Effects of Combustion Chamber Geometry Upon Exit Temperature Profiles

Abstract

The purpose of this research was to investigate the effects of combustion chamber geometry on exit temperature fields using an ambient pressure test rig. The apparatus contained a 120° sector of a combustion section of a Rolls Royce (previously Allison) T56-A-15 gas turbine engine. A thermocouple rake acquired high-resolution temperature measurements in the combustion chamber exit plane. Rig test conditions were set to simulate an engine operating condition of 463 km/h (250 knots) at 7620 m (25000ft) by matching the Mach number, the equivalence ratio and the Sauter mean diameter of the fuel spray. To quantify the geometric deviations of the combustion chamber specimens, which varied in service conditions, a three-dimensional laser scanning system was used. Combustion chamber geometric deviations were extracted through comparison of the scanned data to a reference model using the selected software. The relationship between combustion chamber exit temperature profile and geometric deviation was then compared. The main conclusion of this research was that small deviations from nominal dimensions in the dilution zone of the combustion chamber correlated to an increase in pattern factor. A decrease in the mixing of the products of combustion and dilution air was observed as damage in the dilution zone increased. This reduction in mixing created a more compact, higher temperature core flow. The results obtained from this research were compared to past studies.

Emissions From a Gas Turbine Sector Rig Operated With Synthetic Aviation and Biodiesel Fuel

“…As such, a T56 (pressure) fuel nozzle was modified by blocking its secondary flow circuit, which was verified to produce a fuel droplet size distribution and cone angle that closely simulated an unmodified nozzle in an in-flight operation [16]. A target equivalence ratio of 0.23 was chosen for tests.…”

“…These studies have focused on fuel performance and the impact of fuel nozzle and combustion chamber damage on exhaust temperature pattern factor [15][16][17]. While the combustion systems within the rig comprise actual T56 components, the inlet, air delivery, and fuel systems are custom designs.…”

Effects of Combustion Chamber Geometry Deviations Upon Exit Temperature Profiles for Populations With Varied Service Limitations

“…A synopsis of research into pattern factor completed by Sjöblom [5], Friedman and Carlson [12], Cox and George [13], and Lefebvre [6,14] can be found in Ref. [2]. The present research focused on maintaining consistent dilution, cooling, and primary zone temperatures, in an attempt to segregate the effects of changes to the combustion chamber geometry.…”

“…Previous research by Kötzer et al [2] investigated the effects of geometrical deviations on exit temperature profiles. A threedimensional laser scanning system was used to acquire the geometrical data and an ambient pressure combustion chamber sector rig was used to obtain the temperature profiles.…”

“…The main objective of the present research was to validate the model created by Kötzer et al [2], correlating geometric deviations to changes in temperature fields. This was completed using a specimen population of 25 combustion chambers which varied in service life limitations from the population to develop the initial correlation.…”