Modelling the Transient Behavior of Heat Exchangers in Aircraft Engine Preliminary Design
Aytunc YILDIRIM, Marc SCHMELCHER, Alexander GÖRTZ
Abstract. Compact heat exchangers must be integrated into advanced aero-engine concepts; therefore, thorough analysis is needed in the preliminary phase. This work advances an early aero-engine heat-exchanger design tool by extending methods beyond stationary analyses to fully transient operation. Flight conditions change within seconds during maneuvers, so pressures, temperatures, and mass flows on both sides of a heat exchanger vary simultaneously. Steady analyses cannot capture response times, while many transient models treat only single-inlet disturbances or simple layouts. High-fidelity simulations are also too slow for broad design sweeps of the preliminary phase. The proposed tool retains the three-dimensional, cell-based framework and solves an unsteady wall energy balance with finite differences to represent thermal inertia. Between cells, fluid enthalpy information is propagated using the concept of residence time, allowing for arbitrary, coupled inlet ramps. Validation against a Modelica benchmark model shows close agreement for fluid temperatures. Runtime remains in minutes on modest hardware, enabling rapid exploration of the parameter space. A multipass counter-crossflow hydrogen conditioner is further evaluated for a Go-Around maneuver, revealing a lag between boundary changes and temperature propagation, as well as a nonlinear dependence of transient duration on ramp time.
Keywords
Aero Engines, Heat Exchangers, Transient Modelling, Hydrogen Conditioning, Response Time, Wall Thermal Inertia, Residence Time
Published online 7/20/2026, 6 pages
Copyright © 2026 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Aytunc YILDIRIM, Marc SCHMELCHER, Alexander GÖRTZ, Modelling the Transient Behavior of Heat Exchangers in Aircraft Engine Preliminary Design, Materials Research Proceedings, Vol. 69, pp 583-588, 2026
DOI: https://doi.org/10.21741/9781644904251-104
The article was published as article 104 of the book CEAS – AIDAA Conference 2025
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
References
[1] M. Schmelcher, J. Häßy, A. Görtz, M. El-Soueidan, Methods for the preliminary design of heat exchangers in aircraft engines, Volume 5: Cycle Innovations. Turbo Expo (2023), https://doi.org/10.1115/GT2023-102959
[2] M. Spiga, G. Spiga, Step response of the crossflow heat exchanger with finite wall capacitance, International Journal of Heat and Mass Transfer, 35 (1992), https://doi.org/10.1016/0017-9310(92)90290-9
[3] J. Yin, M.K. Jense, Analytic model for transient heat exchanger response, International Journal of Heat and Mass Transfer, 46 (2003), https://doi.org/10.1016/S0017-9310(03)00118-2
[4] R. Yang, C.T. Tran, A. Zoughai, An analytical model to study the dynamic response of heat exchanger network, International Journal of Heat and Mass Transfer 176 (2021), https://doi.org/10.1016/j.ijheatmasstransfer.2021.121461
[5] A. Görtz, K. Kyprianidis, D. Bermperis, Implementation of intercompressor cooling in the cycle analysis of hydrogen powered gas turbine engines using scalable heat exchanger maps, Journal of Engineering for Gas Turbines and Power 147 (2025), https://doi.org/10.1115/1.4069486
