Leading edge noise is a significant broadband noise source in aircraft engines, and is the primary broadband noise mechanism in outlet guide vane noise in turbofans, and broadband rotor wake interaction noise in contra-rotating open rotor engines. Previous authors have studied the effects of various aspects relating to this noise source, including airfoil geometry effects, cascade effects, and ...

The behaviour of steady transonic dense gas flow is essentially governed by two nondimensional parameters characterising the magnitude and sign of the fundamental derivative of gas dynamics (Γ) and its derivative with respect to the density at constant entropy (Λ). The resulting response to external forcing is surprisingly rich and studied in detail for the canonical problem of 2D flow past com...

We consider maps between Riemannian manifolds in which the map is a stationary point of the nonlinear Hodge energy. The variational equations of this functional form a quasilinear, nondiagonal, nonuniformly elliptic system which models certain kinds of compressible flow. Conditions are found under which singular sets of prescribed dimension cannot occur. Continuity results are given for the tra...

We study a Riemann problem for the unsteady transonic small disturbance equations that results in a diverging rarefaction problem. The self-similar reduction leads to a boundary value problem with equations that change type (hyperbolic-elliptic) and a sonic line that is a free boundary. We summarize the principal ideas and present the main features of the problem. The flow in the hyperbolic par...

where a is the speed of sound, p is the density, _ is the potential, and the subscripts denote partial deriva-The nonuniqueness problem occurring at transonic tives. In the absence of shock waves, both forms of the speeds with the conservative potential equation is in-equation are equivalent. When shock waves are present, vestigated numerically. Evidence is given supporting use of the conservat...