Optical Diagnostics in a High-g Combustion Cavity
Document Type
Conference Proceeding
Publication Date
7-22-2016
Abstract
An Ultra-Compact Combustor (UCC) is a solution for increased gas turbine engine design efficiency. Implementation of the UCC involves removing the primary combustion zone to a recessed, circumferential cavity around the engine outer diameter. Portions of the compressor exit mass flow are diverted to the circumferential cavity (CC) wherein fuel injection and ignition takes place before migrating from the cavity back into the core flow. One approach to the design of the CC is to inject air with some tangential component in order to induce bulk circumferential swirl, known as "high-g", around the engine centerline. Current research has focused on optimization of the parameters within the circumferential cavity configuration in order to achieve fluid and thermal dynamics, which allow efficient combustion and optimal exit-plane characteristics. This paper presents a detailed analysis of the CC subject to several variations in flow geometry. The design of the high-g UCC test rig at the Air Force Institute of Technology allows optical access into the CC, thereby enabling the use of several unique diagnostic methods to study the combustion within the cavity. In this report, results from Laser Induced Breakdown Spectroscopy (LIBS) and thin filament pyrometry (TFP) measurements are presented and supported by simulations performed using a steady-state partially-premixed flamelet-generated manifold (FGM) method. Significant transient effects are observed in the experimental measurements. Averaged measurements of the LIBS data agree fairly well with the RANS CFD: combustion in the CC is subject to strong gradients and burning occurs in both rich and lean conditions regardless of the overall equivalence ratio. Agreement of the TFP measurements is mixed with some important features not reflected in the CFD.
Source Publication
52nd AIAA/SAE/ASEE Joint Propulsion Conference, 2016
Recommended Citation
Cottle, A. E., Gilbert, N. A., Polanka, M. D., Goss, L. P., & Goss, C. Z. (2016). Optical Diagnostics in a High-g Combustion Cavity. 52nd AIAA/SAE/ASEE Joint Propulsion Conference, 2016, Session: Air-Breathing Combustors I. https://doi.org/10.2514/6.2016-4560
Comments
This conference paper is available through subscription or purchase from the publisher, AIAA, using the DOI link below.
Conference Session: Air-Breathing Combustors I
Author notes:
Andrew Cottle was an AFIT PhD candidate at the time of this conference. (AFIT-ENY-DS-16-D-037, December 2016)