A low pressure drop air flowmeter (10) for an automotive engine is disclosed. The meter includes a main air flow passage (26), a relatively small venturi tube (28) receiving a portion of the air flow, a pressure port (74) for sensing stagnation pressure in the main passage, a pressure port (70) for sensing static pressure in the throat of the venturi, and a complimentary pair of sets of stationary swirl vanes (30 & 32) disposed adjacent the outlet of the venturi and operative to jointly impart a swirl through the remainder of the air in the main passage, thereby creating a reduced pressure at the venturi outlet for amplifying the pressure difference between the stagnation and static pressures without appreciably increasing the pressure drop across the flowmeter. The sets of swirl vanes are rotationally displaceable with respect to one another, allowing some of the air to bypass the effect of the swirl vanes without being diverted to a separate passageway. This arrangement results in a fluid flowmeter having a characteristic pressure drop which is less than that for a conventional device, particularly at high flow rates, and which can be easily reconfigured to suit a specific application. Also disclosed is a solenoid valve (54) operative to selectively sample stagnation pressure in the main flow passage and signal pressure in the throat of the venturi and generate an electrical output signal as a function of the difference between these two pressure signals.
A critical flow venturi with either a movable centerbody or a fixed replaceable centerbody is provided for fluid flow measuring or fluid flow control by changing the critical flow rate area of the venturi. The critical flow venturi and its associated centerbody may be used with a wide variety of fluids including liquids, gases and mixtures thereof. A critical flow venturi with easily exchangeable centerbodies can conveniently provide a range of discrete high capacity calibration grade flow rates near atmospheric pressure. The discharge coefficient for each critical flow venturi may be accurately determined analytically to potentially eliminate the need for experimental calibrations. For pressurized applications, a remotely actuated centerbody may be preferred. The movable centerbody may be contoured to achieve unique flow characteristics, such as a linear change in critical flow rate in response to changes in the longitudinal position of the centerbody relative to the throat of the venturi. Alternatively, a movable centerbody may provide a uniform critical flow rate with changing fluid conditions such as temperature, pressure and composition upstream from the venturi.
A venturi tube fluid flow meter comprising an inlet section with a first pressure probe upstream of the throat section that is an inner-end closed tube traversing the diameter of the inlet section and pressure probe that is a capped tube extending into the flow path of the throat section at the minimum diameter thereof with this tube containing two perforations 180.degree. apart and orthogonal to the center line of the throat section.
A method of measuring a gas mass fraction (X) in a mass of liquid and gas flowing in direction (A) along pipeline (2) which includes a venturi formed by throat (10), convergent portion (12) and divergent portion (14). Adjacent the venturi (12, 10, 14) but upstream is a flow conditioner (28) creating a uniform mixture of gas and liquid downstream so as to reduce or avoid slip between the gas and liquid phases in the venturi. Differential pressure (DP1) is measured between a position upstream of the flow conditioner and a position intermediate the flow conditioner and venturi. Differential pressure (DP2) is measured between the throat and a position intermediate the flow conditioner and venturi. Differential pressure (DP3) is measured across the venturi. Computer (50) calculates the gas mass fraction (X) using a formula that may take the form: X=a.multidot.(DP1).sup.b.multidot.(DP2).sup.c.multidot.(DP3).sup. d.multidot.(DP2-DP3).sup.e.multidot.(DP1+DP3).sup.f, in which a, b, c, d, e and f are constants.
An apparatus for determining the relative flows of a two phase flow using differential pressure to obtain mass flow having a bend portion for concentrating the dense phase toward an outside of the bend; a perforated plate downstream of the bend for passing the portion of the light phase; a nozzle for channelling the portion of the flow having high density phase toward the center of a venturi throat which is positioned downstream of the perforated plate; and four pressure sensors strategically located for measuring pressure differences at various points in the flow meter.
An apparatus for dispersing the relative flows of a separated two phase flow using a nozzle positioned immediately downstream from a bend in a pipe. The inlet of the nozzle is adjacent an external wall of the pipe and the outlet of the nozzle is substantially on a longitudinal axis of the pipe. The dense phase is collected and transported through the nozzle back into the center of the pipe for uniform mixing and dispersion.
