The FBN Package for Measuring Fluid-Borne Noise
The fluid-borne noise characteristics of positive displacement hydraulic pumps can be measured using the Secondary Source test method. This forms the basis of British Standard BS6335 pt. 1 and ISO 10767-1: 1996 for the rating of pump fluid-borne noise. Hydraulic motors, valves and hoses can also be tested using this method.
The Secondary Source method is used for determining the flow ripple and impedance of hydraulic components. Flow ripple provides very useful information which would be difficult to achieve by other means. Flow ripple is extremely difficult to measure directly, but is determined indirectly in the Secondary Source method by mathematical analysis of pressure ripple measurements at three points along a pipe. The FBN package performs data acquisition, analysis and plotting for the test method.
FBN runs on a PC using a high speed data acquisition card. The software offers high productivity; results can be processed and displayed graphically within seconds of initiating a measurement. Part of a typical flow ripple and impedance display is shown here.
The package has been extensively used for testing a wide range of piston, gear, vane, gerotor and plunger pumps, as well as motors, accumulators, hoses and valves. Several pump and system manufacturers regularly use the software in-house. A particularly strong area of application has been the testing of automotive power steering pumps and flexible hoses, which has led to a number of pump and system design improvements.