Patent GB-1459983-A (GB)
Title: Apparatus for measuring the flow rate and/or viscous character istics of fluids
IPC: G01F1/48
Filed: 1975-03-20
Abstract: 1459983 Measuring fluid-flow CANADIAN PATENTS & DEVELOPMENT Ltd 20 March 1975 [22 March 1974] 11688/75 Headings G1R and G1S An apparatus for measuring the flow-rate and/or the viscous characteristics of a fluid, comprises: (a) a casing having a fluid passage or a plurality of identical passages, a fluid inlet cavity for connection to a source of pressurized fluid and forming a substantially unobstructed flow-path for fluid to the whole area of an inlet end of the or each fluid passage, normal to the direction for flow of fluid in the fluid passage(s), and a fluid outlet cavity for the escape of fluid from the casing and forming a substantially unobstructed flow-path for fluid from substantially the whole area of an outlet end of the fluid passage(s), normal to the direction for flow of fluid in the fluid passage(s). (b) fluid-pressure detecting and indicating means in the casing for indicating a fluid-pressure differential between spaced positions in the or at least one fluid passage in the direction for flow and (c) the ratio of the mean breadth to the mean width of the fluid passage area, normal to the direction for flow of fluid therein, is at least ten to one for at least the portion of the passage which extends between the spaced positions, (d) the area of the passage, normal to the direction for flow of fluid in the passage, and for at least the portion of the passage which extends between the spaced positions, continuously reduces in size in the direction for flow of the fluid such that laminar fluid-flow will be maintained in the passage, and such that when using substantially pure water at 70‹F as a standard, (i) if the fluid-pressure detecting means detects a static pressure differential, the static pressure differential p thereof detected by the pressure detecting means is dependant upon the mass flow-rate G of the substantially pure water through the passage and satisfies the relationship in consistent units: (ii) if the fluid-pressure detecting means detects a total pressure differential, the total pressure differential #P thereof detected by the pressure detecting means is linearily dependent upon the mass flow-rate G of the substantially pure water in the passage, and the pressure differential for static and total pressure differential detection (#p and #P respectively), whichever is used; is  determined over a range of flow-rates for the substantially pure water for which the difference between the maximum Reynolds numbers in the passage between the spaced positions therein is within the range 0 and 8000, where the Reynolds number R e  is defined, in consistent units, by: h = the mean width of the passage at the position between the spaced positions for which the Reynolds number is a maximum, # = the fluid density of the substantially pure water, U = the mean velocity of the substantially pure water at the position between the said spaced positions for which the Reynolds number is a maximum, and p = the absolute viscosity of the substantially pure water, and where in the case of static pressure differential detection means the ratio K 1 /K 2  is greater than 0À01, where K 1  and K 2  are constants for a given fluid passage geometry and are determined for the relationships vhere P 1  = static pressure differential between the spaced position when the maximum Reynolds number in the passage between spaced position is 8000, G 1  = the fluid mass flow-rate of the substantially pure water through the passage when the maximum Reynolds number in the passage between the space position is 8000, # P 2  = static pressure differential between the spaced positions when the maximum Reynolds number in the passage between the said spaced positions is 3500, G 2  = the fluid mass flow-rate of the substantially pure water through the passage when the maximum Reynolds number in the passage between the spaced positions is 3500, so that (e) the fluid characteristics to be measured is related to the pressure differential indicated by the fluid-pressure differential indicating means, and is duducible therefrom in a consistent manner for different fluids. In one embodiment of the invention, the fluid passage 8 is formed between plates 30, 32 monitored by static or total pressure indicators 22, 24, the ratio of x/y being at least 10 for at least a portion of the passage length between the indicators, Figs. 2, 3. A plurality of such passages may be provided between parallel plates, one or more being monitored, Figs. 6, 7 (not shown). A number of detectors may be spaced along the passage, Figs. 10, 11 (not shown) and their outputs may be fed to a computer producing a graph. Pressure may be monitored in inlet and outlet chambers Fig. 9 (not shown). The device may be circular in form with fluid flowing from an outer chamber 112, Figs. 12, 13, through a passage 116 radially inwards to an outlet 118, detectors 114, 146 being provided. As in previously described embodiments, multi-passage variations may be produced, Fig. 15 (not shown). The passage may have radial partitioning elements (160), Figs. 16, 17 (not shown) or an axial inflow channel Fig. 18 passages may be adjustable in height. A circular embodiment may have a flexible passage wall 219, Fig. 23, the deflection of which is indicated by strain gauges 221 or pneumatic gauges 223 to give the fluid-pressures. A jack (224), Fig. 24 (not shown) may adjust the passage height.