**6. References**

398 Mechanical Engineering

Figure 16(b) shows the response to an equivalent moment of inertia I = 700 kgm2. The system has more damping, reducing the time required to reach a new steady state speed at = 186.77 rad/s (f = 59.5 Hz). Therefore, according Table 2, the industrial frequency falls in the tolerable operating zone, contributing not only to maintain the transient stability of the system, but also ensures the integrity of the steam turbine blades, as well as presenting a significant contribution in terms of the quality of electric power. As for the oscillations of frequency in the transient period, it is verified a maximum speed of = 189.4 rad/s (f = 60.3 Hz), at the moment immediately after the contingency. Nevertheless, with the removal from operation of G1, machine G2 reaches a minimum speed of = 185.28 rad/s (f = 59.0

However, the machine G2 varies in speed within the range between 186.61 187.01 rad/s or 59.4 f 59.5 Hz. It can be noticed that the frequency oscillation, according Table 2, remains in the favorable zone of operation, ensuring the

With the main objective to reduce the oscillations, evident in the speed of operation, of the remaining synchronous generator (G2) it was applied an equivalent moment of inertia I = 800 kgm2, the result can be seen in Figure 16(c). There, the damping obtained allows reaching the new steady state more efficiently. This helps to mitigate the harmful effects to the quality of electric power to ensure better response of electrical parameters of the

With regard to changes in speed, the maximum reaches the magnitude =189.3 rad/s (f = 60.3 Hz) at the tolerable zone of operation, but the minimum is settled at = 185.55 rad/s (f = 59.06 Hz) at the extreme operation zone. Thus, one can conclude here and for the other equivalent inertia moments simulated that, at the instant immediately after the removal of generator G1, the synchronous machine G2 presents a significant reduction in its operating speed. In this way, it is generated a sub-frequency costly to the physical and mechanical integrity of the turbine blades, since the obtained frequency, at this instant, fits the extreme region of operation at Table 2. However, oscillations in the transient period do not affect the impeller blades, as they pass inside the tolerable zone. Nevertheless, after the damped transient period, the machine reaches the new steady-state and stabilizes at a speed = 186.77 rad/s (f = 59.5 Hz), similar to that obtained for the

Through the discussions presented along this chapter, there is the need to make the correct and effective study of the synchronous machine speed governors, in order to obtain better dynamic response of the system. However, this goal is achieved from te transfer function of these governors, so it is essential to be aware of the topology of the turbine used, i.e., whether or not this is reheating . It shows that before the model transfer function, yet it is necessary to choose an appropriate software to implement the model. In this way, it can be seen that ATP, through TACS subroutines allows the correct and efficient computational

Hz) at the extreme operation zone.

case illustrated in Figure 16(b).

modeling of both the speed governor and voltage regulator.

**5. Conclusion** 

system.

expected life time for blades of the steam turbine.


*University of Belgrade, Faculty of Mechanical Engineering,* 

Aerospace engineering is the primary branch of engineering concerned with the design, construction and science of flight vehicle. Consequently, they are usually the products of various technological and engineering disciplines including aerodynamics, propulsion, avionics, materials science, structural analysis and manufacturing. These technologies are collectively known as aerospace engineering. It is divided into two major and overlapping

It is typically a large combination of many disciplines that makes up aeronautical engineering. The development and manufacturing of a modern flight vehicle is an extremely complex process and demands careful balance and compromise between abilities, design, available technology and costs. Aeronautical engineers design, test, and supervise the

Aeronautical Engineering is a chapter that encompasses challenging areas such as aircraft design, light-weight structures, stability and control of aeronautical vehicles, propulsion systems, and low and high speed aerodynamics. The field also covers their aerodynamic

This chapter presents a selection of published scientific papers. The work was the subject of research in the following fields of aerodynamics: Subsonic, Transonic and Supersonic, High Angle of Attack, High Lift, Computational Fluid Dynamics, Wind Tunnel and Flight Testing

In this subchapter we shall be looking at many ways in which to solve the problem of unsteady incompressible flow over an aerofoil. The flow being incompressible is a great simplifier to the problem, this allows to take many of the results of steady flow as read. It is

manufacture of aircraft. They also develop new technologies for use in aviation.

characteristics and behaviors, airfoil, control surfaces, lift, drag, and other properties.

**2.1 Unsteady motion of two dimensional airfoil in incompressible inviscid flow** 

branches: aeronautical engineering and astronautical engineering.

The chapter will include all our research and published papers.

**1. Introduction** 

**2. Aerodynamics** 

and Helicopter Rotor Aerodynamics.

still however, not a trivial problem.

Časlav Mitrović, Aleksandar Bengin, Nebojša Petrović and Jovan Janković

*Serbia* 

Dugan, R. C. ; McGranaghan, M. F. ; Santese, S. & Beaty, H. W. *Electrical Power Systems Quality*, McGraw-Hill, New York, 2002. **18** 

Časlav Mitrović, Aleksandar Bengin, Nebojša Petrović and Jovan Janković *University of Belgrade, Faculty of Mechanical Engineering, Serbia* 
