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October 12, 2025Open Access

Numerical Validation of a Multi-Dimensional Similarity Law for Scaled STOVL Aircraft Models

SXShengguan XuNanjing Tech University MLMingyu LiHarbin Institute of Technology XWXiaonan WangJilin University

Key Points

High fidelity of scaled STOVL models was confirmed with plume deflection remaining stable at 12° ± 1° across varying scale factors.
Axial force and mass flow rates followed strict scaling relationships, deviating less than 0.58% from theoretical predictions at a 1:15 scale.
The developed similarity framework can significantly reduce wind tunnel testing costs, aiding in more efficient STOVL aircraft development.
Critical parameters such as intake pressures and temperatures showed less than 2.2% error compared to full-scale models, validating the model's accuracy.

Abstract

The complex jet-ground interactions of Short Take-off and Vertical Landing (STOVL) aircraft are critical to flight safety and performance, yet studying them with traditional full-scale wind tunnel tests is prohibitively expensive and time-consuming, hindering design optimization. This study addresses this challenge by developing and numerically verifying a “pressure ratio–momentum–geometry” multi-dimensional similarity framework, enabling accurate and efficient scaled-model analysis. Systematic simulations of an F-35B-like configuration demonstrate the framework’s high fidelity. For a representative curved nozzle configuration (e.g., the F-35B three-bearing swivel duct nozzle, 3BSD), across scale factors ranging from 1:1 to 1:15, the plume deflection angle remains stable at 12° ± 1°. Concurrently, axial force (F) and mass flow rate (Q) strictly follow the square scaling relationship (F∝1/n2, Q∝1/n2), with deviations from theory remaining below 0.15% and 0.58%, respectively, even at the 1:15 scale, confirming high-fidelity momentum similarity, particularly in the near-field flow direction. Second, a 1:13.25 scale aircraft model, constructed using Froude similarity principles, exhibits critical parameter agreement (intake total pressure and total temperature) of the prototype-including vertical axial force, lift fan mass flow, and intake total temperature—all less than 1.5%, while the critical intake total pressure error is only 2.2%. Fountain flow structures and ground temperature distributions show high consistency with the full-scale aircraft, validating the reliability of the proposed “pressure ratio–momentum–geometry” multi-dimensional similarity criterion. The framework developed herein has the potential to reduce wind tunnel testing costs and shorten development cycles, offering an efficient experimental strategy for STOVL aircraft research and development.

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