Engine Matching and Mass Benefit of Heat Recuperation in a 1000 N Micro Turbojet at Constant Thrust

The benefit of exhaust heat recuperation in a micro turbojet depends on the fuel saved at the required thrust and on recuperator mass and pressure losses. A 1000 N engine with a semicircular-channel matrix is analysed in ASTRA at constant static thrust for temperature recovery ratios θ = 0–0.7. Compressor and turbine characteristics are interpolated, scaled and extrapolated during component matching. Original, half and zero pressure-loss cases retain the same matrix mass. With the original losses, the lowest calculated engine-plus-fuel mass for one hour occurs at θ = 0.3, but the compressor stability margin of 5.856% is below the adopted 10% threshold. Among points meeting this thresh-old, θ = 0.2 leaves 1.565 kg for additional installation mass and requires a turbine inlet temperature (TIT) of 1234.38 K, 65.71 K above the reference. For one hour with 90% nominal operation and no fuel-flow difference during the remaining time, the allowance falls to 0.962 kg. Half-loss and ze-ro-loss cases give one-hour allowances of 4.198 and 7.716 kg. These sensitivities define targets for recuperator design; the mass, thermal strength and life of the complete installed assembly remain to be established.