Drag divergence Mach number

About: Drag divergence Mach number is a research topic. Over the lifetime, 2435 publications have been published within this topic receiving 33363 citations.

The compressible turbulent shear layer: an experimental study

Abstract: The growth rate and turbulent structure of the compressible, plane shear layer are investigated experimentally in a novel facility. In this facility, it is possible to flow similar or dissimilar gases of different densities and to select different Mach numbers for each stream. Ten combinations of gases and Mach numbers are studied in which the free-stream Mach numbers range from 0.2 to 4. Schlieren photography of 20-ns exposure time reveals very low spreading rates and large-scale structures. The growth of the turbulent region is defined by means of Pitot-pressure profiles measured at several streamwise locations. A compressibility-effect parameter is defined that correlates and unifies the experimental results. It is the Mach number in a coordinate system convecting with the velocity of the dominant waves and structures of the shear layer, called here the convective Mach number. It happens to have nearly the same value for each stream. In the current experiments, it ranges from 0 to 1.9. The correlations of the growth rate with convective Mach number fall approximately onto one curve when the growth rate is normalized by its incompressible value at the same velocity and density ratios. The normalized growth rate, which is unity for incompressible flow, decreases rapidly with increasing convective Mach number, reaching an asymptotic vaue of about 0.2 for supersonic convective Mach numbers.

Drag reduction fundamentals

Abstract: Drag reduction by dilute solutions of linear, random-coiling macromolecules in turbulent pipe flow is reviewed. The experimental evidence is emphasized in three sections concerned with the graphical display of established features of the phenomenon, data correlation and analysis, and the physical mechanism of drag reduction. This work has application to increased pipelines capacity, the study of wall turbulence and molecular rheology.

Fluid Dynamic Drag: Practical Information on Aerodynamic Drag and Hydrodynamic Resistance

Abstract: Fluid-dynamic drag: practical information on aerodynamic drag and hydrodynamic resistance , Fluid-dynamic drag: practical information on aerodynamic drag and hydrodynamic resistance , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Details of the drag curve near the onset of vortex shedding

Abstract: A closer look at the drag curve for a circular cylinder near the onset of vortex shedding reveals that there is a sharp transition in the forces acting on a body moving through a fluid when it produces an unsteady wake. In this Letter results from high‐resolution computer simulations are presented to quantify the change in viscous drag, pressure drag, and base pressure coefficients.

Viscous drag reduction in boundary layers

Abstract: The present volume discusses the development status of stability theory for laminar flow control design, applied aspects of laminar-flow technology, transition delays using compliant walls, the application of CFD to skin friction drag-reduction, active-wave control of boundary-layer transitions, and such passive turbulent-drag reduction methods as outer-layer manipulators and complex-curvature concepts. Also treated are such active turbulent drag-reduction technique applications as those pertinent to MHD flow drag reduction, as well as drag reduction in liquid boundary layers by gas injection, drag reduction by means of polymers and surfactants, drag reduction by particle addition, viscous drag reduction via surface mass injection, and interactive wall-turbulence control.