No description available.

No description available.

Approved for public release, distribution is unlimited / Operational characteristics of a valveless pulse detonation engine system were characterized by experimental measurements of thrust, fuel flow, and internal gas dynamics. The multi-cycle detonation experiments were performed on an axis-symmetric engine geometry operating on an ethylene/air mixtures. The detonation diffraction process from a small 'initiator' combustor to a larger diameter main combustor in a continuous airflow configuration was evaluated during multi-cycle operation of a pulse detonation engine and was found to be very successful at initiating combustion of the secondary fuel/air mixture at high frequencies. The configuration was used to demonstrate the benefit of generating an overdriven detonation condition near the diffraction plane for enhanced transmission of the larger combustor. Results have shown that the addition of optical sensors, such as tunable diode lasers, to provide fuel profile data are invaluable for providing high fidelity performance results. The performance results demonstrated the ability of the valveless pulse detonation engine to run at efficiencies similar to valved pulse detonation engine geometries and may be a low cost alternative to conventional air-breathing propulsion systems. / Funded By: N00014OWR20226. / Lieutenant, United States Navy

This work assesses the feasibility of designing and implementing the wave rotor (WR), the pulse detonation engine (PDE) and the internal combustion wave rotor (ICWR) as part of novel Brayton cycles able to reduce emissions of future aircraft. The design and evaluation processes are performed using the simplified analytical solution of the devices as well as 1D-CFD models. A code based on the finite volume method is built to predict the position and dimensions of the slots for the WR and ICWR. The mass and momentum equations are coupled through a modified SIMPLE algorithm to model compressible flow. The code includes a novel tracking technique to ensure the global mass balance. A code based on the method of characteristics is built to predict the profiles of temperature, pressure and velocity at the discharge of the PDE and the effect of the PDEs array when it operates as combustion chamber of gas turbines. The detonation is modelled by using the NASA-CEA code as a subroutine whilst the method of characteristics incorporates a model to capture the throttling and non-throttling conditions obtained at the PDE's open end during the transient process. A medium-sized engine for business jets is selected to perform the evaluation that includes parameters such as specific thrust, specific fuel consumption and efficiency of energy conversion. The ICWR offers the best performance followed by the PDE; both options operate with a low specific fuel consumption and higher specific thrust. The detonation in an ICWR does not require an external source of energy, but the PDE array designed is simple. The WR produced an increase in the turbine performance, but not as high as the other two devices. These results enable the statement that a pressure rise combustion process behaves better than pressure exchangers for this size of gas turbine. Further attention must be given to the NOx emission, since the detonation process is able to cause temperatures above 2000 K while dilution air could be an important source of oxygen.

This work assesses the feasibility of designing and implementing the wave rotor (WR), the pulse detonation engine (PDE) and the internal combustion wave rotor (ICWR) as part of novel Brayton cycles able to reduce emissions of future aircraft. The design and evaluation processes are performed using the simplified analytical solution of the devices as well as 1D-CFD models. A code based on the finite volume method is built to predict the position and dimensions of the slots for the WR and ICWR. The mass and momentum equations are coupled through a modified SIMPLE algorithm to model compressible flow. The code includes a novel tracking technique to ensure the global mass balance. A code based on the method of characteristics is built to predict the profiles of temperature, pressure and velocity at the discharge of the PDE and the effect of the PDEs array when it operates as combustion chamber of gas turbines. The detonation is modelled by using the NASA-CEA code as a subroutine whilst the method of characteristics incorporates a model to capture the throttling and non-throttling conditions obtained at the PDE's open end during the transient process. A medium-sized engine for business jets is selected to perform the evaluation that includes parameters such as specific thrust, specific fuel consumption and efficiency of energy conversion. The ICWR offers the best performance followed by the PDE; both options operate with a low specific fuel consumption and higher specific thrust. The detonation in an ICWR does not require an external source of energy, but the PDE array designed is simple. The WR produced an increase in the turbine performance, but not as high as the other two devices. These results enable the statement that a pressure rise combustion process behaves better than pressure exchangers for this size of gas turbine. Further attention must be given to the NOx emission, since the detonation process is able to cause temperatures above 2000 K while dilution air could be an important source of oxygen.

No description available.

No description available.

No description available.

No description available.