Conventional gas turbine combustors operate with a designed drop in pressure over the length of the device. This is desired in order to encourage mixing within the combustor. Compared to this, pulse pressure gain combustors are an alternative to the conventional combustor that produces an increase in static pressure between the inlet and exhaust of the device. The removal of the combustor pressure loss increases the efficiency of the combustion process by increasing the amount of work produced. Many types of pulsed pressure gain combustors exist. Of these, the valveless pulse combustor is the simplest featuring no moving parts. Whilst some research has been conducted into investigating the performance and workings of a pulse combustor, little has been conducted with the view of cooling the combustor. This has been the focus for the research contained herein.
The research has focussed on establishing an understanding of the heat transfer characteristics within a pulse combustor tailpipe. This has involved experimental, analytical and computational research on a pulse combustor as well as on a cold-flow model of a pulse combustor tailpipe. This has enabled a study into the feasibility of cooling a pulse combustor to be conducted.
The research has found that for conditions where the unsteady velocity amplitude within the cold-flow model of the pulse combustor tailpipe exceeds the mean velocity, an enhancement to the heat transfer coefficient is measured compared to the value expected in a similar non-oscillating flow. When there is no enhancement to the heat transfer coefficient, the cyclic variation of the unsteady heat flux follows the variation of the unsteady pressure within the device. However, at times of enhancement, the instantaneous heat flux structure shows a large deviation from the structure of the pressure field driving the oscillations. This change is shown to be caused by the reversal in the near-wall velocity and may indicate a mechanism for the enhancement in the mean heat flux. The cooling feasibility study showed that with further investigation, it may be possible to cool a pulse combustor within a gas turbine engine.
This thesis is restricted until 1st September 2015. A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.