Fans with a Particularly Low Noise Level

In 2010, we supplied the by far quietest fan of its performance class (3,500 kW) and diameter range (4.7 m) for what is currently the most powerful aero-acoustic wind tunnel worldwide in Braunschweig, Germany, the DNW-NWB being operated by the DNW foundation. In order to reduce the noise of new airliners by 50%, by the year 2020, as planned, the sound engineering of the NWB wind tunnel was reconstructed to the lowest currently feasible sound level in a far-reaching and innovative fashion. The basic prerequisite for complying with the noise specifications of the NWB wind tunnel was to reduce the sound level of the main sound source, namely that of the wind tunnel fan.

With TLT-Turbo’s decades of experience in measuring and calculating the fan sound and in calculating, designing and producing silencers for fans and appropriate flow controls – and in close cooperation with leading research institutes of DNW and DLR – we were able to significantly reduce the acoustic emissions of these large fans. Through a giant leap forward, TLT-Turbo succeeded in reducing the sound level of the NWB fan by more than 10 dB(A) compared to previous designs. The knowledge gained from this project and the crucial aero-acoustic measures has been integrated into the design of TLT-Turbo axial flow fans ever since.

High-temperature Exhaust Fans with Adjustable Blades for Tunnel Ventilation with Extreme Stability Requirements

In 2013, TLT-Turbo supplied special exhaust fans with a diameter of nearly 3 meters and power consumption of 2.3 MW for the new Gotthard Base Tunnel in Switzerland. As part of hot-gas tests at a certified testing laboratory, it could be proven that the requirement of the European standard EN 12101, a safe fan operation with external forced air cooling of the drive motor at 400°C, over a two-hour period, is met. Furthermore, even if the forced air cooling fails, the fan can be operated for additional 90 minutes – far longer than required by other projects. It is also worth highlighting that the structure of the fan components for alternating pressure shocks of up to +/- 10,000 Pa due to train movement had to be designed to be safe in the long run. TLT-Turbo’s design of the fan components met these extreme requirements.

Oil Supply Units with Redundant Proportional Valve Control

TLT-Turbo’s axial flow fans are also used in macro-economically vital industry processes (e.g. power plants, refineries, tunnels etc.). The failure of a fan often also results in a significant reduction in operation or even failure of the whole system. As the “availability” of a plant in recent years has become an issue of growing importance for technical and economic reasons, TLT-Turbo’s development of “redundant proportional valve control” has significantly increased in particular the availability of “blade adjustment”. The option of “redundant proportional valve control” being available for our oil supply unit comprises the control element of the blade adjustment unit. TLT-Turbo GmbH has been granted a patent for it.

Thus, the failure of a proportional valve no longer means a contemporaneous failure of the blade adjustment unit. By switching over to the second, redundant hydraulic circle, the fan remains in the normal operation mode and the whole system remains available without restrictions. Furthermore, it is also possible to upgrade fans of previous series with the innovative “redundant proportional valve control”. It is not necessary to modify the existing fan.

Cyrogenic Wind Tunnel Fan

In 1994, TLT-Turbo supplied a two-stage fan with variable speed drive, a maximum power consumption of 65,000 kW and a diameter of about 4.5 m for the European Transsonic Wind Tunnel (ETW) in Cologne, Germany. This wind tunnel is used to measure the aerodynamic quality of scaled aircraft models of international aircraft manufacturers with highest precision reaching the supersonic range. During operation, the main fan components, including a special silencer in the fan diffuser, have to regularly resist a temperature change between +40°C and approx. -190°C as well as simultaneous low-pressure or up to 4.5 bar (abs.) of overpressure.

These extraordinary demands required the application of a highest quality carbon fibre construction for the blades and special cryogenic steel for rotors and housings. To date, the highly stressed fan of the ETW regularly operates to the customer’s utmost satisfaction in this worldwide leading cryogenic wind tunnel. Based on this experience, we are enhancing the fibre composite technology for the lightweight construction of our blades and over recent years we have successfully implemented this technology for highly dynamic fans with diameters of over 6 m in the sector of Formula 1 and motor vehicle wind tunnels.