Work

Omitted Loading Noise Contribution of Surface Normal Variation: Farassat’s Formulation 1A Revisited

Year: 2026

Type: article

Abstract: Farassat's Formulations 1 and 1A have been extensively employed for propeller noise prediction. However, in the derivation of Formulation 1A from Formulation 1, the contribution associated with the temporal variation of the direction of the unsteady force is omitted, appearing mathematically as the temporal derivative of the local surface normal vector. Through rigorous mathematical derivation, this study demonstrates that the omitted term constitutes an indispensable component of the acoustic source representation. Accordingly, a Modified Formulation 1A is proposed by explicitly retaining the normal vector temporal derivative term in the time-domain formulation. Far-field acoustic predictions for propellers are performed to evaluate the proposed formulation, and the results confirm both its theoretical consistency and predictive capability.

Source: AIAA Journal

DOI: 10.2514/1.j067503

Authors: Qitian Tao, Chen He, Xiaohua Liu, Zhengwu Chen, Jiale Lu

Institutions: Shanghai Jiao Tong University, China Aerodynamics Research and Development Center

Language: English

Topic: Aerodynamics and Acoustics in Jet Flows

Subfield: Aerospace Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: green

Funder: National Natural Science Foundation of China

Awards: G625143541, G7261358102