Flow Rate Sensor (MA)

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

Since R2023a

• 

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

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.

• Open Model

Ports

Output

M — Mixture mass flow rate, kg/s

physical signal

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

Dependencies

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

V — Mixture volumetric flow rate, m^3/s

physical signal

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

Dependencies

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

φ — Mixture energy flow rate, W

physical signal

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

Mw — Water vapor mass flow rate, kg/s

physical signal

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.

Mg — Trace gas mass flow rate, kg/s

physical signal

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.

Md — Water droplet mass flow rate, kg/s

physical signal

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.

Conserving

A — Sensor inlet

moist air

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

B — Sensor outlet

moist air

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

Parameters

Mass flow rate — Control output port visibility for measuring mass flow rate

On (default) | Off

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

Volumetric flow rate — Control output port visibility for measuring volumetric flow rate

Off (default) | On

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

Volumetric flow measurement conditions — Specify conditions for measuring volumetric flow rate

Actual conditions (default) | Standard conditions

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, and relative humidity.

Dependencies

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

Standard pressure — Moist air pressure at standard conditions

0.10132 MPa (default)

Moist air pressure at standard conditions.

Dependencies

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

Standard temperature — Moist air temperature at standard conditions

20 degC (default)

Moist air temperature at standard conditions.

Dependencies

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

Standard relative humidity — Moist air relative humidity at standard conditions

0.65 (default)

Moist air relative humidity at standard conditions.

Dependencies

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

Energy flow rate — Control output port visibility for measuring energy flow rate

On (default) | Off

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

Water vapor mass flow rate — Control output port visibility for measuring water vapor mass flow rate

On (default) | Off

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

Trace gas mass flow rate — Control output port visibility for measuring trace gas mass flow rate

On (default) | Off

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

Water droplets mass flow rate — Control output port visibility for measuring water droplets mass flow rate

Off (default) | On

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

Extended Capabilities

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

Version History

Introduced in R2023a

R2024b: Model water droplets suspended in moist air flow

Blocks in the moist air domain can now model water droplets suspended in a moist air flow. To model water droplets, select Enable entrained water droplets in the Moist Air Properties (MA) block connected to your moist air network.

R2023a: Usability enhancement for moist air sensors

In R2023a, separate Mass & Energy Flow Rate Sensor (MA) and Volumetric Flow Rate Sensor (MA) blocks have been combined into a single Flow Rate Sensor (MA) block that lets you measure mass flow rate, energy flow rate, and volumetric flow rate. The new block lets you use the block parameters to expose only the ports that you need for measurements in a particular model, which helps to reduce clutter and improve the block diagram layout.

This change has no compatibility impact when you use these Foundation library blocks in your models. When you open an existing model, the Mass & Energy Flow Rate Sensor (MA) and Volumetric Flow Rate Sensor (MA) blocks within it are automatically replaced by Flow Rate Sensor (G) blocks with the appropriate ports exposed.

However, if you use the Mass & Energy Flow Rate Sensor (MA) and Volumetric Flow Rate Sensor (MA) blocks in your custom composite components, you need to update the composite component code.

Sensor Block to Update	Old Syntax	New Syntax
Mass & Energy Flow Rate Sensor (MA)	sensor = foundation.moist_air.sensors.mass_flow_energy_flow_sensor;	sensor = foundation.moist_air.sensors.flow_sensor;
Volumetric Flow Rate Sensor (MA)	sensor = foundation.moist_air.sensors.volumetric_flow_sensor;	sensor = foundation.moist_air.sensors.flow_sensor(volumetric_flow_measure=true);