Modeling of stratosphere airship
The dynamics and kinematics model is very important for the analysis of stability, manipulation and control of stratosphere airship. A full modeling approach that includes the computation of aerodynamics of airship and the added mass for the nonlinear dynamics simulation of stratosphere airships is proposed in this paper. In this approach, the aerodynamics of airship is calculated based on a panel method, an engineering estimation and theory approach. A new numerical method for calculating added masses of airship is developed by using the CFD method. This model can simulate the motion of stratosphere airships quickly and accurately.
The Aerodynamic Forces on Airship Hulls
The new method for making computations in connection with the study of rigid airships, which was used in the investigation of Navy's ZR-1 by the special subcommittee of the National Advisory Committee for Aeronautics appointed for this purpose is presented. The general theory of the air forces on airship hulls of the type mentioned is described and an attempt was made to develop the results from the very fundamentals of mechanics.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.