Thermodynamic effects of Bardeen black hole surrounded by perfect fluid dark matter under general uncertainty principle

In this paper, the thermodynamics of Bardeen black hole surrounded by perfect fluid dark matter is investigated. We calculate the analytical expresses of corresponding thermodynamic variables, e.g. the Hawking temperature, entropy of the black hole. In addition, we derive the heat capacity to analyze the thermal stability of the black hole. We also compute the rate of emission in terms of photons through tunneling. By numerical method, an obvious phase transition behavior is found. Furthermore, according to the general uncertainty principle, we study the quantum corrections to these thermodynamic quantities and obtain the quantum-corrected entropy containing the logarithmic term. At last, we investigate the effects of the magnetic charge g, the dark matter parameter k and the generalized uncertainty principle parameter α on the thermodynamics of Bardeen black hole surrounded by perfect fluid dark matter under general uncertainty principle.

Numerical Study on the Effect of Fuel Rich n-Heptane on In-Cylinder Fuel Reforming Characteristics in an HCCI Engine

The effect of in-cylinder fuel reforming on an n-heptane homogenous charge compression ignition engine has been studied. A dedicated cylinder without a complex control system is proposed for fuel enrichment reforming, which can provide part of the power for the engine. The effects of different reforming species on engine performance and chemical reaction have been simulated by a numerical study. By comparing the combustion characteristics of n-heptane with different equivalence ratios in the reformer cylinder, the optimal n-heptane equivalence ratio has been determined. The enrichment of n-heptane produces sufficient hydrogen (H2) and carbon monoxide (CO), while the hydrocarbon content of the reforming species was low. It was found that the addition of reforming species retards the combustion phase of n-heptane, thereby providing a means of controlling engine performance. In addition, the laminar flame speed and the adiabatic flame temperature of n-heptane increased by adding H2 and CO. Fuel reforming reduced the emission of ethylene, propyne, allene, propylene, butadiene, and nitrogen oxide, but it increased the emissions of acetylene and CO. Moreover, chemical, dilution, and thermodynamic effects of the reforming gas have been studied. The results showed that the chemical effect of the reforming species was less significant than the dilution and thermodynamic effects. These simulation results showed that in-cylinder fuel reforming can effectively improve engine performance and thereby reduce emissions.

Equivalent Analysis of Thermo-Dynamic Blow-Off Impulse under X-ray Irradiation

X-ray thermodynamic effect is an important damage mode for spacecraft. Blow-off impulse as the main thermodynamic damage parameter has been widely studied by combining laboratory and numerical simulations. In this paper, most calculations and analyses have been carried out by using the self-developed software RAMA, including the equivalent calculation of blow-off impulse of monoenergetic and blackbody X-ray, and soft/hard blackbody X-ray irradiated at different incidence angles of LY-12 aluminium target. The results show that the characteristic mono-energetic X-ray can be exploited to simulate the blow-off impulse of the blackbody X-ray under certain conditions as a feasible equivalent method for the equal-flux and equal-impulse relations between mono-energetic and intense pulse blackbody of blow-off impulse. Moreover, the equivalent thermodynamic effect can be achieved between the point source radiation and parallel X-ray of X-ray. Furthermore, the cosine distribution of blow-off impulse is conducive to designing and calculating X-ray radiation load of hard aluminium corresponding to 1–5 keV blackbody spectrum. The mentioned results can be referenced for pulse X-ray simulation source and enhance the fidelity of the thermal-mechanical effect by electron beam. It is noteworthy that the study on the thermodynamic effects of intense pulsed X-ray is of high significance.

The Blow-Off Impulse Equivalence of Typical Missile Homogeneous Al-Alloy under Multienergy Composite Spectrum Electron Beam and Powerful Pulsed X-ray

The electron beam, one of the most effective approaches to simulate the irradiation effects of powerful pulsed X-ray in the laboratory, plays an important role in simulating the thermodynamic effects of powerful pulsed X-ray. This paper studies the thermodynamics equivalence between multienergy composite spectrum electron beam and blackbody spectrum X-ray, which is helpful to quickly determine the experimental parameters in the simulation experiment. The experimental data of electron beam are extrapolated by numerical calculation, to increase the range of energy flux. Through calculating the blow-off impulse of blackbody spectrum X-ray irradiation, we obtained the curve of X-ray blow-off impulse varying with energy flux, and then found two categories of equivalent relations—equal-energy flux and equal-impulse—by analyzing the calculation results of electron beam and X-ray blow-off impulse. Based on such relations, we could directly or indirectly obtain the results of blackbody spectrum X-ray irradiation blow-off impulse via electron beam experiment.

Idealized Simulations of Mei-yu Rainfall in Taiwan under Uniform Southwesterly Flow using A Could-Resolving Model

In this study, idealized cloud-resolving simulations are performed for horizontally uniform and steady southwesterly flow at fixed direction/speed combinations to investigate rainfall characteristics and the role of the complex topography in Taiwan during the Mei-yu season, without the influence of a front or other disturbances. Eight directions (180° to 285°, every 15°) and eight speeds (5 to 22.5 m s−1, every 2.5 m s−1) are considered, and near-surface relative humidity (RH) is also altered (from 55–100 %) in a subset of these tests to further investigate the effects of moisture content, yielding a total 109 experiments each having a integration length of 50 h. Three rainfall regimes that correspond to different ranges of the wet Froude number (Frw) are identified from the idealized simulations (with a grid size of 2 km). The low-Frw regime (Frw ≤ ~0.3) where the island circulation from thermodynamic effects during daytime is the main cause of rainfall in local afternoon. The lower the wind speed (and Frw), the more widespread and amount of rainfall. On the other hand, the high-Frw regime (Frw ≥ ~0.4) occurs when the flow at least 12.5 m s−1 impinges on Taiwan terrain at a large angle to favor the flow-over scenario. Thus, topographic rainfall production becomes dominant through mechanical uplift of unstable air. In this scenario, the faster and wetter the flow, the heavier the rainfall on the windward slopes, with the most favorable direction from 240°–255°. Between the two regimes above, a third and mixed regime also exists. The idealized results are discussed for their applicability to the real atmosphere.

Thermodynamic Effects on Pressure Fluctuations of a Liquid Oxygen Turbopump

Liquid oxygen turbopumps are an important component of rocket engines. The instability induced by cavitation flow in turbopumps has received considerable attention because of thermodynamic effects. In this study, unsteady numerical simulations of a turbopump with thermodynamic effects were performed. The frequency composition and source of pressure fluctuations in a turbopump were analyzed, and the difference in pressure fluctuations with/without thermodynamic effects was revealed. The results showed that the pressure fluctuations were mainly caused by the interaction between the impeller and diffuser, and the thermodynamic effects slightly increased the amplitudes of the characteristic frequencies. In addition, in the inducer and impeller, three characteristic frequencies (4.089fn, 2.519fn, and 3.238fn, where fn is the rotational frequency) were confirmed. Analyses revealed that the 4.089fn was due to the periodic shedding of cavitation structures on the suction surfaces at the inducer outlet, 2.519fn was induced by the periodic occurrence and collapse of cavitation on the suction surfaces at the impeller inlet; and 3.238fn was from the periodic shedding of cavitation structures on the suction surfaces at the impeller middle blades. The existence of thermodynamic effects decreased the frequency of cavitation shedding and increased the frequency of the periodic occurrence and collapse of cavitation.