Inlet System Research Articles

Investigation of Seasonal Settlement and Clam Harvest Pressure in the Sechelt Inlet System, British Columbia, Canada, Through Sclerochronology and Stable Oxygen Isotope Analyses

ABSTRACT The Sechelt inlet system (SIS), situated on the inner Sunshine Coast of British Columbia, lies within the territory of the shíshálh Nation. This study focuses on ∼1000 years of shíshálh shellfish harvesting from 930-0 cal. BP. Specifically, we investigated the seasonal timing of shellfish collection, relative shellfish harvesting pressure and paleo-temperature reconstruction at four archaeological sites. Thirty archaeological butter clam shells (Saxidomus gigantea) from the SIS underwent high-resolution shell oxygen isotope (δ18O) analysis and 662 individual archaeological shell fragments were analysed for growth stage determination. The δ18O results showed a pattern of year-round collection with an emphasis on spring collection at village sites. Results from shell growth stage analysis suggest an intensive pattern of shellfish harvesting in the region, regardless of the site type. Archaeological shells show a larger δ18Oshell range, possibly reflecting a greater sea surface temperature amplitude than modern shells (i.e. a difference of ∼6.5°C; modern range: ∼3.7–20.4°C; archaeological range: ∼ −0.8–22.4°C). We contextualise our results with previous studies of seasonal timing and intensity of shellfish harvesting from the Pacific Northwest Coast, while interpreting these new data in the context of shíshálh occupation and landscape use.

Experimental research on a novel dynamic composite distortion simulator

Large-scale dynamic distortion vortexes are generated in advanced complex inlet systems, which can cause serious dynamic distortion flows and influence the performance of engines. Thus, this paper proposes a novel dynamic distortion simulator design method, which uses a column to produce a large-scale streamwise vortex and a rotating valve to enhance the dynamic characteristics, to simulate the complex distortion flow field. Experimental studies were conducted in this paper. The results show that circumferential total pressure and swirl distortion were generated regardless of the valve position. The range of the distortion region decreased significantly when the valve changed from fully closed to fully opened. When the valve rotated continuously, the dynamic total pressure and swirl distortion were generated behind the simulator. At the section, three diameters away from the simulator, the comprehensive distortion index was 7.69%, and the turbulence intensity was 46.4%. The main frequency of the distortion flow field was the same as the switching frequency of the inner channel in the column.

Revision of an open-split-based dual-inlet system for elemental and isotope ratio mass spectrometers with a focus on clumped-isotope measurements

Abstract. In this work, we present a revision of an open-split-based dual-inlet system for elemental and isotope ratio mass spectrometers (IRMSs), which was developed by the division of Climate and Environmental Physics of the University of Bern 2 decades ago. Besides discussing the corresponding improvements we show that with this inlet system (NIS-II, New Inlet System II) external precisions can be achieved that are high enough to perform measurements of multiply substituted isotopologues (clumped isotopes) on pure gases. For clumped-isotope ratios 35/32 and 36/32 of oxygen, we achieved standard deviations of 3.4×10-9 and 4.9×10-9, respectively, that we calculated from 60 interval means (20 s integration) of pure-oxygen gas measurements. Moreover, we report various performance tests and show that delta values of various air components can be measured with precisions of the order of tens of per meg and higher with the NIS-II. In addition, we demonstrate that our new open-split-based dual-inlet system allows us to measure some of these delta values with significantly higher precisions than an NIS-I (precursor of the NIS-II) and conventional changeover-valve-based dual-inlet systems (tests performed with two dual-inlet systems built by Elementar and Thermo Finnigan). Especially, our measurements point out that our inlet system provides reliable results at short idle times (20 s) and that the corresponding data do not need to be corrected for non-linearity. However, the sample consumption of our open-split-based dual-inlet system is several orders of magnitude higher than that of changeover-valve-based ones (0.33 sccm versus 0.005 sccm; standard cubic centimetres per minute). Due to the successful preliminary tests regarding measurements of clumped-isotope ratios, we will continue our work in this area to perform clumped-isotope studies according to common practices.

Microplastic in industrial aquaculture: Occurrence in the aquatic environment, feed and organisms (Dicentrarchus labrax)

The increasing use of plastics and the growing concern about their impact on the environment and living beings makes it necessary to study how microplastics (MP) affect aquaculture systems. In order to gain an in-depth understanding of these systems, this study covers the water intake, the purification treatment at the inlet, the water in the culture tanks, as well as the feed used in the feeding and the organism itself. For this purpose, five samples were taken, both in the water line, feed and sea bass during the weeks of the experiment. It is shown that the available purification systems reduce the amount of MP entering from the receiving environment. However, new MP are observed in the sea bass tank, which may be due mainly to those added through the feed and found in the feed, as well as in the piping and other materials used in current aquaculture systems (PTFE, PA, among others). If focusing on the feed that can reach the consumer, in the case of this study, carried out with sea bass, some types of MP (PE, PTFE, PS and PA) were found in 4 head samples and 4 skin/muscle samples. Although inlet water purification systems manage to reduce a high percentage of MPs in the system, it is observed that there are other access routes that should be considered and reduced in aquaculture facilities to prevent them from reaching the human consumer.

Assessment of Total Pressure and Swirl Distortions in a Busemann Inlet at Mach 6

Flow distortions in high-speed inlet systems are complex, and high-performance air-breathing propulsion systems. In this paper, large eddy simulations are performed to study the total pressure and swirl distortions in a Busemann inlet at freestream Mach number 6. The on-design flow condition with both the Attack Angle and Sideslip Angle equal to zero and two off-design conditions (Attack Angle = 6 deg, Sideslip Angle = 0 deg and Attack Angle = 6 deg, Sideslip Angle = 6 deg) are considered to explore the flow characteristics inside the inlet duct as well as the distortions at the inlet exit plane. It is found that under the on-design flow condition, the shock structures and boundary layer development are nearly axisymmetric about the inlet axis. The captured freestream is compressed smoothly through inlet duct. The total pressure loss is limited primarily to within the boundary layer region, and nearly no swirling flow is introduced during the flow compression process. Under the off-design flow conditions, the shock structures inside the inlet duct become non-axisymmetric, and localized strong shock–boundary layer interactions occur. In the case of the off-design flow condition with Attack Angle = 6 deg, Sideslip Angle = 0 deg, a large flow separation zone appears owing to the incidence of a strong curved shock on the wall surface at the leeward side in the inlet duct, and the low-kinetic-energy flow contained in this flow separation zone leads to an obvious total-pressure reduction at the exit plane of inlet. Meanwhile, a large-scale swirling flow is formed at the exit plane of inlet owing to the appearance of a nonuniform transverse pressure gradient. Under the off-design conditions, a pair of vortex is observed at the exit plane of inlet. The shock wave–boundary layer interactions under the off-design conditions are stronger than those under the on-design condition, which results in more intense total pressure and swirl distortions. The averages of the fluctuating distortions are more evident than the temporal-averaged total-pressure and swirl distortions. These results show that turbulent flow fluctuations are important in determining the overall distortion level in a Busemann inlet.

Numerical simulation and optimization of a circular open channel for fish farming using Computational Fluid Dynamics (CFD)

Open canals are one of the most common and cost-effective methods in water supply networks; they are widely used in different industries such as agriculture, water and sewage treatment, urban drainage, pisciculture and water parks. Due to global warming, the demand in clean energy to replace fossil fuels has caused using water turbines in riverbeds and aqueducts to be important. On this basis, optimizing key parameters such as flow motion and canal turbulence is crucial to reduce breakdowns while designing canals. In fact, the inappropriate adjustment of velocity and pressure within the canals may lead to the system failure: imbalance between inlet and outlet will increase the water level and the pressure on canal walls thus, leading to breakdown. In this paper, a circular open canal was designed for a pisciculture system. The velocity and height of the water canal is controlled by the canal inlet and outlet system and the water flows continuously inside the canal. By keeping the canal water volume constant in any time and the flow motion with constant velocity, the system makes the fishes feel infinite movement. Furthermore, the water particles and impurities (e.g., food and fish feces) are removed by the outlet from the canal bottom, transferred to the filtration system, and returned to the fish farm by the canal inlet after the filtration procedure; the mentioned technique causes the water canal to be kept at its optimal level. Computational Fluid Dynamics (CFD) has been used to simulate the canal flow. Solving the Navier-Stokes equations numerically and assuming incompressible, unsteady, and two-phase flow, the parameters of the canal flow were extracted. Also, by mounting the system outlet along the path of water movement, greatly reduces the adverse effects of the outlet suction force on the canal main flow. Moreover, by dividing the canal inlet with guide vanes, the inlet has been modified for the entrance of the clean water simultaneously with the distribution of the inlet flow to several smaller flows in order to make the canal water continue to move continuously without any turbulence.

Study on Aerodynamic Design of the Front Auxiliary Inlet

Submerged inlets have been widely used in advanced aircraft due to their excellent stealth characteristics, but they also suffer from poor aerodynamic performance. To improve the aerodynamic efficiency while maintaining stealth capabilities, this paper proposes a design scheme for a front auxiliary inlet with an inlet grille. The front auxiliary inlet is connected to the main inlet to form a composite inlet system. The low-energy upstream airflow that accumulates at the inlet is guided by the front auxiliary inlet to flow into the mainstream, resulting in a stable and high-quality airflow. A certain type of cruise missile was used as the research subject, and intake systems with and without front auxiliary inlets were constructed to compare the inlet performance of the two configurations using the CFD method. Additionally, a sensitivity analysis of the main design parameters of the front auxiliary inlet was carried out. The study reveals that a reasonable design of the front auxiliary inlet can prevent low-energy airflow, which accumulates on the missile body surface, from directly entering the inlet. Moreover, the front auxiliary inlet can inject additional mechanical energy into the low-energy airflow, inhibit airflow separation, and improve the uniformity of the flow field. Under cruise conditions, the total pressure recovery coefficient of the front auxiliary inlet configuration increased by 12.39% compared to the model without a front auxiliary inlet configuration. Furthermore, the total pressure distortion index was reduced by 47.24%.

An innovative gas inlet design in a microwave plasma chemical vapor deposition chamber for high-quality, high-speed, and high-efficiency diamond growth

A novel design of the gas inlet system in a diamond microwave plasma chemical vapor deposition growth chamber has been reported in this paper. The design is targeting for high-quality, high-speed, and high-efficiency diamond material fabrication. By introducing a gas inlet hole into the susceptor, we expand the ways of gas introduction for diamond growth. After extensive numerical and experimental investigation, we have found that the introduction of methane and doping gas inlet from the hole of below while the hydrogen from the top is feasible for realizing the target. The growth and doping species could be confined around the substrate, making efficient usage of the precursors. The plasma state change caused by the difference of the gas inlet modes has been ascribed to the resulted gas distribution in the chamber. The measured growth rate has been increased to 32 μm h−1, which is 16 times higher than traditional gas inlet configuration. Meanwhile, a large improvement of the nitrogen doping concentration has been achieved. Besides, with the increase of growth rate and nitrogen incorporation efficiency, the crystal quality and surface morphology keep in an acceptable degree. In this mode, the dual gas flow system can perfectly solve the contradiction among the crystal quality, growth rate, and doping efficiency, commonly existing during the material fabrication process, the chamber contamination could be significantly suppressed due to the constrained distribution of methyl and doping species, making the fabrication cost much lower. The results of repetitive experiments indicate that other residual impurities present in the chamber of microwave plasma chemical vapor deposition could likely regulate the threshold concentration of nitrogen required for accelerating the growth rate during the nitrogen doped diamond growth, which have a significant effect on the diamond growth.

Determination of Lu and Hf Mass Fractions and 176Hf/177Hf Ratios in Mafic‐Ultramafic Rock Reference Materials by Multi‐Collector Inductively Coupled Plasma‐Mass Spectrometry

Reported data for Lu, Hf mass fractions and 176Hf/177Hf isotopic ratios of mafic‐ultramafic rock reference materials (RMs) are rare at present, hampering the comparison of data quality between difference laboratories. Herein, we measured the Lu and Hf mass fractions and the 176Hf/177Hf isotopic ratios of ten mafic‐ultramafic rock RMs, including OKUM (komatiite), WPR‐1 (serpentinised peridotite), NIM‐N (norite), NIM‐P (pyroxenite), UB‐N (serpentinised peridotite), JP‐1 (peridotite), NIM‐D (dunite), MUH‐1 (serpentinised harzburgite), HARZ01 (harzburgite), DTS‐2b (dunite), which contain extremely low amounts of Lu and Hf (Lu, 2–150 ng g−1; Hf, 5–500 ng g−1). All measurements were conducted on a Neptune Plus multi‐collector inductively coupled plasma‐mass spectrometer employing an Aridus II desolvator inlet system and Jet sample/X skimmer cone configuration. The following RMs, OKUM, WPR‐1, UB‐N, JP‐1, NIM‐D, HARZ01 and DTS‐2b, have 176Hf/177Hf precision of less than 60 ppm (2s) at test portions of 0.06 to 0.3 g, and are good ultramafic RMs for Lu‐Hf systems. In contrast, significant Hf mass fraction and isotopic variability were observed in NIM‐N, NIM‐P and MUH‐1 at test portion masses of 0.1 to 0.3 g. Collectively, our study provides a new database that can be used by the geochemical community for evaluating the Lu‐Hf system of mafic‐ultramafic rocks.

Numerical study of mixed phase ice accumulation in aero-engine inlet system

The phenomenon of mixed phase/ice crystal ice accumulation widely exists in the icing process of aero-engine inlet system. It is urgent to investigate the internal icing of aero-engine inlet system and ensure flight safety to carry out the corresponding calculation method and systematically analyze the icing characteristics of mixed phase/ice crystal. The aero-engine flow field model, the mixed phase sticking model, the mixed phase impact model and the ice accretion model under the condition of mixed phase icing are established for the aero-engine inlet system (Nacelle, Nosecone, Fan, Bypass, IGV). Moreover, the effects of different air velocity, liquid water content/total water content (LWC/TWC) and water droplet diameter changes on the icing mass capture of each component of the aero-engine inlet system and the changes of ice growth of each component were investigated. The results show that mass capture on nacelle and nosecone surfaces increases with the increase of airflow velocity. For the bypass surface, mass capture with 90% span is 16.84% of mass capture with 30% span when s/c = 0 and the airflow velocity is 200 m/s. Mass capture on the nacelle surface increases with the increase of melting rate. As the diameter of the droplets increases, the mass capture on both the nacelle and nosecone surfaces increase. At droplet diameter is 100 μm, mass captures at s/c = 0 at 30% and 90% IGV spans are 0.005 and 0.0153 kg/m2 s, respectively. Ice growth is most severe at the front of the nosecone. Under the same airflow velocity, the ice growth of fan, bypass and IGV increases significantly with the increase of span. Finally, through the analysis of mixed phase icing characteristics of aero-engine inlet system, it is necessary to design anti-icing of aero-engine inlet system. Meanwhile, in the anti-icing design, it is necessary to pay attention to the pressure side of the fan, the bypass surface and the IGV as well as the area with large span.

Morphological Dynamics on Tidal Inlet System by Generating Variability of Tidal-Wave Energy Regimes; A Process-Based Model Approach of Tide Dominated Case and Mixed Tide Dominated Case

A process-based approach of 2D morphodynamic modeling is an alternative technique to investigate the morphological evolution in the long-term period. In the conceptual model application, there is two methodologies of morphodynamic model; realistic-based model (short time scale model in days/months) and realistic-analogue model which is called process-based model (long time scale model in ~100 years). Realistic-based model is the representative of generating force with complexity of real condition model in the field, however process-based model is the simplification of forcing model by representing the major factor. In this study, the domain model is as the adaptation of Dutch Wadden Zee tidal inlet system. A couple model technique of Flow module (Delft3d) and Wave module (X-Beach) is implemented into the model system. The tidal forcing is based on one main harmonic tidal component of M2 and super harmonic tidal component of M4 and M6 from the analysis harmonic of ZUNO model. The wave forcing is 1.4 m and 330 deg as the representative wave climate condition in Wadden Zee. A process-based model shows that initially the morphological response leading into establish-state condition. Tidal wave propagation which leads to stronger cross-shore ebb-flow perpendicular to the coastline contributes in morphological evolution inside the basin and forming the outer part of the inlet (ebb-tidal delta). Wave induce current in mixed-tide energy case are as the major contribution of stirring up sediments from the sea bed, leads to transport sediment because of longshore currents process, undertow, mass transport.

Imaging VOC distribution and tracing emission sources in surface water by a mobile shipborne spray inlet proton transfer reaction mass spectrometry

Volatile organic compound (VOC) pollution in surface water can affect the growth of microorganisms and even cause damage to human health. Quickly obtaining VOC distribution and tracing emission sources are of great significance to ensure the security of water quality. In this study, we developed a mobile shipborne spray inlet proton transfer reaction mass spectrometry (S-SI-PTR-MS) instrument for rapid and on-line detection of volatile organic compounds (VOCs) in surface water. It mainly consists of a shipborne platform, a spray inlet system, a proton transfer reaction mass spectrometer, and geographic information software (GIS). During the navigation, VOCs in water can be quickly extracted to gaseous state by the SI system and transferred into the proton transfer reaction mass spectrometry (PTR-MS) for detection. The GIS can receive VOC and longitude-latitude data at the same time. And then the identification and concentration information can be shown on an electronic map in real time. The limit of detection and response time were 1.32 μg/L∼9.43 μg/L and 56 s∼114 s, respectively. The spatial resolution is 0.14 m in a common navigation experiment (5 km/h, dwell time=0.1 s), allowing for high-resolution monitoring of VOCs in water. Finally, field experiments were performed on the lower Nanfeihe River and some surfaces of Chaohu Lake in China. During tracing pollution in Nanfeihe River, two VOC emission sources in the downstream were located, nearing a sewage outlet and a wharf, respectively. During imaging VOC distribution in the Chaohu Lake, we found the areas with high-concentration VOCs were mainly along the ship channel. The newly developed S-SI-PTR-MS can monitor water quality in surface water in real time and has the potential to assist environmental protection enforcement.

Hydrodynamics and Sediment-Transport Pathways along a Mixed-Energy Spit-Inlet System: A Modeling Study at Chincoteague Inlet (Virginia, USA)

Tidal-inlet systems are dynamic features that respond to short-term (e.g., storms) and longer-term processes (e.g., sea-level rise, changes in tidal prism). The Chincoteague Inlet system, located along the northern Eastern Shore of Virginia (USA), is a dynamic coastal complex that experiences rapid change associated with sediment redistribution and a shifting inlet throat due to the southern elongation of adjacent Assateague Island. In this study, a numerical model based on Delft3D with coupled flow–waves, multiclass sediment transport, and morphologic feedback was developed to quantify the hydrodynamic and geomorphic controls within this rapidly evolving inlet–spit system and to develop a more comprehensive understanding of regional to local controls on sediment-transport pathways. Model results show that most of the sand transport along southern Assateague Island is sequestered nearshore and proximally in deeper sinks within Fishing Point, and, of that, only finer sand sizes are transported around the spit, confirming previous analysis and hypothesis. The model also showed that sand transport toward the south increases along Wallops Island and quantified spatially explicit transport trends for selected sediment classes, revealing that coarser sediment bypassing is a punctuated process that is proportional to storms.

Optimal structure design and heat transfer characteristic analysis of X-type air-cooled battery thermal management system

This paper develops an X-type double inlet and outlet symmetrical air-cooled battery thermal management system (BTMS) that overcomes the high temperature, large temperature difference, and high power dissipation problems. The proposed method extends previous symmetrical BTMSs, i.e., single inlet and outlet BTMS, single inlet and double outlet BTMS, and double inlet and single outlet BTMS. However, compared with the existing symmetrical BTMS, the suggested X-type BTMS improves performance and reduces the maximum temperature, maximum temperature difference, and maximum power dissipation by 4.33 K, 74 %, and 62.9 %, respectively. Additionally, the inlet and outlet parameters of the X-type BTMS are optimized with orthogonal analysis, and the optimum settings defined as 71 mm near the outlet, 135 mm near the inlet, 90° for the outlet angle, and 150° for the inlet angle, among which the outlet position and inlet angle significantly affect the performance of the BTMS. The original X-type BTMS is optimized to reduce the maximum temperature and maximum temperature difference by 4 K and 76.5 %, respectively. Furthermore, the heat transfer correlation expression for the X-type BTMS is obtained through theoretical analysis within an 8 % deviation, providing a reference for the design of BTMS.

Preparation and Analysis of Experimental Findings on the Thermal and Mechanical Characteristics of Pulsating Gas Flows in the Intake System of a Piston Engine for Modelling and Machine Learning

Today, reciprocating internal combustion engines are used in many branches of the economy (power engineering, machine engineering, transportation, and others). In order for piston engines to meet stringent environmental and economic regulations, it is necessary to develop complex and accurate control systems for the physical processes in engine elements based on digital twins, machine learning, and artificial intelligence algorithms. This article is aimed at preparing and analysing experimental data on the gas dynamics and heat transfer of pulsating air flows in a piston engine’s intake system for modelling and machine learning. The key studies were carried out on a full-scale model of a single-cylinder piston engine under dynamic conditions. Some experimental findings on the gas-dynamic and heat-exchange characteristics of the flows were obtained with the thermal anemometry method and a corresponding measuring system. The effects of the inlet channel diameter on the air flow, the intensity of turbulence, and the heat transfer coefficient of pulsating air flows in a piston engine’s inlet system are shown. A mathematical description of the dependences of the turbulence intensity, heat transfer coefficient, and Nusselt number on operation factors (crankshaft speed, air flow velocity, Reynolds number) and the inlet channel’s geometric dimensions are proposed. Based on the mathematical modelling of the thermodynamic cycle, the operational and environmental performance of a piston engine with intake systems containing channels with different diameters were assessed. The presented data could be useful for refining engineering calculations and mathematical models, as well as for developing digital twins and engine control systems.

Real-time gas mass spectroscopy by multivariate analysis

Early and significant results for a real-time, column-free miniaturized gas mass spectrometer in detecting target species with partial overlapping spectra are reported. The achievements have been made using both nanoscale holes as a nanofluidic sampling inlet system and a robust statistical technique. Even if the presented physical implementation could be used with gas chromatography columns, the aim of high miniaturization requires investigating its detection performance with no aid. As a study case, in the first experiment, dichloromethane (CH2Cl2) and cyclohexane (C6H12) with concentrations in the 6–93 ppm range in single and compound mixtures were used. The nano-orifice column-free approach acquired raw spectra in 60 s with correlation coefficients of 0.525 and 0.578 to the NIST reference database, respectively. Then, we built a calibration dataset on 320 raw spectra of 10 known different blends of these two compounds using partial least square regression (PLSR) for statistical data inference. The model showed a normalized full-scale root-mean-square deviation (NRMSD) accuracy of 10.9mathrm{%} and 18.4mathrm{%} for each species, respectively, even in combined mixtures. A second experiment was conducted on mixes containing two other gasses, Xylene and Limonene, acting as interferents. Further 256 spectra were acquired on 8 new mixes, from which two models were developed to predict CH2Cl2 and C6H12, obtaining NRMSD values of 6.4% and 13.9%, respectively.

A Genetic Algorithm approach for optimization of geothermal power plant production: Case studies of direct steam cycle in Kamojang

Indonesia has enormous geothermal potential, but it only contributes 5% to Indonesia's energy matrix. During 37 years of operation, PT. Pertamina Geothermal Energy Kamojang area has been operating to produce electricity and is currently capable of supplying and distributing electricity to the Java-Bali area with a capacity of 60 MWe. However, this can run into a decrease in the efficiency and effectiveness of system performance due to energy losses in several geothermal power plant components during energy conversion. In this case, exergy analysis at PT. Pertamina Geothermal Energy Kamojang area Unit 4 direct-dry steam cycle was done on each component and state. This aims to know the energy and exergy stream and where it happened irreversibly at the component. The biggest irreversibility value occurred at the turbine and main condenser, with a value of 21,693.890 kW and 21,688.148 kW. The total irreversibility of all systems is 58,326.201 kW, while the total exergy inlet systems is 119,308.457 kW, so the value efficiency exergy obtained is 51.13%. Based on the environment as dead state analysis, an efficiency exergy value is inversely proportional to the irreversibility value and ascending environment temperature. System optimization was done with the genetic algorithm method, with variable values at the pressure wellhead and inlet turbine for the overall exergy efficiency value. The value obtained from optimization is 11.98 bar at the wellhead and 10.023 bar at the inlet turbine, and the overall efficiency exergy increased by 51.22%.

Research on configuration and performance of water ramjet pressurized water intake system

Water ramjet is the most ideal power propulsion device for high-speed underwater weapons. However, failure to start it at low-speed makes it hard for the engine to be widely used. In order to solve the problem of starting water ramjet at low-speed, a configuration scheme of water ramjet pressurized water intake system of the micro-turbine driving micro-mixed-flow pump is proposed. The design method of micro-turbine and micro-mixed-flow pump is perfected. And the simulation model of turbine and mixed-flow pump is established. The rationality of the design results was verified by numerical simulation. The matching design of the turbine and the mixed-flow pump is completed. And the working performance of the pressurized water inlet system is analyzed. The results show that the maximum relative deviation between the design results of the turbine and the pump and the target value is less than 3.2%, and the booster system can increase the fluid pressure by 2.0 MPa, reducing the starting speed of the ramjet from 90 to 63 m/s. The research results of this paper have reference value for the engineering application of water ramjet technology.

Design and Simulation of Aerosol Inlet System for Particulate Matter with a Wide Size Range

A novel aerodynamic lens-based inlet system was developed for a wide particle size range, and it could extend the size range of transmitted particulate matter (PM) to 50 nm–10 μm. The lens system adopted a seven-stage aerodynamic focusing orifice to extend the range of transmitted PM, and a relaxation system with a virtual impact function was introduced at the front of the aerodynamic lens. Through the innovative design, the system could concentrate the input samples as well as effectively enhance the focusing effect on large PM. Furthermore, an additional aerodynamic pre-focusing inlet system was innovatively added to the front of the sampling orifice of the traditional aerodynamic lens, and it could pre-focus large PM into the axis region before it entered the small orifice and then solve the previous problem with loss of large PM. Fluid simulations indicated that the inlet system could achieve 100% effective transmission and focusing for PM in the range of 0.18–10 μm. The characterization and verification results obtained from the improved single-particle aerosol mass spectrometer (SPAMS) were remarkably consistent with the theoretical values. The practical tests indicated that bioaerosol particles up to 10 μm could be detected. Compared with the observation for the same type of lens, the focusing performance of this novel lens system has better advantages in particle size range and transmission efficiency and therefore, it has broad application prospects in bioaerosol research, single-cell analysis, etc.

Using tunable infrared laser direct absorption spectroscopy for ambient hydrogen chloride detection: HCl-TILDAS

Abstract. The largest inorganic, gas-phase reservoir of chlorine atoms in the atmosphere is hydrogen chloride (HCl), but challenges in quantitative sampling of this compound cause difficulties for obtaining high-quality, high-frequency measurements. In this work, tunable infrared laser direct absorption spectroscopy (TILDAS) was demonstrated to be a superior optical method for sensitive, in situ detection of HCl at the 2925.89645 cm−1 absorption line using a 3 µm inter-band cascade laser. The instrument has an effective path length of 204 m, 1 Hz precision of 7–8 pptv, and 3σ limit of detection ranging from 21 to 24 pptv. For longer averaging times, the highest precision obtained was 0.5 pptv with a 3σ limit of detection of 1.6 pptv at 2.4 min. HCl-TILDAS was also shown to have high accuracy when compared with a certified gas cylinder, yielding a linear slope within the expected 5 % tolerance of the reported cylinder concentration (slope = 0.964 ± 0.008). The use of heated inlet lines and active chemical passivation greatly improve the instrument response times to changes in HCl mixing ratios, with minimum 90 % response times ranging from 1.2 to 4.4 s depending on inlet flow rate. However, these response times lengthened at relative humidities >50 %, conditions under which HCl concentration standards were found to elicit a significantly lower response (−5.8 %). The addition of high concentrations of gas-phase nitric acid (>3.0 ppbv) were found to increase HCl signal (<10 %), likely due to acid displacement with HCl or particulate chloride adsorbed to inlet surfaces. The equilibrium model ISORROPIA suggested a potential of particulate chloride partitioning into HCl gas within the heated inlet system if allowed to thermally equilibrate, but field results did not demonstrate a clear relationship between particulate chloride and HCl signal obtained with a denuder installed on the inlet.