The Hot-Acoustic Testrig, which was erected and is operated in close cooperation between DLR department of engine acoustics and Technischen Universität Berlin, chair of aero engines, is a unique facility for acoustic and aerodynamic test at surfaces exposed to high temperature and grazing flow in aero engines. The basic principle of operation is the same as for the atmospheric facility Atmospheric liner test rig (DUct aCoustic Test rig, DUCT). The HAT facility consists of two sections with microphones and the test object in between. It does have anechoic terminations at both ends in order to suppress acoustic end-reflections. For the investigation of cylindrical and plane liner samples, there are test sections with circular and rectangular cross section, respectively.
Reynolds number –
Mach number or maximum velocity 0,6
Maximum mass flow 0,78 kg/s
Maximum temperature/ pressure 11 bar; 823 K
Duct diameter/ test section dimensions (diameter or height/ width) 0,004 m² (= diameter 70 mm)
Measurement instruments Acoustic tests at HAT
• 10 microphone probes, 5 upstream and 5 downstream of test section, respectively
• 10 additional microphone locations at the circumference (e.g. for in-situ calibration)
• Acoustic excitation via loudspeaker 160 – 2800 Hz (plane wave regime)
• Cut-on frequency of first higher-order mode 2850 Hz (at ambient temperature, Ma=0)
• Determination of dissipation curve for liners with error of less than 3%
Maximum rotating speed
Duct diameter: 70mm
Max flow temperature: 823 K
Max pressure in the duct/test section: 11 bar (abs)
Max massflow: 0.78 kg/s
Mach number (see figure) 0 – 0.7