An Innovative Thermal Flow Management Approach for High-Altitude Turboshaft Test Benches

This article presents the design concept and preliminary analytical assessment of altitude engine test benches for aircraft propulsion systems, covering piston engines up to 1000 HP and turboshaft engines up to 2000 HP. The benches replicate environmental conditions from sea level to altitudes above 11,000 m, with ambient pressures down to 22,600 Pa and temperatures as low as −56.5∘C, encompassing the full flight envelope from takeoff to high-altitude cruise. Key system requirements include high-capacity air supply and vacuum subsystems to maintain precise pressure, temperature, and airflow profiles. First-order analytical calculations estimate air intake mass flowrates of 1.6–2.0 kg/s for piston engines and 8–9 kg/s for turboshaft engines, with required cooling power of about 769 kW. The power for vacuum generation is estimated between 1.5 MW and 1.9 MW, depending on technology (mechanical vacuum pumps or steam ejectors). Capital costs are estimated at $300,000–$500,000, while operating costs range from $606,000 to $1,725,000 per year. Cooling strategies, including liquid nitrogen and closed-loop cryogenic systems, are compared, highlighting trade-offs in operational and capital costs. Decompression subsystems are analyzed through mechanical vacuum pumps and steam ejectors, assessing accuracy, control, and cost. The study is based on analytical calculations; no numerical simulations, experimental validation, or uncertainty analysis are included. Results provide initial guidance for high-fidelity engine testing and serve as a foundation for future work on integrated control, exhaust management, and dynamic simulation of complex mission profiles.