Experimental Investigation and Numerical Analysis on Influence of Foundation Excitation on the Dynamics of the Rotor System

Rotor system of modern aero-engine together with the case mounted on the wing represents a uniform system that is supposed to be considered as a rotor-bearings-foundation structure. Nowadays rotating machinery such as modern aircraft engines usually designed, marketed and sold for the most part based on analytical and numerical predictions. In such a way methods to incorporate the foundation effect in rotordynamic calculations are very important. For investigation purposes a rotor-foundation test rig, which can simulate the aero-engine’s typical operating condition such as wing vibration and hard landing, was built to study the influence of foundation behavior on the dynamic characteristics of rotor system. To predict natural frequencies for the full system simplified models based on FEM approach were created. Moreover, simple numerical model was created to study influence of foundation kinematic excitation on behavior of rotor disk orbit. Furthermore simulation results were compared with experimental to understand influence of main parameters which define foundation vibration on rotor deviation from normal operation condition. Obtained numerical and experimental results can help to understand principles of rotating structure-foundation interaction when the later one subjected to excitation and could be further used for improving of more complicated models for design and enhancement of aircraft engines.

A Study on a Passenger Car Diesel Engine Fueled with Butanol-Diesel Blend under Typical Operating Condition

The effects of butanol-diesel blending ratio, injecting timing and pilot injection quantity on combustion and emissions were experimentally investigated for a passenger car diesel engine. The results showed that under the typical operating condition of 2000r/min engine speed and 0.2MPa BMEP engine load, the engine’s combustion phase retarded, the peak combustion pressure and maximum in-cylinder mean temperature decreasing with the delay of the main injection timing using both the neat diesel and diesel-butanol blends. And the engine smoke level increased, while the NOx and CO emissions decreased. However, at the same main injection timing, with the increase of the butanol in the blends, the ignition delay of the combustion prolonged, the burn rate and brake specific fuel consumption increased, NOx and soot emissions decreased, and HC and CO emissions increased, while the peak in-cylinder pressure was slightly influenced. The results of this study indicate that the selection of the butanol-diesel blend ratio and injection timing should consider the engineering balances among the engine’s fuel economy and emissions.

Comparison of Combustion Models and Reaction Mechanisms for FLOX® Combustion

Flameless combustion is characterized by very low NOx and CO emissions. It has successfully been used in technical furnaces under atmospheric conditions for many years. For the use in modern gas turbines the combustors have to be redesigned to meet the typical operating condition, i.e. high pressure and temperature. The flameless combustion under gas turbine relevant conditions has successfully been simulated using a detailed chemistry model [1]. However computational costs and turnaround times are very high for these simulations. In this work the influence of different reduced reaction mechanisms on the heat release and on the temperature and flow field depending on the implied combustion model are investigated. As a benchmark the simulations are compared to experimental data obtained by OH* chemiluminescence and OH LIF measurements [2]. The simulations are performed on the basis of the commercial software package ANSYS CFX 11.0.