Integration of Inlet and Combustor Subsystem Models into a TBCC Engine Performance Model

The growing suit of engineering modeling tools eases the development of individual component subsystems, but it also complicates the integration of these subsystems into a fully integrated model. Highly specialized tools enable engineers to develop subsystems – thermal management, propulsion, controls, aerodynamics, avionics – with increasing efficiency, since these tools have specific libraries, methods, and solvers pre-developed that can simply be plugged into or utilized by the subsystem designer. Although specialized engineering tools ease the development of individual subsystems, integrating and managing the various subsystem models becomes increasingly complex. This paper explains how a complex inlet model and complex combustion model were integrated into a full-system performance model of a turbine-based combined cycle (TBCC). For successful integration of the inlet and combustor subsystems, a reliable interface was needed between each subsystem and the engine performance model. The TBCC engine model discussed in this paper was developed using the Numerical Propulsion System Simulation (NPSS) software, which acted as the driving testbed for managing the execution sequence of the other subsystems. The inlet subsystem was developed and calibrated using Excel, the combustion subsystem was developed in python, and a visualization framework was utilized for visualizing the entire system. NPSS, Excel, and python each offered unique capabilities that made them ideal for developing their respective subsystems. Since simulation time is an important consideration, especially as more subsystem models are integrated into a high-fidelity digital twin testbed, it is important to increases simulation speed as much as possible. One way to improve simulation speed is via different communication patterns. For this reason, synchronous and asynchronous communication patterns were explored with the NPSS TBCC model. It was found that a synchronous communication pattern with the inlet subsystem, combined with an asynchronous communication pattern for the combustor subsystem yielded the fastest solution time. It was also found that eliminating the visual IDE framework improved solution time. This paper discusses the development of the digital twin TBCC model in NPSS, the integration of the subsystem models, and the different communication patterns that were evaluated. A discussion and summary of the results is provided at the end.