Abstract

Dry Low Emissions (DLE) combustion technology is an established and proven capability of the Siemens SGT-A35 (Industrial RB211). Since the introduction of a gas-only variant in the 1990s, there have been 200 engine units sold of this type, with over 7 million combined fleet operational hours and over 140,000 fleet leader operational hours.

In 2005, a DLE dual-fuel variant was introduced, but this variant was prone to combustion noise at certain specific, although infrequent, operating modes. The complex geometry of the injector, the lack of real estate, and the use of conventional manufacturing methods led to suboptimal locations for gas-fuel delivery points.

An engineering development program was initiated to optimize the location of the injector gas-fuel holes by exploiting the full potential provided by additive manufacturing. Using high temperature superalloy additive manufacturing technology, the original manufacturing constraints were eliminated, and the injector design was enhanced to improve engine operability by reducing the amplitude of thermo-acoustic instabilities.

This development program used a combination of theoretical and computational methods and conducted through validation via high-pressure testing. Several duel-fuel injector designs were manufactured and tested within a short time frame.  These new designs were intended to reproduce the same behavior as the gas-only variant, which is known to have good thermo-acoustic signature. Noise maps were generated for each design and for different engine acceleration curves. The validation also confirmed that all other combustion attributes matched the existing variant and were inline with the proven gas-only reference.