Showing papers on "Thermal mass flow meter published in 1991"

High turndown mass flow control system for regulating gas flow to a variable pressure system

Abstract: A high turndown mass flow control system for the regulation of gas flow to a variable pressure system such as a gas turbine engine. The herein described system controls the flow of gas into a load system where the gas delivery pressure at the load varies directly as a function of the mass flow. The system employs flow control and mass flow measurement subsystems, controlling the mass flow to maintain a mass reference value called for by an outside master control. Flow control apparatus includes a throttling control valve while the flow measurement subsystem includes a flow restriction element, δP, pressure and temperature transducers while using a flow calculation algorithm to calculate the actual gas mass flow passing through the system. The high turndown mass flow control characteristic of the invention acquired by an unique placement and usage of the gas restriction element allows the reading of δP parameters with conventional instrumentation.

Unitary fluid flow production and control system

Abstract: A fluid flow production and control system includes a variable speed pump defining a fluid flow path therethrough and a fluid flow path outlet, for operating at a speed determined by an input speed control signal. Also included is a pressure sensor for detecting the pressure of fluid at the outlet, and a flow rate sensor for detecting the flow rate of fluid at the outlet. One or more dimensional parameters of the flow path, such as the cross-sectional area, venting ports along the direction of the flow path, and the like, may be varied in response to a parameter control signal. A control unit coupled to the pressure sensor and flow rate sensor and responsive to detected pressures and flow rates supplies an input speed control signal to the pump and a parameter control signal to the dimensional parameter varying mechanism to thereby produce a selected flow rate and fluid pressure at the outlet.

An experimental investigation of thermally induced flow instabilities in a convective boiling upflow system

Abstract: The two-phase flow instabilities in a single channel, forced convection, open loop, up-flow system have been investigated experimentally using R-11 as the working fluid. The effects of mass flow rate, heat input, inlet liquid temperature and upstream compressible volume on two-phase flow instabilities have been investigated. Two heater surfaces were tested at five different heat inputs with constant inlet temperature, and four different inlet temperatures with constant heat input. For each case, the mass flow rate was varied over a wide range covering the entire scope for boiling two-phase flows. Experiments were also conducted at different compressible volumes, with constant heat input, inlet fluid temperature, and average mass flow rate. The oscillations of inlet mass flow rate, heater inlet pressure, and heater wall temperature were recorded. The effects of mass flow rate, inlet liquid temperature and heat input on the amplitudes and periods of inlet pressure and thermal oscillations are presented in tabular and graphical forms.

Non-intrusive flow meter for the liquid based on solid, liquid or gas borne sound

Abstract: A method for measuring the mass flow rate of liquid flow exiting a two phase (gas/liquid) feed nozzle. The method includes determining the Power Spectral Density from the output of an accelerometer in close proximity to the restriction orifice controlling the gas flow, or determining the Power Spectral Density from the output of a pressure transducer in contact with the gas flow on the down stream side of the restriction orifice. The liquid flow can then be obtained from a predetermined correlation between the RMS Vibrational Signal and the mass or liquid flow rate.

Method for in-line calibration verification of mass flow meters

Abstract: An apparatus for verifying the calibration of a flow meter contains a flow sensor assembly which has a flow tube defining an axial fluid path through the flow sensor assembly; an upstream temperature sensor in thermal contact with the flow tube; a downstream temperature sensor in thermal contact with the flow tube, the two sensors being operationally connected to a means for producing an output in response to a temperature difference between the first and second sensors; and means for asymmetrically transferring heat to the first and second temperature sensors independently of fluid flow through the flow tube. The calibration of the flow meter's thermal and electronic systems is verified by measuring the flow meter's output in response to a first asymmetric heat transfer to the upstream and downstream temperature sensors when the flow meter is calibrated. The output of the flow meter in response to a second asymmetric transfer to the upstream and downstream sensors is subsequently measured and comparison of the two readings verifies whether the flow meter's thermal and electronic systems remains calibrated.

Compact gas flow meter using electronic microsensors

Abstract: A compact dual microanemometer-based flow meter for a gaseous fluid includes a dynamic microanemometer flow sensor located in a measuring nozzle of reduced diameter directly exposed to the main fluid flow stream and a static microanemometer sensor located so as to be in communication with the main flow stream but not in direct contact with the main flow stream. Particulate matter is excluded by a particulate trapping system located upstream of the flow sensors and has a plurality of sequentially encountered particulate traps including dead-end trap and settling traps and a honeycomb laminarizing device is positioned in the stream between the particulate trapping system and the microanemometers.

A micromachined flow sensor for measuring small liquid flows

Abstract: A flow sensor for measuring small liquid flows in chemical measurement systems has been fabricated using bulk silicon micromachining techniques. The liquid flow sensor utilizes the measurement principle of thermal transit time, where a heat pulse is injected into the liquid and the velocity of the heat pulse is measured. The sensor consists of a silicon wafer mounted between two glass plates. A flow channel is anisotropically etched into the front side of the wafer, and on the back side electrical components for heat delivery and temperature detection are made. The flow sensor shows excellent accuracy, speed, and long-term stability. Due to the well-defined geometry easily obtainable in this technology, the mechanical, thermal, and flow properties of the flow sensor are very reproducible. There is firm mechanical insulation between the fluid system and the electrical parts of the sensor. Good thermal coupling between the fluid and the temperature controlling components is ensured, since silicon is an excellent heat conductor. >

Method and apparatus for measuring mass flow and energy content using a linear flow meter

Abstract: The present invention is a method and apparatus for monitoring in real time the mass and energy flow rate of a gas through a pipeline. The invention determines the mass flow ratio of a pipeline gas flowing through a pipeline compared to sample gas tapped from the pipeline line when the volumetric flow of pipeline gas through the pipeline is measured by a linear flow meter. Sample gas tapped from the pipeline is flowed to a chamber having a section with a fixed volume until the pressure in the chamber section is substantially equal to the pipeline gas pressure. The sample gas is maintained at substantially the same temperature as the gas in the pipeline while the sample gas is in the chamber section. A timer measures the time interval for the sample gas to flow from the chamber section at a selected rate for a calculated pressure drop the selected rate being controlled by a flow controller. The mass flow ratio is computed using the measured time interval and a signal from the linear flow meter. The energy flow rate of the pipeline gas is determined by measuring the energy flow rate of the sample gas and relating that value to the mass flow ratio of the pipeline gas compared to the sample gas.

Micro flow sensor and integrated magnetic oxygen sensor using it

Abstract: A thermal micro mass flow sensor was developed. A micro bridge heater was fabricated by micromachining. The sensor has high sensitivity and quick response because of its small thermal capacity and small thermal time constant. Micro bridge differential heaters were used to detect mass flow in a small flow range. An integrated magnetic oxygen sensor was fabricated using the micro thermal flow sensor. The flow sensor and the micro valve will be applied in integrated gas control systems. >

Flow meter and measuring method therefor

Abstract: A flow meter is provided which employs a thermal flow sensor and a correcting flow meter, for example, a Karman vortex flow meter such that the output from the thermal flow sensor is corrected by the Karman vortex flow meter, thereby making it possible to accurately and stably measure the flow rate of fluids in a wide range even if the composition of fluids changes.

Flow meter and method of fluid flow measurement

Abstract: A flow meter is provided which employs a thermal flow sensor (1) and a correcting flow meter (2), for example, a Karman vortex flow meter such that the output from the thermal flow sensor is corrected by the Karman vortex flow meter, thereby making it possible to accurately and stably measure the flow rate of fluids in a wide range even if the composition of fluids changes.

Is-enthalpic control of a thermal printing head

Abstract: Is-enthalpic temperature control of the operation of the thermal printing head of a thermal printing device is attained by use of a transfer area at the head to transfer heat from the head to a coolant fluid moved by a fluid mover across the transfer area at a flow rate controlled by a circuit on the basis of a sensor that measures the flow rate of electrical energy being fed to the head, and sensors that sense the mass flow rate of the fluid and its rise in temperature upon flow across the transfer area for determining the flow rate of energy being removed from the head. The circuit controls the fluid mover to adjust the fluid flow rate so that the net energy in the head remains substantially constant.

Flowmeter for open duct - has flow sensor movable across channel to supply computer with flow speeds measured at several points

Abstract: A flow probe (15) immersed in the liquid, is fitted at a positioning device (11) and can be moved under the control of a computer (20) The flow probe is movable to numerous measuring points distributed in a measurement plane running at right angles to the duct (10) and their flow speeds are measured and stored in the computer The computer, in a calibrating phase, determines an average flow speed of the measurement points and determines a reference flow speed at a reference position The computer (20), in a measurement phase, a sets the flow probe to the reference position and according to the relationship obtained in the calibrating phase between the average flow speed and the reference flow speed computes the actual total flow speed ADVANTAGE - Facilitates exact determination of flow rate at different level heights, even with duct cross-section varying wrt time

Hot-electrical-resistance type gas flow meter and internal combustion engine with hot-electrical-resistance type gas flow meter

Abstract: An object of the present invention is to provide a hot-electrical-resistance type gas flow meter wherein a deterioration of a gas-cooled hot-electrical-resistance is prevented at the maximum flow rate, a decrease of sensitivity is prevented at the minimum flow rate and a wide dynamic range is achieve, and a structural feature of such gas flow meter is that the gas flow meter includes auxiliary path flow resistance changing means for changing a flow resistance of the auxiliary path so that the larger the flow rate of the flow is, the larger the flow resistance of the auxiliary path is.

Low volume flow meter

Abstract: The low flow monitor provides a means for determining if a fluid flow meets a minimum threshold level of flow. The low flow monitor operates with a minimum of intrusion by the flow detection device into the flow. The electrical portion of the monitor is externally located with respect to the fluid stream which allows for repairs to the monitor without disrupting the flow. The electronics provide for the adjustment of the threshold level to meet the required conditions. The apparatus can be modified to provide an upper limit to the flow monitor by providing for a parallel electronic circuit which provides for a bracketing of the desired flow rate.

Combination water meter for large and small flows - has changeover valve for Woltmann meter and auxiliary meter operated according to flow rate

Abstract: A Woltmann meter (1) is used as the main meter to ascertain the larger flow. An auxiliary meter (3) in a neighbouring line (2) at the side of the main meter measures the smaller flow. A change-over valve (4) behind the main meter opens upon reading a certain flow rate. The outlet (6) of the auxiliary line (2) merges into a side of the valve housing (5). The closure piece of the valve is slidable along the length axis of the valve by means of a central glide bolt. The closure force is provided by a magnetic stopper and a pretensioned pressure spring. The opening force is created by the pressure difference between the pressure of the steady water in the main meter and the low pressure arising from flow through the auxiliary meter. ADVANTAGE - By simple means, change-over valve operates automatically without outside help and without giving rise to measuring errors.

Method and apparatus for determining flow rates of well fluid constituents

Abstract: A method and apparatus for determining flow rates of well fluid constituents on a much smaller scale than with prior art equipment. Rather than testing the total fluid stream, a sample stream portion is diverted from the total fluid stream and tested. The sample fluid stream portion is separated into its various constituents, and the mass flow rate of each constituent is determined. The total mass flow rate of the total fluid stream is measured and compared with the total mass flow rate of fluid flowing through the sample stream portion, so the total flow rate of each constituent may be calculated.

Low Flow Vortex Shedding Flow Meter for Hypergolics/all Media

Abstract: A family of vortex shedding flow meters, for measurement of hypergol flows, was designed and fabricated. The test loops to evaluate the flow meters for water flow, as well as Freon -113 flow which simulates the hypergolic fluids, were modified and constructed to utilize a pump system which has an output capacity of 200 gpm. Test runs were conducted on the small 1/2 inch model with Freon 113 and on the larger models with water. Results showed that the linearity between the frequency of the vortices and the flow rate of the fluids was very close to that of the turbine flow meter. It is suggested that the vortex shedding flow meter is a possible replacement for the existing turbine type.

1991 nasa/asee summerfaculty fellowshipprogram

Abstract: SUMMARYCurrent turbine flow meters have been used to measure the loading of hypergolsinto the Space Shuttle Orbiter. Because of the problems associated with therefurbishment of these meters after each launch, NASA has considered the developmentof a vortex shedding flow meter which would have no internal moving parts. Theobjective of the current project was to develop a family of vortex shedding flow meterswith outside diameters varying from 1/2" to 2" for a low flow environment.To test the meters with the flow of water and Freon 113 which has fluid propertiessimilar to hypergols, two flow test loops were designed and built. One loop was for the1/2" model using Freon 113 as operating fluid. Another loop consisted of a pump systemwas designed for the larger models of 3/4", 1", 1.5" and 2" 0.0. using water asoperating fluid. A family of flow meter models consisted of 13 different configurationswere designed and fabricated. Test runs were conducted successfully on the 1/2" modelswith Freon 113 and the others with water.Results showed that the linearity between the frequency of the vortices and the flowrate of Freon 113 and water for all flow meters with a rectangular shedder bar wasvery close to that of the turbine type. It is concluded that the vortex shedding flow meteris a possible replacement for the turbine flow meter being used on the space shuttle.