Search

The paper considers the problem of increasing fuel efficiency and reducing emissions of gas turbine power plants. The aim of the work is to develop a method for burning extra-lean fuel mixtures. The method of ignition by a streamer high-frequency discharge was considered. The discharge was ignited in the presence of the resonator by a quasioptical beam of microwave radiation with a wavelength of 8.9 - 12.5 cm. The resonant ignition method was 20 to 100 times more energy efficient than laser and plasma ignition methods. The method combines an experiment and mathematical modeling of a streamer discharge. The result was the ignition of an extremely lean mixture with an air fuel rate of more than 30. A regime of flameless combustion was detected, when a flame wasn’t visible, but heat generation as a result of a chemical reaction has occurred. Stable combustion of the lean mixture was obtained at a flow rate of up to 30 m/s. These conditions simulated combustion in a tubular combustion chamber. A pulse with a wavelength of about 2.5 cm couldn’t create a streamer discharge and couldn’t be used for multi-point ignition. Burning front speed was 2-4 times higher than in spark ignition. Traditional low-emission combustion chambers have large dimensions and a very complex design. This makes it difficult to use them in microturbine. The application of the method described in the article makes it possible to create significantly more compact low-emission and highly economical combustion chambers for power gas turbine plants.

The problem of increase of the unit power on the shaft of an energy microturbine is of current interest. One of the problems is the small single unit power of microturbines, limited by the low capacity of gas-dynamic air bearings. The problem could be solved by replacing gas-dynamic bearings with hybrid ones with a higher load-bearing capacity. Hybrid bearings use self-aligning turning segments and forcing gas into the lubricating layer. The scientific result of the work is the method of designing grooves that distributes gas, the shape of which repeats the pressure isoline on the segment’s surface when the microturbine is operating at the rated rotation speed. Method is based on solving Reynolds equations for a thin lubricating layer at the grooves. The developed system of grooves provides static stability of the segment in stationary modes and dynamic in transient modes, vibration suppression, automatic response to changes in load and speed. The calculation method allows finding the optimum thickness of the lubricant layer for a given accuracy of shaft and segment manufacture. It is shown that the load-bearing capacity is maximal when the resultant forces act on a segment, and not between segments. Numerical calculations and experiments have shown that the developed hybrid bearing has a maximum bearing capacity at a given air flow rate for the power range on the shaft from 200 kW to 2000 kW, with a load on the shaft up to 300 kg and a speed of up to 100.000 rpm.