Flow Rate Sensor (MA)

R2026b

Measure mass, energy, and volumetric flow rates in moist air networks

Since R2023a

expand all in page
  • Flow Rate Sensor (MA) block

Libraries:
Simscape / Foundation Library / Moist Air / Sensors

Description

The Flow Rate Sensor (MA) block represents an ideal sensor that measures mass flow rate, energy flow rate, and volumetric flow rate in a moist air network. There is no change in pressure, temperature, specific humidity, or trace gas mass fraction across the sensor.

Because the flow rates are Through variables, the block must connect in series with the component being measured.

The relative orientation of ports A and B establishes the measurement sign. The sign is positive if flow occurs from port A to port B. Switching port connections reverses the measurement sign.

Five physical signal ports are available to output the measurement data:

  • Port M outputs the mass flow rate.

  • Port V outputs the volumetric flow rate.

  • Port φ outputs the energy flow rate.

  • Port Mw outputs the water vapor mass flow rate.

  • Port Mg outputs the trace gas mass flow rate.

  • Port Md outputs the water droplets mass flow rate.

These ports have conditional port visibility on the block icon. Use the block parameters to expose only the ports that you need for measurements in a particular model.

Connect the measurement ports to PS-Simulink Converter blocks to transform the output physical signals into Simulink® signals, for example, for plotting or additional data processing.

Examples

Aircraft Environmental Control System

Aircraft Environmental Control System

Models an aircraft environmental control system (ECS) that regulates pressure, temperature, humidity, and ozone (O3) to maintain a comfortable and safe cabin environment. Cooling and dehumidification are provided by the air cycle machine (ACM), which operates as an inverse Brayton cycle to remove heat from pressurized hot engine bleed air. Some hot bleed air is mixed directly with the output of the ACM to adjust the temperature. Pressurization is maintained by the outflow valve in the cabin. This model simulates the ECS operating from a hot ground condition to a cold cruise condition and back to a cold ground condition.

Ports

Output

expand all

Physical signal output port for the mixture mass flow rate measurement.

Dependencies

To enable this port, select the Mass flow rate check box.

Programmatic Use

Port: M

Physical signal output port for the mixture volumetric flow rate measurement.

Dependencies

To enable this port, select the Volumetric flow rate check box.

Programmatic Use

Port: V

Physical signal output port for the mixture energy flow rate measurement.

Programmatic Use

Port: PHI

Physical signal output port for the water vapor mass flow rate measurement.

Dependencies

To enable this port, select the Water vapor mass flow rate check box.

Programmatic Use

Port: Mw

Physical signal output port for the trace gas mass flow rate measurement.

Dependencies

To enable this port, select the Trace gas mass flow rate check box.

Programmatic Use

Port: Mg

Physical signal output port for the water droplets mass flow rate, in kg/s.

Dependencies

To enable this port, select the Water droplets mass flow rate check box.

Programmatic Use

Port: Md

Conserving

expand all

Moist air conserving port. Flow rates are positive if air flows from port A to port B.

Programmatic Use

Port: A

Moist air conserving port. Flow rates are positive if air flows from port A to port B.

Programmatic Use

Port: B

Parameters

expand all

Selecting this check box exposes the output port M, which lets you measure mass flow rate.

Programmatic Use

Parameter: mass_flow_measure
Values: "true" | "false"

Selecting this check box exposes the output port V, which lets you measure volumetric flow rate.

Programmatic Use

Parameter: volumetric_flow_measure
Values: "true" | "false"

Select whether the sensor calculates volumetric flow rate at actual working conditions or at a standard pressure, temperature, and relative humidity:

  • Actual conditions — The sensor calculates the volumetric flow rate by using the moist air density at the actual working conditions of the system.

  • Standard conditions — The sensor calculates the volumetric flow rate by using the moist air density at standard conditions. When you select this option, additional parameters become available to let you specify the standard pressure, temperature, humidity, and trace gas amount.

Dependencies

To enable this parameter, select the Volumetric flow rate check box.

Programmatic Use

Parameter: volumetric_flow_conditions
Values: "foundation.enum.volumetric_flow_conditions.actual" | "foundation.enum.volumetric_flow_conditions.standard"

Moist air pressure at standard conditions.

Dependencies

To enable this parameter, set Volumetric flow measurement conditions to Standard conditions.

Programmatic Use

Parameter: p_std

Moist air temperature at standard conditions.

Dependencies

To enable this parameter, set Volumetric flow measurement conditions to Standard conditions.

Programmatic Use

Parameter: T_std

Method to specify the initial moist air humidity.

Dependencies

To enable this parameter, set Volumetric flow measurement conditions to Standard conditions.

Programmatic Use

Parameter: humidity_spec
Values: "foundation.enum.HumiditySpec.RelativeHumidity" | "foundation.enum.HumiditySpec.SpecificHumidity" | "foundation.enum.HumiditySpec.MoleFraction" | "foundation.enum.HumiditySpec.HumidityRatio" | "foundation.enum.HumiditySpec.WetBulbTemperature"

Moist air relative humidity at standard conditions.

Dependencies

To enable this parameter, set Standard humidity specification to Relative humidity.

Programmatic Use

Parameter: RH_std

Specific humidity in the moist air at standard conditions. The specific humidity is the mass fraction of water vapor to the combined total mass of water vapor, trace gas, and dry air.

Dependencies

To enable this parameter, set Standard humidity specification to Specific humidity.

Programmatic Use

Parameter: x_w_std

Mole fraction of the water vapor in the moist air channel at standard conditions. The water vapor mole fraction is relative to the combined molar quantity of water vapor, trace species, and dry air.

Dependencies

To enable this parameter, set Standard humidity specification to Mole fraction.

Programmatic Use

Parameter: y_w_std

Humidity ratio in the moist air channel at standard conditions. The humidity ratio is the ratio of the mass of water vapor to the mass of dry air and trace gas.

Dependencies

To enable this parameter, set Standard humidity specification to Humidity ratio.

Programmatic Use

Parameter: HR_std

Wet-bulb temperature at standard conditions. The block uses this value to calculate humidity.

Dependencies

To enable this parameter, set Standard humidity specification to Wet-bulb temperature.

Programmatic Use

Parameter: Tw_std

Measurement type of trace gas.

Dependencies

To enable this parameter, set Volumetric flow measurement conditions to Standard conditions.

Programmatic Use

Parameter: trace_gas_spec
Values: "foundation.enum.trace_gas_spec.mass_fraction" | "foundation.enum.trace_gas_spec.mole_fraction"

Amount of trace gas in the moist air by mass fraction at standard conditions. The mass fraction is relative to the combined total mass of water vapor, trace gas, and dry air.

The block ignores this parameter if the Trace gas model parameter in the Moist Air Properties (MA) block is None.

Dependencies

To enable this parameter, set Standard trace gas specification to Mass fraction.

Programmatic Use

Parameter: x_g_std

Amount of trace gas in the moist air by mole fraction at standard conditions. The mole fraction is relative to the combined molar total of water vapor, trace gas, and dry air.

The block ignores this parameter if the Trace gas model parameter in the Moist Air Properties (MA) block is None.

Dependencies

To enable this parameter, set Standard trace gas specification to Mole fraction.

Programmatic Use

Parameter: y_g_std

Relative humidity above which condensation occurs.

Dependencies

To enable this parameter, set Volumetric flow measurement conditions to Standard conditions.

Programmatic Use

Parameter: RH_ws

Selecting this check box exposes the output port φ, which lets you measure energy flow rate.

Programmatic Use

Parameter: energy_flow_measure
Values: "true" | "false"

Selecting this check box exposes the output port Mw, which lets you measure water vapor mass flow rate.

Programmatic Use

Parameter: vapor_flow_measure
Values: "true" | "false"

Selecting this check box exposes the output port Mg, which lets you measure trace gas mass flow rate.

Programmatic Use

Parameter: gas_flow_measure
Values: "true" | "false"

Selecting this check box exposes the output port Md, which lets you measure the water droplets mass flow rate.

Programmatic Use

Parameter: droplets_flow_measure
Values: "true" | "false"

Extended Capabilities

expand all

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2023a

expand all

See Also

Topics