Session: 04-33: Combustion Dynamics - Experiments III

Paper Number: 82665

82665 - Nonlinear Dynamic Analysis of the Pressure Signals on a Swirl-Stabilized Atmospheric LDI Burner Across Different Operating Conditions 

Lean Direct Injection (LDI) burners are a promising technology aimed at reducing NO_x emissions in new generation aeroengines. However, one of the main drawbacks of this technology is the appearance of combustion instabilities at certain operating conditions. In order to investigate these issues, a confined, atmospheric, swirl-stabilized LDI burner has been set up at the CMT Institute for Thermal Engines. In this configuration, air mass flow, temperature, and fuel mass flow rate, which is controlled by the injection pressure, can be independently modified to reach different combustion states. In this paper, a parametric study of the equivalence ratio (0.3 ≤ Ф ≤ 0.8), air temperature (50, 100 ,150 ºC) and injection pressure (6, 9, 12 , 15, 18 bar) has been performed to assess their influence on the dynamics of the system through the evaluation of the chamber’s pressure signals.

These signals have been collected from two piezoresistive sensors flush mounted to the combustor’s wall at the same axial distance but in opposite sides of the chamber. Large-amplitude unsteady oscillations are detected for some combinations of the variables of interest. Equivalence ratio variations are shown to affect deeply the dynamic features of the pressure signal, obtaining more stable configurations either close to the lean limit (Φ = 0.3) or at the richest condition tested (Ф = 0.8). Mid-range equivalence ratio values (0.4 ≤ Ф ≤ 0.7) are shown to display the most unstable behaviour, featuring large pressure oscillations that remain nearly constant on time (quasi-steady states) or signals that experience sudden variations in their amplitude (intermittent states). Since turbulent swirl-stabilized spray flame combustors may experience complex flow-flame interactions that could lead to nonlinear behaviour of these combustion regimes, several signal processing techniques like three-dimensional phase space reconstruction or recurrence plots have been applied to the experimental data in order to obtain better insight into these highly dynamic features.

Presenting Author: Jorge García-Tíscar Universitat Politècnica de València

Presenting Author Biography: Dr. Jorge García-Tíscar holds a position of Senior Lecturer of Aerospace Engineering at the CMT Institute for Thermal Engines of the Universitat Politècnica de València. His research interests include experimental and numerical aeroacoustics in turbomachinery and combustion chambers, aerothermal characterization of surface heat exchangers for aeroengines, and vibroacoustic and fluid-structure interaction research for both aerospace and automotive applications, having published more that 30 journal papers and conference contributions in these topics. He participates in various research projects from the european H2020 and Clean Sky 2 programmes, along with others at state and regional levels, in collaboration with leading institutions from both the academic and the industrial sectors.

Authors:

Antonio Torregrosa Universitat Politècnica de València
Alberto Broatch Jacobi Universitat Politècnica de València
Jorge García-Tíscar Universitat Politècnica de València
Marc Rodríguez Pastor Universitat Politècnica de València