ABSTRACT: This article describes the run time characteristics of a gas turbine performance simulation using different solvers and components off-design performance database formats. Two different nonlinear systems of equation solvers, Newton-Raphson's and Broyden's, and two different formats of compressor and turbine off-design performance database (maps), tabulated values and fitted surface equations, were compared. Based on the results it is then possible to trade off and select the most appropriate combination of solver and component map type for the gas turbine performance simulation for real-time application.

ABSTRACT Industry and universities around the world invest time and money to develop digital computer programs to predict gas turbine performance. This study aims to demonstrate a brand new digital model developed with the ability to simulate gas turbine real time high fidelity performance. The model herein described run faster than 30ms per point, which is compatible with a high-definition video refresh rate: 30 frames per second. This user-friendly model, built in Visual Basic in modular structure, can be easily configured to simulate almost all the existing gas turbine architectures (single, 2 or 3 shaft engines mixed or unmixed flows). In addition, its real time capability enables simulations with the pilot in the loop at earlier design phases when their feedback may lead to design changes for improvements or corrections. In this paper, besides the model description, it is presented the model run time capability as well as a comparison of the simulated performance with a commercial gas turbine tool for single, 2 and 3 shaft engine architecture.

ABSTRACT: The Instituto Tecnológico de Aeronáutica (ITA) is an Engineering school maintained by the Air Force Command, Ministry of Defense. The aim of the Turbomachines Department at ITA is the human resources training for design and development of aeronautical and industrial gas turbines, necessary for the Gas Turbine Program of the Departamento de Ciência e Tecnologia Aeroespacial (DCTA). The human resources training is carried out in undergraduate and graduate courses at ITA, where topics in gas turbine and turbomachinery are taught. The gas turbine topic is taught in the undergraduate degree, in Mechanical-Aeronautical Engineering course, and focuses on gas turbines' performance for different configurations (turboshaft, turbojet and turbofan). Lecture notes containing the essential elements of the course are made available for the students, addressing the basic theory of the gas turbines required for the performance study at the design and off-design point. The technological aspects are presented and discussed during detailed studies of the actual cycle. Simple gas turbines and more sophisticated ones are studied, for both aeronautical and industrial application. Performance calculations at design and off-design point of the main engine's components and the cycle are done manually, encouraging students to develop spreadsheets. The theory is complemented with laboratory classes and technical visits, when the practicalities involving gas turbines operation and tests are presented to the students. As an activity laboratory class, the students perform disassembly-assembly of a small industrial gas turbine.

ABSTRACT: The noise source distribution of a short-cowl coaxial jet operating at different velocity ratios is described in this work. This was motivated by an ongoing research about noise prediction of coaxial jets through Acoustic Analogy with purposes of industrial engine application. This research has been carried out between Universidade Federal de Uberlândia (UFU), Brazil and the Institute of Sound and Vibration Research (ISVR) at Southampton University, UK. The numerical approach employed is originally based on Lighthill Acoustic Analogy. This technique, although likely known, is associated with an improved energy transfer time-scale, used in the turbulence two-point correlation function, in order to enhance the source model. The source model is coupled with the aerodynamic calculation of flow through turbulence quantities evaluated by using a standard k-ε turbulence modeling. The Computational Fluid Dynamics data have also been used to provide complementary information about the coaxial jet noise production mechanisms. Experimental data were used in order to corroborate the results from the current model. Good agreement has been found, showing that high and low frequency contributors to the radiated noise for low velocity ratio are aggregated in a region about seven to ten secondary diameters downstream, while at higher velocity ratios sources are continuously spread from about one up to ten secondary diameters from the jet exit.