On the path to carbon neutrality to reduce greenhouse gas (GHG) emissions, the Korean government has mandated legislation for controlling and monitoring GHG emissions emitted from smokestacks. A ...continuous emission measurement (CEM) method is considered to be the most reliable for determining CO2 emissions from stationary sources. In Korea, an S-type Pitot tube is the most popular technique to measure the gas velocity in a smokestack, but it will result in a certain error when the non-axial velocity components exist. To vanquish this limitation, Korea Research Institute of Standards and Science (KRISS) developed a nulling smokestack flow measurement (NSFM) instrument equipped with 3D Pitot tubes for taking on-site stack gas velocity measurements. 3D Pitot tubes used in this research, such as prism Pitot tube and sphere Pitot tube, are calibrated in the KRISS airspeed system. The instrument using 3D Pitot tubes with the nulling technique is expected to diminish the restriction on S-type Pitot tubes, and to enhance the quality of the GHG emission measurements in the smokestack. The 3D Pitot tubes can measure both axial and non-axial velocity components of a flow, whereas the S-type Pitot tubes can measure only the axial velocity component. The averaged axial velocity of the stack gas as measured by this instrument has expanded uncertainty of 3.3% (P = 95%, k = 2) for both prism and sphere Pitot tubes.
•The aim of the present work: to develop a nulling smokestack flow measurement (NSFM) system that can be utilized practically for velocity measurements on-site by 3D Pitot tubes. The developed nulling smokestack flow measurement system is used to measure the gas velocity in a smokestack of a practical combined heat and power plant in Korea.•In order to vanquish this limitation, the prism-type and sphere-type 3D Pitot tubes are used for measuring the gas velocity in a smokestack. As a result, the stack gas velocity measured by the 3D Pitot tubes is more reliable because the non-axial velocity components are also measured with the axial velocity component.•The value of the average axial velocity as measured by the 3D Pitot tubes is in good agreement with the value determined by the S-type Pitot tube for TMS. The results measured by this instrument equipped with the 3D Pitot tubes will adhere to Korean regulations to monitor the emissions in smokestacks more reliably compared to the S-type Pitot tube.•KRISS NSFM equipped with 3D Pitot tubes that operates according to the nulling method noticeably enhances the quality of average axial velocity measurements with the quantitative analysis of measurement uncertainty by international guidelines.
In rough environments (train’s underbody, wind carrying sand etc.), the only feasible means of measuring flow speed is with a Pitot tube. Unsteady (gusty) flow effects can cause large errors in flow ...speed measurements. In this short communication work, an attempt has been made to identify these errors. Based on potential flow theory, a term that takes into account the unsteady effects has been proposed to correct the Pitot tube measurements in unsteady (gusty) flow conditions. Experiments have been performed in an open circuit-closed test-section, low-speed wind tunnel, designed and built at the Instituto de Microgravedad “Ignacio Da Riva” of the Universidad Politécnica de Madrid (IDR/UPM). Different types of Pitot tubes have been used to check the validity of the correction term proposed. It has been shown that the distance between the total and static pressure taps has a major influence on the Pitot tube correction term.
•The effect of an unsteady flow in Pitot tube measurements have been investigated.•Based on the potential flow theory, a correction term, Tct have been proposed.•Influence of the Tct have been investigated with four types of Pitot tubes.•Influence of the distance between static and total pressure taps xe is investigated.•.•It is mandatory to check the Pitot tubes measurements in a gusty wind tunnel.
This paper presents an attempt to determine the dynamic properties of a measuring system based on total pressure measurement with the use of a Pitot tube and a semiconductor pressure transducer. The ...presented research uses computed fluid dynamics (CFD) simulation and real data from the pressure measurement system for determination of the dynamical model of the Pitot tube with the transducer. An identification algorithm is applied to the data from the simulation, and the model in the form of a transfer function is an identification result. The oscillatory behavior is detected, and this result is confirmed by frequency analysis of the recorded pressure measurements. One of the resonant frequencies is the same in both experiments, but the second is slightly different. The identified dynamical models permit the possibility to predict deviations caused by dynamics and to select the appropriate tube for a particular experiment.
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.
•The disturbance induced by the downstream damper on the averaging Pitot tube airflow measurement is investigated.•A novel empirical formula for the averaging Pitot tube is proposed to compensate the error caused by the damper.•The proposed method improves the performance of current air flow control station products.
•The staggered arrangement of plates has an optimal bubble-breaking effect.•The lower installation position of the plate facilitates the breaking of bubbles.•The bubble motion and liquid phase shear ...forces cause liquid velocity fluctuations.•The radial distribution of dimensionless εg and uL are predicted.
The bubble-breaking plate is a crucial internal component in the scrubbing-cooling chamber. The study of hydrodynamics under its influence is the basis for designing and scaling up industrial installations. Experimental measurements of characteristic bubble parameters and liquid phase structure parameters at local locations were carried out using a conductivity probe and a pitot tube, respectively, to investigate the effects of five types of bubble-breaking plate installation on the hydrodynamic properties of the annular gap bubble bed. The experimental results show that the staggered placement of two plates is the most favorable for increasing the gas holdup, reducing the bubble size, increasing the gas–liquid interface area, improving the liquid velocity distribution and suppressing the turbulence fluctuations. In addition, a dimensionless mathematical model predicted the radial distribution of local gas holdup and axial time-averaged liquid velocity, and the expected results agreed with the experimental values.
Cyclists need to measure aerodynamic resistance accurately and reliably, as well as economically. Devices such as Notio Aerostick, an equipment device that includes one pitot tube, have appeared for ...this purpose. The aim of this study is, therefore, to test the reliability and degree of agreement in the evaluation of the CdA (coefficient of aerodynamic drag), assessed by means of the Notio Aerostick compared to the Virtual Elevation (VE) and Martin mathematical models.
Seventeen professional cyclists rode in a 250-metre-long velodrome covered with a concrete surface with their own time trial bikes. Each cyclist completed three rides of 15 laps at constant speed for the evaluation of the CdA, each of them in a different position Baseline (B), Change 1 (C1) and Change 2 (C2).
The differences in CdA between methods were found for Martin in comparison with VE in all positions (
<.001) and with Notio Aerostick in B and C2 (
> .05). About differences of CdA for each method, considering between position changes, the results were the same for VE and Martin, but different for Notio Aerostick.
Findings suggest that, notwithstanding Notio Aerostick is valid if we compare CdA values with respect to VE, since the direction of their between-positions CdA changes differs, the results of their aerodynamic evaluation could lead us to recommend different final setups. We need studies that evaluate different units of the Notio Aerostick device as well as the reliability and precision of each sensor that includes Notio Aerostick.HighlightsThe CdA calculated by the Notio Aerostick and VE, a mathematical model previously validated, can be interchangeable, however the final position recommended by each method may be different, since the changes in the following position are given by the changes of the CdA in the previous position.None of the three methods allowed elite cyclists to measure statistically significant differences between the proposed setups.Although the CdA differences between positions were not significant, they can be decisive in the final result of a time trial competition.
The data measured by the pitot tube (PT) is related to airspeed indication and flight safety. However, there are few methods to solve the problem of failure prediction and predictive maintenance of ...PT. This study proposes a method for predicting the remaining useful life (RUL) of the PT based on dynamic operating data. First, an exposure index (EI) characterizing the severity level of operating conditions is proposed based on multiple dynamic operating and environmental parameters, then a cumulative exposure model (CEM) is developed to calculate the cumulative exposure. Dynamic covariate information is incorporated into the time‐to‐failure distribution of PT through the CEM, the RUL distribution of the individual PT is then obtained by Monte Carlo simulation. A case study is carried out based on actual data of a commercial aircraft fleet and shows that the proposed CEM can effectively use historical aircraft environmental information and truncated failure data of the components. The relative error of the remaining life prediction is substantially improved compared to the traditional reliability analysis methods, which means that the proposed model can provide more reliable RUL results based on historical operating conditions, providing better support for PT risk assessment and condition‐based maintenance decisions.
•Velocity measurements using a Pitot tube was created to validate the computer code.•Two turbulent models were used in the code for thermal-hydraulic analysis.•A test fuel assembly model of 19 rods ...with spacers was used in the measurements.•The performance of total pressure drops was measured for two kinds of spacers.•A comparison between the outcome of calculations and the measurements was done.
The paper contains experimental data and analysis of the velocity distribution and pressure drop of turbulent flow through a fuel bundle of 19 rods as a partial model of the VVER-440 reactor core. Also, results from the code calculations at the outlet of the test assembly at different flow rates and comparison with experimental data are presented. A pitot tube was used to measure the velocity and pressure drop. Detailed measurements of the velocity distribution in a fuel bundle are done in a fully developed turbulent flow region. Moreover, detailed measurements of the pressure drop of wire and spacer grids typical for PWRs are discussed together with the total pressure drops performance. The experimental result was compared with the predictions by our code and good agreement was found. The calibration protocol and uncertainties of the measurements are presented.
Surface dielectric barrier discharges are investigated in order to explore the combined effects of barrier thickness and microstructure of the exposed electrode on the ion wind generation. Actuators ...with straight and structured high voltage electrodes with characteristic sizes of 200 and 250 µm and dielectric thicknesses of 0.5, 1 and 2 mm are compared. It is observed that: i) actuator efficiency of ion wind generation strongly depends on the applied voltage amplitude; ii) operation voltage depends on the dielectric thickness logarithmically; iii) electrode microstructure slightly increases the dynamic pressure (few percent in maximum), however the effect decreases with thicker dielectrics and smaller electrode structures; iv) the pattern of the most intensive discharge parts as well as the dielectric erosion repeats the regular structure of the electrodes down to 200 µm. Several identical samples are tested during different days to estimate the impact of the air humidity and the degradation of the dielectric. The microscale precision of the sample manufacture was accomplished by a commercial facility for printed circuit boards.
Due to the increasing demand for water resources worldwide, this commodity and its spatial and temporal properties are of the interest of decision makers and scientists. In this respect, the accuracy ...in detecting the physical characteristics of the water movement such as velocity and its associated phenomena should be preauthorized in hydraulic studies. Although velocity, as the deriving factor of the water flow, can be determined with the help of theoretical or practical approaches, researchers continuously pushes the limits of science by improving the existing methods to the best. The pitot tube, which is not widely used in open channel hydraulic practices, is one of these methods. In this study, we have addressed a case from design to conducting a set of laboratory experiments. A 3D-printed pitot-tube is designed and used in a set of experiments carried out in an open channel, with different flow rates (three experiments). As a result, the relative error rates were interpreted by comparing the velocity rates obtained with the help of the water level difference in the differential manometer (Vm) and the velocity rates obtained from the flow continuity equation in the open channel (Vo). Results indicated a 50% bias in the experiments, while scatter analysis showed that the associated deviations matches a linear equation.
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