Apparatus and method for compressor and turbine performance simulation
A method and an apparatus for simulating the operation of a pressured air source or sink such as a compressor or a turbine for a vehicle internal combustion engine calculates momentum sources at interfaces in the compressor or the turbine. A model stores steady state values of mass flux and enthalpy change related to rotational speed, inlet pressure and temperature and outlet pressure. The simulation can be an input to an engine control module for controlling the operation of the vehicle engine connected with the compressor or turbine.
1. A method for simulating behavior of an engine compressor or turbine comprising the steps of:
providing an engine control module for controlling the operation of the engine;
providing a model means connected to said engine control module for generating a simulation of an operational behavior of the turbine whereby said engine control module is responsive to the simulation in real time for controlling the operation of the engine; and
providing a program for engine control which includes the steps of
a. defining a mass flux at an interface between upstream and downstream nodes in a turbine or compressor as a function of a mass flux at the interface at a previous time, an upstream mass flux, an upstream velocity, a downstream mass flux, a downstream velocity, an area of the interface, an upstream static pressure, a downstream static pressure, and a momentum source, said step being performed by defining the mass flux at time “n+1” as equal to the mass flux at time “n” plus a value obtained by multiplying a quantity by the ratio of the time between “n” and “n+1” to a distance between the upstream and downstream nodes;
b. providing look up maps or a calculation of steady state values of mass flow and pressures wherein the steady state mass flux and enthalpy change are functions of a rotational speed of the compressor or turbine, an inlet temperature, an inlet pressure and an outlet pressure, or wherein an outlet steady state pressure or a steady state pressure ratio are functions of the rotational speed, the mass flux, the inlet pressure and the inlet temperature;
c. calculating the momentum source at the interface using the steady state values in the look up maps or the calculation of steady state values; and
d. simulating the behavior of the turbine or compressor by performing step c. at a first interface between an inlet duct and a control volume and a second interface between the control volume and an outlet duct.
2. The method of claim 1 wherein said quantity is to the upstream mass flux times the upstream velocity, minus the downstream mass flux times the downstream velocity, plus the interface area times the difference between the upstream pressure and the downstream pressure, plus the interface area.
3. An apparatus for controlling an internal combustion engine having a turbine comprising:
an engine control module for controlling the operation of the engine;
a model means connected to said engine control module for generating a simulation of an operational behavior of the turbine whereby said engine control module is responsive to the simulation in real time for controlling the operation of the engine; and
a program for engine control which includes the steps of:
a. defining a mass flux at an interface between upstream and downstream nodes in said turbine as a function of a mass flux at the interface at a previous time, an upstream mass flux, an upstream velocity, a downstream mass flux, a downstream velocity, an area of the interface, an upstream static pressure, a downstream static pressure, and a momentum source, said step being performed by defining the mass flux at time “n+1” as equal to the mass flux at time “n” plus a value obtained by multiplying a quantity by the ratio of the time between “n” and “n+1”to a distance between the upstream and downstream nodes;
b. providing look up maps or a calculation of steady state values of mass flow and pressures wherein the steady state mass flux and enthalpy change are functions of a rotational speed of the turbine, an inlet temperature, an inlet pressure and an outlet pressure, or wherein an outlet steady state pressure or a steady state pressure ratio are functions of the rotational speed, the mass flux, the inlet pressure and the inlet temperature;
c. calculating the momentum source at the interface using the steady state values in the look up maps or the calculation of steady state values; and
d. simulating the behavior of the turbine or compressor by performing step c. at a first interface between an inlet duct and a control volume and a second interface between the control volume and an outlet duct.
4. The apparatus according to claim 3 wherein said model means stores steady state values in look up maps or calculates them and calculates a momentum source at interfaces in the turbine using the calculated steady state values or the steady state values in the look up maps, said interfaces including a first interface between an inlet duct and a control volume and a second interface between the control volume and an outlet duct.
5. An apparatus for controlling an internal combustion engine having a compressor comprising:
an engine control module for controlling the operation of the engine; and
a model means connected to said engine control module for generating a simulation of an operational behavior of the compressor whereby said engine control module is responsive to the simulation in real time for controlling the operation of the engine; and
a program for engine control which includes the steps of:
a. defining a mass flux at an interface between upstream and downstream nodes in said compressor as a function of a mass flux at the interface at a previous time, an upstream mass flux, an upstream velocity, a downstream mass flux, a downstream velocity, an area of the interface, an upstream static pressure, a downstream static pressure, and a momentum source, said step being performed by defining the mass flux at time “n+1” as equal to the mass flux at time “n” plus a value obtained by multiplying a quantity by the ratio of the time between “n” and “n+1” to a distance between the upstream and downstream nodes;
b. providing look up maps or a calculation of steady state values of mass flow and pressures wherein the steady state mass flux and enthalpy change are functions of a rotational speed of the compressor, an inlet temperature, an inlet pressure and an outlet pressure, or wherein an outlet steady state pressure or a steady state pressure ratio are functions of the rotational speed, the mass flux, the inlet pressure and the inlet temperature;
c. calculating the momentum source at the interface using the steady state values in the look up maps or the calculation of steady state values; and
d. simulating the behavior of the compressor by performing step c. at a first interface between an inlet duct and a control volume and a second interface between the control volume and an outlet duct.
6. The apparatus according to claim 5 wherein said model means stores steady state values in look up maps or calculates them and calculates a momentum source at interfaces in the compressor using the calculated steady state values or the steady state values in the look up maps, said interfaces including a first interface between an inlet duct and a control volume and a second interface between the control volume and an outlet duct.