Search for Extra Dimensions in Boson and Fermion Pair Production in e+e- Interactions at LEP

Extra spatial dimensions are proposed by recent theories that postulate the scale of gravity to be of the same order as the electroweak scale. A sizeable interaction between gravitons and Standard Model particles is then predicted. Effects of these new interactions in boson and fermion pair production are searched for in the data sample collected at centre-of-mass energies above the Z pole by the L3 detector at LEP. In addition, the direct production of a graviton associated with a Z boson is investigated. No statistically significant hints for the existence of these effects are found and lower limits in excess of 1 TeV are derived on the scale of this new theory of gravity

Effect of jet azimuthal angle on the flow field within a Hybrid Solar Receiver Combustor

DAY 2 Plenary Session - Concentrating Solar Thermal - Receivers. Stream – Concentrating Solar Power - Long, S. paper.This paper reports on a systematic experimental and numerical study that investigates the interaction between four isothermal jets within a cylindrical chamber under conditions relevant to a Hybrid Solar Receiver Combustor (HSRC). The HSRC features a cavity that is operable as a combustion chamber, or as a cavity receiver with an aperture to admit the concentrated solar radiation, multiple burners to direct fuel and air into the chamber and tubular heat exchangers to transfer the heat to the heat transfer fluid. The HSRC geometry is simplified here to the cylindrical cavity with four jets, representing the burners, which are configured in an annular arrangement and aligned at an angle to the axis with a swirling component. The aperture to the cavity is closed while the four jets interact with each other and with the cavity wall. The jet inclination angle (αj) was fixed at 25°, while the jet azimuthal angle (θj) was varied from 5° to 15°. The inlet Reynolds number for each injected jet and the number of jets were fixed at ReD = 10500 and 4, respectively. Measurements obtained with Particle Image Velocimetry (PIV) were used together with numerical modelling employing Reynolds-Averaged Navier-Stokes (RANS) methods to characterise the large-scale flow field within the HSRC device. The results reveal a significant dependence of the mean flow-field on the jet azimuthal angle (θj) and have implications on the heat transfer within the HSRC.S.Long, T.C.W. Lau, A. Chinnici, Z.F. Tian, B.B. Dally and G.J. Natha