Wave Rotor Topping Cycles
for Gas Turbine Engines
1-D Single Passage Simulation
A numerical model has been developed at
the NASA Glenn Research Center which follows a single wave rotor
passage as it rotates past the various ports. The model can predict
both the unsteady flow quantities within the passage and the steady
averaged flow quantities in the ports. It is based on the
assumptions of one-dimensional, unsteady, perfect gas flow.
full size (1024x768, 51K)
Under these
assumptions the passage flow field is essentially governed by the Euler
equations. The high resolution, CFD model integrates these equations in
time, thereby tracking not only the dominant wave behavior including shock
losses, but the loss effects of leakage from the passage ends, viscosity,
heat transfer to and from the passages, mixing of non-uniform flows in the
ports, and finite passage opening time. The losses due to leakage,
viscosity, and heat transfer are accounted for using source terms in the
governing equations. The finite passage opening time losses are accounted
for using modified boundary conditions. The model operates in the rotor
reference frame; however, modified boundary conditions are also used to
account for the often significant circumferential velocity component of the
rotor. This latter modification allows the internal computational scheme to
remain in the rotor reference frame, while quantities such as inlet duct
stagnation properties may be specified in the fixed or absolute reference
frame. Accurate modelling of this effect is critical to successful wave
rotor analysis and design, particularly in off-design predictions where the
flows in the inlet ducts are mis- matched with the rotor passages and
significant turning may take place (i.e. work is done on the gas). The
relative simplicity of the model, combined with robust boundary condition
procedures which allow either inflow, outflow or both in any given port,
make it useful for design, optimization, and analysis, of wave rotor cycles
for many applications.
External components such as valves and combustors, which
supply boundary conditions to the single passage model are
treated as lumped volumes and updated every complete cycle.
Steady state convergence is considered achieved when the gas
state in the volumes is no longer changing and the sum of the
mass flows through either end of the passage are zero over the
course of one cycle.
This model has been validated extensively using several
past wave rotor experiments.
full size (1024x768, 36K)
full size (1024x768, 30K)
full size (1024x768, 29K)
full size (1024x768, 28K)
Contact: Daniel E.Paxson
email: dpaxson@grc.nasa.gov
Project Contact:
Daniel E. Paxson
Phone: (216) 433-8334
email: dpaxson@grc.nasa.gov
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