Research on the rotational inertia of radial piston pump and the optimization method of the pump parameters
This paper aims to propose a method of optimizing the structure of radial piston pump from the aspect of reducing the rotational inertia. A modeling method based on basic dimensions and scale factors is developed. By using this method, three different types of radial piston pumps are studied. And the relative rotational inertia coefficient is adopted to evaluate the difference among them. Further study states that the relative rotational inertia coefficient changes along with the eccentricity ratio and the thickening factor. Finally a criterion is obtained, which could be used to optimize the structure and the dimensions of radial piston pumps.
THE DESIGN OF A VEHICLE INERTIA MEASUREMENT FACILITY
This paper describes the design of a vehicle inertia measurement facility (VIMF) used to measure: (1) vehicle center of gravity position; (2) vehicle roll, pitch, and yaw mass moments of inertia; and (3) vehicle roll/yaw mass product of inertia. The rationale for general design decisions and the methods used to arrive at the decisions are discussed. The design is inspired by the desire to have minimal measurement error and short test time. The design was guided by analytical error analyses of the contributions of individual system errors to the overall measurement error. A National Highway Traffic Safety Administration (NHTSA) database of center of gravity position and mass moment of inertia data for over 300 vehicles was used. This database was used in conjunction with the error analyses to design various VIMF components such as the roll and yaw spring sizes. This provides for a design that yields good experimental repeatability for the full range of lightvehicles that can be tested on the VIMF. The paper also discusses aspects of the VIMF software, for example: (a) the analytical curve fitting; and (b) the error checking of results. Results from the VIMF for two calibration fixtures are presented and compared to the computed center of gravity position and inertia values. For the covering abstract of the conference see IRRD 875861.
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.