Bidirectional Flowmeter Research Articles

Bidirectional Interferometric Flowmeter With Linear Sensitivity and Large Dynamic Range

We propose a bidirectional flowmeter based on specialty fiber interferometry by controlled mode excitation for measuring the frequency of the vortices induced by a bluff body. The proposed arrangement of the cylindrical bluff body with a slit and the interferometric system based on modal excitation allows the bidirectional flowmeter to determine the flow velocities in either direction precisely and effectively. We have encapsulated the specialty fiber interferometer in a protective metal casing, which not only allows the interferometer to respond to the vortex frequency but also provides mechanical stability to the whole flowmeter so at to operate in a harsh environment. Experiments are conducted by introducing the modal interferometer in the slit of the cylindrical bluff body at various flow rates ranging from Reynolds number (Re) = 7200 to 56 600. A linear response is observed between the flow velocity and the vortex frequency from both directions. Thus, this work provides a reconfigurable bidirectional flowmeter, which is sensitive even at low flow rates and demonstrates a large operating range.

Discus flowmeter: A new concept

Abstract The present paper introduces a new concept of a flowrate measuring device named ‘Discus flowmeter’ in the class of obstruction flowmeter. The device has a symmetrical body creating the obstruction and the flow is thru the annulus. It works on the same principle as other obstruction type pressure differential flowmeters. The investigation is carried out for different diameter ratios (β-values) using three pressure tap combinations in the range of 103 ≤ Re ≤ 106 to explore the effect of these parameters on the performance of Discus flowmeter. The evaluation of discharge coefficient (Cd) is done for three pressure tap combinations and the permanent pressure loss coefficient is also evaluated. The variation of Cd with Reynolds number shows that for the pressure tap combination of 1D upstream and the stagnation point downstream of the body is nearly independent of β-value. The mean Cd value is almost the same as that of the V-cone flowmeter as laid down in ISO 5167-5. The permanent pressure loss coefficient for the Discus flowmeter is lower compared to the V-cone flowmeter for all β-values studied. As the body is symmetric in x-y plane, the flowmeter could also be used in both the directions (bi-directional flowmeter). It is expected that the Discus flowmeter could be a better alternative to the conventional obstruction flowmeters.

Optimizing Design of the Guide-Vane Attached to the New Bidirectional Flowmeter

Performances of vanes with various numbers and front oriented-body with different shapes such as half sphere, half ellipsoid and cone are simulated by RNG κ-ε model and standard wall functions method in order to optimize the parameters of the front oriented-body attached on the new bidirectional flowmeter. The performances of weakening-vortex and the pressure losses attaching to various models are analyzed and compared with each other. The results show that the structure with cone guide-head and 6 vanes can obtain the minimum range of flow pulsation, the least pressure loss and the least reverse flow. The simulation methods and results will be used for reference to analyze the similar annular flow and design the steady device.

A static turbine flow meter with a micromachined silicon torque sensor

A new class of flow sensors is introduced where a static turbine converts the volume flow into a torque. The structure consists of a turbine fixed to a torque sensor, which in turn is connected to the pipe wall giving a perfectly symmetric, bidirectional flowmeter. In contrast to conventional turbine flowmeters, the wheel does not rotate and consequently it is insensitive to bearing friction and wear that conventional, rotating turbines experience. Furthermore, the flow passing the wheel is distributed over the circumference of the wheel and levels out nonuniform flow profiles leading to profile independent volumetric flow measurement. The torque-sensing element is a 300-/spl mu/m-thick silicon cantilever, 2 mm wide and 16 mm long. The stiffness of the torque sensor, and thereby the sensitivity, is mainly determined by lateral dimensions of specially designed stiffness reduction parts defined by photolithography, thus giving good control of the sensitivity. Two polysilicon strain gauges are placed on each side of the cantilever, measuring the bending moment from the turbine wheel. The torque sensor has been evaluated for different geometries and together with the turbine to evaluate the flow sensing performance. A turbine with a blade length of 2.7 mm and a blade angle of 30/spl deg/ has a sensitivity of 4.0 /spl mu/V/V/(1/min)/sup 2/ when measured using the silicon torque sensor. The output signal shows good symmetry between different flow directions.

Magnetic fluid flow meter for gases

The paper presents the constructive details and functioning principle of an electronic volumetric flow meter for gases, which exploits the properties of magnetic fluids and has no moving mechanical components. It is a bidirectional flow meter, operating both in static and in moving conditions. The flow meter has a sensing unit, which consists of two sensors, one for differential pressure and an other for acceleration or inclination angle and of a tubular measuring element, as well as an electronic measuring system. Details are given an the hydrodynamic-electronic correction mechanism, which eliminates the influences of inclinations and accelerations on the volumic flow signal, followed by a description of the main features of the electronic system. The experiments performed showed the possibility of metering even very small gas volumes, such as 0.1 cm/sup 3/ at a flow rate of 50 cm/sup 3//min. The metering at higher flow rate values, up to 100 m/sup 3//h, needed only the insert of the measuring element corresponding to the requested flow rate domain.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Simple single phase and homogeneous multiphase bidirectional flowmeter

The flowmeter described is based upon the bending of a slender spring steel beam in a fluid stream. The pressure exerted on the beam is determined by attaching strain gauges to the beam. The direction of flow can be determined by the sign of the bridge current when inbalance occurs, singe the gauges will change from the tension to the compression mode. The flowmeter may be used with corrosive and hot fluids since coated beams may be used, and for increased sensitivity silicon strain gauges with temperature compensation can be used, and the system may then be used for determining gas flow rates.