Characterization of multiphase flow through Venturi nozzle using gamma-ray tomography

Differential pressure flow meter is a kind of very promising flow measuring instrument, the application range is very wide. But aiming at the defects that the mechanical structure of all kinds of existing flow meters is complex, the throttling way disturbs the fluid greatly and the stability of differential pressure signal is insufficient, a kind of new inside and outside tube differential pressure flow meter was designed.

A testbed for differential pressure flow meter was built and tested. The testbed is targeted for intravascular pressure and flow monitoring applications. The testbed consists of a data acquisition system and two MEMS pressure sensors (SM5108) measuring 0.65×0.65×0.65mm. The MEMS pressure sensors were wire bonded to gold plated ceramic pads and placed inside vinyl tubing. The signals from the pressure sensors were amplified using two low-power high performance instrumentation amplifiers. These amplifiers are a part of the data acquisition system which is designed to acquire data from the pressure sensors and communicate with a user in real time. For simplicity our initial evaluation of the testbed was using air flow. Air was pumped across a simulated blockage (a valve) and pressure was built up to intravascular pressure ranges (35 to 230 mmHg (gauge)). The base fractional flow rate (FFR) equation was used to calculate flow, hinting that the SM5108 pressure sensors can become a part of an implantable differential pressure flow meter.

Development of an accurate and reliable differential pressure flow meters is needed for industry. The relationship between the Reynolds number (Re) and the discharge coefficient (Cd) was investigated using a differential pressure flow meter. Venturi meter is a type of baffle meter, widely used in industry for flow measurement. The ISO standard (ISO-5167-1) provides discharge coefficient values for classic Venturi tubes in turbulent flow with Reynolds number values above 2x105. This study shows that various discharge coefficient decrease rapidly and constant discharge coefficient values vary with meter design. The main focus of this study is to compare experimental results with theoretical predictions and estimate the optimal value of thevmeter discharge coefficient at various flow rates. The experimental results showed that the optimal value of the venturi tube discharge coefficient of about 0.983 was obtained.

To fabricate thick-walled hollow glass microspheres (HGMs) for inertial confinement fusion (ICF) targets by sol-gel technology, we investigated the effects of glass composition, blowing agent, refining temperature, pressure and composition of furnace atmosphere on the wall thickness of HGMs by numerical simulation and experiments. The results showed that the residence times of the thick-walled HGMs in the encapsulating and refining phases decreased with the increase of wall thickness of HGMs. As a response to this challenge, glass composition must be optimized with the object of high surface tension and low viscosity at refining temperature, and the blowing agents with high decomposition temperature should be used, furthermore the concentration of blowing agents in gel particles must also be precisely controlled. The higher volume fraction of argon gas in the furnace atmosphere, the thicker the wall of HGMs. Due to the limited operating range of furnace atmosphere pressure, changing furnace atmosphere pressure could not significantly increase the wall thickness of HGMs. Although increasing refining temperature can improve the yield of high quality HGMs, a higher furnace atmosphere temperature may lead to a decrease in the wall thickness of HGMs. When the volume fraction of argon gas in the furnace atmosphere ranged from 80% to 95%, the furnace atmosphere pressure ranged from 1.0×105 Pa to 1.25×105 Pa, and the refining temperature ranged from 1600°C to 1800°C, we produced thick-walled (5–10 μm) HGMs with good sphericity, wall thickness uniformity and surface finish. However, the yield of high quality HGMs needs to be further improved. The compressive strength, tensile strength and permeation coefficient to deuterium gas of thick-walled HGMs at ambient temperature decreased with increase of the wall thickness.

The development and performance characterization of a new differential pressure-based flow meter for human breath measurements is presented in this article. The device, called a "Confined Pitot Tube," is comprised of a pipe with an elliptically shaped expansion cavity located in the pipe center, and an elliptical disk inside the expansion cavity. The elliptical disk, named Pitot Tube, is exchangeable, and has different diameters, which are smaller than the diameter of the elliptical cavity. The gap between the disk and the cavity allows the flow of human breath to pass through. The disk causes an obstruction in the flow inside the pipe, but the elliptical cavity provides an expansion for the flow to circulate around the disk, decreasing the overall flow resistance. We characterize the new sensor flow experimentally and theoretically, using Comsol Multiphysics® software with laminar and turbulent models. We also validate the sensor, using inhalation and exhalation tests and a reference method.

Wet gas metering by differential pressure flow meters is gaining prominence in the oil and gas industry, owing to their simple construction. Slotted orifice, a modified version of the standard orifice meter has been found promising by many researchers. This novel flow meter is shown to be insensitive to the upstream flow profile with lower head loss and faster pressure recovery compared to the standard orifice. In the present work, the effect of geometry of slots and pressure on the performance of the slotted orifice has been studied by CFD modeling of the wet gas flow. The performance of slotted orifice with rectangular perforations (1.5 ≤ l/w ≤ 3.0) and circular perforations has been compared with that of the standard orifice having same β-ratio of 0.40. Simulation results reveal that the shape of perforation of the slotted orifice has no effect on the differential pressure. However, the pressure recovery with the rectangular slots is found to increase with increasing aspect ratio. Moreover, at low pressure, slotted orifice is found to be more sensitive to liquid presence than the standard orifice. The relatively higher over reading values obtained in this work is consistent with the results of Geng et al (2006) that for slotted orifice, a low beta ratio is more sensitive to the liquid presence in the stream and hence is preferable for wet gas metering. Homogeneous model, Steven’s and De Leeuw’s correlations, are found to be better than orifice correlations for wet gas mass flow prediction.

A new differential pressure method for hydraulic flow measurement was proposed. Dynamic response of the flow meter was improved from two choke points. One chock point was canceling the oil induce pipes of traditional ways which limit the dynamic characteristics for liquid volume effect. Pressure differences were generated and measured inside the oil pipe. The other chock point was using a MEMS (Microelectromechanical System) differential sensor in place of normal transducers. Without liquid induce pipes and moving components, this new flow meter measures transient flow perfectly. Working principle of this flow sensor was analyzed theoretically. Using CFD software, the flow field was simulated. Also, in a hydraulic testing system the sensor was calibrated ranging from 0-60L/min. A fast data acquisition system-wavebook 512 was applied during the experiment. It presents good linearity and can meet general hydraulic system use.

A study of a pressure differential flow meter that is insensitive to inlet conditions

We explore the impact of diffusive cosmic rays (CRs) on the evolution of the interstellar medium (ISM) under varying assumptions of supernova explosion environment. In practice, we systematically vary the relative fractions of supernovae (SN) occurring in star-forming high-density gas and those occurring in random locations decoupled from star-forming gas to account for SN from run-away stars or explosions in regions that have been cleared by prior SN, stellar winds, or radiation. We find that in the simple system of a periodic stratified gas layer the ISM structure will evolve to one of two solutions: a ‘peak driving’ state where warm gas is volume filling or a ‘thermal runaway’ state where hot gas is volume filling. CR pressure and transport are important factors that strongly influence the solution state the ISM reaches and have the ability to flip the ISM between solutions. Observable signatures such as gamma-ray emission and H i gas are explored. We find that gamma-ray luminosity from pion decay is largely consistent with observations for a range of model parameters. The thickness of the H i gas layer may be too compact, however, this may be due to a large cold neutral fraction of mid-plane gas. The volume fraction of hot gas evolves to stable states in both solutions, but neither settles to a Milky Way-like configuration, suggesting that additional physics omitted here (e.g. a cosmological circumgalactic medium, radiation transport, or spectrally resolved and spatially varying CR transport) may be required.

<strong class="journal-contentHeaderColor">Abstract.</strong> To investigate the mechanical properties of sea ice in the current summer Arctic, two ice blocks were lifted using ship crane during an Arctic expedition in the summer of 2021. Examination of ice crystal structure showed a granular ice layer at the top underlain by a columnar ice layer. Sea ice samples were then machined from the ice blocks for mechanical experiments performed in the laboratory. Three-point bending tests were conducted at ice temperatures of &minus;12 to &minus;3 &ordm;C, and uniaxial compressive strength tests were conducted at ice temperatures of &minus;8 to &minus;3 &ordm;C with a strain rate range of 10^&minus;6&ndash;10^&minus;2 s^&minus;1. The ice density and salinity of each sample were measured to determine brine and gas volume fraction as well as porosity. Results showed that sea ice flexural strength decreased with increasing porosity, but did not change with varying brine or gas volume fractions. A parameterization was proposed to relate sea ice flexural strength to porosity. The sea ice strain modulus was also independent on porosity and volume fractions of gas and brine. The uniaxial compressive strength decreased with increasing porosity at both ductile and brittle strain rate regimes. Furthermore, three-dimensional surfaces were obtained to depict the sea ice uniaxial compressive strength varying with porosity and strain rate, based on which the transition strain rate from ductile to brittle behaviors was determined. It was found that the transition strain rate decreased with increasing porosity. Comparisons with previous studies on sea ice strength showed that the previously reported equations for sea ice flexural strength and strain modulus did not agree with the measured data. Compared with the strength calculated using early reported sea ice porosity, the flexural strength and uniaxial compressive strength of summer Arctic sea ice decreased in recent decades, which probably brings positive feedback to the Arctic navigation.

<strong class="journal-contentHeaderColor">Abstract.</strong> To investigate the mechanical properties of sea ice in the current summer Arctic, two ice blocks were lifted using ship crane during an Arctic expedition in the summer of 2021. Examination of ice crystal structure showed a granular ice layer at the top underlain by a columnar ice layer. Sea ice samples were then machined from the ice blocks for mechanical experiments performed in the laboratory. Three-point bending tests were conducted at ice temperatures of &minus;12 to &minus;3 &ordm;C, and uniaxial compressive strength tests were conducted at ice temperatures of &minus;8 to &minus;3 &ordm;C with a strain rate range of 10^&minus;6&ndash;10^&minus;2 s^&minus;1. The ice density and salinity of each sample were measured to determine brine and gas volume fraction as well as porosity. Results showed that sea ice flexural strength decreased with increasing porosity, but did not change with varying brine or gas volume fractions. A parameterization was proposed to relate sea ice flexural strength to porosity. The sea ice strain modulus was also independent on porosity and volume fractions of gas and brine. The uniaxial compressive strength decreased with increasing porosity at both ductile and brittle strain rate regimes. Furthermore, three-dimensional surfaces were obtained to depict the sea ice uniaxial compressive strength varying with porosity and strain rate, based on which the transition strain rate from ductile to brittle behaviors was determined. It was found that the transition strain rate decreased with increasing porosity. Comparisons with previous studies on sea ice strength showed that the previously reported equations for sea ice flexural strength and strain modulus did not agree with the measured data. Compared with the strength calculated using early reported sea ice porosity, the flexural strength and uniaxial compressive strength of summer Arctic sea ice decreased in recent decades, which probably brings positive feedback to the Arctic navigation.

Multiphase flow metering is very important in the oilfield. We construct four new liquid metering models (Falling Model I, Falling Model II, Open Channel Model and Element Resistance Model) and a gas metering model based on the online multiphase flow metering equipment without separation. The experimental study was carried on indoors at the multiphase flow metering equipment, and the model coefficients can be figured out by the method of date classification. We can figure out the error of each phase, and evaluate all the metering models. Through errors analysis, the average error of the liquid metering models can be within 10%. The error of gas metering model can be controlled within 20%. The experiment results proved that these metering models can be used in the multiphase metering with different viscosity. The metering precision is rather high in the wide range of gas phase and liquid phase flow rate. And it fits in with outdoor application.

Dynamically enhanced membrane foaming

Multi-phase flow simulations of E779A and DTMB5168 propellers' tip vortex flow field are conducted to qualify the improved Sauer cavitation model in propeller tip vortex local flows prediction, under non-cavitation and initial inception conditions. Mesh refinement strategies pointing to blocking-structured and stream-adaptive grid for vortex flow are concluded in this process. The models account for the effects of mass and volume fraction of the noncondensable gas (NCG) and the turbulence on both cavitation inception and bubble growth by means of mixture density formula and phase-changing threshold pressure formula explicitly. With comparison to the experiments, open water performances of two propellers are both predicted satisfactory with cavitation model un-activated. The simulated propeller cavity pattern and cavitating area under moderately cavitation level are very close to the measurements after cavitation model activated. The circumferentially averaged axial, circumferential and radial velocity components on wake cross plane correspond very well with the measurements outer 0.9R radius. The predicted peaks of three velocity component variation with circumferential theta show a discrepancy to the tests up to about 5%, 40% and 20% respectively at 0.92R, and a maximum prediction error smaller than 10% at 0.7R. The predicted trajectories of tip vortex core are very close to the experiment at front of the downstream 0.3R wake plane, wherein a bigger predicted core radius than the tests further away. Results above show that the mesh strategies introduced in conjunction with the adopted numerical models are positive and beneficial to the vortex-dominated flow of propeller.

ABSTRACTAir-assisted steam flooding is a new promoting technique for enhanced oil recovery compared to the other traditional thermal recovery methods. In this study, five experiments, including one steam flooding experiment, three combined steam–air flooding experiments, and one combined steam–N2 flooding experiment were studied, under the conditions of 180 °C and back-pressure valve of 8 MPa, with sand-packed model. The volume fraction of mixed gas in these four combined steam–air (or N2) flooding experiments were 80% steam+20% air, 60% steam+40% air, 40% steam+60% air, and 60% steam+40% N2, respectively. The experimental results showed that air-assisted steam flooding could enhance the oil displacement efficiency when the volume fraction of air and steam was in a certain number, and the optimal condition is 60% steam+40% air. Furthermore, water cut curves and saturate, aromatic, resin, and asphaltene (SARA) analysis results also demonstrate that the low-temperature oxidation reaction in air-assisted steam flooding process advantageous to profile control of generating high viscosity “PLUG” to seal high-permeability channel in reservoir.