Automatic Control Example

A selection of automatic control functions can be included in the Combustion Control System software to perform particular operations on the test stand.  These functions can reduce operator workload and enhance the safety of system operation.

The Main Combustor Auto Start function, is an example of a CCS automatic control function.  The objective of this function is to provide a reliable start of the main combustor.

The Auto Start function can be configured to use combustor temperature for control of the main combustor start process.  With reference to the plot at right, the function operates as follows.  Upon detecting stable igniter operation at the origin of the time axis (t=0), the main run valves of the combustion system would typically be opened and fuel and oxygen begin flowing into combustor.  Three possible outcomes and the corresponding response of the Auto Start function are as follows.

1. Nominal Combustor Ignition - The combustor temperature rises above the user-defined "Combustor Ignition Threshold Temperature" and stabilizes below a user-defined "Maximum Combustor Temperature".  Normal steady state operation of the combustion system would then occur.
2. Combustor Ignition Failure - The combustor temperature does not reach the Combustor Ignition Threshold Temperature within the user-defined "Maximum Time to Threshold Temperature".  In this case, an abort sequence is automatically executed to terminate the test and return the test stand to a safe state.
3. High Combustor Temperature - The combustor temperature exceeds the "Maximum Combustor Temperature" upon opening the run valves. This condition could occur if the ratio of oxidizer to fuel is too high.  To avoid possible damage from excessively high temperatures, an abort sequence is automatically executed and the test is terminated to return the test stand to a safe state.

While this description of the Auto Start function featured the use of combustor temperature as the monitored parameter, other measurable parameters, including chamber pressure and IR or UV emissions could also be used, either alone or in combination, as inputs to the Auto Start function.

Main Combustion Auto Start Function