Ph.D. Proposal
Ezgi Balkas
(Advisor: Prof. Dimitri Mavris)
"Certification by Analysis in the Context of Non-Conventional Thermal Management Systems"
Wednesday, June 28
8:00 a.m.
Virtual: Microsoft Teams Link
Abstract
The aviation industry shifts to electric and hybrid electric aircraft with new materials to satisfy aggressive environmental goals. However, this paradigm shift has introduced more complex and harsher thermal management system (TMS) architecture that require novel certification methods. Certification by Analysis (CbA) is a computational analysis approach used for aircraft and engine certification, replacing the traditional physical testing and simulations. CbA can eliminate all the expensive procedures while sustaining similar safety levels.
In tradition, to make sure of the systems’ safety through physical testing, fan and core compartment components are heavily instrumented with thermocouples and transducers to capture their temperature and flow behavior. These conducted ground and flight tests necessitate an excessive amount of engineering time with cost. In addition to that introducing new architectures along with their higher waste product and heat flux will exacerbate the existing challenges related to certification and safety concerns such as excessive heat loads on FADEC and thermal runway in battery systems.
To certify the TM cooling system, exploiting CbA would bring a comprehensive digital model of it that simulates all the edge cases from operating envelope to identify the potential failure modes. However, CbA itself presents several challenges. One issue would be the accuracy of the models, especially integrated systems (electric or more electric architectures) with many potential interrelationships between the different elements. It must account for the diverse heat sinks, the heat sources with different heat transfer modes and the dynamic nature of the thermal environment during different phases of flight. The current review of literature showed that there is a need for robust validation processes to build the model’s accuracy, requiring extensive test and comparison with real-world data.
Besides, computational fluid dynamics (CFD) with multi-physics simulations are computationally expensive and time consuming, potentially neutralizing some of the benefits of CbA approach. With the breakthroughs in high performance computing (HPC), this logistic barrier is gradually disappearing.
The main goal of this study is to establish an efficient CbA methodology with comprehensive analysis of non-conventional commercial aircraft TM cooling system ensuring precise, informed engineering judgements across all the design phases. The proposed approach integrates aerothermal analyses and 14 CFR Part 25 subpart E rules to reduce variability. Moreover, different engineering tools are integrated for assessing the components’ fit, shape and performance. The safety criteria will be assessed with components transient temperature behavior throughout the mission.
Committee
- Prof. Dimitri Mavris – School of Aerospace Engineering (advisor)
- Prof. Daniel Schrage – School of Aerospace Engineering
- Prof. Brian German – School of Aerospace Engineering
- Dr. Angela Campbell – System Safety Section, FAA
- Dr. Eric S. Hendricks – Propulsion Systems Analysis Branch/LTA
- Dr. Jonathan Gladin - School of Aerospace Engineering
- Dr. Evan Harrison - School of Aerospace Engineering