Thermal Management Optimization in Next-Generation Hybrid-Electric Rocket Propulsion Systems

1. Introduction

The transition toward reusable and high-efficiency launch vehicles necessitates propulsion architectures that balance thrust-to-weight ratios with operational sustainability. Hybrid-electric systems have emerged as a promising alternative to conventional chemical rockets, particularly for in-space propulsion and upper-stage applications. However, thermal management remains a critical challenge due to the extreme heat fluxes generated during prolonged combustion cycles and the limitations of traditional regenerative cooling methods.

AeroVance has long championed innovative thermal control solutions, leveraging advances in computational modeling and additive manufacturing. This study builds upon our prior work on micro-channel cooling geometries and extends the analysis to pulsed supercritical coolant regimes, which have shown theoretical promise in mitigating thermal boundary layer breakdown.

2. Methodology

2.1 System Architecture

The propulsion system under analysis consists of a dual-stage hybrid thruster utilizing liquid methane (CH₄) and liquid oxygen (LOX) as primary propellants, augmented by a solid-state battery-driven electric heater for supplemental combustion chamber pressurization. The thermal management subsystem integrates a micro-channel regenerative cooling jacket surrounding the combustion chamber and nozzle throat.

2.2 Computational Modeling

CFD simulations were conducted using ANSYS Fluent 2024 R2, employing the Realizable k-ε turbulence model and the Lee two-phase flow formulation for supercritical methane. Boundary conditions reflect nominal launch profiles: chamber pressure at 8.5 MPa, mixture ratio O/F = 3.4, and burn duration of 180 seconds.

2.3 Experimental Validation

Ground tests were performed at AeroVance’s Nevada Test Facility using a 1:5 scale hardware mockup. Infrared thermography and embedded thermocouple arrays provided real-time thermal mapping across 48 measurement points.

3. Results & Analysis

The pulsed supercritical methane cooling architecture demonstrated significant thermal performance improvements over conventional continuous-flow designs. Key findings include:

• Peak wall temperatures reduced from 1,850 K to 1,445 K
• Coolant pressure drop decreased by 18%, reducing turbopump power requirements
• Specific impulse improved from 312 s to 356 s under full-thrust conditions
• Structural fatigue life extended by 3.2x due to reduced thermal cycling stress

Notably, the pulsed flow regime induced controlled micro-turbulence within the coolant channels, enhancing convective heat transfer coefficients without increasing pumping power penalties. This phenomenon aligns with recent theoretical models proposed by Chen et al. (2023) on supercritical fluid dynamics in micro-confinements.

4. Conclusion

This study validates the efficacy of pulsed supercritical methane cooling in hybrid-electric propulsion systems, offering a scalable solution for next-generation launch vehicles. The 22% reduction in peak thermal loads and 14% Isp improvement position this architecture as a viable pathway for high-efficiency, reusable orbital transfer stages. AeroVance plans to integrate this thermal management subsystem into the Orion-Next upper stage program, with flight qualification testing scheduled for Q4 2026.