A method of adjusting turbine engine transient test data for the effects of variations in environmental conditions

In a turbine engine altitude test facility, it is desirable to maintain steady environmental test conditions during engine throttle transients. In practice, limited variations from the desired steady test conditions are acceptable. These small variations can affect the analysis of the transient performance of the test engine. An alternative is to adjust transient test data to account for variations from the desired environmental conditions.

Using a set of equations that describe the incremental relationships among turbine engine performance parameters, an analytical method has been developed to adjust turbine engine throttle transient test data for variations in environmental test conditions from the desired values. The method was evaluated using validated turbine engine mathematical model data.

Results were compared with model predictions for the desired conditions and also with model data adjusted from simulated test cell conditions (as-tested) to desired conditions using a method commonly used on steady-state data. The results indicated that for throttle transients with no limiting control action, the analytical method made effective adjustments to the as-tested model data for pressure variations of less than ten percent and for temperature variations of less than one percent. The analytical method adjustments for total pressure variations were comparable to other adjustment methods, but the static pressure and inlet temperature adjustments using the analytical method were superior within the constraints mentioned above.