Effect of reduced aft diameter and increased blade number on high-speed counterrotation propeller performance

Performance data of 0.17-scale model counterrotation pusher propeller configurations were taken in the NASA Lewis 8- by 6-Foot Supersonic Wind Tunnel at Mach numbers of 0.66, 0.71, 0.75, and 0.79. These tests investigated the aerodynamic performance of the unducted fan (UDF) demonstrator propeller engine developed in a joint program by General Electric and NASA. Data were recorded to show the effect on counterrotation propeller cruise efficiency of two takeoff noise-reduction concepts. These two concepts are reduced aft blade diameter and increased forward blade number. The four configurations tested were a baseline (F1/A1 8/8) configuration, a reduced aft diameter (F1/A3 8/8) configuration, an increase forward blade number (F1/A1 9/8) configuration, and a combination of the latter two (F1/A3 9/8) configurations. Data were collected with a complex counterrotation propeller test rig via rotating thrust and torque balances and pressure instrumentation. Data comparisons documented the power differences between the baseline and the reduced aft diameter concepts. Performance comparisons to the baseline configuration showed that reducing the aft blade diameter reduced the net efficiency, and adding a blade to the front rotor increased the net efficiency. The combination of the two concepts showed only slightly lower net efficiency than the baseline configuration. It was also found that the counterrotation demonstrator propeller model (F7/A7 8/8) configuration outperformed the baseline (F1/A1 8/8) configuration

Dissipative hydrodynamic evolution of hot quark matter at finite baryon density

High-energy heavy ion collider experiments at RHIC and LHC have revealed that relativistic hydrodynamic models describe the hot and dense quark matter quantitatively. In this study, I develop a novel dissipative hydrodynamic model at finite baryon density to investigate the net baryon rapidity distribution. The results show that the distribution is widened in hydrodynamic evolution, which implies that the transparency of the collisions is effectively enhanced. This suggests that the kinetic energy loss for medium production at the initial stage could be larger. Furthermore, the net baryon distribution is found sensitive to baryon diffusion, implying that dissipative hydrodynamic modeling would be important for understanding the hot medium.Comment: 8 pages, 5 figures - To appear in the conference proceedings for Quark Confinement and the Hadron Spectrum X, October 8-12, 2012, TUM Campus Garching, Munich, German

Biological characteristics of the gill net catch from the 1989-90 Pacific herring, Clupea pallasi, roe fishery in California

The Tomales-Bodega Bay catch this season was from northern Bodega Bay, and the possibility that this season's catch may be from a different stock must be considered. In the Tomales-Bodega Bay area, 5- through 8-yr-old herring, Clupea pallasi, comprised 89% by number of the 1989-90 season's gill net catch. Recruitment of the 1986 year class (4-yr olds) was relatively poor, comprising only 9% of the gill net catch by number. Average length of the Tomales-Bodega Bay area gill net catch increased to 204 mm BL because the number of 3- and 4-yr olds in the catch decreased to 11%, the lowest level since the 1982-83 season. The average weight at age of 4-through 8-yr-old herring did not change significantly this season. In San Francisco Bay, for the first time since the 1982-83 season, 5-, 6-, and 7-yr-old herring were the dominant age groups comprising 79% by number of the gill net catch. This reverses a trend toward younger and smaller herring in the gill net catch. The average length of herring in the San Francisco Bay gill net catch increased to 196 mm BL. The change in the size and age composition is attributed to better enforcement of the 2 1/8 in. gill net mesh regulation. The sex ratio of the gill net catch also improved. Females comprised 53% of the catch in both San Francisco and Tomales bays. (19pp.

Critical Fluctuations at RHIC

On the basis of universal scaling properties, we claim that in Au+Au collisions at RHIC, the QCD critical point is within reach. The signal turns out to be an extended plateau of net baryons in rapidity with approximate height of the net-baryon rapidity density approximately 15 and a strong intermittency pattern with index s_2=1/6 in rapidity fluctuations. A window also exists, to reach the critical point at the SPS, especially in Si+Si collisions at maximal energy.Comment: 8 pages, 3 figure