Leakage flow simulation in a specific pump model

This paper deals with the influence of leakage flow existing in SHF pump model on the analysis of internal flow behaviour inside the vane diffuser of the pump model performance using both experiments and calculations. PIV measurements have been performed at different hub to shroud planes inside one diffuser channel passage for a given speed of rotation and various flow rates. For each operating condition, the PIV measurements have been trigged with different angular impeller positions. The performances and the static pressure rise of the diffuser were also measured using a three-hole probe. The numerical simulations were carried out with Star CCM+ 8.06 code (RANS frozen and unsteady calculations). Comparisons between numerical and experimental results are presented and discussed for three flow rates. The performances of the diffuser obtained by numerical simulation results are compared to the performances obtained by three-hole probe indications. The comparisons show few influence of fluid leakage on global performances but a real improvement concerning the efficiency of the impeller, the pump and the velocity distributions. These results show that leakage is an important parameter that has to be taken into account in order to make improved comparisons between numerical approaches and experiments in such a specific model set up

Transient behavior of a radial vaneless diffuser

The paper refers to the behavior of a radial flow pump vaneless diffuser during a starting period. Results obtained with a 1D numerical model are compared with some new experimental data which have been obtained using 2D/3C High repetition rate PIV within the diffuser coupled with unsteady pressure measurements. These tests have been performed on a test rig with a radial impeller matched with a vaneless diffuser. They have been made in air, on a test rig well adapted for studies on interactions between impeller and diffuser, as well as for the use of optical methods and especially Particle Image Velocimetry (PIV) as there is no volute downstream of the diffuser. The present study refers to new experiments combining pressure measurements and 2D/3C High Speed PIV at partial flow rates within a vaneless diffuser with a large outlet radius. Four Brüel & Kjaer condenser microphones are used for the unsteady pressure measurements. They were flush mounted on the shroud side of the diffuser wall and on the suction pipe of the pump. The sampling frequency was 2048 Hz. For PIV measurements, the laser sheet was generated by a Darwin PIV ND:YLF Laser at three heights within the diffuser. PIV snapshots have been recorded by two identical CMOS cameras. A home made software has been used for the images treatment. The results consist in fields of 80 x 120 mm2 and 81 x 125 velocity vectors with a temporal resolution of 250 velocity maps per second. For each flow rate and each laser sheet height in the diffuser, two acquisitions of about 1500 velocity maps have been realised. The experimental data are compared with the ones provided by a 1D transient model of the flow within the diffuser

Multi-layer semantic interpretation of Aeronautical information

We present a hybrid architecture for knowledge extraction, in our future digital assistant for pilots in commercial aircraft. We need to automatically decode aeronautical messages known as NOTAM (Notice to Airmen) and ATIS (Automatic terminal area information service). Those messages include natural language sentences for operationally relevant information, particularly about the availability of runways or taxiways, related limitations or procedures. For example, ILS APCHS IN USE RWY 36R, RNAV RWY 36L APCHS IN USE (“APCHS” stands for approaches, “RWY” stands for runway). Such messages need to be reliably interpreted into a logical form, in order to: push relevant notifications to the pilot, answer his questions, or monitor flight’s compliance with applicable constraints. Moreover, in case of pilot incapacitation during a single pilot flight, the aircraft should be able to autonomously divert the flight

Financement des universités : pour un SYstème de répartition des Moyens à l\u27Activité et à la Performance (SYMPA) (le)

Sénat - Rapport d\u27information n° 382 (2007-2008) du 10 juin 2008 - par MM. Philippe ADNOT, Jean-Léonce DUPONT, Christian GAUDIN, Serge LAGAUCHE, Gérard LONGUET et Philippe RICHERT, fait au nom de la commission des Affaires culturelles et de la commission des Finances, du contrôle budgétaire et des comptes économiques de la Natio

Comparisons Between Numerical Calculations and Measurements in the Vaned Diffusor of SHF Impeller

The authors wish to thank Region Nord-Pas de Calais and CNRS for their financial support in the frame of the CISIT programThe paper presents analysis of the performance and the internal flow behaviour in the vaned diffusor of a radial flow pump using PIV (Particle Image Velocimetry) and pressure probe traverses. PIV measurements have already been performed at mid height inside one diffusor channel passage for a given speed of rotation and various mass flow rates. These results have been already presented in several previous communications. New experiments have been performed using a 3 holes pressure probe traverses from hub to shroud diffusor width at different radial locations between the two diffusor geometrical throats. Numerical simulations are also realized with the commercial codes Star CCM+ 7.02.011 and CFX. Frozen rotor and fully unsteady calculations of the whole pump have been performed. Comparisons between numerical results, previous experimental PIV results and new probe traverses one’s are presented and discussed for one mass flow rate. In this respect, a first attempt to take into account fluid leakages between the rotating and fixed part of the pump has been checked since it may affect the real flow structure inside the diffuse

High-speed stereoscopic PIV study of rotating instabilities in a radial vaneless diffuser

This paper presents an experimental analysis of the unsteady phenomena developing in a vaneless diffuser of a radial flow pump. Partial flow operating conditions were investigated using 2D/3C high repetition rate PIV, coupled with unsteady pressure transducers. Pressure measurements were acquired on the shroud wall of the vaneless diffuser and on the suction pipe of the pump, whereas PIV flow fields were determined on three different heights in the hub to shroud direction, inside the diffuser. The classical Fourier analysis was applied to both pressure signals to identify the spectral characteristics of the developing instabilities, and the high-order spectral analysis was exploited to investigate possible non-linear interaction mechanisms between different unsteady structures. A dedicated PIV averaging procedure was developed and applied to the PIV flow fields so as to capture and visualize the topology of the spectrally identified phenomena. The influence of these phenomena on the diffuser efficiency was also investigated.CISIT - Region Nord pas de calai

Chronique d’une invention : le phonautographe d’Édouard-Léon Scott de Martinville (1817-1879) et les cercles parisiens de la science et de la technique

Cette étude, entreprise par la Commission d’histoire de la Société d’encouragement après la visite récente de chercheurs américains à la poursuite des grands ancêtres de l’enregistrement sonore, nous a conduits sur les traces d’un « artiste » peu connu aujourd’hui, Édouard-Léon Scott de Martinville [1817-1879]. L’activité de cet inventeur, précurseur des études modernes de phonétique acoustique, témoigne du fonctionnement des milieux académiques et industriels du Second Empire, à la charnière de la science et de la technique. Et ses apports se sont avérés aller bien au-delà de ce qu’il avait pu lui-même imaginer.Following a recent visit of two American scholars in Paris, looking for the great ancestors of the sound recordings, some members of the Historical Commission of the « Société d’encouragement pour l’industrie nationale » undertook a study on Edouard-Léon Scott de Martinville (1817-1879) and his activities. This inventor, who is not very well-known today, is one of the precursors of modern studies on acoustical phonetics. Scott’s activities illustrate the part played by academic and industrial circles during the French Second Empire for connecting between science and technology. Surprisingly, Scott’s contributions went beyond those he himself imagined