SAE ARP 876C provides a method for predicting major elements of the exhaust noise of a jet. It is incomplete in that no recommended method for shock-free coaxial flows is included. As discussed in the Addendum (Appendix C) to ARP 876C, the lack of a recommended method reflects the difficulties incurred in attempting to correlate satisfactorily data that have become available since the mid 1970s. During that period, three proposed methods were reviewed by the Gas Turbine Propulsion Subcommittee of the SAE A-21 Aircraft Noise Committee, none of which received the necessary level of support to allow publication in ARP 876C. Accordingly this AIR is issued to make available to those wishing to predict turbofan exhaust noise the main candidate procedures thus far considered by the Subcommittee.
