Airflow modification patch and method
An airflow modification patch 14 for reducing aeroacoustic noise generated by an aircraft assembly. The patch has a substrate 14 a and a plurality of airflow disruption elements 14 b.
1. An aircraft assembly including a patch for reducing noise generated by an airflow negotiating a noise-inducing component of the aircraft assembly, the patch comprising:
a substrate arranged to be attached to the noise-inducing component, or an upstream component, on the aircraft assembly; and
a plurality of airflow disruption elements associated with the substrate and being arranged to induce turbulence in the airflow to reduce the noise generated by the airflow negotiating the noise-inducing component;
wherein one or more of the airflow disruption elements comprises a protrusion which projects from the substrate by at least 0.5 mm and is arranged in use to increase drag.
2. An aircraft assembly according to claim 1 , wherein a plurality of the airflow disruption elements each comprise a protrusion extending from the substrate in a direction generally away from the noise-inducing component.
3. An aircraft assembly according to claim 2 , wherein a first one of the protrusions has a first shape and a second one of the protrusions has a second shape different from the first shape.
4. An aircraft assembly according to claim 2 , wherein one or more of the protrusions project from the substrate by between about 0.5 mm and about 20 mm.
5. An aircraft assembly according to claim 2 , wherein the protrusions collectively have a flow-facing surface area of at least 1 mm 2 .
6. An aircraft assembly according to claim 1 , wherein the substrate has a major face having a surface area of between about 20 mm 2 and about 5 m 2 .
7. An aircraft assembly according to claim 1 , wherein the airflow disruption elements are removably coupled to the substrate.
8. An aircraft assembly according to claim 7 , wherein the substrate includes a plurality of mounting elements arranged to position the airflow disruption elements.
9. An aircraft assembly according to claim 1 , wherein the substrate is arranged to define a regular or irregular array of protrusions.
10. An aircraft assembly according to claim 1 , wherein the disruption elements are arranged to increase drag by at least a factor of 1.1.
11. An aircraft assembly according to claim 1 , wherein an edge of the patch defines a generally serrated edge.
12. An aircraft assembly according to claim 1 comprising an aircraft landing gear, a high lift device or an aircraft panel.
13. An aircraft assembly comprising:
a noise-inducing component; and
a patch for reducing noise generated by an airflow negotiating the noise-inducing component, the patch comprising:
a substrate arranged to be attached to the noise-inducing component, or an upstream component, on the aircraft assembly; and
a plurality of airflow disruption elements associated with the substrate and being arranged to induce turbulence in the airflow to reduce the noise generated by the airflow negotiating the noise-inducing component;
wherein the patch is formed from a woven or sponge-like material.
14. An aircraft landing gear comprising:
a noise-inducing component; and
a patch for reducing noise generated by an airflow negotiating the noise-inducing component, the patch comprising:
a substrate arranged to be attached to the noise-inducing component, or an upstream component, on the aircraft assembly, and
a plurality of airflow disruption elements associated with the substrate and being arranged to induce turbulence in the airflow to reduce the noise generated by the airflow negotiating the noise-inducing component,
wherein one or more of the airflow disruption elements comprises a protrusion which projects from the substrate by at least 0.5 mm and is arranged in use to increase drag.