Aerospace

Discovering design rules is essential for advancing interpretable and intelligent propeller design. This paper proposes a knowledge–data hybrid-driven method for discovering design rules for high-efficiency propellers, with the aim of expanding the pool of comparable design data while reducing the search space for candidate rule parameters. Based on the propeller ideal efficiency theory, an efficiency factor is introduced to address the lack of comparability among performance data caused by differences in propeller loading, thereby enabling all designs in the database to be used for data mining. Dimensionless composite features are then constructed using the principle of dimensional homogeneity and screened through correlation analysis within a knowledge–data hybrid-driven framework. Six characteristic load ratios are identified as rule parameters, yielding the following design rule: a propeller has a high efficiency factor when all six ratios lie within their respective optimal ranges. Finally, the rule is validated on 12 independent designs, including three designs of a different propeller. The proposed knowledge–data hybrid-driven feature-engineering framework provides a viable approach to design-rule discovery and may support inverse design and intelligent propeller design.

Electrical products of reusable launch vehicles (RLVs) face corrosion problems that expendable rockets never encounter: sea/land recovery introduces salt-fog and damp-heat exposure; repeated flights bring thermal-cycling-driven “breathing” condensation; and the “recover–refurbish–refly” mode makes corrosion damage accumulate across missions. Current standards (e.g., the salt-fog/damp-heat tests of GJB 150 and MIL-STD-810) target single-stress qualification of expendable products and lack reuse-oriented cumulative-damage criteria. This paper proposes a life-cycle corrosion prevention and control system for RLV electrical products covering five phases—design, manufacturing, testing, operation, and maintenance—including exposure-class-driven finish/coating/sealing selection, ionic-contamination control, combined-stress testing, post-recovery desalting, corrosion-specific inspection, and SCC screening of metallic housings and fasteners. A mechanism-specific state-model framework is then introduced: each corrosion mechanism is assigned its own drivers and inspectable state variable, state limits are converted to normalized life-consumption fractions, and failure/limit life is distinguished from operationally allowable life. Connector fretting corrosion is modeled with an environmental acceleration factor that preserves mechanical wear in dry enclosures. A flight-heritage data-acquisition board is used only as a case-study application, not as flight validation of corrosion behavior. The illustrative calculation shows how contact-resistance data, vibration-derived cycle counts, and operational thresholds can be linked, while Monte Carlo uncertainty propagation demonstrates the sensitivity of absolute life estimates and precludes a definitive mechanism ranking. The main contribution is therefore a reproducible method and calibration pathway for incorporating corrosion into RLV reuse decisions; product-specific test and inspection data remain necessary for validated life predictions.

Future commercial engines require higher bypass ratios and smaller cores, leading to open tip clearances exceeding 4% (s/H ≥ 4%) in rear stages. The resulting leakage flows show strong three-dimensional unsteady features that challenge numerical prediction, while experimental data inside open clearances with moving endwalls remain limited. In this study, a Stereo Particle Image Velocimetry (SPIV) system was applied to a high-speed moving-endwall cascade test rig. Measurements were conducted for a Controlled Diffusion Airfoil (CDA) cascade at Mach 0.3, an endwall speed of 900 r/min, and a relative clearance of 7.14%. Velocity fields were obtained on two spanwise planes, 2 mm (MP1) and 3.5 mm (MP2) from the endwall. Results show that the tip leakage vortex develops continuously along the span but differs between planes. In MP2, dominated by blade pressure difference, the leakage jet forms a broader high-velocity region and a more compact vortex, with higher blockage, shear gradient, and turbulent kinetic energy than in MP1. In MP1, endwall shear stretches the leakage flow pitchwise, reducing blockage and weakening mixing. This work demonstrates the feasibility of dual-camera SPIV measurements inside moving-endwall clearances and provides benchmark data for numerical validation.