ANALYSIS OF AVERAGING METHODS FOR NON-UNIFORM TOTAL PRESSURE FIELDS

A common objective in the analysis of turbomachinery components (nozzle guide vanes or rotor blades, for example) is to calculate performance parameters, such as total pressure or kinetic energy loss coefficients, from measurements in a non-uniform flow-field. These performance parameters can be represented in a range of ways. For example: line-averages used to compare performance between different radial sections of a 3D component; plane-averages used to assess flow (perhaps loss coefficient) development between different axial planes; and fully mixed-out values used to determine the total loss associated with a component. In this paper, we compare a range of methods for calculating aerodynamic performance parameters including plane-average methods with different weighting schemes and several mixed-out methods. We analyse the sensitivities of the different methods to the axial location of the measurement plane, the radial averaging range, and the exit Mach number. We use high-fidelity experimental data taken in several axial planes downstream of a cascade of engine parts: high pressure (HP) turbine nozzle guide vanes (NGVs) operating at transonic Mach number. The experimental data is complemented by CFD. We discuss the underlying physical mechanisms which give rise to the observed sensitivities. The objective is to provide guidance on the accuracy of each method in a relevant, practical application.

Physical characteristics of pipes as indicators of structural state for decision-making considerations in sewer asset management

Sewer deterioration is a problem that affects many cities of the world. This affects the structural state of the sewer systems, as well as its hydraulic capacity and the service level. As a consequence, the sewer system stakeholders are working on the development of a proactive sewer management to make decision in time and avoid public emergencies. Therefore, the objective of this work was to predict the variable state using a clustering algorithm (k-means) in Bogotá’s sewer pipes based on its physical characteristics. Among the most representative results was to find a relationship between pipes’ characteristics and their structural state (chi-squared). Furthermore, the slope and ground level variables were the most related ones to the state of the pipes. The detected relationships are linear and can be used to make management decisions when pipes are clustered and the clusters are mapped on a principal component plane.

Class Definition and Mixture Class Definition by Means of Construction of Convex Hull Boundaries: Application to Analysis for Animal Fat Adulteration

A visual classification technique based on the construction of convex hull boundaries in combination with a principal component analysis is described. This combined technique was evaluated in the situation in which a distinction has to be made between 2 pure animal fat classes and the corresponding mixture class. In the first instance, a principal component analysis is carried out to ensure the 2-dimensional and thus visual aspect of the technique. Convex hulls are then constructed in the 2-dimensional principal component plane to delimit the boundaries of the different classes to be defined. The effectiveness of the constructed hull boundaries in the definition of class-membership was investigated by means of the classification of different simulated test samples. The results show that, at least for the tested applications, the technique is valid, although some false positive classifications occur. The detection of outliers especially seemed to pose problems. Therefore, some propositions are made of how to refine the developed hull technique to enhance the classification results.