Conical Chamber Research Articles

Evaluation of the mixing index in a micromixer of side feeds in a conical chamber

This study delves into the investigation of mixing efficiency in microdevices by augmenting angular momentum within a truncated cone-shaped micromixer through side-feedings. While microchannel flows are typically dominated by molecular transport, characterized by parallel streamlines, this hinders rapid responses in mixing quality. To address this, we evaluate a micromixer featuring side-feedings coupled to a 2D truncated cone, followed by a wavy microchannel. The research assesses the impact of feed arrangement in the entrance section, Reynolds number (Re), and the curvatures of bumps in the wavy microchannel. Symmetrical lateral feeds promote homogeneous mixing in the inlet section where streamlines intersect. At the device outlet, all bump curvatures contribute to a mixing index exceeding 0.90 within a Reynolds number range of 20 to 40. Additionally, lower Reynolds numbers (Re = 0.1) yield a mixing index above 0.90, but with a slower and predominantly diffusive flow. Notably, a sharper curvature geometry results in smaller pressure drops while maintaining a comparable mixing index to other geometries, indicating it as a promising choice for bump curvature.

Effects of structural parameters on air consumption and mechanical energy characteristics of airflow in the vortex spinning nozzle

Reducing energy consumption during textile production processes has currently become one of the key concerns. In order to design the nozzle of the vortex spinning machine with reduced air consumption, numerical simulation of the airflow in the nozzle is performed to investigate the effect of the length and the inlet diameter of the conical chamber in the intermediate section of the vortex tube on the air consumption and the mechanical energy characteristics of the airflow. A spinning experiment conducted to measure the flow rate and yarn tenacity is adopted to verify the numerical simulation results. The simulation results show that the air consumption of the nozzle is insignificantly affected as the length increases from 7.3 mm to 7.7 mm, while a decreasing trend has been found as the length increases from 7.7 mm to 8.1 mm. As the inlet diameter increases from 4.6 mm to 5.0 mm, the air consumption of the nozzle increases monotonically. The mechanical energy of airflow in the nozzle exhibits a minor difference between cases of lengths of 7.3 mm, 7.5 mm, and 7.7 mm, while it decreases significantly in cases of lengths of 7.9 mm and 8.1 mm. The mechanical energy of airflow in the vortex chamber increases as the inlet diameter increases. The experimental results are consistent with the numerical predictions. This work is expected to provide a reference for the design of the vortex spinning nozzle and an approach to reducing the energy consumption in the yarn production process.

Development of a centrifugal bioreactor for rapid expansion of CD8 cytotoxic T cells for use in cancer immunotherapy.

One of the current difficulties limiting the use of adoptive cell therapy (ACT) for cancer treatment is the lack of methods for rapidly expanding T cells. As described in the present report, we developed a centrifugal bioreactor (CBR) that may resolve this manufacturing bottleneck. The CBR operates in perfusion by balancing centrifugal forces with a continuous feed of fresh medium, preventing cells from leaving the expansion culture chamber while maintaining nutrients for growth. A bovine CD8 cytotoxic T lymphocyte (CTL) cell line specific for an autologous target cell infected with a protozoan parasite, Theileria parva, was used to determine the efficacy of the CBR for ACT purposes. Batch culture experiments were conducted to predict how CTLs respond to environmental changes associated with consumption of nutrients and production of toxic metabolites, such as ammonium and lactate. Data from these studies were used to develop a kinetic growth model, allowing us to predict CTL growth in the CBR and determine the optimal operating parameters. The model predicts the maximum cell density the CBR can sustain is 5.5 × 107 cells/mL in a single 11-mL conical chamber with oxygen being the limiting factor. Experimental results expanding CTLs in the CBR are in 95% agreement with the kinetic model. The prototype CBR described in this report can be used to develop a CBR for use in cancer immunotherapy.

155 A test Chamber to Quantify Emission Factors for Welding Fumes

Abstract A conical test chamber was built to quantify emission factors for various types of welding processes. The chamber was built according to American Welding Society (AWS) standard F1.2:2013. Fumes were collected on pre-dried and pre-weighted 293 mm glass fiber filters using a high-volume sampling pump running at approximately 30 cfm. Consumables were weighted before and after welding to calculate the amount of fume emitted per weight of consumable. All the welding was performed by a professional welder. The chamber was calibrated prior to any use to adjust the flowrate inside the chamber. The test chamber was used to calculate emission factors for Shielded Metal Arc Welding process using four different electrodes (E6013, E6011, E7018, E7014) and three different currents for each electrode as fume emission increases with current. Each test was done in triplicates to investigate for variation. Emission factors were calculated by diving the amount of fume on the filters by the weight of consumables used (g/kg). In general test were reproducible with coefficient of variations varying from 0.2 to 18.1% with most variation below 15%. Emission factors were highly dependent on the type of electrode with the lowest values found for E6013 and the highest for E6011. Emission factors increased significantly with increasing current. The chamber works properly and can be used to test other processes such as Gas Metal Arc Welding, Metal Core Arc Welding, Flux Core Arc Welding, as well as Gas Tungsten Arc Welding. Emission factors will also be calculated for metals.

Development of a flat conical chamber-based non-dispersive infrared CO2 gas sensor with temperature compensation.

In order to accurately monitor CO2 concentration based on the non-dispersive infrared technique, a novel flat conical chamber CO2 gas sensor is proposed and investigated by simulation analysis and experimental verification. First, the optical design software and computational fluid dynamics method are utilized to theoretically investigate the relationship between the energy distribution, absorption efficiency of infrared radiation, and chamber size. The simulation results show that the chamber length has an optimal value of 8cm when the cone angle is 5° and the diameter of the detection surface is 1cm, which makes infrared absorption efficiency optimal. Then, the flat conical chamber CO2 gas sensor system is developed, calibrated, and tested. The experimental results indicate that the sensor can accurately detect CO2 gas concentrations in the range of 0-2000 ppm at 25 °C. It is found that the absolute error of calibration is within 10 ppm, and the maximum repeatability and stability errors are 5.5 and 3.5%, respectively. Finally, the genetic neural network algorithm is presented to compensate for the output concentration of the sensor to solve the problem of temperature drift. Experimental results demonstrate that the relative error of the compensated CO2 concentration is varied from -0.85 to 2.32%, which is significantly reduced. The study has reference significance for the structural optimization of the infrared CO2 gas sensor and the improvement of the measurement accuracy.

Using Particle Residence Time Distributions as an Experimental Approach for Evaluating the Performance of Different Designs for a Pilot-Scale Spray Dryer

The performances of four different designs for a pilot-scale spray dryer have been evaluated and compared based on experimentally measured particle residence time distributions (RTD), recovery rates and physical properties of spray-dried fresh skim milk. The RTDs have been measured using a dye pulse injection method, and the measurements have been fitted to models using continuous stirred-tank reactors in series (CSTR-TIS) for quantitative performance evaluation and comparison. Conical drying chambers and a box connection design have been used in the latest dryer design to reduce the amount of wall deposition and provide a smoother gas flow pattern. The particle-to-gas mean residence time ratio for the latest design is significantly closer to unity (1.6 s/s to 1.0 s/s) compared with earlier designs (2.6 s/s to 1.5 s/s). The latest design has a wider spread of RTD (n = 5–8) compared with earlier designs (n = 13–18), which may be linked to the recirculation zone in the box connection. Although the latest design has a wider spread of RTD, the conical design has shown promising results compared with a cylindrical drying chamber in terms of overall wall deposition behaviours.

Estimation of parameters of radio-frequency ion injector with an additional magnetostatic field

The paper presents the results of theoretical study for the influence of an additional magnetostatic field applied to the radio-frequency discharge region on the operating parameters of radio-frequency ion injector, taking into account the shape of its discharge chamber. The integral characteristics are calculated for three injector configurations: with a cylindrical, conical, and hemispherical discharge chamber. For calculations, we used a mathematical model, in which the charged particle behavior in plasma is described by relations close to magnetohydrodynamic, while the neutral particle distribution is determined using an approximate analytical solution obtained when considering a one-dimensional problem of gas flow in a tube. Simulation was carried out in the COMSOL Multiphysics software package. According to the calculation results, an additional magnetostatic field can improve the ion injector performance with any discharge chamber configuration. The greatest operation efficiency increase was observed with a cylindrical discharge chamber. However, according to calculations, the best performance can be obtained if a hemispherical chamber is used.

Experimental generation of spherical converging shock waves

Spherical converging shock waves with incoming Mach number 1.18 are generated in a conical test chamber fitted to a conventional square-section shock tube. A wave cutter is employed to ensure a proper shock transition from the square to a cylindrical straight pipe installed upstream of the convergent section. The incident planar wave is transformed into a spherical shock by the use of an ellipsoidal membrane acting as a gas lens separating two gases with different densities. The transmitted shock wave propagates within the conical section, and accelerates towards the apex. The trajectory and the shape of the shock wave are both characterized by planar Mie scattering. The spherical shock follows the similarity solution proposed by Guderley (1942), whose trajectory agrees very well with the numerical simulation of the Chester-Chisnell-Whitham (CCW) theory for the geometry considered. The procedure demonstrated here provides a potential method for future investigations of shock focusing and Richtmyer–Meshkov instability in spherical geometry.

Importance of Geometrical Factors on Spray Characteristics of Spill-Return Atomizers

An experimental investigation into small pressure-swirl spill-return atomizers was made to determine the effect of the entry port number, swirl-chamber shape, spill-line design, and the manufacturing precision on the spray quality and stability. The atomizers were studied using phase-Doppler anemometry, high-speed visualization, and mechanical patternation. Jet A-1 fuel was sprayed at inlet pressures of 0.5, 1.0, and 1.5 MPa and for spill-to-feed ratios of 0, 0.4, and 0.8. The chamber shape influenced the spray characteristics of the simplex atomizers only moderately with no systematic effect of conical chambers to the others. The spray was found to be circumferentially heterogeneous; its uniformity improved with increase in the pressure, while the effect of swirling port number was negligible. Atomizers with axial spill orifice demonstrated strong spray pulsations at a spill-to-feed ratio of zero. A periodic decay of the air core was identified as a possible reason for the pulsations. Atomizers with off-axis spill orifices always produced a stable spray. Atomizers with tangential inlet ports provided a finer spray than those with helical ports. Manufacturing precision, axial symmetry, and matching of the surfaces of connected parts were found important for the spray symmetry and homogeneity.

Estimation of Dense Plasma Temperature Formed under Shock Wave Cumulation.

The research was carried out by means of implosion plasma generators with conical and hemispherical compression chambers to conduct a quantitative assessment of the boundary temperature of super dense plasma jets. It was proved experimentally that nuclear transformations in metals are caused by the impact of super dense plasma jets (11, ..., 12) × 103 kg/m3. The boundary temperature of these jets was evaluated. It was estimated that the nominal boundary temperature of the studied implosion plasma generators is 106 К. The pressure in the target at the penetration of the super dense jet (~12,000 kg/m3) at the speed of 28,000 m / sec is more than 30 ТPa. The boundary temperature was estimated and proved to depend on the pre-determined values only slightly. It was experimentally established that stable isotopes of manganese Mn55 (up to 27%) are formed in iron targets as a result of high temperature plasma jet penetration. The appearance of manganese must be related to iron transformation into stable isotopes Fe56 and Fe54. The obtained results may be applied for investigating structural changes in metals under the conditions of impulsive super high temperatures and pressures. This method can be also used as a testing ground for studying the physical conditions of forming chemical elements as well as super dense plasma jets.

Thermal Performances Investigation of Anti-Gravity Heat Pipe with Tapering Phase-Change Chamber

The objective of this study was to fabricate anti-gravity heat pipes with a tapering column phase-change chamber and changeable cross-sectional wick structure. The thermal performances of the anti-gravity heat pipes were experimentally investigated. Results show that the thermal resistances of the different heat pipes are less than 0.03 °C/W, except for the sharp conical chamber heat pipe under anti-gravity heating conditions (0.121 °C/W). Start-up times of different types of heat pipes are similar and the temperatures are steady within 3 to 5 min. The heat transfer ability of a conical chamber is always better than that of a cylindrical one. The performance of the sharp conical chamber heat pipe is the best under gravity assistance heating conditions. Contrarily, the blunt conical chamber heat pipe has the best heat transfer ability under anti-gravity heating conditions. Moreover, the heat transfer capability of the blunt conical chamber heat pipe is unaffected by the relative position of the heat and cold sources, which is suitable for constant temperature cooling applications with frequent switching of the heat and cold sources.

Isogeometric analysis for geometric modelling and acoustic attenuation performances of reactive mufflers

In the present study, the acoustic attenuation performances of mufflers are predicted by employing three-dimensional isogeometric analysis (IGA) and multi-patch technique for the first time. Circular, elliptical and conical reactive expansion chamber mufflers are exactly parameterized by non-uniform rational B-splines (NURBS), and the Helmholtz equation governing the interior acoustic field is also solved by NURBS. Compared with traditional finite element method (FEM) which is rooted in Lagrange and Hermite functions, IGA can effectively avoid the time-consuming meshing and totally preserve exact geometrical information during the modelling-analysis process. The computational effectiveness of multi-patch IGA for calculating transmission loss is verified by comparing with experimental approach, boundary element method and other numerical methods from available research articles. The effects of geometry, such as shapes of the expansion cavity and lengths of the extended inlet/outlet are discussed in detail.

Experimental investigation of electric discharge parameters in correlation with peak pressure at industrial electrohydraulic forming

The paper shows the investigation results of correlating electric discharge and pressure field parameters aimed to improvements in the electrohydraulic impact forming (EHF) technology at industrial application. The experimental research was performed by using a conical discharge chamber equipped with a set of two electrodes in semi-industrial EHF installation. Pressure fields along round flat area were measured by applying the multi-point membrane pressure gauge methodology. The conditions of the tests include a wide range of spark gaps with four levels of charge voltage and energy. Measurements of discharge voltage and current are performed with voltage divider, Rogovsky coil and electronic oscilloscope. Other electric discharge parameters were calculated from the recorded voltage and current curves. The essence of investigation is to analyse energy parameters for peak pressure of shock wave generated by these discharge energy parameters. Though these dependencies were earlier analysed theoretically and tested in electrohydraulic plants under laboratory conditions, the practical interest in this experimental investigation is to reveal influence of conditions of real semi-industrial EHF press designed for batch production of sheet parts. Conducted experimental investigation has shown that industrial applications of high-voltage non-initiated discharges can significantly deviate from the theoretical and laboratory results. Dependencies of peak pressure from maximum power during the first semi-period of discharge current and slope of power curve appeared to be not so strong. These deviations in peak pressure can reach 20–30%. Among the assumed additional factors influencing energy and pressure parameters are: condition of current-conductive rod of electrode (erosion, rust, radius); condition (wear) of electrode insulator (increase of naked area of current-conductive rod); variations in shape, position and length of discharge channel relative to spark gap; “shadowing” effect of electrodes at some positions of discharge channel relative to electrode;, several discharge channels at small spark gap and other. To reveal effect of these factors the authors plan to carry-out tests with wire-initiated discharges to check the variations in shape, position and length of discharge channel relative to spark gap in the same discharge chamber configuration.

Influence of suction chamber profile on flow field of annular jet pump

Jet pump is a kind of fluid machinery, which uses jet shear and turbulent diffusion to transfer mass and energy. It is widely used in water project, civil engineering and other fields. In order to investigate the influence of suction chamber profile on flow field of annular jet pump, the conical suction chamber and the streamlined suction chamber were compared by applying turbulence numerical simulation method. The performance, pressure characteristics, velocity and turbulent energy distributions of annular jet pumps with two suction chambers are analysed. The calculation shows that compared with the traditional conical suction chamber, the efficiency of annular jet pump with streamlined suction chamber is improved at low flow ratio, and the change is not obvious at high flow ratio. In the same section, the cross sectional area of streamlined suction chamber is slightly larger than that of conical suction chamber, so the primary flow velocity near the wall is slightly lower, which can reduce the friction loss caused by high speed wall-attached flow. In addition, the smooth turning of the primary flow in streamlined suction chamber can weaken the extrusion on the entrained flow field. Different from the conical suction chamber, the streamlined suction chamber is smoothly connected with throat without sudden corner change, which can eliminate the low pressure near the inlet wall of throat, improve the wall pressure distribution and reduce the possible cavitation. The research results of suction chamber profile of annular jet pump can provide scientific basis for the popularization and application of jet pump.

Numerical Modelling of Internal Flow in Water Mist Injectors: Effect of Nozzle Geometry and Operating Conditions

Water mist fire fighting has achieved a well established position in fire protection for industrial and civil applications. The performances of water mist nozzles, largely used in water mist production, are deeply influenced by the internal nozzle flow characteristics and CFD modelling is a powerful tool to analyse them in details. The paper focuses on the numerical investigation of the internal flow in pressure swirl injectors for water mist applications. 3D large eddy simulations based on the Volume-Of-Fluid methodology have been implemented. The flow is assumed to be incompressible and under isothermal non-reacting conditions. Validation of the model against available experimental data is performed with satisfactory results. The effect of internal nozzle geometry on the injector behaviour is investigated by modifying the inclined swirling channels (five configurations) and the injection pressure in the range 5 to 320 bar. The effect of the size of cylindrical and conical swirl chambers are also independently investigated. Three different flow regimes can be distinguished as a function of imposed swirl and injection pressure and a map is reported to clarify the effect of these parameters. When a stable hollow cone spray is formed the mass flow rate fluctuations are < 5%, corresponding to a discharge coefficient between 0.34 and 0.50. When no air core is present in the discharge hole, mass flow rate fluctuations as high as 16% are observed, which correspond to discharge coefficient as high as 0.7. A detailed quantification of in-nozzle characteristics, like swirl number and momentum flux distribution along the nozzle and lamella thickness in the discharge hole, is reported and discussed, with particular emphasis on stability and transient behaviour of the atomiser internal flow, which represents the main novelty of the present study.

Automated drosophila heartbeat counting based on image segmentation technique on optical coherence tomography

Drosophila and human cardiac genes are very similar. Biological parametric studies on drosophila cardiac have improved our understanding of human cardiovascular disease. Drosophila cardiac consist of five circular chambers: a conical chamber (CC) and four ostia sections (O1–O4). Due to noise and grayscale discontinuity on optical coherence tomography (OCT) images, previous researches used manual counting or M-mode to analyze heartbeats, which are inefficient and time-consuming. An automated drosophila heartbeat counting algorithm based on the chamber segmentation is developed for OCT in this study. This algorithm has two parts: automated chamber segmentation and heartbeat counting. In addition, this study proposes a principal components analysis (PCA)-based supervised learning method for training the chamber contours to make chamber segmentation more accurate. The mean distances between the conical, second and third chambers attained by the proposed algorithm and the corresponding manually delineated boundaries defined by two experts were 1.26 ± 0.25, 1.47 ± 1.25 and 0.84 ± 0.60 (pixels), respectively. The area overlap similarities were 0.83 ± 0.09, 0.75 ± 0.11 and 0.74 ± 0.12 (pixels), respectively. The average calculated heart rates of two-week and six-week drosophila were about 4.77 beats/s and 4.73 beats/s, respectively, which was consistent with the results of manual counting.

Influence of Some Axially Symmetric Stepped Forms of Discharge Chambers on the Efficiency of Electrohydraulic Forming

A mathematical simulation of the electrohydraulic forming using some types of stepped axisymmetric discharge chambers is performed. The mathematical model is tested on the basis of experimental data obtained using the optical method of measuring the deflection of a plate. It is shown that a change in the shape of the discharge chamber can significantly affect the efficiency of electrohydraulic forming with the same parameters of the discharge circuit. It is found that the conical discharge chamber provides the highest forming efficiency.

A field experiment demonstrating risk on the seafloor for planktonic embryos

AbstractMost solitary marine eggs are shed into the plankton. Presumably the seafloor is more dangerous than the plankton for small solitary embryos, but estimates of benthic mortality of solitary embryos are few. To assess risk, we introduced suspensions of sinking, early stage embryos into conical chambers whose basal surfaces differed in mesh size and distance of mesh from the sediment surface. Surviving embryos hatched as blastulae and swam upward into an apical collection tube, later removed for counting. Test embryos were of a clypeasteroid echinoid. The two test sites, within a coastal lagoon in the NE Pacific, differed in sediments. At both sites, mean proportion of embryos retrieved was 0 and near 0 in chambers floored with 0.9 mm and 0.08 mm meshes at the sediment surface, but greater in chambers floored with a 0.08 mm mesh about 6 cm above the sediment (0.40 and 0.42) and also with a different chamber design with finer (0.055 mm) mesh at the sediment (0.42). Mean proportion retrieved was still greater (0.68 and 0.67) with chambers floored with a complete barrier at the sediment surface and similar to retrieval with chambers in laboratory aquaria without sediment. Estimated mortality rates for embryos on the sediment exceeded published estimates from the plankton. The results support the hypothesis that solitary eggs are released to the plankton because of benthic risks. This method can be used at varied sites on the seafloor, with varied embryos, and with varied protective barriers to test the generality of these results.

Experimental Study of the Effect the Basic Geometrical Parameter and the Active Gas Nozzle Expansion Ratio Have on the Performance Characteristics of Supersonic Gas Ejectors Fitted with a Conical Mixing Chamber

The article presents the results from experimental investigations of supersonic gas ejectors equipped with a conical mixing chamber having different lengths carried out for a number of values of the basic geometrical parameter and the active gas nozzle expansion ratio. Certain results obtained from a thermodynamic analysis of the ejectors have been confirmed in a wide range of geometrical parameters, specifically, that there is a possibility to obtain—at the same ejection factor—the first and second critical modes, which differ from each other in the motion pattern of mixing flows and in the efficiency of mixing processes occurring at different passive gas pressures; that there exist three zones in the throttle performance, which correspond to two critical modes and one subcritical mode (it is worthy of noting that the transition from the first critical mode to the subcritical mode that occurs during a growth of back pressure is accompanied by a step-like increase of passive gas pressure, whereas the transition from the subcritical mode to the second critical mode and vice versa occurs without a break in the continuity of changing the ejector’s throttle performance parameters); and that there may be two varieties of the second critical mode: with supersonic and sonic gas mixture flow velocities in the conical chamber outlet section. It is shown that the basic geometrical parameter and the active gas nozzle expansion ratio strongly influence the ejector’s operating and throttling performance characteristics, as well as the mixing chamber optimal length. Experimental dependences of the supersonic gas ejector’s adiabatic efficiency on the conical mixing chamber length are obtained at different values of the basic geometrical parameter and the active gas nozzle expansion factor for the first and second critical modes. It is shown that the optimal mixing chamber length depends on the ejector operating mode. Recommendations for selecting the optimal length of the supersonic gas ejector’s conical mixing chamber within the studied range of parameters for the first and second critical modes are given.

Structural and functional characterization of the contractile aorta and associated hemocytes of the mosquito Anopheles gambiae.

The primary pump of the circulatory system of insects is a dorsal vessel that traverses the length of the insect. The anterior portion, located in the head, neck and thorax, is the aorta, and the posterior portion, located in the abdomen, is the heart. Here, we characterize the structure and function of the aorta and conical chamber of the mosquito, Anopheles gambiae The aorta begins in the head with an excurrent opening located above the dorsal pharyngeal plate and ends at the thoraco-abdominal junction where it joins the conical chamber of the heart. The aorta lacks ostia, and based on the diameter of the vessel as well as the density and helical orientation of muscle, consists of three regions: the anterior aorta, the bulbous chamber, and the posterior aorta. The aorta contracts in the anterograde direction, but these contractions are independent of heart contractions and do not play a major role in hemolymph propulsion. Intravital imaging of the venous channels, the first abdominal segment and the neck revealed that hemolymph only travels through the aorta in the anterograde direction, and does so only during periods of anterograde heart flow. Furthermore, hemolymph only enters the thoraco-abdominal ostia of the conical chamber when the heart contracts in the retrograde direction, propelling this hemolymph to the posterior of the body. Finally, very few hemocytes associate with the aorta, and unlike what is seen in the periostial regions of the heart, infection does not induce the aggregation of hemocytes on the aorta.