Performance, environmental, and mobility analysis of large capacity fast rotorcraft configurations for the European regional air traffic market

Fast, large rotorcraft are of interest in the future European air transport system due to their runway independent operation and potential mobility improvements for the passenger. Both a tiltrotor and a coaxial compound concept model were developed for a 70 passenger, 500 NM design mission that would compete with regional fixed-wing aircraft. These models were flown along virtual trajectories representing possible use-cases and assessed for environmental performance in comparison to an in-service baseline aircraft using comparable engine technology levels. Further, the travel time and mobility improvement available to the intermodal transport network through the inclusion of these concept rotorcraft was examined with promising results. Future work is suggested to address the shortfall in environmental performance

A study of an artificial viscosity technique for high-order discontinuous Galerkin methods

Prediction of heat loads during hypersonic re-entry is of great interest in space exploration and in the topic of space debris as well. To date, there is no accurate method to reproduce either experimentally or numerically the physics in re-entry conditions. On the numerical side, high-order discontinuous Galerkin methods have potential to improve results achieved with state-of-the-art finite volume methods. However, they suffer from Gibbs-type oscillations around discontinuities such as shocks. This work uses artificial viscosity to tackle this issue.The artificial viscosity method used in this work contains three user-defined parameters which specify the magnitude, location and width of the artificial viscosity. A parametric study of these parameters on a steady inviscid wedge test case at Mach 2 showed that tuning their values is a non-trivial task and it appeared that in some cases shock smoothness and shock thickness need to be traded-off. Furthermore, it was observed that sufficient refinement in mesh size or polynomial order was needed to obtain satisfying results. The Sod test case was considered to test the method in an unsteady inviscid case. Good results were obtained, although the shock was better resolved than the contact discontinuity. The method was also tested on another unsteady inviscid test case, the Shu-Osher problem. The latter is more challenging due to the shock strength varying in time. Specifying the artificial viscosity parameters was challenging since the set had to account for variation of the shock strength in time. The test case also highlighted the need for a method that keeps variables within their physical bounds.Prediction of the heat flux on the surface of a half-cylinder in a hypersonic flow was attempted. However, this was unsuccessful and the Mach number was eventually reduced to 3.25. Strong non-physical oscillations appeared in the heat flux profile even with smooth contour plots and pressure profile at the surface of the half-cylinder. The key to obtain a smooth heat flux profile was to ensure no artificial viscosity at all is inserted in the boundary layer. Also, a symmetric mesh was needed to obtain a symmetric profile. Overall, the heat flux results showed that it is possible to simulate this challenging test case with discontinuous Galerkin and a combination of simple methods, including the Lax-Friedrichs flux and a basic smoothing of the artificial viscosity field.A new strategy to tune the user-defined parameter specifying the location of the artificial viscosity was implemented and tested on the Shu-Osher and half-cylinder test cases. It was found to be greatly beneficial in terms of stability and user-friendliness, but did not fully eliminate the issues in simulating these challenging test cases. This strategy allowed to run the half-cylinder test case beyond the Lax-Friedrichs flux and a polynomial order of 1. The heat flux profile with SLAU came very close to that with Lax-Friedrichs, whereas the difference was significant between first and second orders.Aerospace Engineerin

Figures created during the work on "Design of experiments: a statistical tool for PIV uncertainty quantification"

 This dataset contains figures created during the work on "Design of experiments: a statistical tool for PIV uncertainty quantification". The proposed UQ approach is applied to estimate the uncertainties in time-averaged velocity and Reynold normal stresses in planar PIV measurements of the flow over a NACA0012 airfoil. The approach is also used to the investigation by stereoscopic PIV of the flow at the outlet of a ducted Boundary Layer Ingesting (BLI) propulsor. The figures in this dataset show the results from these two experimental cases.  </p

Design of experiments: A statistical tool for PIV uncertainty quantification

A statistical tool called design of experiments (DOEs) is introduced for uncertainty quantification in particle image velocimetry (PIV). DOE allows to quantify the total uncertainty as well as the systematic uncertainties arising from various experimental factors. The approach is based on measuring a quantity (e.g. time-averaged velocity or Reynolds stresses) several times by varying the levels of the experimental factors which are known to affect the value of the measured quantity. Then, using Analysis of Variances, the total variance in the measured quantity is computed and hence the total uncertainty. Moreover, the analysis provides the individual variances for each of the experimental factors, leading to the estimation of the systematic uncertainties from each factor and their contributions to the total uncertainty. The methodology is assessed for planar PIV measurements of the flow over a NACA0012 airfoil at 15 degrees angle of attack considering five experimental factors, namely camera aperture, inter-frame time separation, interrogation window size, laser sheet thickness and seeding density. Additionally, the methodology is applied to the investigation by stereoscopic PIV of the flow at the outlet of a ducted Boundary Layer Ingesting propulsor. The total uncertainty in the time-averaged velocity as well as the constituent systematic uncertainties due to the experimental factors, namely camera aperture, inter-frame time separation, interrogation window size and stereoscopic camera angle, are quantified.Aerodynamic

Figures created during the work on "Design of experiments: a statistical tool for PIV uncertainty quantification"

 This dataset contains figures created during the work on "Design of experiments: a statistical tool for PIV uncertainty quantification". The proposed UQ approach is applied to estimate the uncertainties in time-averaged velocity and Reynold normal stresses in planar PIV measurements of the flow over a NACA0012 airfoil. The approach is also used to the investigation by stereoscopic PIV of the flow at the outlet of a ducted Boundary Layer Ingesting (BLI) propulsor. The figures in this dataset show the results from these two experimental cases.  </p

Figures created during the work on "Design of experiments: a statistical tool for PIV uncertainty quantification"

 This dataset contains figures created during the work on "Design of experiments: a statistical tool for PIV uncertainty quantification". The proposed UQ approach is applied to estimate the uncertainties in time-averaged velocity and Reynold normal stresses in planar PIV measurements of the flow over a NACA0012 airfoil. The approach is also used to the investigation by stereoscopic PIV of the flow at the outlet of a ducted Boundary Layer Ingesting (BLI) propulsor. The figures in this dataset show the results from these two experimental cases.  </p