How did Hans Holzwarth’s explosion turbine operate?

Hans Holzwarth’s explosion turbine, which he began developing in 1905, operated on an intermittent combustion cycle rather than the steady-flow process used in modern gas-turbine engines.1

The system functioned through the following process:

• Charging: A compressor introduced a charge of air and fuel into a constant-volume combustion chamber.1
• Combustion: Once ignited, the fuel-air mixture underwent combustion, creating high-pressure gases within the chamber.1
• Expansion: These hot, high-pressure gases were released through spring-loaded valves into nozzles, which directed the flow against the blading of a turbine.1
• Discharge and Reset: The valves remained open until the gases were fully discharged. Once the chamber was empty, the process repeated as a fresh charge was introduced.1

A key engineering advantage of this design was its tolerance for lower compressor efficiency; because the pressure increase achieved during combustion was significantly higher than the pressure increase provided by the compressor (roughly four times greater), the unit could remain operational despite the limitations of early compressor technology. Holzwarth continued to refine this design for over 30 years before it was eventually replaced by modern gas-turbine technology.1