Chamber Performance

The screen Chamber Performance consists of 4 tabs Thermodynamic properties, Performance, Altitude performance, and Throttled performance.

You can print out the results, clicking the button Print, or save the results as ASCII or HTML file, clicking the button Save As... at the right-bottom corner of the screen.

Thermodynamic properties

The tab Thermodynamic properties displays the parameters of reaction products and their mass fractions at the chamber stations involved into the analysis.

Thermodynamic properties (Lite Edition)

Thermodynamic properties (Standard Edition)

The current propellant components ratio (either explicitly defined on the screen Propellant Specification, or found by optimizer) is displayed in the header of the top table on the tab:

If the problem is configured to solve the parameters in the combustion chamber (see chapter Nozzle Flow Model), the only available nozzle station is Injector, otherwise the available chamber stations are Injector, Nozzle inlet, Nozzle throat and Nozzle exit (see figure Thermodynamic properties above).

Injector thermodynamic properties

If the problem is configured to calculate the performance for the combustion chamber with infinite cross section area, the parameters for Nozzle inlet station are identical to that at Injector station:

The thermodynamic parameters are displayed in the current units, defined in the Preferences Dialog.

You can shrink or heighten the top table while the bottom table will be heightened or shrunk, dragging the horizontal bar between the tables down or up.

Performance

The tab Performance displays the theoretical (ideal) performance of the chamber, as well as its estimated delivered performance and the correction factors used to calculate the delivered performance.

Chamber performance (Lite Edition)

Chamber performance (Standard Edition)

Note: if you are analysing a pressure-fed-cycle or staged-combustion-cycle engine, the calculated performance is actually an engine performnce.

The current propellant components ratio (either explicitly defined on the screen Propellant Specification, or found by optimizer) is displayed in the header of the both tables on the tab:

If the problem is configured to solve the combustion parameters at Injector station (see chapter Nozzle Flow Model), the performance parameters are not available, otherwise the tab displays calculated performance of the chamber at the sea level conditions (pa=1 atm, or 14.7 psi), optimum nozzle expansion (pe=pa), and vacuum conditions (pa=0).

In case if flow separation occurs in the nozzle, the additional column displays the performance at sea level with respect to the flow separation.

Chamber performance with flow separation

Ambient conditions for optimum nozzle expansion (altitude and ambient pressure) are displayed at the bottom of the tab:

The performance parameters are displayed in the current units, defined in the Preferences Dialog.

You can shrink or heighten the top table while the bottom table will be heightened or shrunk, dragging the horizontal bar between the tables down or up.

Altitude performance

The tab Altitude performance displays the theoretical (ideal) performance of the chamber in the specified ambient conditions.

Altitude performance

If the problem is configured to solve the combustion parameters at Injector station (see chapter Nozzle Flow Model), the performance parameters are not available, otherwise the tab displays calculated performance of the chamber at the defined altitude and ambient pressure.

You can plot the the diagram "specific impulse vs. altitude", clicking the button Plot at the bottom-right corner of the tab. The altitude of the optimum expansion, as well as the altitude of flow separation (if occurs) is shown on the diagram by corresponded vertical marker line/s.

Plot - altitude performance

Plot - altitude performance with flow separation

Ambient conditions for optimum nozzle expansion (altitude and ambient pressure) are displayed at the bottom of the tab.

The performance parameters are displayed in the current units, defined in the Preferences Dialog.

Throttled performance

The tab Throttled performance displays the theoretical (ideal) performance of the chamber at the specified throttle values.

Throttled performance

If the problem is configured to solve the combustion parameters at Injector station (see chapter Nozzle Flow Model), the performance parameters are not available, otherwise the tab displays calculated performance of the rocket engine at the sea level conditions (pa=1 atm, or 14.7 psi), optimum nozzle expansion (pe=pa), and vacuum conditions (pa=0) at the defined throttle values.

You can plot the the diagram "specific impulse vs. throttle value", clicking the button Plot at the bottom-right corner of the tab. The throttle value where flow separation occurs is shown on the diagram by corresponded vertical marker line.

Plot - throttled performance

The performance parameters are displayed in the current units, defined in the Preferences Dialog.

Last modified: February 22, 2011