This paper presents results of numerical investigation, based on two-dimensional model, of a wave disk micro-engine concept taking into account full set of unsteady, centrifugal, Corriolis forces existing in such configuration. Even in two-dimensional simplification, the engine model derived guarantees conservation of mass flow through the simulated combustion chamber. A series of different geometrical configurations is analyzed. Investigation concentrates on the pure unsteady wave engine configuration. The waveengine design investigation presented in recent paper focused on two main problems: realization of gas compression and simultaneously a torque generation. Compression performance has been confirmed in almost any considered configuration but the torque generation was much below the expectations. Results of numerical simulations are presented in form of pressure, temperature and velocity distributions as well torque variations.

抄録全体を表示

The power production planning problem has been deeply investigated. Maintenance management and load allocation problems have been assumed as crucial aspects for achieving maximum plant profitability. Modeling of life consumption of hot section components has been considered as one of the key feature necessary to simulate the plant behaviour. The approach takes market scenarios, as well as actual status and performance of plant components into account. A supervisor algorithm provides the operating parameters needed to establish each plant loading. Economic implications related to maintenance strategies including postponement or anticipation of maintenance interventions are investigated and results obtained by the numerical simulation are presented and widely discussed.

抄録全体を表示

This article deals with the conceptual approach to optimize efficiency and power of a highly loaded gas turbine flow path design. Different problems were analyzed during low pressure turbine (LPT) preliminary design of high-bypass aircraft jet engine.

抄録全体を表示

Numerical study was carried out on a transonic compressor rotor, NASA Rotor 37, with different configurations of circumferentially contoured endwalls to understand the fundamental flow mechanisms of casing treatment effect. The result showed the wall contouring above the blade leading edge had significant stall margin improvement and insignificant efficiency and pressure ratio drops. By applying the second invariant Q, two major vortex structures were observed near the stall conditions. One was tip leakage vortex and the other was rotating instability vortex. The rotating instability vortex seemed to be induced by the interaction between the inflow and reverse flow near the endwall. In the case with wall contouring, enlarged clearance gap encouraged the tip clearance flow and relieved the interaction that caused the rotating instability vortex. Alleviation of the vortex led to the improvement of stall margin as a consequence.

抄録全体を表示

The aim of the present study is to investigate effects of the axial gap between rotor and stator upon the stage performances and flow field of a single axial flow turbine stage. In this paper experimental and numerical studies are performed for three axial gaps by moving the stator vane axially. Five-hole probe measurements are made to obtain total pressure loss and time-averaged flow field upstream and downstream of the rotor blades. In addition, large-scale unsteady three-dimensional RANS-based numerical simulation, in which blade-count ratio is almost the same as that of the actual turbine stage, is executed to understand interaction between the stator and the rotor. These results show that overall turbine stage efficiency with the smallest axial gap is the highest among the three gaps. This is because the stator wakes are diffused by expanding axial gap, inducing the growth of the secondary flow near the endwall.

抄録全体を表示