Engine Definition

In the RPA Lite Edition, Engine Definition screen is used to define the engine name, the description and the combustion chamber pressure.

Engine Definition screen (Lite Edition)

Engine Definition in Express Analysis view

Engine name and description are optional parameters, whereas the combustion chamber pressure is obligatory parameter. Note that engine name is used in results print out to identify the problem.

The pressure is an absolute pressure and can be entered using one of the following units: MPa, atm, kg/sm2, bar, psi, Pa.

In the Express Analysis view the only parameter that is visible and can be changed is combustion chamber pressure.

In the RPA Standard Edition, Engine Definition screen is also used to define the parameters for the combustion chamber and nozzle sizing.

Engine Definition screen (Standard Edition)

The program can estimate the size of the combustion chamber and nozzle matching one of the following requirements:

• Nominal thrust at the certain ambient pressure
• Nominal mass flow rate
• Throat diameter

Chamber and nozzle sizing parameters

If specified number of chambers is greater than 1, the given thrust is a total engine thrust, and the given mass flow rate is a total mass flow rate.

If ambient pressure is not specified, it is assumed that the engine nominally operates in vacuum condition.

The user can specify the nozzle shape on the screen Nozzle Shape and Efficiencies, and sizing parameters on the screens Nozzle Conditions and Chamber Geometry.

All parameters can be entered using either SI or American Customary units:

• thrust: kN, kg, lbf, N
• mass flow rate: kg/s, lbm/s
• throat diameter: mm, in, m, ft

Last modified: February 22, 2011