Experimental and numerical curved flow study for metrology purposes

 

F. Sánchez, A. Gómez, M. Toledo, P. Quinto, & V. Zurita.

 

Laboratorio de Ingeniería Térmica e Hidráulica Aplicada. SEPI-ESIME-IPN-COFAA U.P. "Adolfo López Mateos", edif. 5, 3er piso C.P. 07738, México D. F. Tel. (5) 729 6000 ext. 54754. E-mail: fsilva@maya.esimez.ipn.mx; abdielgomez@hotmail.com

 

Received: September 22^th 2000.
Accepted: May 8^th 2002.

 

ABSTRACT

Most of the current volumetric flow measurement methods represent an important investment for many industries. However, when the accuracy requirements for the processes are not too high, curved pipes could be used as primary elements for this purpose. Unfortunately, there is a lack of information for this device as flowmeter, so more experimental and numerical research is required for its full characterization. This paper reports the experimental work conducted on three commercial 90° elbows, installed horizontally. All of them were short curvature radius with 0.75, 1 and 1.5 inches of internal diameter; water maintained at 24 °C was employed for the experiments. Pressure taps on the elbows were located at 45 ° along the curvature radius, on both inside and outside the wall. The performance of the elbow was compared against a calibrated orifice plate. A numerical study using CFD-2000 provided more information about the pressure and velocity fields, so it was posible to develop a model to describe the curvature effects on the radial pressure gradient. Experimental results show that there is a greater sensibility of the element when the curvature radius decreases, this means, a larger pressure gradient is obtained. If this radial pressure gradient is used in the typical equation for the orifice plate, a good concordance between the measurements of both elements is observed.

Keywords: Flow measurement, two-phase flow, elbows.

 

RESUMEN

La mayor parte de los métodos de medición de flujo volumétrico representan una inversión considerable para muchas industrias. Sin embargo, cuando los requerimientos de precisión en los procesos no son muy altos, los tubos curvados pueden ser utilizados como elementos primarios para este propósito. Desafortunadamente, hay mucha falta de información sobre este tipo de medidores de flujo, de manera que más investigación experimental y teórica se requiere para su completa caracterización. Este trabajo reporta el trabajo experimental conducido en tres codos comerciales a 90° instalados horizontalmente, con radios de curvatura pequeños y un diámetro interno de 0.75, 1 y 1.5 pulgadas respectivamente y tomas de presión a 45° sobre el radio de curvatura. Los resultados experimentales muestran una gran sensibilidad del elemento cuando el radio de curvatura disminuye, dando un mayor gradiente de presión, del cual se puede derivar el valor del flujo.

 

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