To meet the requirements of fuel pumps with high efficiency, high power density, and low flow ripple for modern advanced aircraft, we hereby propose a two-dimensional piston pump (called 2D pump). A single piston with both rotary and linear motions is used to combine the flow distributing and volumetric varying functions together. The leakage spots are reduced to the clearance between the piston and the cylinder. As the radial force of the piston is balanced, a small piston clearance is selected to reduce leakage. Furthermore, a 2D tandem pump formed by two 2D pump units connected in series was introduced to eliminate the geometric flow ripple. The flow ripple characteristics were studied through analytical techniques, CFD numerical methods, and experiments. The results show that the flow ripple of 2D pump obtained by the measured pressure wave is 6.3%, while the pump has a high volumetric efficiency of up to 96% within a speed range of 1000-8000 r/min, indicating that reducing the leakage increases the average actual flow and reduces the flow ripple. Therefore, the proposed 2D pump is suitable for modern advanced aircraft.

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Aiming at the problem that common flame arresters can only extinguish deflagration flame, but cannot effectively extinguish detonation flame in large pipelines, this paper proposes a novel structure of detonation arrester based on heat transfer theory to improve the detonation flame extinguishing efficiency. The flame arresting element is composed of a large disk with long triangular slits and is used as the quenching part of detonation arrester in a monolithic structure. Compared with common flame arrester consists of several small fires retarding elements, the proposed monolithic structure is safer due to its integrity. In addition, this paper explores the relationship between flame extinguishing ability, detonation pressure, and temperature change. This investigation determined that the diameter of the quenching part and the parameters(length and height) of the long triangular slits were the key factors affecting the quenching characteristics, and as the diameter and porosity increase, the detonation pressure at the front of the flame arrester will decrease. Finally, the rationality and applicability of the structure are verified by simulation experiments. These preliminary conclusions are helpful to reveal the nature of the proposed structure and solve the technical problem of preventing detonation flame propagation of coal mine gas in large pipelines.

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Physically-based parameter estimations are essential to improve the simulation performance of a hydrologic model and to produce physically reasonable parameters with spatial consistency. This study proposed a parameter derivation strategy to improve the Sacramento Soil Moisture Accounting (SAC-SMA) model simulation performance based on the publicly accessible Harmonized World Soil Database (HWSD). The HWSD soil properties were used to estimate the soil moisture characteristics, and the HWSD soil texture classifications and International Geosphere-Biosphere Programme (IGBP) land cover types were used to identify the Soil Conservation Service (SCS) runoff curve number (CN). After the soil moisture characteristics and CNs were identified, the major parameters of the SAC-SMA model were derived. The simulation results were evaluated using the Nash efficiency coefficient (NSEC), and Free Search (FS) algorithm was used to further adjust and calibrate the parameters. Compared with the simulation accuracy (NSEC = 0.66~0.88) and parameter transferability (NSEC = 0.22~0.83) obtained for the SAC-SMA model using directly calibrated parameters, the HWSD data-derived parameters allowed the SAC-SMA model to achieve a similar simulation accuracy (NSEC = 0.65~0.86) and a better transferability (NSEC = 0.61~0.85).