Eduardo Blanco-Marigorta

Angular Range and Uncertainty Analysis of Nonorthogonal Crossed Hot Wire Probes

Crossed hot wire probes are widely used for measuring two-dimensional flows. Many applications in fluid mechanics like turbomachinery require an angular range as large as possible and a reasonable uncertainty in both direction and velocity values. The classic design places the wires orthogonally, while an angle between the probe wires allows a wider angular range to be obtained. We show an experimental and a theoretical study of the response of this kind of probes, by analyzing the dependence of the calibration procedure and uncertainties of flow angle and velocity with the angle between the wires

Total unsteadiness downstream of an axial flow fan with variable pitch blades

Variable pitch axial flow fans are widely used in industrial applications to satisfy variable operating conditions. The change of the blade pitch leads to a different rotor geometry and has a major influence on the unsteady operation of the machine. In this work, an experimental research on an axial flow fan with variable pitch blades has been carried out. First of all, the fan performance curves has been obtained. Then the flow field has been measured at ten radial locations both at the inlet and exit rotor plane using hot wire anemometry. Velocity components and total unsteadiness were determined and analyzed in order to characterize the influence of pitch blade and operating conditions on the flow structure

An Open Water Numerical Model for a Marine Propeller: A Comparison With Experimental Data

The open water model tests technique is well known and commonly used to predict propellers performance. In this paper, a quite different approach is intended and the main propeller variables are numerically modelled using a finite volume commercial code. Particularly, a fishing-boat propeller is numerically treated using a three-dimensional unstructured mesh. Mesh dependency and different turbulent models are considered together with an sliding technique to account for the rotation. Typical turbomachinery boundary conditions for a volume containing the propeller are imposed (inlet velocity and outlet static pressure). In order to get the open water test performance coefficients for the considered propeller (KT , KQ , η), different advance coefficient (J) are imposed as boundary conditions for the numerical model. The results of such simulations are compared with experimental data available for the open water tests of the propeller. Once the model is validated with the experimental data available, a wake field simulation would be possible and would lead to the definition of the fluid-dynamic variables (pressure, iso-velocity maps, etc.) which are needed during any design process. Also some comparisons with real scale thrust measurements are intended.Copyright

Hot Wire Measurements During Rotating Stall in a Variable Pitch Axial Flow Fan

This work deals with a series of experiments on the influence of the blade pitch on the rotating stall phenomenon in an industrial variable pitch, low-speed axial flow fan with low hub-to-tip ratio.Two simple hot wires were used to detect the rotating stall. One in the absolute frame and the other in the relative frame rotating with the rotor. The rotating stall features were determined, ranging from the non-existence in the whole flow range with the lowest pitch tested to one and two flow cells with the greatest pitch.Then, a triple hot wire, calibrated by a direct method, was used to measure the absolute flow field upstream and downstream from the rotor, before and during rotating stall for five distinct blade pitches. These measurements allow us to characterize different rotating stall structures.To understand the phenomena better, some tests were carried out in the relative frame, with the probe rotating with the rotor. An intermediate blade pitch with a single rotating cell was selected and measurements were taken at three radial positions. Velocity maps for all these measurements are presented.Copyright