A deterministic model of sonic boom propagation through a turbulent atmosphere

The propagation of a weak normal shock wave through a turbulent atmosphere is studied in terms of an idealized model. The turbulent field is assumed to be weak and represented by the superposition of two inclined shear waves of opposite inclination to the mean flow. The resulting flow is of a cellular nature. The cells are rectangular in shape...

A simple model of shock cell noise generation and its reduction

Based on the data of near field surveys of the sound pressure from a choked jet, a simple model is proposed for the mechanism of the screech generation. A convected wave propagates downstream along the jet boundary and is modulated by its interaction with the shock-expansion waves of the jet. These interactions generate strongdipoleradiations....

Analysis of the flow past a shockless lifting airfoil in design and off-design conditions

A shockless lifting airfoil designed for shockless inviscid flow at M∞ = 0. 75 with CL = 0. 63 was tested at high Reynolds numbers up to 27 X 10σ in design and off-design conditions. The experimental results are compared against theoretical results, showing in general good agreement.

Higher-order theory of two-dimensional subsonic wall interference in a perforated wall wind tunnel

The analytic solution for the interference velocity potential due to a source and a vortex between perforated wind tunnel walls has been extended to higher-order singularities. This allows a more accurate construction of the primary perturbation potential at the walls produced by the tested airfoil, and the evaluation of wall interference on the...

Parametric approximations for compressible laminar boundary layers with mass transfers

The momentum integral method for laminar boundary layers according to Loitsianskii' s universal equations approach has been extended to compressible flows with mass transfers. The universal forms of the compressible boundary layer equations are derived and series solutions in terms of the pressure gradient and the mass transfer parameters are...

Effective source distribution in a choked screech jet

Using experimental measurements of the sound pressure and phase in the near field of a choked screech jet, a method is proposed for computing the effective source positions, their strengths and phases. Two models are considered. The first assumes a distribution of point sourees along the jet axis and the second assumes ring sources along the jet...

Plane sound waves of finite amplitude in a non-dissipative medium

A theoretieal treatment of plane progressive sound waves of finite amplitude in a non-dissipative medium produced by a piston whose motion contains many different frequeney components is presented herein. The solution of the seeond-order wave equation is represented in the form of a Fourier series and the eoeffieients are expressed in terms of...

Computations of incompressible turbulent boundary layers on rough surfaces

The extended mixing length formulation for the computation of incompressible turbulent boundary layers has been applied with success to flows over rough surfaces. The roughness effect is introduced into the computation scheme through the boundary conditions by defining a slip velocity at the surface. The method predicts the mean velocity and the...