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Showing papers on "Thermal mass flow meter published in 1995"


Patent
24 Jul 1995
TL;DR: In this article, the authors present an approach for detecting and correcting various fault conditions in an operating Coriolis effect mass flowmeter, including the presence of a crack in the flow tubes and stopping the flow of material to prevent release of the material through a cracked flow tubes.
Abstract: Apparatus and methods for detecting and correcting various fault conditions in an operating Coriolis effect mass flowmeter. The apparatus of the present invention receives information from an operating Coriolis mass flowmeter and compares the information to threshold signatures representing various fault conditions. When a fault condition is detected, output signals are applied to inform an operator and to control the mass flow rate through the flowmeter to correct the fault condition. Specifically, the methods of the present invention detect the presence of a crack in the flow tubes and stop the flow of material to prevent release of the material through a cracked flow tubes. Other methods of the present invention detect the void fraction of material flowing through the flow tubes, compute a corrected actual mass flow rate, and control the mass flow rate through the flowmeter to compensate for the effects of the void fraction. Signature information relating to threshold values for measured frequency, drive power, temperature and mass flow of the operating flowmeter as well as the slope and curvature of changes in each measured operating parameter are stored in memory within the fault detection apparatus of the present invention.

99 citations


Patent
18 Apr 1995
TL;DR: Several Radial Mode Coriolis mass flow rate meter geometries and electronic circuits that may be made to be sensitive to pressure or density changes are described in this paper, where a method is described that allows for the accurate measurement and compensation of both pressure and density.
Abstract: Several Radial Mode Coriolis mass flow rate meter geometries and electronic circuits are described that may be made to be sensitive to pressure or density changes. In one embodiment, the meter comprises: (A) a flow conduit (1) for containing a fluid having a physical characteristic, the fluid (21) adapted to flow in the conduit at an unknown rate, (B) a drive circuit (16, 17) for creating a vibration in the flow conduit (1), the fluid (21) altering the vibration as a function of the physical characteristic and the flow rate, (C) a detector circuit (10-15) for measuring the altered vibration at a working point (38, 55) and producing a signal representing an uncompensated mass flow rate (M1) of the fluid and (D) a computation circuit for calculating a compensated mass flow rate (M2) of the fluid proportional to the uncompensated rate by 1/Φ1n, where Φ1 is a driven natural frequency of the flow conduit and n is a number chosen as a function of the working point, the compensated rate thereby reduced of effects of the physical characteristic. A unique mathematical algorithm is also described that allows for a much wider variety of design geometry while maintaining insensitivity to pressure or density without having to measure or compensate for either. In addition, a method is described that allows for the accurate measurement and compensation of both pressure and density.

95 citations


Patent
07 Jun 1995
TL;DR: In this article, a precise fluid flow meter fabricated by micromachining techniques measures a wide range of fluid flow rates, and the transit time of the thermal pulse between the two sensor elements measured the fluid flow velocity.
Abstract: A precise fluid flow meter fabricated by micromachining techniques measures a wide range of fluid flow rates. Two serial portions of an enclosed channel have different cross-sectional areas, and therefore different flow velocities. The fluid carries the thermal pulse through the flow channel to two sensor elements spaced apart along the channel downstream from the heating element. The transit time of the thermal pulse between the two sensor elements measures the fluid flow velocity.

79 citations


Proceedings ArticleDOI
29 Jan 1995
TL;DR: A liquid flow sensor based on the measurement of the pressure difference across a flow restriction integrated between two silicon pressure sensors is presented in this paper, which is used in a system consisting of a silicon micro-pump and an electronic controller.
Abstract: A liquid flow sensor based on the measurement of the pressure difference across a flow restriction integrated between two silicon pressure sensors is presented. Depending on the channel size, the FS flow measurement ranges from 50 pl/hr up to 20 ml/hr, with a non-linearity better than 1 %FS. This device is used in a system consisting of a silicon micro-pump and an electronic controller to achieve a high precision flow rate. The fast response of the sensor, < 2 ms, allows for minute dosing with a resolution of 0.1 pl. Introduction Silicon fluid handling systems have been built in the past years for use in chemical analysis and medical applications. These systems generally lack a consistent liquid delivery over an extcnded period of time, typically tens of hours. Thus, they require frequent rccalibration to ensure the accuracy needed. However, their capability of delivering minute quantity of liquid makes them very attractive for such applications. The addition of a sensor that measure the actual flow in such systems allows for improved consistency and accuracy. This paper presents the design, fabrication and the characterization of such a sensor. Sensor description The sensors have been fabricated starting from piezoresistive low pressure sensor wafers devcloped at ASCOM. The addition of a restriction channel between two adjacent pressure sensor die forms the flow sensor device, as depicted in figure 1. The risk of unstability and degradation of the sensor is rcduced because only the backside of the sensors is exposed to the liquid. ~104 in Flow out Figure 1. Device cross section (principle) 0-7803-2503-6

75 citations


Journal ArticleDOI
TL;DR: In this paper, a low-cost silicon sensor for measuring the mass flow rate of gases and liquids has been developed based on heat transfer from heated resistors to a flowing fluid (electrocaloric principle).
Abstract: A low-cost silicon sensor for measuring the mass flow rate of gases and liquids has been developed. Its operation is based on heat transfer from heated resistors to a flowing fluid (electrocaloric principle). The difference between the temperature of the sensors on the chip, the heating power, and the heater temperature can be used to measure the mass flow. It is important to realize that sensors are produced in silicon through the usage of micro-technology. Nitrogen and water are used for testing the sensor. The sensor has a high dynamic response and is suitable for dynamic fluid measurements. The possible measuring flow rates range from 0 to 500 ml/min for gases and 0 to 500 or 0 to 10 ml/min for liquids.

55 citations


Patent
08 Dec 1995
TL;DR: In this article, a signal processing and method for measuring a mass flow rate of a fluid flowing in conjunction with a surface of a Coriolis mass flow meter and a field-provable CME is presented.
Abstract: A signal processing apparatus and method for measuring a mass flow rate of a fluid flowing in conjunction with a surface of a Coriolis mass flow meter and a field-provable Coriolis mass flow meter The apparatus includes: (1) a driver for creating a prescribed vibration in the surface, (2) a motion sensor for measuring a motion of the surface, (3) response characteristic determination circuitry, coupled to the motion sensor, for determining a response characteristic of the surface and (4) flow rate calculation circuitry, coupled to the response characteristic determination circuitry, for calculating a measured mass flow rate of the fluid as a function of the motion and the response characteristic The field-provable meter employs the response characteristic to monitor or compare meter performance without requiring a separate proving device

52 citations


Patent
John David Marrelli1
15 Jun 1995
TL;DR: In this paper, a three phase meter is used to measure the oil/water/gas fractions of a multi-phase fluid flow using a fraction meter and a flow meter to calibrate flow with the fraction meter sending mixture density information to the flow meter.
Abstract: A three phase meter to measure the oil/water/gas fractions of a multi-phase fluid flow uses a fraction meter and a flow meter to calibrate flow with the fraction meter sending mixture density information to the flow meter to make the calculation.

49 citations


Patent
30 Aug 1995
TL;DR: In this article, a high void fraction multi-phase fluid flow meter and method is presented, where a first fluid flow path including a multiphase flow measuring device disposed in series with a liquid flow restrictor is provided in parallel with a second fluid flowpath including a gas flow measurement device.
Abstract: A high void fraction multi-phase fluid flow meter and method, wherein a first fluid flow path including a multi-phase flow measuring device disposed in series with a liquid flow restrictor is provided in parallel with a second fluid flow path including a gas flow measuring device. The presence of liquid flow in the flow meter is detected. When liquid flow is detected, a valve in the second fluid flow path operates to cut off fluid flow through the second fluid flow path. Otherwise the valve in the second fluid flow path operates to divert gas flow through the second fluid flow path. Alternatively, a negative pressure differential is produced across the second fluid flow path when liquid flow is present, by passing the incoming liquid flow through a jet pump nozzle, to prevent liquid flow into the second fluid flow path. A check valve is then disposed in the second fluid flow path to prevent backflow from the output of the multi-flow measuring device into the second fluid flow path. A computer outputs an indication of the liquid flow, typically oil flow and water flow, through the multi-phase flow meter, and the combined total amount of gas flow through the two flow meters.

47 citations


Journal ArticleDOI
TL;DR: In this paper, four different sensing techniques are discussed based on capacitive, electrostatic, microwave and nucleonic principles with regard to their homogeneous sensing characteristics, and the mass flow rate of randomly distributed solids flowing in pneumatic conveyors is measured.

41 citations


Journal ArticleDOI
TL;DR: In this article, a high precision gas meter suitable for low rates of flow (< 5 cm3 min−1) which can be interfaced with data acquisition software for continuous on-line measurement is described.

30 citations


Patent
06 Nov 1995
TL;DR: In this article, a microcontroller-based processing circuit is employed to measure the capacitance of the probe sensors, and the circuit employs high speed timer and counter circuits to provide a high resolution measurement of the time interval required to charge each capacitor in the probe assembly.
Abstract: A quality and/or flow meter employs a capacitance probe assembly for measuring the dielectric constant of flow stream, particularly a two-phase flow stream including liquid and gas components. The dielectric constant of the flow stream varies depending upon the volume ratios of its liquid and gas components, and capacitance measurements can therefore be employed to calculate the quality of the flow, which is defined as the volume ratio of liquid in the flow to the total volume ratio of gas and liquid in the flow. By using two spaced capacitance sensors, and cross-correlating the time varying capacitance values of each, the velocity of the flow stream can also be determined. A microcontroller-based processing circuit is employed to measure the capacitance of the probe sensors. The circuit employs high speed timer and counter circuits to provide a high resolution measurement of the time interval required to charge each capacitor in the probe assembly. In this manner, a high resolution, noise resistant, digital representation of each of capacitance value is obtained without the need for a high resolution A/D converter, or a high frequency oscillator circuit. One embodiment of the probe assembly employs a capacitor with two ground plates which provide symmetry to insure that accurate measurements are made thereby.

Patent
31 Jul 1995
TL;DR: An intake air flow measuring apparatus for internal combustion engine apparatus has a thermal type air flow meter, a response delay correcting unit and air flow direction unit, and a unit for detecting the direction of the flow of intake air as mentioned in this paper.
Abstract: An intake air flow measuring apparatus for internal combustion engine apparatus has a thermal type air flow meter, a unit for correcting the response delay of the thermal type air flow meter, and a unit for detecting the direction of the flow of intake air so that an amount of reverse air flow is detected by the response delay correcting unit and air flow direction unit, and that a true amount of sucked air flow is calculated from the output of the thermal type air flow meter and the amount of reverse air flow.

Patent
18 May 1995
TL;DR: In this paper, a controller compares the desired exhaust gas recirculation flow to the maximum mass air flow to generate an error signal if the desired air flow exceeds the maximum air flow error.
Abstract: An apparatus for determining a number of cylinders to operate in a variable displacement engine includes a signal representative of air charge temperature, a signal representative of barometric pressure, a desired mass air flow evaluator, a maximum mass air flow evaluator, a desired exhaust gas recirculation flow evaluator, a maximum exhaust gas recirculation flow evaluator, and a controller. The controller compares the desired mass air flow to the maximum mass air flow, generating a mass air flow error signal if desired mass air flow error exceeds maximum mass air flow error. The controller also compares the desired exhaust gas recirculation flow to the maximum exhaust gas recirculation flow, generating an exhaust gas recirculation flow error signal if desired exhaust gas recirculation flow exceeds maximum exhaust gas recirculation flow. The two flow error signals are combined and compared to an acceptable error threshold, and a number of cylinders upon which to operate the variable displacement engine is recommended responsive thereto.

Journal ArticleDOI
TL;DR: In this paper, the performance of a turbine meter in two-phase (water/air) flow in a vertical pipe is assessed and a technique for using measurements of the fluctuations in the turbine meter rotor velocity to determine void fraction (= air flowrate/total flowrate) is described.

Patent
Hans Hecht1, Dieter Tank1, Konzelmann Uwe1
27 Mar 1995
TL;DR: In this paper, an air mass aspirated by an internal combustion engine is detected, and a characteristic of the air mass meter representing a relationship between an output voltage of the meter and a flow air mass is determined by changing the characteristic in a return flow region relative to the measured characteristic, and the change of the characteristic is performed so that the relationship between the output voltage and the measured air mass are adjusted to minimize error measurements.
Abstract: In a method for correcting an output signal of an air mass meter, an air mass aspirated by an internal combustion engine is detected, so that first a characteristic of the air mass meter representing a relationship between an output voltage of the air mass meter and a flow air mass is determined, the characteristic in a region which the air mass can flow back is corrected by changing the characteristic in a return flow region relative to the measured characteristic, the change of the characteristic is performed so that the relationship between the output voltage of the air mass meter and the measured air mass is adjusted to minimize error measurements, and the computations of the aspirated air mass is therefore performed with the aid of the corrected characteristic.

Patent
13 Jun 1995
TL;DR: An air flow rate measuring apparatus for measuring an intake air amount of an internal combustion engine by use of a thermal air flow meter comprises means inputted with the output of the TAF for correcting a response delay of the output and outputting the corrected output.
Abstract: An air flow rate measuring apparatus for measuring an intake air amount of an internal combustion engine by use of a thermal air flow meter comprises means inputted with the output of the thermal air flow meter for correcting a response delay of the output and outputting the corrected output, and means inputted with the output of the correcting means for transforming it to a value corresponding to an air flow rate on the basis of the characteristic of the thermal air flow meter stored beforehand.

Patent
23 Mar 1995
TL;DR: In this paper, a dual sensor vortex flow meter providing fluid connections for two sensors and containing isolation valves providing the further capability of separate valve control of the fluid communication to each of the dual sensors is described.
Abstract: A dual sensor vortex flow meter providing fluid connections for two sensors and containing isolation valves providing the further capability of separate valve control of the fluid communication to each of the dual sensors is herein disclosed. The vortex flow meter is mounted onto a flow meter body having an existing sensor cavity for housing a single sensor. The vortex flow meter is fitted into the existing sensor cavity by means of a dummy-cast sensor. On either side of the dummy sensor are apertures coupled to flow passages that transmit the alternating differential pressure fluctuations caused by the vortices from each side of the dummy sensor to the corresponding sides of each of the dual sensors. The dual sensor vortex flow meter may also include valves for controlling the process flow transmission to each of the sensors.

31 Dec 1995
TL;DR: The use of a venturi meter for the measurement of refrigerant liquid-vapor mass flow rate in a horizontal pipe is presented in this paper, where various models that utilize the output of the venturi flowmeter and the measured void fraction and/or quality to calculate the two-phase mass flow ratio were examined.
Abstract: The use of a venturi meter for the measurement of refrigerant liquid-vapor mass flow rate in a horizontal pipe is presented. Various models that utilize the output of the venturi flowmeter and the measured void fraction and/or quality to calculate the two-phase mass flow rate were examined. It was found that the applicability of the various models is dependent on the quality range. When the quality is less than 50%, the use of the momentum density model provides the best accuracy. For higher qualities, the use of the homogeneous equilibrium model is recommended.

Journal ArticleDOI
Sze-Foo Chien1, J.L.G. Schrodt1
TL;DR: In this article, a method for measurement of steam quality and flow rate has been developed, laboratory tested, and packaged for thermal EOR applications, which consists of an orifice flow meter in series with a critical flow meter.
Abstract: A method for measurement of steam quality and flow rate has been developed, laboratory tested, and packaged for thermal EOR applications. The method consists of an orifice flow meter in series with a critical flow meter. The flow through the orifice is subcritical. The critical-flow meter can be a static choke, a venturi, a nozzle, or a thick orifice, etc. Steam flow rate equations for orifice flow and for critical flow were established with empirically derived constants. These two equations were combined and solved to determine the steam quality and flow rate. The basic mechanical parts of the measurement system are rugged and inexpensive. The pressure transmitters and flow computer are portable and can be used for spot checks or for continuous monitoring. The steam quality and flow rate information obtained make it possible to evaluate the performance of steam distribution systems and thus to identify where modifications to the distribution system piping are needed.

Patent
29 Mar 1995
TL;DR: In this article, a multiphase flow meter is provided, by which the constitution can be comparatively simplified, and a flow by each phase can be measured with high accuracy, by detecting fluctuation caused by the flow of a mixed phase fluid to obtain the delay time corresponding to the peak of the correlation function of the respective signals.
Abstract: PURPOSE: To provide a multiphase flow meter, by which the constitution can be comparatively simplified, and a flow by each phase can be measured with high accuracy. CONSTITUTION: Impedance measuring circuits 22, 32 measure a change of electrostatic capacity between electrodes varied according to a dielectric constant of a mixed-phase fluid of multiphase by applying the voltage, the frequency of which is varied between the electrodes. Arithmetic circuits 23, 33 receive the output of the impedance measuring circuits 22, 32 to obtain the ratio of each phase of a mixed-phase fluid by operation. Further, there are provided two sets of mixed-phase density meters 20, 30 constructed so that both electrodes are installed at a designated space in a pipeline 10 where a mixed-phase fluid to be measured flows, and a correlative arithmetic circuit 40, to which ratio signals obtained from two sets of mixed-phase density meters 20, 30 are added, and which is adapted to obtain a flow by each phase of a mixed-phase fluid by detecting fluctuation caused by the flow of a mixed-phase fluid to obtain the delay time corresponding to the peak of the correlation function of the respective signals. COPYRIGHT: (C)1996,JPO

Patent
22 Jun 1995
TL;DR: In this article, a flow meter senses the pressure differential across an orifice plate and provides a fluid flow rate signal in accordance with the pressure and the fluid density, and individual gas, water and oil volumetric flow rate signals can thereby be obtained.
Abstract: A monitor (22) obtains signals representative of the gas, oil and water fractions in a multi-phase flow and thereby a density signal representative of the fluid mixture density. A flow meter (26) senses the pressure differential across an orifice plate (30) and provides a fluid flow rate signal in accordance with the pressure differential and the fluid density. Individual gas, water and oil volumetric flow rate signals can thereby be obtained.

31 Dec 1995
TL;DR: In this paper, a simple method that combines the outputs of venturi and turbine flowmeters, without the need for void fraction or quality measurement, was examined, and the results showed that this method can be used to determine the two-phase mass flow rate relatively well for the entire quality range.
Abstract: In determining the mass flow rate of refrigerant R-134a liquid-vapor in a horizontal tube, a simple method that combines the outputs of venturi and turbine flowmeters, without the need for void fraction or quality measurement, was examined. The results showed that this method can be used to determine the two-phase mass flow rate relatively well for the entire quality range. This method was particularly accurate in determining the mass flow rate data in the high-quality range, i.e., in annular flow. Moreover, this method also showed a reasonable accuracy in predicting the void fraction. The use of this method in predicting the two-phase mass flow rate was compared with the use of a venturi meter or a turbine flowmeter and a void fraction meter. The comparison showed that at qualities higher than 0.6, the present method, which combines the output signals of both the turbine and venturi meters, is superior to those that use one of the flow signals and void fraction and/or quality measurement. At lower qualities, the present method still offers a fairly accurate technique for measuring the liquid-vapor refrigeration mass flow rate.

Patent
26 Jun 1995
TL;DR: In this article, a reverse flow map (flow rate map of the reverse side) for converting a signal from a heating resistor into the air flow rate is corrected, and then the corrected reverse flow rate upon the occurrence of reverse flowing is corrected in two steps by utilizing the corrected flow map.
Abstract: PURPOSE: To obtain a heating type air flow rate measuring device having good measuring accuracy even to a dynamic air flow condition by providing output, memory and calculation means and also providing a correction means which corrects a reverse side air flow rate conversion function before the calculation means converts a reverse flow signal to an reverse air flow rate. CONSTITUTION: Reverse flow of an air flow in a passage is detected. Before correction of air flow rate to the reverse flow is executed, a reverse side air flow rate conversion function, i.e., a reverse flow map (flow rate map of the reverse side) for converting a signal from a heating resistor into the air flow rate is corrected. Then, the air flow rate upon the occurrence of the reverse flowing is corrected in two steps by utilizing the corrected reverse flow map. Thereby, it is possible to improve the measuring accuracy of a heating type air flow rate measuring device. Thus, the corrected reverse flow map that the map represented by static characteristics is changed beforehand to the map suitable for a dynamic air flow condition is used so that it is possible to obtain the heating type air flow rate measuring device having good measurement accuracy to the dynamic air flow condition.

Patent
11 Apr 1995
TL;DR: In this paper, the authors present a method and apparatus for monitoring in real time the mass and energy flow rate of a gas through a pipeline, where a linear flow meter is used to measure the volumetric flow of pipeline gas through the pipeline.
Abstract: The present invention is a method and apparatus for monitoring in real time the mass and energy flow rate of a gas through a pipeline The invention determines the mass flow ratio of a pipeline gas flowing through a pipeline compared to sample gas tapped from the pipeline line when the volumetric flow of pipeline gas through the pipeline is measured by a linear flow meter Sample gas tapped from the pipeline is flowed to a chamber having a section with a fixed volume until the pressure in the chamber section is substantially equal to the pipeline gas pressure The sample gas is maintained at substantially the same temperature as the gas in the pipeline while the sample gas is in the chamber section A timer measures the time interval for the sample gas to flow from the chamber section at a selected rate for a calculated pressure drop the selected rate being controlled by a flow controller The mass flow ratio is computed using the measured time interval and a signal from the linear flow meter The energy flow rate of the pipeline gas is determined by measuring the energy flow rate of the sample gas and relating that value to the mass flow ratio of the pipeline gas compared to the sample gas

Patent
11 Oct 1995
TL;DR: The mass flow meter is based on the reaction force working according to Coriolis principle which is produced by acceleration of fluid flowing through straight measuring tube, and has a sensor system for determining the voltage, which is caused axially in the measuring tube as discussed by the authors.
Abstract: The mass flow meter is based on the reaction force working according to Coriolis principle which is produced by acceleration of fluid flowing through straight measuring tube, and has a sensor system (10) for determining the voltage, which is caused axially in the measuring tube (2). A correction unit (9) corrects the measured value of the mass flow rate, on the basis of the output signal of the sensor system. The correction unit includes a mass flow rate correction unit for the correction of one part of the measured value, which corresponds to the actual flow rate of the fluid. A zero point correction unit is also provided, for correcting another part of the measured value, which corresponds to the zero point shift, which remains if the fluid is not flowing.

Patent
26 Jan 1995
TL;DR: In this paper, the authors used the sum of the voltage across the current measurement resistor and the voltage or a partialvoltage across the air flow measurement resistor as a measure of air flow.
Abstract: For determining the air mass flow in the intake pipe of an internal combustion engine by means of an electrical bridge, normally the current flowing through the current measurement resistor when balancing the bridge is evaluated as an indirect measure of the air mass flow. The primary measured quantity for the air mass flow is, however, the power converted at the air flow measurement resistor around which the air flows so that the indirect measurement always includes an error. To reduce this measurement error, the invention utilizes the evaluation of the sum of the voltage across the current measurement resistor and the voltage or a partial-voltage across the air flow measurement resistor as a measure of the air flow.

Journal Article
01 Jan 1995-Water SA
TL;DR: In this paper, the combined application of a portable insertion flow meter, a velocity-area method of flow determination together with the use of a velocity profile function provides a cost-effective method for the in situ evaluation of the accuracy of large in-line flow meters within the water supply and distribution network.
Abstract: The combined application of a portable insertion flow meter, a velocity-area method of flow determination together with the use of a velocity profile function provides a cost-effective method for the in situ evaluation of the accuracy of large in-line flow meters within the water supply and distribution network. The calibration of large in-line now meters in the field is required because of differing site conditions which affect a flow meter's performance, the expense of testing on off-site facilities and the practical problems associated with the removal and testing of some types of flow meters. Research has indicated the relative accuracy of velocity-area methods for both axisymmetric and asymmetric flow profiles. The log-linear method appears to be relatively more accurate and cost-effective in its application than other velocity-area methods of flow determination. The modified Pao equation is a function which is independent of the friction factor and which describes the velocity profile within a pipe. It is dependent, however, on the actual positions where the mean axial velocity occurs and the value of the centreline velocity. These characteristics facilitate the practical application of the function in establishing a flow reference standard. The position of the mean axial velocity in a pipeline varies and this position has to be determined for each situation and application. Practical guidelines given in this paper ensure the cost-effective application of a portable insertion flow meter, the log-linear method and the modified Pao equation for providing a flow reference standard. Research is required to establish the accuracy of this flow reference standard with respect to the national flow standard.

31 Dec 1995
TL;DR: Gasunie has performed tests on two types of installation effects on multipath ultrasonic gas meters with a diameter of 500 mm and showed that small amounts of liquids do not affect the meter error, and that the meter itself can detect if signal to noise ratios are distorted so much that proper functioning is no longer possible.
Abstract: Gasunie has performed tests on two types of installation effects on multipath ultrasonic gas meters with a diameter of 500 mm. The effect of mildly wet flows was studied by injecting liquids in the gas flow and monitoring changes in signal and noise levels and in the meter error. It was concluded that small amounts of liquids do not affect the meter error, and that the meter itself can detect if signal to noise ratios are distorted so much that proper functioning is no longer possible. The effect of swirling flow was studied for two types of meter with significantly differing path geometries: a 4-path criss-cross arrangement and a 5-path reflection arrangement. For swirl angles up to 10 degrees, the effect on the meter errors was up to 0.8% and 0.4% resp.

31 Dec 1995
TL;DR: In this article, a k-var_epsilon CFD model was used to predict the flow downstream of obstruction plates having one large or nine small holes, and mean velocity, turbulent kinetic energy, k, and the dissipation rate of turbulent energy was calculated and compared against measured data.
Abstract: Perforated plate flow conditioners are used to generate a fully developed turbulent flow profile upstream of an orifice meter. It is very time-consuming to measure the effect of a flow conditioner for different upstream flow profiles. Therefore a project is initiated to evaluate the performance of a computational fluid computer code for this purpose. If the code correctly predicts the flow characteristics downstream of more complex flow conditioners. In this study a k-{var_epsilon} CFD-model was used to predict the flow downstream of obstruction plates having one large or nine small holes. Both mean velocity, turbulent kinetic energy, k, and the dissipation rate of turbulent kinetic energy, {var_epsilon}, were calculated and compared against measured data. The results indicate that it is possible to predict the mean velocity well and that the accuracy of the predicted k and {var_epsilon} depends on the complexity of the flow.

Patent
07 Nov 1995