Sound measurement roomCopyright: © ifas
The anechoic measuring chamber is used for acoustic measurement and optimization of hydraulic and pneumatic components and systems, such as displacement units or power supplies. At the same time, an efficiency measurement can be carried out to characterize the respective systems.
Sound measurement chamber
The sound measurement chamber of ifas is a half-field free room certified by Fraunhofer IBP according to ISO 3745, quality class 1, which has a free volume of the half-field of approx. 135 m³. The acoustic properties are achieved by means of a decoupled double-walled structure and the application of highly effective flat absorbers.
A machine foundation with a mass of 40 t, which is vibrationally decoupled from the rest of the room, is used to mount the test objects on a clamping plate measuring 3.0 x 2.1 m², so that structure-borne noise influences are prevented. This clamping plate can also serve as the reflecting plane of the half-space, provided that the test object has a projected floor area of less than 1.5 x 0.6 m and an evaluation in the frequency range of 125 Hz to 12.5 kHz is sufficient. For larger test objects and evaluations at lower frequencies (up to 50 Hz possible), an additional anechoic horizontal plane with a larger area must be used to meet the normative requirements.
The test specimens are brought in via a hinged door with a clear dimension of (WxH) 2.50 x 2.65 m² and a gantry crane with a load capacity of 1.6 t.
Drive InfrastructureCopyright: © ifas
For the measurement of electrical equipment, a direct connection to the institute's high-current power supply with up to 1 MW is possible. Dissipation of heat loss is also possible on the same scale by means of the central machine cooling supply. Furthermore, the university-wide 6 bar compressed air network (Nominal Size 100 mm) and the ifas-internal 14 bar network are available for the measurement of pneumatic systems.
The measurement of pumps and hydraulic motors is carried out, e.g., according to DIN 45635 in the quarter space, so that all other sound sources, such as the electrical drives, pumps, etc., are isolated from the test specimen by the vertical separation plane. To realize this, two shaft passages into the neighboring acoustically isolated drive train room and various line ducts are available in the ifas measuring room. The drive train is currently under reconstruction and will have an electrical drive power of 450 kW after completion, which can be utilized at a variable speed of up to 3000 rpm on one shaft. Hydraulic recuperation to reduce energy consumption and the installation of a low-reflection line terminator (RALA) for operating pressures of up to 450 bar are also planned.
Measurement EquipmentCopyright: © ifas
In addition to a torque measuring shaft, the planned measuring equipment for the hydraulic-mechanical drive train includes sensors for measuring the speed as well as the volume flow and pressure. A parallel investigation of efficiency, pulsation, and acoustics as well as their correlation is therefore possible.
Six microphones in combination with a Siemens SCADAS measuring system with eight inputs are available for airborne sound investigation. This system is used for data acquisition and processing. Measured variables are, for example, the sound pressure level, loudness and sharpness. It is also possible to integrate acceleration sensors into the measurement system, for example to perform modal analyses.