Averaging Pitot Tube Research Articles

Online Measurement of Wet Gas Mass Flowrate Based on Averaging Pitot Tube-Vortex Integrated Sensor

Online Measurement of Wet Gas Mass Flowrate Based on Averaging Pitot Tube-Vortex Integrated Sensor

AVERAGING PITOT TUBE WITH A FLOW COEFFICIENT EQUAL TO ONE, THE EFFECT OF THE REYNOLDS NUMBER

AVERAGING PITOT TUBE WITH A FLOW COEFFICIENT EQUAL TO ONE, THE EFFECT OF THE REYNOLDS NUMBER

Analysis of variable air volume unit pressure sensor factors with specific reference to measurement of low air velocity

The purpose of this study was to identify the optimal construction of an averaging pitot tube and measure flows typical in building ventilation, considering low-velocity flows. The construction should be simple to implement in variable air volume (VAV) controllers. This paper presents mostly novel constructions, which have not been tested before, and fills the existing gap in low-velocity measurements, which is important considering the correct control with airflow reduction in the VAV system. Eleven constructions based on a circular section of the basic element were chosen. Empirical studies were conducted to determine the aerodynamic properties. The tests were conducted within a typical velocity range in ventilated systems (0.6–7.5 m/s), based on measuring the pressure difference at suitable locations on the upstream and downstream surfaces. The magnification factor (m) was obtained and compared. Sensors consisting of two parallel and slightly separated tubes from each other with upstream and sideward ports on the inner side of the sensor were characterised by a constant and highest value of the factor m (approximately 2.0). These sensors yielded approximately 25% higher values of m than the lowest values. The best sensor constructions among the tested structures were the variants with two parallel tubes with front and side ports from the inner side of the sensor. The application of narrowing and placing of the side port enabled a stable operation in the highest range of velocity.

Airflow measurements using averaging Pitot tube under restricted conditions

This paper studies the effect of the air damper placed downstream of an averaging Pitot tube (APT) on the flow measurement in air distribution systems. Experiments are conducted to obtain the characteristic curve of the APT under different damper positions. The analysis of variance (ANOVA) is applied and the results reveals a statistically significant correlation between them. A mathematical model for the pressure coefficient with respect to the damper opening angle is proposed to compensate the systematic error caused by the damper. The model is validated under various Reynolds numbers (Re) varying from 6.38 × 103 to 19.1 × 103 with RMSE < 0.02. By applying the proposed model, the flow measurement errors are reduced below 0.6% for all tested cases, and the highest accuracy (0.02%) is achieved when Re = 9.57 × 103. The proposed model significantly improves the performance of current air flow control stations (AFCS) where the ATP is placed immediately upstream of the air damper. This research can be helpful for manufactures to provide AFCS with higher accuracy and larger operating range.

Flow measurement of wet CO2 using an averaging pitot tube and coriolis mass flowmeters

The flow measurement of wet-gas is an active field with extensive research background that remains a modern-day challenge. The implication of wet-gas flow conditions is no different in Carbon Capture and Storage (CCS) pipelines. The associated complex flow regime with wet-gas flow makes it difficult to accurately meter the flow rate of the gas phase. Some conventional single-phase flowmeters like the Coriolis, Orifice plate, Ultrasonic, V-Cone, Venturi and Vortex have been tested for this application, usually accompanied with special recommendations. Often, a correlation equation valid within a certain range of specific conditions is required to correct the response of the flowmeter. This paper presents investigations into the suitability and performance of one of the most advanced averaging pitot tubes for the flow measurement of wet CO2 gas. The averaging pitot tube with flow conditioning wing geometry (APT-FCW) was studied and experimentally assessed in earlier work for the flow measurement of pure and dry CO2 within an error of ±1%. Under wet-gas conditions, however, the APT-FCW sensor is found to give an error of up to ±25% and within ±1.5% after appropriate correcting solutions are applied for a liquid fraction of up to 20%.

Numerical and experimental research on pentagonal cross-section of the averaging Pitot tube

Averaging Pitot tubes have been widely used in many fields because of their simple structure and stable performance. This paper introduces a new shape of the cross-section of an averaging Pitot tube. Firstly, the structure of the averaging Pitot tube and the distribution of pressure taps are given. Then, a mathematical model of the airflow around it is formulated. After that, a series of numerical simulations are carried out to optimize the geometry of the tube. The distribution of the streamline and pressures around the tube are given. To test its performance, a test platform was constructed in accordance with the relevant national standards and is described in this paper. Curves are provided, linking the values of flow coefficient with the values of Reynolds number. With a maximum deviation of only ±3%, the results of the flow coefficient obtained from the numerical simulations were in agreement with those obtained from experimental methods. The proposed tube has a stable flow coefficient and favorable metrological characteristics.

Flow measurement of CO2 in a binary gaseous mixture using an averaging Pitot Tube and Coriolis mass flowmeters

To combat the growing emissions of CO2 from industrial processes, Carbon Capture and Storage (CCS) and Carbon Capture and Utilization technologies (CCU) have been accepted worldwide to address these pressing concerns. So as to efficiently manage material and financial losses across the entire stream, accurate accounting and monitoring through fiscal metering of CO2 in CCS transportation pipelines are core and required features for the CCS technologies. Moreover, these technical requirements are part of the legal compliance schemes and guidelines from various regulatory bodies. The CO2 transportation pipelines will likely have multiple inputs from different capture plants, each with varying composition of CO2 and thus introducing impurities into the CO2 stream. The presence of other ordinary or hydrocarbon gases in the CO2 gas stream could affect the functionality of metering instruments by introducing additional errors, particularly in the case of volumetric flowmeters. In this study, volumetric and direct mass measurement methods for the flow measurement of CO2 mixtures using two totally different metering principles are experimentally evaluated. An Averaging Pitot Tube with Flow Conditioning Wing (APT-FCW) and Coriolis mass flowmeters (CMF) are used to assess the flow metering of CO2 in a binary gaseous mixture. Different gases (nitrogen, air, oxygen, argon and propane) are diluted as contaminants into the pure CO2 gas flow for various mass fractions to produce an adulterated mixture of the CO2 gas. Comparative analysis of the measurement results under these flow conditions relative to that of pure CO2 gas show that the measurement error of the APT-FCW sensor increases with the mass fraction of the diluent component, and gases with density closer to that of CO2 have a much lesser effect on the performance of the APT-FCW flow sensor for smaller mass fractions. The CMF proved to be very reliable in the gas combination processes and as a reference meter for the APT-FCW sensor. Further analytical observations are discussed in detail.

Validating a Multi-Port, Averaging Pitot Tube for Measuring Fan Airflow Rates

A multiport averaging Pitot tube (MAPT) system was evaluated for measuring airflow rates from large agricultural fans in confined poultry facilities. The MAPT system consisted of a copper tube with multiple pressure ports along its length to respond to the velocity pressure profile across the full fan diameter. The tube was connected to a low-pressure transducer that provided a differential voltage signal, which was recorded by a data logger, in response to fan airflow. The best performance was observed when the tubes were positioned on the intake of a test fan and operated with pressure ports facing the downstream direction of the fan. The responses of two tube lengths were calibrated in measuring airflow delivered by a 91- or 122-cm diameter wall-mounted exhaust fan by comparing measurements to a Fan Assessment Numeration System (FANS) used as a reference. There was a strong linear relationship between the square root of voltage outputs from the MAPT pressure sensor and the reference FANS air velocity readings. Linear regression equations were used to compute flow rates of additional fans using MAPT measurement. Airflow rates based on MAPT measurement were highly correlated with the reference FANS values with mean deviation less than 3% and 9% for 91- and 122-cm diameter fans, respectively. The MAPT system is particularly useful for applications such as farm energy audits that require fast and easy estimates of airflow from large, wall-mounted agricultural exhaust fans.

Calibration of an Averaging Pitot Tube for Gaseous CO2Flowmetering

In this paper, an averaging pitot tube (APT) with flow conditioning wing (FCW) geometry is used as a practical sensing device to measure and characterize the flow of single-phase gaseous carbon dioxide (CO2). This technique demonstrates a simple, cost-effective, and potentially accurate option toward the measurement, accurate accounting, and characterization of CO2 in carbon capture and storage pipelines. The metrological performance of the flow sensor is verified using air medium before being applied for gaseous CO2. With a Coriolis mass flowmeter acting as a secondary calibration reference to further validate the performance of the APT-FCW flow sensor, both metering instruments were evaluated against a weighing scale apparatus. From the experimental and calibration data with air, the APT-FCWs average $K$ -factor and linearity error are found to be 0.5091 and 0.725%, respectively. With operating conditions remaining unaltered in this particular flow measurement application and a target metering error within ±1%, the errors achieved for the Coriolis meter and the APT-FCW are better than ±0.6% and ±1.2%, respectively. Total uncertainty estimations under the stipulated environmental and working conditions are within ±1% and ±1.5% for the Coriolis meter and APT-FCW, respectively. The test results and other performance evaluation of the instruments are also discussed.

Effect of gas temperature on flow rate characteristics of an averaging pitot tube type flow meter

The flow rate characteristics passing through an averaging Pitot tube (APT) while constantly controlling the flow temperature were studied through experiments and CFD simulations. At controlled temperatures of 25, 50, 75, and 100°C, the flow characteristics, in this case the upstream, downstream and static pressure at the APT flow meter probe, were measured as the flow rate was increased. The flow rate through the APT flow meter was represented using the H-parameter (hydraulic height) obtained by a combination of the differential pressure and the air density measured at the APT flow meter probe. Four types of H-parameters were defined depending on the specific combination. The flow rate and the upstream, downstream and static pressures measured at the APT flow meter while changing the H-parameters were simulated by means of CFD. The flow rate curves showed different features depending on which type of H-parameter was used. When using the constant air density value in a standard state to calculate the H-parameters, the flow rate increased linearly with the H-parameter and the slope of the flow rate curve according to the H-parameter increased as the controlled target air temperature was increased. When using different air density levels corresponding to each target air temperature to calculate the H-parameter, the slope of the flow rate curve according to the H-parameter was constant and the flow rate curve could be represented by a single line. The CFD simulation results were in good agreement with the experimental results. The CFD simulations were performed while increasing the air temperature to 1200 K. The CFD simulation results for high air temperatures were similar to those at the low temperature ranging from 25 to 100°C.

Research of Intelligent Integrated Averaging Pitot Tube Flowmeter

Averaging Pitot tube flowmeter often uses a separated structure which is not convenient. The research uses a design of integration to overcome the problems and creates an intelligent system to process data. Some improvement methods such as the non-linear correction of meter factor, temperature and pressure compensation are proposed to improve the accuracy of flow rate. In experiments, by comparisons of the results before and after improvements, it comes to a conclusion that the intelligent integrated averaging Pitot tube flowmeter shows a higher performance.

Numerical Simulation of the Effect of Section Size on Averaging Pitot Tube

Averaging pitot tube has been applied in practice more often in these years. This paper set up the two-dimensional model of the bullet-shaped averaging pitot tube, numerical simulation based on CFD was used to investigate the changes of flow coefficient along with the Reynolds number. The geometric size of the section was changed to investigate how it influences the flow coefficient and differential pressure. To guarantee the accuracy of the simulation, the grid and the simulation model were investigated too.

Calibration of an averaging pitot tube by numerical simulations

An averaging pitot tube is used to measure the thermally induced air flow through the sodium to air heat exchanger used to remove the decay heat generated in the core of a fast breeder reactor after its shutdown. It is practically impossible to calibrate the averaging pitot tube with exact upstream and downstream conditions in the laboratory as in the decay heat removal system. Hence the averaging pitot tube was calibrated experimentally with approximate upstream and downstream conditions and the same was transposed to the site conditions through numerical studies. This paper gives the details of the averaging pitot tube calibration by experiments and numerical method and the comparison between the two methods. The results obtained by both methods were in agreement with a maximum difference of ±4% in flow coefficient CD.

Radiative and Total Heat Transfer Measurements to a Titan Explorer Model

This paper reports on the design and testing of a heat transfer gauge suitable for the spectrum of radiation encountered during entry to the atmosphere of Titan. Experiments were performed on a 70° sphere-cone in the X3 expansion tube at average freestream velocity, pitot pressure, static pressure, and density of 5:83 km=s, 76 kPa, 1.15 kPa, and 2:43 × 10 -3 kg=m 3, respectively. The radiation gauges used thin-film-sensing elements mounted behind a borosilicate window on the windward surface and were therefore shielded from the convective heat transfer. The assembled gauges are uniformly sensitive for radiation in the wavelength range from 0.347 to 2 mand give an integrated measurement of the total radiant flux in this band. Externally mounted thermocouple gauges were used to measure the total heat transfer and the ratio of radiant to the total heat flux found. The Titan atmosphere was simulated by a mixture of 5% methane (by volume) in nitrogen. Comparative tests using pure nitrogen confirmed that, without the methane content, negligible radiation was produced, which is consistent with cyanogen being the primary radiator. Results from this study demonstrate that the gauges and the superorbital expansion tube facility are useful resources for the study of nonequilibrium radiating flows.

Analysis of the Effect of Body Shape of Multiport Averaging Pitot Tube on Permanent Pressure Loss Using ANSYS/FLUENT

This paper presents the results of simulations of the air flow in a circular pipe with multiport averaging Pitot tube and the effect of the shape of this probe to the permanent pressure loss. The four different types of shapes were evaluated and the flow around them was simulated in ANSYS/Fluent 13.0. It was found that the shape of the cross section has effect on the permanent pressure loss that causes the flowmeter inserted into the pipe. However permanent pressure loss at the multiport averaging Pitot tube is lower in comparison with permanent pressure loss caused by the orifice plate.

A comparative study of flow rate characteristics of an averaging Pitot tube type flow meter according to H parameters based on two kinds of differential pressure measured at the flow meter with varying air temperature

A new averaging Pitot tube flow meter that has a shape similar to an Annubar® type flow meter was designed and its flow rate characteristic was evaluated. The air temperature supplied to the developed flow meter was maintained at a constant by controlling electric power supply to an electric heater during the calibration. Two kinds of differential pressure measured at the flow meter were used in calculating the H parameters, which represent characteristics of the developed flow meter. One H parameter (HΔP1) which was newly proposed in this research was calculated based on the difference between upstream pressure (stagnation pressure) at the flow meter and static pressure of the measured flow. The differential pressure is equivalent to the dynamic pressure of the flow. The other H parameter (HΔP2) which is used in a typical Annubar® type flow meter was calculated based on the difference between upstream and downstream pressure at the developed flow meters. Relationship curves between the two H parameters and the mass flow rate at the developed flow meter were obtained. The curves based on the HΔP2 parameter, which uses the difference between up and down stream pressure, show different gradients for varying the controlled air temperature. However, the other curve, based on the other HΔP1 parameter, which uses the dynamic pressure, can be represented by one linear curve even with varying air temperature.

Experimental and numerical investigations of the averaging Pitot tube and analysis of installation effects on the flow coefficient

Flows around a cylinder and other shapes, which imitate the cross section of an averaging Pitot tube, have been carried out using computational fluid dynamics. Correct calculations allow one to obtain the location of flow separation and the differential pressure between ports of the annubar. In numerical investigations the mesh concentration, turbulence models and turbulence intensity level at the inlet were taken into consideration. Pressure distributions around the cylinder surface was compared with experimental data. Moreover various shapes of the cross section were modeled to obtain a larger value of the differential pressure and a lower value of the permanent pressure loss. Experimental examinations concentrate on the determination of the flow coefficient K of the averaging Pitot tube and its relative change Δ K , which result from the installation effect. The results were presented as a function of the distance upstream of the annubar (between the element and the averaging Pitot tube).

Numerical and experimental research on new cross-sections of averaging Pitot tubes

The paper presents numerical and experimental tests of a new averaging Pitot tube. A geometric profile that gives a relatively high differential pressure was selected from a number of sensor cross-sections. A mathematical model of flow around the sensor was formulated and the model equations were solved. The results of a numerical simulation were used to optimize the sensor geometry. The obtained solutions were experimentally verified. The proposed sensor has favourable metrological characteristics.

High-Pressure Nozzle Bank for a Chemical Oxygen Iodine Laser

A new nozzle bank for an ejector-chemical oxygen-iodine laser consisting of two-dimensional slit nozzles with a trip-jet mixing system was designed, fabricated, and tested with a nitrogen flow operation regime. Computational fluid dynamics (CFD) was used to optimize the trip system design. Horizontal Pitot scan experiments demonstrated that the mixing ability of the trips is excellent. The Mach number of the mixed flow was approximately 3. The average Pitot pressure at the laser cavity was more than 100 Torr. Backpressure tests were conducted, and the results of these tests revealed that the static pressure in the cavity remains constant at approximately 10 Torr until the supersonic diffuser breaks back and the cavity unstarts at a backpressure of approximately 80 Torr.

603 内燃機関排気脈動流における平均化ピトー管式流量計の非定常特性(GS-7.8 噴霧微粒化・排気・CVT)

In recoil years, for reduction measures of exhaust gas, measurement method called CVS (Constant Volume Sampling) has a limit in precision to measure concentration. Therefore, it comes to need that exhaust gas concentration is directly measured in the tail pipe. However, it is quite difficult to measure pulsating flow rate with back flow at idling. Consequently, the purpose of this study is to develop the most suitable flowmeter for measurement of pulsating flow. From author's previous reports, fiequency counted among output of averaging pitot tube flowineter conesponded with frequency of pulsating flow in several flowmeters. For such occasions, for further clarification of the dynamic characteristics of its flowmeter, the experimental tests (output characteristics of its flowmeter, visualization by Mie scattering and LDV for pulsating flow) was conducted.