**8. Gas turbine diagnostics**

This chapter focuses on reliability of gas path diagnosis. New solutions are proposed to reduce the gap between simulated diagnostic process and real engine maintenance conditions. Thermodynamic models, data validation and tracking the deviations, fault classification, fault recognition techniques, multi-point diagnosis, diagnosis under transient

**1** 

*Italy* 

Roberto Capata

 *Faculty of Engineering, Roma* 

**Ultra Micro Gas Turbines** 

*Department of Mechanical and Aerospace Engineering, University of Roma 1,* 

Object of the present work is the detailed study, in every its aspect, of Ultra-Micro-Gas-Turbine Generator, that is a power device with high power density. These generators, although the covered power range oscillates between 100 and 500W, is characterized by very reduced overall dimensions: this introduces complications in the design and, above all, the realization of the mechanical components who represents the greater difficulty to exceed. The advanced searches in this field preview the realization of the characteristic

• the impellers, both turbine and compressor, can be manufacturing with silicon,

• the combustion chambers can be obtained in toroidal spaces with the possible lowest volume: this involves the necessity to construct fuel injection device technologically complicated, inside the same combustion chambers; a different model is constituted, in some NATO devices, by a 2-D geometry combustion chambers (an example is visible in

• the electrical generators are constituted by a highest number of polar braces due to high rotational speed of the machine (> 100 000 rpm). Their realization is realized by micro manufacturing of planned rings that have been inserted in the case (for the statoric part), and the other ring is located on the faces the rotor impeller (usually the

• the rotational speed is within 150 000 ÷ 350 000 rad/s (in some cases > 500.000)

Fig. 1. Typical compressor a) and b) turbine D geometry [Epstein 2003]

**a) b)**

**1. Introduction 1.1 State of art** 

figure 2);

structures of the machine with high tech systems:

titanium or special alloys micro laser techniques (figure 1);

compressor, to avoid the high temperatures problems);

conditions, and system identification techniques are presented. Practical recommendations are given to develop an effective condition monitoring system.
