No abstract

No abstract

This paper presents turbulence measurements and detailed flow analysis in an axial turbine stage. Fast response aerodynamic probes were used to resolve aperiodic fluctuations along the three directions. Assuming incompressible flow, the effective turbulence level and Reynolds stress are retrieved by evaluating the stochastic velocity component out of the measured time-resolved pressure and flow angle fluctuations along the streamwise, radial, and circumferential direction. A comparison between turbulence intensity and measured total pressure shows that flow structures with higher turbulence level are identified in the region of loss cores at the exit of the second stator passage. Turbulence intensity is evaluated under isotropic and nonisotropic assumption in order to quantify the departure from isotropic conditions. The measurements show that locally the streamwise fluctuating component can be twice bigger than the radial and tangential component. The current analysis shows that multisensor fast response aerodynamic probes can be used to provide information about the mean turbulence levels in the flow and the Reynolds stress tensor, in addition to the measurements of unsteady total pressure loss. Nomenclature c = absolute velocity vector e = mean unit vector in the secondary flow definition p = static pressure p d = dynamic head s, , r = streamwise, circumferential, and radial directions T=T 0 = blade passing period fraction t = time u = streamwise velocity component u,ṽ,w = periodic velocity component: phase-lock averaged u 0 , v 0 , w 0 = stochastic (aperiodic) velocity components v = circumferential velocity component w = radial velocity component = yaw angle = pitch angle x = absolute uncertainty of quantity x = density Subscripts/superscripts 1 = probe position 1 iso = isotropic assumption NS = nonsimultaneous sec = secondary flow vector

No abstract

This paper communicates a novel and robust method for the mechanical testing of thin layers of soft biological tissues with particular application to porcine skin. The key features include the use of a surgical dermatome and the highly defined deformation kinematics achieved by pure shear testing. Thin specimens of accurate thickness were prepared using a dermatome and were subjected to different quasi-static and dynamic loading protocols. Although simple in its experimental realisation, pure shear testing provides a number of advantages over other classic uni-and biaxial testing procedures. The preparation of thin specimens of porcine dermis, the mechanical tests as well as first representative results are described and discussed in detail. The results indicate a pronounced anisotropy between the directions along and across the cleavage lines and a strain ratedependent response.