THRUST is an extension of the toolkit FLUIDAPRO adding capabilities for general aerospace propulsion modelling and simulation. The toolkit provides the user with the capability of simulating fluid systems through different components such as volumes, heat exchangers, chemical reactors, tanks, pumps, compressor, turbines, pipes, valves, actuators, etc.
THRUST includes an extensive fluid database of perfect gases, perfect liquids or real (NIST) fluids and a set of thermodynamic functions able to handle four different categories of fluids:
Using drag & drop methodology and the large palette of components provided by THRUST, the user can quickly create the model to be analysed through an intuitive fluid diagram with a similar appearance to the real system.
Model description
This model represents a complete SSME cycle type. Input data are rough values, the aim of this example being only to demonstrate the capabilities of THRUST Libraries’ regarding this type of complex staggered engines.
Besides the correct definition of turbo machinery operational data, one of the most difficult parts of the transient case adjustment has been to define appropriate valve areas and opening laws able to yield the correct ignition of the pre-burners and the main chamber.
Steady conditions are maintained between 4 and 5 seconds only, sufficient to reach a stationary response. The shutdown sequence is:
Results
It can be checked during start-up that the values calculated by the EcosimPro model match closely those the reference.
We present below some plots obtained:
A transient model of the Space Shuttle Main Engine has been successfully simulated in THRUST. The results reveal a typical transient evolution caused by the start-up and shutdowns of the engine, similar to the ones reported in the open literature.
This simplified model represents a Hall-Effect Thruster fed by a constant mass flow of Xenon, where the discharge voltage between the anode and cathode is applied by a constant voltage source. The aim of this example is to match the semi-empirical model of the thruster to some experimental measures by adjusting the data of the component.
Five optimizations will be carried out, each of them corresponding to one mass flow rate of Xenon, according to the reference. Hence, for each propellant mass flow condition, a parameters estimation is performed in such a way that the thrust obtained by the model matches with the thrust measured in the test bench at certain discharge voltages.
The following figure shows the observed value of the thrust and the fitted value provided by the model versus the discharge voltage for each Xenon mass flow:
Modelling of a gridded-ion thruster coupled with control and electrical elements. The model consists of one control loop that regulates the opening of the valve to keep a certain Xenon mass flow, and a second one that varies the current through the coil of the thruster to maintain the ion-generated thrust constant.
With this model, the user can obtain the performance of the thruster for a wide range of mass flows at certain grids voltages maintaining the thrust generated by the ions at a specific value. To do this, transient calculations inside of a FOR loop are run enough time up to the system reaches a steady state, then the steady values are plotted.
In this regard, the different contributions to the net thrust generated by the device for several propellant mass flows are showed:
The thruster is also capable to estimate both the electron (GIT.TeV, in eV) and the ionized gas (GIT.Tg) temperatures:
Finally, the particles densities within the thruster chamber are plotted versus the mass flow, where:
And the specific impulse generated by the thruster, that takes typical values for this kind of electric thrusters:
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