The effects of HSS (heat-stable salts) on the corrosion behaviours of 20 steel were explored using self-designed HTHP autoclave. The charateristics of corrosion scales were investigated by SEM, EDS and XRD. Corrosion scales of 20 steel formed in the liquid phase environment were mainly composed of FeS₂, Fe₃O₄, and Fe. HSSs affected the corrosion rate through changing the morphology of corrosion scales of 20 steel. Inorganic salts enhanced the attractive force between ions and the hydrolysis of CH₃COO⁻ in organic salts promoted the ionisation of HS⁻, which accelerated the deposition of FeS on the surface of 20 steel to form a dense corrosion scales, thereby significantly reducing the corrosion rate of 20 steel. Inorganic–organic salts reduced the bonding opportunity between Fe²⁺ and S²⁻ and allowed the formation of porous corrosion scales on the surface of 20 steel, thus increasing the corrosion rate of 20 steel.

Turbofan engines with afterburners usually have variable nozzle throat area, and the nozzle throat area may increase by 50–100% during afterburning. An axisymmetric divergent bypass dual throat nozzle (ADBDTN) can offer high thrust vectoring efficiency without requiring additional secondary flow in the pitch and yaw directions. In this study, a variable ADBDTN configuration with flow adaptive capability, wide nozzle throat area adjustment range, and excellent overall performance was designed and investigated numerically. The nozzle throat and exit area can be controlled mechanically, while thrust vectoring is achieved via fluidic methods. Both the original variable geometry schemes and their corresponding improved schemes, namely, “slider-rocker mechanism & rotation” (SRM-R) and “slider-rocker mechanism & slide” (SRM-S) schemes, along with their improved schemes, were proposed and investigated. Results indicated that compared to the original variable geometry schemes, the nozzle configurations with improved variable geometry schemes not only achieve 50% increase in the nozzle throat area but also acquire flow adaptive capability and excellent overall performance by appropriately adjusting the nozzle exit area. At a nozzle pressure ratio (NPR) of 4.47, the highest thrust coefficient reaches 0.940; the largest pitch thrust-vector angle is 19.52 deg; and the discharge coefficients are 0.968 and 0.970 under the nonafterburning and afterburning states, respectively. In addition, compared to the improved SRM-R scheme, the nozzle configuration with improved SRM-S scheme possesses better overall performance.