Multistage Superchargers

The operating point where the compressor speed lines, and the engine’s operating line meet is critical. Thus, improvement of the efficiency at that point is of paramount importance. Through systematic development of the single-stage supercharger by (i) incremental improvements to the compressor impeller, (ii) the arrangement and development of the diffuser vanes, and (iii) the shape of the outer volute/spiral, significant gains in the performance of the single-stage compressor have been made.

Technology optimization on the rapid excavation in inclined shaft

Through a lot of investigation, many times of demonstrating scheme, the in-depth theoretic analysis, a large scale numeric simulation tests and the field tests, the operating line of the rapid excavation is equipped which are consisting of the way of the drilling and blasting, the bolt-mesh-spurting supporting and the trackless transportation. The key technology which includes the stable technology of controling the surrounding rock, the optimization technology of transportation system, the excavating technology of layered drilling and the technology of parallel and cross operation develops the integral management framework and the advanced technology framework with the operating line, which realizes the safe and efficient construction and provides rich experience for the similar mines.

A Comprehensive Study of Propulsion Torque Distribution for a Parallel Hydraulic Hybrid Heavy Bus

The purpose of this paper is to improve the fuel economy of a parallel hydraulic hybrid heavy bus. And an optimal distribution strategy of the propulsion torque was proposed based on engine working points of the conventional bus. The universal characteristics map of the engine was divided into three zones by the optimal operating line and the fuel contour CBF. The results indicated this strategy can not only overcome the low energy density disadvantage of the accumulator but also prohibit frequent switching between the engine and the pump/motor. The HHP can provide most of the required torque and make most working points of the engine around or on the optimal operating line. When the value of the fuel contour CBF is 213g/kw.h, the bus has the minimal fuel consumption in the typical urban bus cycle and the fuel economy of the engine improves 24.8% compared to the conventional bus.

An Investigation Into Performance Modeling of a Small Gas Turbine Engine

A small gas turbine performance modeling and testing project has been completed as part of a DSTO research program. The main objective of the program was to enhance capability in understanding and modeling the thermodynamic and performance characteristics of gas turbine engines. The secondary objective of the program was development of a simple, low-cost test apparatus for basic thrust augmentation technologies and infrared suppression studies. Engine performance modeling was conducted using commercial software (Gasturb) and an in-house developed code. Various techniques were used in predicting component performance which included scaling of published performance data, use of standard empirical performance models, mean-line and through flow codes and detailed Computational Fluid Dynamics (CFD) analysis. A comparison of the advantages and disadvantages of each method was made and compared with engine test data. The AMT Olympus HP turbojet engine was used as the test engine. The engine was instrumented using a bell mouth to measure mass flow rate, load cell to measure thrust, tachometer to measure engine rotational speed, thermocouples to measure flow total temperature and pressure transducers to measure wall static pressure at various stations along the engine. A pair of Olympus engines were tested for comparison during baseline testing, with consistent results between the two. The first engine was fully instrumented and used in all of the tests. This engine was used to test the engine standard operating line tests to determine bulk performance and establish compressor operating line. Tests were repeated and error analysis conducted to ensure repeatability and validity of the data. The second engine was used as a control engine with only the OEM supplied instrumentation, thrust and bell mouth used for benchmarking purposes. The data from both engines have been compared with the engine performance model and OEM data. A number of other tests were completed to “stress” the engine and shift its operating line closer to the compressor stall line. This was accomplished through various types of exhaust blockage. Stall behaviour was clearly evident in the initial commissioning tests where a large nozzle blockage resulted in engine stall and incomplete start-up. Engine performance and compressor map results from the tests have been compared to the engine performance model with good agreement.

Characterisation of the Uncertainties of the Operating Conditions in Turbomachinery Design

In computational engineering design the robust analysis comprises a prerequisite towards the successful development of future gas turbines. However, reliable determination of the statistical characteristics of variation of the operating conditions in a turbomachine is crucial. Initially, the variability of the physical operating conditions along the operating line on the compressor map is developed with the assistance of a through flow analysis tool. The probability density functions of the variability of the pressure profiles, mass flow, input angles, etc. of each individual stage of the compressor can be extracted and processed accordingly for 3D aerodynamic shape robust design. In this way, flexibility in detailed design is developed leading to innovative and creative thinking in modern turbomachinery design, but at the same time the intelligence and level of robust design is improved, and hence the quality of the designed product. For a particular compression system of a turbo-shaft engine all the details can be extracted, along the whole operating line, covering all the possible scenarios of individual operating conditions of each component. With this methodology the appropriate information is developed for robust analysis at the preliminary or detailed design phases of a compression system.