Numerical Estimation of the Pile Toe and Shaft Unit Resistances During the Installation Process in Sands

Numerical simulations of a pile jacking were carried out. A Coupled Eulerian-Lagrangian (CEL) formulation was used to treat with large deformation problems. An Abaqus, a commercial Finite Element Method software suit, was used as a computing environment. The Mohr-Coulomb constitutive model was applied and the Coulomb model of friction was used to describe pile-soil interaction. Calculations were made for three different pile diameters. Toe and shaft unit resistances versus depth for each pile were investigated and plotted. CPT-based solutions were compared with the results of numerical simulations.

Microscale Radial-Flow Compressor Impeller Made of Silicon Nitride: Manufacturing and Performance

A microscale, high-speed compressor impeller (12 mm diameter, 800,000 rpm) was tested for feasibility in regard to aerodynamic performance. The compressor was designed for application in a first-sized gas turbine generator. To survive high stresses at such high temperatures, the rotor was manufactured as a single turbine/compressor/shaft unit in silicon nitride, by the Mold SDM process. Performance testing was conducted in a cold-flow rig at reduced speed of 420,000 rpm. Results from a CFD code compared favorably to measured data at this speed. Extrapolation from test conditions to full design speed was accomplished by application of CFD applied at both speeds.

Micro-Scale Radial-Flow Compressor Impeller Made of Silicon Nitride: Manufacturing and Performance

A micro-scale, high-speed compressor impeller (12mm diameter, 800,000 rpm) was tested for feasibility in regard to aerodynamic performance. The compressor was designed for application in a fist-sized gas-turbine-generator. To survive high stresses at such high temperatures, the rotor was manufactured as a single turbine/compressor/shaft unit in silicon nitride, by the Mold SDM process. Performance testing was conducted in a cold-flow rig at reduced speed of 420,000 rpm. Results from a CFD code compared favorably to measured data at this speed. Extrapolation from test conditions to full design speed was accomplished by application of CFD applied at both speeds.

Requirements for Educational Gas Turbines

Many university and college laboratories operate gas turbines which were installed about 15 years ago, and some thought must be given to eventual replacement. This paper reviews the requirements of gas turbines suitable for this market and compares the relative merits of single-shaft and free turbine units. It is suggested that a single-shaft unit with a load compressor has considerable merit with regard to operating flexibility, versatility, and performance, and design aspects of a suitable unit are discussed.

Comparison of Operating Characteristics of a Two-Shaft Gas Turbine With a Single-Shaft Gas Turbine for Gas Line Pumping

Gas turbines are playing an important role in the ever-expanding gas-transportation industry. Coupled to a centrifugal compressor the gas turbine provides a low-cost, flexible prime mover for gas transmission. The two types of gas turbines most commonly used in this field are the single-shaft unit and the two-shaft unit. This paper describes and compares the operating characteristics of each unit along a typical centrifugal-compressor loading line for constant station discharge pressure. Horsepower-speed relationships and specific fuel consumption are considered in this comparison.