destruction of micro-thruster stability. The heat loss had great effects on the micro-thruster performance as it decreased the thrust by 21.7% and specific impulse by 11.8%.

Simulation Analysis on the Deep Drawing Property of Brake Chamber Shell

Brake chamber shell is an important part in brake system, and it is produced by twice deep drawing process. This paper adopts the DYNAFORM software, simulate drawing process of brake chamber shell by using FEM method, and make a comparison with the actual production. The result shows that there is a high consistency between the simulation results and semifinished products produced by twice deep drawing process, meanwhile, analysis results of Dynaform sheet forming are accurate with high reliability.

Simulation Analysis on Structure Safety of Two Typical Refuge Chamber Shell Forms Under Explosion Load

Abstract In order to reduce the risk of sealing and improve the structural strength safety for coal mine mobile refuge chamber, two models with certain proportion were set up after mechanical analysis. One was one-piece coal mine mobiles refuge chamber form which involves less sealing problems between sections, the other was segmented coal mine mobiles refuge chamber form which is easy to transport. A simulation analysis method was used to confirm their structure safety. Verified finite element analysis method was used to simulate the responses under blast loading. Considering the harsh conditions, the maximum pressure of the triangle impact load was 0.8 MPa, and the pulse width was 300ms. The maximum stress of one-piece one is less than segmented one. It demonstrated that section connecting position can cause more stress concentration. The maximum displacement one of one-piece is more than segmented one. It demonstrated that segmented type had lower displacement. Weak part of one-piece was middle position of front and back end shell. Weak parts of segmented type were middle position of sides and section connecting position. Based on their weak places analyzed, suggestions were put forward for the two kinds. Arc structure might be used in the front and back end shell. The front and back end shell might be thickened. Only inclined shaft with larger wellhead is suitable for this type. Segmented type could be used in large or medium-sized one.