Minimizing boundary layer bleed for a mixed compression inlet

An experimental investigation of a full scale mixed compression inlet sized for the TF30-P-3 turbofan engine was conducted at Mach 2.5 and 2.0 operating conditions. The two cone axisymmetric inlet had minimum internal contraction consistent with high total pressure recovery and low cowl drag. At Mach 2.5, inlet recovery exceeded 0.90 with only 0.02 centerbody bleed mass-flow ratio and zero cowl bleed. A centerbody bleed of approximately 0.05 gave a maximum inlet unstart angle-of-attack of 6.85 deg. Inlet performance and angle-of-attack tolerance is presented for operation at Mach 2.5 and 2.0

Distortion in a full-scale bicone inlet with internal focused compression and 45 percent internal contraction

The distortion characteristics were investigated at the subsonic diffuser exit of a full-scale, Mach 2.5, axisymmetric, mixed compression inlet. Performance and steady-state distortion characteristics were obtained at zero and maximum angle of attack and during an inlet unstart-restart sequence. For the configuration with no cowl bleed, steady-state distortion P(max)P(min)P(bar) ranged from 0.10 for critical inlet operation at 0 deg angle-of-attack to 0.306 for supercritical inlet operation at 6.84 deg angle-of-attack. Vortex generators provided a 50 percent reduction in steady-state distortion for critical operation. Bleed has a smaller effect on steady-stated distortion

Performance of vortex generators in a Mach 2.5 low-bleed full scale 45-percent-internal-contraction axisymmetric inlet

Steady-state and dynamic flow characteristics associated with two sets of vortex generators having different mixing criteria were determined. The inlet performance with and without these vortex generators is presented. The vortex generators were successful in eliminating separation, increasing area-weighted total pressure recovery, and decreasing distortion. Transmission times obtained from cross-correlations of the wall static pressures and the diffuser exit total pressure showed no effect of the upstream flow characteristics on the diffuser exit pressures when generators were used. Without generators, separation occurred and the upstream pressure characteristics had immediate effects on the diffuser exit pressure characteristics

Boundary layer bleed system study for a full-scale, mixed-compression inlet with 45 percent internal contraction

The results of an experimental bleed development study for a full-scale, Mach 2.5, axisymmetric, mixed-compression inlet were presented. The inlet was designed to satisfy the airflow requirements of the TF30-P-3 turbofan engine. Capabilities for porous bleed on the cowl surface and ram-scoop/flush-slot bleed on the centerbody were provided. A configuration with no bleed on the cowl achieved a minimum stable, diffuser exit, total pressure recovery of 0.894 with a centerbody-bleed mass flow ratio of 0.02. Configurations with cowl bleed had minimum stable recoveries as high as 0.900 but suffered range decrement penalties from the increased bleed mass flow removal. Limited inlet stability and unstart angle-of-attack data are presented

Performance and surge limits of a TF30-P-3 turbofan engine/axisymmetric mixed-compression inlet propulsion system at Mach 2.5

Steady-state performance and inlet-engine compatibility were investigated with a low-bleed inlet. The inlet had minimum internal contraction, consistent with high total pressure recovery and low cowl drag. The inlet-engine combination displayed good performance with only about 2% of inlet performance bleed. The inlet-engine combination had 5.58 deg angle-of-attack capability with 6% bleed

The von Neumann-Wigner type potentials and the wave functions' asymptotics for the discrete levels in continuum

One to one correspondence between the decay law of the von Neumann-Wigner type potentials and the asymptotic behaviour of the wave functions representing bound states in the continuum is established.Comment: latex, 7 page

Simple Max-Min Ant Systems and the Optimization of Linear Pseudo-Boolean Functions

With this paper, we contribute to the understanding of ant colony optimization (ACO) algorithms by formally analyzing their runtime behavior. We study simple MAX-MIN ant systems on the class of linear pseudo-Boolean functions defined on binary strings of length 'n'. Our investigations point out how the progress according to function values is stored in pheromone. We provide a general upper bound of O((n^3 \log n)/ \rho) for two ACO variants on all linear functions, where (\rho) determines the pheromone update strength. Furthermore, we show improved bounds for two well-known linear pseudo-Boolean functions called OneMax and BinVal and give additional insights using an experimental study.Comment: 19 pages, 2 figure

Tradeoff between extractable mechanical work, accessible entanglement, and ability to act as a reference system, under arbitrary superselection rules

Superselection rules (SSRs) limit the mechanical and quantum processing resources represented by quantum states. However SSRs can be violated using reference systems to break the underlying symmetry. We show that there is a duality between the ability of a system to do mechanical work and to act as a reference system. Further, for a bipartite system in a globally symmetric pure state, we find a triality between the system's ability to do local mechanical work, its ability to do ``logical work'' due to its accessible entanglement, and its ability to act as a shared reference system.Comment: 5 pages, no figures. Extended resubmitted version. Slightly modified title. Transferred to PR

A conceptual study on the use of a regenerator in a hybrid energy storage unit (LIQHYSMES)

Wind and photovoltaic parks raise the issue of a discontinuous electrical generation. As an energy carrier with high volumetric energy density, liquid hydrogen is an inevitable choice for large-scale energy storage. But, since balancing loads or rapidly evolving fluctuations on the grid with just hydrogen is unrealistic due to ist slow response, it is necessary to integrate it with an electrical energy storage device that enables rapid response. This approach combines the use of a liquefaction plant for hydrogen, and a superconducting magnetic energy storage (SMES). Besides, in this case, conventional liquefaction methods are not a viable solution, meaning that a substantial simplification of the process is possible where a regenerator/recuperator is employed and only if temporary/intermediate storage is required. A study is conducted to develop a regenerator (among other parts) for a proof of concept small scale LIQHYSMES system. A 1D model of differential equations is implemented to investigate the regenerator performances, addressing parameters such as regenerator configuration, material and fluid properties, temperature profiles, etc. Results are then analysed and discussed