GB958700A - Improvements in or relating to flow meters - Google Patents

Abstract

958,700. Transverse momentum flowmeters. CENTRAL ELECTRICITY GENERATING BOARD, and L. YOUNG. Nov. 16, 1962 [Nov.21, 1961], No. 41656/61. Heading G1R. [Also in Division F1] A rotary meter for measuring the mass flow of fluid through a pipe comprises cylindrical casings 10, 12 coupled together by a tube 14 of non- magnetic material e.g. brass, an inlet guide member 30 having six stationary radial vanes 31, a freely rotatable rotor 40 having six radial vanes 41, a rotatably mounted flow straightener 50 including a plurality of axially disposed tubes 51 of various diameters whose angular displacement is controlled by a spring 58 (Fig. 2), and a stationary outlet guide member 70 having four radial vanes 72. The guide members 30, 70 serve as supports for an axially disposed tube 39 (Fig. 2) on which the rotor 40 and the flow straightener 50 are mounted. The rotor vanes 41 are coupled together by an anodised copper shroud ring 42 and mounted on an inner cylinder 43 which is supported by bearing members 44, 46, the innermost bearing members 46 being integral with a tubular sleeve 47 which closely surrounds the tube 39. The tubes 51 are located between concentric cylinders 52, 53, the innermost cylinder 53 being supported by bearing members 54 engaging with complementary bearing members 56 which are integral with a tubular sleeve 57 similar to sleeve 47. The vanes 31 are shaped to give the velocity of the fluid entering the meter a tangential component and the vanes 41 on the rotor are of aerofoil section such that the rotor is driven by fluid passing through the meter, the trailing portions of the vanes 41 being parallel to the axis of the rotor. The tube 14 is surrounded by twelve magnetic pole pieces 19 and energising coils 20 which are coupled to a source of electricity through leads 21 whereby eddy currents are induced in the copper shroud ring 42 and a load is applied to the rotor which can be manually, or automatically, controlled. The shroud ring 42 is provided with a peripheral groove 48 in which a plurality of pellets of radio-active material are located, the radiation from which is detected by a scintillation counter 49 whereby the speed of the rotor can be determined. The torque produced by the flow straightener 50 is indicated by a further scintillation counter 65 which detects the radiation from a triangular strip of radio-active foil 67 attached to the outer surface of the cylinder 52. Alternatively, the speed of the rotor and the torque produced by the flow straightener are detected by pick-up coils attached to the casings 10,12, permanent magnets being attached to the rotor and the flow straightener in known manner. The speed of the rotor is maintained constant whereby the angular velocity of the fluid entering the flow straightener has a predetermined value and the torque produced by the flow straightener in absorbing the angular momentum of the fluid indicates the mass flow of the fluid through the meter. Alternatively, the torque produced by the flow straightener is maintained constant by varying the load on the rotor and the speed of the rotor indicates the mass flow through the meter. The load on the rotor may be automatically controlled by control means (not shown) responsive to the output of the counter 49 to keep the speed of the rotor constant, or the output of the counter 65 to keep the torque produced by the flow straightener constant. The flow straightener may alternatively, comprise a plurality of straight radial vanes (not shown) in place of the tubes 51. The bearing members 44, 46, 54, 56 are lubricated by liquid supplied through a union 34, a passage 33 in one of the vanes 31 communicating with passages leading to the interior of the tube 39, and ducts 76 communicating with the bearing members 46, 56. When the fluid passing through the meter is a liquid the bearings are lubricated by some of this liquid entering the bearings through passages 75, 86 in nose cones 32, 74, or a small proportion of this liquid may be bled from the main stream through a groove 36 across one of the vanes 31 which communicates with a union 35, and this liquid may then be pressurised and fed to the union 34.