Linking the unsteady force generation to vorticity for a translating and rotating cylinder

A boundary layer surface vortex sheet is utilized to investigate the development of the unsteady forces acting on a rotating and surging cylinder at a Reynolds number of 20 000. Planar particle image velocimetry and force balance measurements are employed to assess the flow field and force response. The boundary layer vortex sheet is categorized into non-circulatory and circulatory components. During acceleration the non-circulatory or added mass vortex sheet is successfully recovered from experimental data. This makes a decomposition of the forces, calculated only from particle image velocimetry measurements, possible. They compare well to force balance data. Additionally, the evolution of the boundary layer vortex sheet is assessed as the flow separates to form a vortical structure in the surrounding flow. When the influence of varying freestream velocity and rotation rate are removed, the surface vortex sheet at the location of separation varies little during vortex formation, even as the separation point moves along the surface of the cylinder

Carbon dioxide concentration system Interim report no. 1

Electrochemical carbon dioxide concentration system for purifying space cabin atmospher

Characteristics of shock-induced boundary layer separation on nacelles under windmilling diversion conditions

The boundary layer on the external cowl of an aero-engine nacelle under windmilling diversion conditions is subjected to a notable adverse pressure gradient due to the interaction with a near-normal shock wave. Within the context of Computational Fluid Dynamics (CFD) methods, the correct representation of the characteristics of the boundary layer is a major challenge to capture the onset of the separation. This is important for the aerodynamic design of the nacelle as it may assist in the characterization of candidate designs. This work uses experimental data obtained from a quasi-2D rig configuration to provide an assessment of the CFD methods typically used within an industrial context. A range of operating conditions is investigated to assess the sensitivity of the boundary layer to changes in inlet Mach number and mass flow through a notional windmilling engine. Fully turbulent and transitional boundary layer computations are used to determine the characteristics of the boundary layer and the interaction with the shock on the nacelle cowl. The correlation between the onset of shock induced boundary layer separation and pre-shock Mach number is assessed and the boundary layer integral characteristics ahead of the shock and the post-shock recovery evaluated and quantified. Overall, it was found that the CFD is able to discern the onset of boundary layer separation for a nacelle under windmilling conditions

Assessment of Computational Fluid Dynamics (CFD) Models for Shock Boundary-Layer Interaction

A workshop on the computational fluid dynamics (CFD) prediction of shock boundary-layer interactions (SBLIs) was held at the 48th AIAA Aerospace Sciences Meeting. As part of the workshop numerous CFD analysts submitted solutions to four experimentally measured SBLIs. This paper describes the assessment of the CFD predictions. The assessment includes an uncertainty analysis of the experimental data, the definition of an error metric and the application of that metric to the CFD solutions. The CFD solutions provided very similar levels of error and in general it was difficult to discern clear trends in the data. For the Reynolds Averaged Navier-Stokes methods the choice of turbulence model appeared to be the largest factor in solution accuracy. Large-eddy simulation methods produced error levels similar to RANS methods but provided superior predictions of normal stresses

Investigation of the double ramp in hypersonic flow using luminescent measurement systems

Compression ramp flows in supersonic and hypersonic environments present unique flow patterns for shock wave-boundary layer interaction studies. They also represent the generic geometry of two-dimensional inlets and deflected control surfaces for re-entry vehicles. Therefore, a detailed knowledge of the flow behaviour created by such geometries is critical for optimum design. The flow is made more complicated due to the presence of separation regions and streamwise Görtler vortices. The objective of the current research is to study the behaviour and characteristics of the flow over the double ramp model placed in hypersonic flow at freestream Mach number of 5. Three different incidence angles of 0°, −2°, and −4° are studied using colour Schlieren and luminescent paints consisting of anodized aluminium pressure-sensitive paint (AA-PSP) and the temperature-sensitive paint (TSP) technique. The colour Schlieren provides description of the external flow while the global surface pressure and temperature distribution is obtained through the AA-PSP and TSP methods. The TSP technique also proves that it is very effective in identifying the location and properties of the Görtler vortices; revealing the effect of incidence on the magnitude and pattern of Görtler vortices formed

LES investigation into the generation of momentum deficits in the supersonic wake of a micro-ramp

Implicitly implemented large eddy simulation (LES) with a fifth-order WENO scheme was conducted in this study. Based on Navier-Stokes equations, this LES was carried out to explore the origin of momentum deficit caused by a supersonic micro-ramp at flow conditions of M a = 2.5 and Re θ = 5760. The numerical results were validated through qualitative and quantitative comparisons with existing experimental data. After describing the aerodynamic properties of the supersonic wake, such as the deficit and the streamwise vortices, the momentum deficit was later detected to originate from the lower portion of the upstream boundary layer, while the high momentum fluid originated from close to the wall at the upper portion. Position alternation trigged by the micro-ramp was finally proposed as a revised mechanism

Gα11 mutation in mice causes hypocalcemia rectifiable by calcilytic therapy

Heterozygous germline gain-of-function mutations of G-protein subunit α11 (Gα11), a signaling partner for the calcium-sensing receptor (CaSR), result in autosomal dominant hypocalcemia type 2 (ADH2). ADH2 may cause symptomatic hypocalcemia with low circulating parathyroid hormone (PTH) concentrations. Effective therapies for ADH2 are currently not available and a mouse model for ADH2 would help in assessment of potential therapies. We hypothesised that a previously reported dark skin mouse mutant (Dsk7), which has a germline hypermorphic Gα11 mutation, Ile62Val, may be a model for ADH2 and allow evaluation of calcilytics, which are CaSR negative allosteric modulators, as a targeted therapy for this disorder. Mutant Dsk7/+ and Dsk7/Dsk7 mice were shown to have hypocalcemia and reduced plasma PTH concentrations, similar to ADH2 patients. In vitro studies showed the mutant Val62 Gα11 to upregulate CaSR-mediated intracellular calcium and MAPK signaling, consistent with a gain-offunction. Treatment with NPS-2143, a calcilytic compound, normalised these signaling responses. In vivo, NPS-2143 induced a rapid and marked rise in plasma PTH and calcium concentrations in Dsk7/Dsk7 and Dsk7/+ mice, which became normocalcemic. Thus, these studies have established Dsk7 mice, which harbor a germline gain-of-function Gα11 mutation, as a model for ADH2; and demonstrated calcilytics as a potential targeted therapy