Structural Dynamic Design Process of NovaLT™  Annular Combustors

NovaLT^TM  family gas turbines are new addition to BHGE product portfolio covering 0-35MW power segment, setting a new standard in their class. These Gas Turbines are designed for high efficiency, maximized availability, longer maintenance intervals with modular replacement approach and equipped with low emission annular combustors.

Combustors are typically subjected to several failure mode mechanisms such as Low Cycle Fatigue (LCF), High Cycle Fatigue (HCF), creep, buckling, oxidation, wear out and their interactions. The design of combustor for High Cycle Fatigue (HCF) is key challenge due to many unknown/uncertain parameters in operation such as constraints of hardware, damping capability, nature and magnitude of dynamic loads.

This paper is focused on structural dynamic design process of NovaLT^TM annular combustors. While operating in inherent vibratory environment, caused by either combustion process or stationary/rotating structure, can result in HCF cracking of combustion hardware due to resonance conditions coupled with unavailability of adequate damping in system.

Thus, a robust yet proportionately conservative structural dynamic design, successfully operating in various engine conditions, allowing flexible combustion operability limits, is needed.

Main purpose of this paper is to discuss about product design cycle, challenges and key observations through Annular Combustor design case studies, including experimental measurement of vibratory loads and dynamic response in real operating conditions, as well as a data matched structural dynamic prediction.