Kahn Series 404 dynamometers

Product Announcement from The Kahn Companies

Fully compatible with advanced, fast-response FADEC (Full Authority Digital Electronic Control) engine control systems, the Series 400 hydraulic dynamometers meet or exceed the test specifications of all current high-speed turboshaft engines, including the following: Allison/Garrett T800, General Electric T58, T700, Rolls-Royce Gnome, Rolls-Royce/ Turbomeca RTM 322, Turbomeca Makila, Turmo.


When operating at high rotational speed and high power density, conventional vaned rotor or perforated disc hydraulic dynamometers are plagued by severe cavitation erosion, which, in many instances, has led to the complete deterioration of the power elements within only a few hundred operating hours.

Equipped with smooth-disc power elements which absorb power by viscous shear rather than through highly turbulent vortex formation, the Kahn Series 400 hydraulic dynamometers inherently discourage cavitation inception, thereby eliminating the need for frequent replacement of the power elements.

Designed and built to meet the most demanding test requirements, the Kahn Series 400 dynamometers offer a number of important design benefits:

• Cavitation-free, smooth-disc power elements provide a service life in excess of 10,000 operating hours, saving money and downtime.

• Inherently steep, open-loop torque-speed characteristic assures stable steady-state operation.

• Low moment of inertia and small working water volume permit rapid transient response.

• Inherently low minimum power absorption characteristic permits performance of transient load bursts originating at near zero load.

• Smooth-disc power elements absorb full power in both directions of rotation.


The power output from the turbine is absorbed by viscous shear generated in the boundary layers adjacent to the rotor and stator surfaces. The resulting drag applies a moment to the dynamometer housing which is measured by a coaxial strain-gage torque reaction sensor mounted to the dynamometer flange.

Absorbed power varies with rotational speed and with the mass of water contained in the rotor chambers. With fully filled rotor chambers, absorbed power increases and decreases with the cube of speed. The amount of water in the dynamometer is modulated with the inlet and outlet control valves.