气体系统

How the Foundation Library gas components can be used to model a controlled pneumatic actuator. The Directional Valve is a masked subsystem created from Variable Local Restriction (G) blocks to model the opening and closing of the flow paths. The Double-Acting Actuator is a masked subsystem created from Translational Mechanical Converter (G) blocks to model the interface between the gas network and the mechanical translational network.

How a pneumatic vane motor can be modeled using the Simscape™ language. The Pneumatic Motor component is built using the Simscape Foundation gas domain. It inherits from the foundation.gas.two_port_steady base class, which contains common equations that implement the upwind energy flow rate and the gas properties at the ports. The Pneumatic Motor subclass implements equations that describe behaviors specific to the component, such as the motor torque and flow rate characteristics and the mass and energy balance. The Pneumatic Motor block is inserted into the model using the Simscape Component block without the need to generate a separate library.

The choking behavior of a gas orifice modeled by the Local Restriction (G) block. The Controlled Reservoir (G) blocks are used to set up controlled pressure and temperature boundary conditions from the Reservoir Inputs subsystem to test the gas orifice.

Models a gas turbine auxiliary power unit (APU) based on the Brayton Cycle. The Compressor and Turbine blocks are custom components based on the Simscape™ Foundation Gas Library. The power input to the system is represented by heat injection into the combustor; actual combustion chemistry is not modeled. A single shaft connects the compressor and the turbine so that the power from the turbine drives the compressor. The APU is a free turbine that further expands the exhaust stream to produce output power.

此示例对建筑中的通风回路进行建模。建筑内部的空气体积被划分为四个区域。通风机组将冷空气吹入 Zone 1，并抽出 Zone 3 中的空气。抽出的空气可选择性地循环回 Zone 1。Zone 4 中的门可被打开，将空气排到大气中。

Model a Gamma Stirling engine using gas, thermal, and mechanical Simscape™ components and domains.

The Fanno flow model is an analytical solution of an adiabatic (perfectly insulated) compressible perfect gas flow through a constant area pipe with friction. This example shows a comparison and validation of the Simscape™ Pipe (G) block against the Fanno flow model. While you typically need empirical data to validate a block over a range of scenarios, it may still be useful to perform limited validation against analytical models for specific scenarios. This is because the theory and derivation behind the analytical model may provide more insight into where the block works well and how to address limitations. The comparison shows that, for short to moderate pipe lengths, the Simscape pipe model agrees well with the Fanno flow model. For long pipe lengths, a segmented pipe model agrees well with the Fanno flow model.

Gas flow through a compressor which is modeled using a simple controlled mass flow rate source. The compressor map that governs this mass flow rate is modeled using the PS Scattered Lookup (2D) block whose data coordinates are the pressure ratio (Pa/Pa) and the engine RPM, and the output is the mass flow rate (kg/s). The scattered lookup block performs delaunay triangulation on the input data (which is shown in plots below), and uses this to interpolate and calculate the mass flow rate based on the input. Scattered lookup allows modeling of the compressor even if the data provided is in an unstructured format.