Improvements in or relating to apparatus for measuring the mass flow of fluids

摘要

1,027,291. Rotary mass-flow meters. PLESSEY-U. K. Ltd. Jan. 31, 1963 [Feb. 2, 1962; May 21, 1962; Oct. 4, 1962], Nos. 4088/62, 19535/62 and 37580/62. Heading F1F. [Also in Division G1] A rotary mass flow meter comprises a stationary deflector device including variable angle deflector vanes imparting a swirl to the fluid flowing in a duct, a device responsive to the swirl including a swirl-operated bladed rotor, a device responsive to the torque reaction produced by the swirling movement applied to the fluid including a torque-responsive reactor, fluid-flow-responsive means automatically decreasing and increasing the angle of the deflector vanes in the longitudinal direction of the duct in response to increases and decreases in the fluid flow rate and computer means fed with the outputs of the swirl and torqueresponsive devices to determine the mass flow as the quotient of the two outputs. As shown, a duct 1, Fig. 1 (not shown), through which liquid or gas flows in the direction of arrow 2, houses pivotally-mounted deflector vanes 4 loaded by springs 8 in opposition to fluid flow so that as the rate of fluid flow increases the angle of the vanes relative to the duct axis decreases. The vanes 4 impart swirl to the fluid to rotate a bladed turbine 7 which co-operates with a pulse counter 14 connected to a pulse-rate meter 15 to record the flow rate. After passing through the turbine 7 the flow is straightened by passage through axially disposed vanes 10 of a torque-responsive reactor member 9 secured to a shaft 11 subject to the action of a temperature-compensated spring 12. The rotation of the shaft 11 under the reaction torque being measured by a torquemeter 13, the output of which together with that from the pulse-rate meter 15 is fed to a computer 16. To ensure that turbine speed is proportional to circumferential speed of the fluid leaving the vanes 4, part of the flow passes through an aperture 21 in a conical fairing 20 to act on a piston 18 connected by a shaft 17 to the turbine 7. The hub 6 of the turbine 7 being tapered to permit radial expansion of the fluid and pressure to act on the rear face of the turbine 7 in opposition to that acting on the piston 18 to control the opening of a ring of ports 19 through which the fluid entering the conical fairing 20 leaks. Instead of the spring-loaded vanes 4, vanes 145, Fig. 9 (not shown) of flexible material may be fitted associated with rigid plates 146 to prevent the vanes taking up an S formation at high flow rates. In another embodiment, the turbine and torque reactor include hollow bodies to the turbine and torque reactor which function as buoyancy chambers to reduce the effective weight of these parts. The turbine and torque reactor are mounted in sapphire bearings and jointly balanced against axial thrust.