11月17日-22日INTERNATIONAL GAS TURBINE CONGRESS (IGTC) 2019 TOKYO にてセンターメンバーが研究発表

Keywords: Aerodynamic and Design of Turbines, Soot and Particulates, Component Damage, Failure, and Life Assessment
Abstract: Jet engines of airplanes may ingest foreign objects such as sand and ash particles. These particles go through fans, compressor, and combustor in the engine, and will be heated up to extremely high temperature. The particles will be softened due to hot gas and behave as melted glass because the main component of sand or volcanic ash is SiO2. The softened particles may impinge to high-pressure turbine vanes at high speed and adhere to the vanes. Those adhered particles change the vane shape and may deteriorate aerodynamic performance. Moreover, the deposited materials on the vane surface may block the cooling holes for the film cooling. The film cooling is necessary to cool down and protect the turbine vanes from high-temperature gas. If the deposited materials blocked the holes, the vanes will be damaged and broken due to the increase in surface temperature. Thus, the deposition phenomenon on high-pressure turbine vane is a dangerous event, which may cause severe trouble or accident during the flight. However, the deposition mechanism is not known very well, so the clarification of the phenomena is demanded. The aim of this study is set to simulate the deposition phenomenon on high-pressure turbine vane at the real operating condition of the jet engine. To numerically investigate the deposition phenomenon, UPACS is used to calculate the flow field and behavior of the particles. UPACS is an abbreviation for Unified Platform for Aerospace Computational Simulation, and it is the CFD solver developed by JAXA. At the first step of this study, several deposition models were selected from earlier studies and compared with experimental data under 2 test cases. Then, the OSU deposition model was screened and implemented to UPACS. At the second step, deposition phenomena with several conditions on a high-pressure turbine vane were simulated. The particle was JBPS sub-bituminous ash, and the vane material was a nickel-base single crystal superalloy. The numerical results showed that the particle temperature, the impinging velocity, and the impinging angle were seemed to be the important parameters for the possibilities of the particle adhesion.

Keywords: Aerodynamic and Design of Turbines, Materials degradation and damage mechanisms, Component Damage, Failure, and Life Assessment
Abstract: Recently, ceramic matrix composite (CMC) is expected to use for a gas turbine engine component because of its low density, high strength, and high rigidity under high temperature conditions. How-ever, since the erosion resistance of CMC is very low, any measure must be taken. For the purpose, we can adopt a material approach and/or an aerodynamic approach. One typical material approach is to apply the environmental barrier coating (EBC), which has high erosion resistance, to the CMC surface. In the present study, we fo-cused on the aerodynamic approach by using a blade lean. Numer-ical simulations of sand erosion phenomenon on high-pressure tur-bine vanes were performed, and the relationship between lean and erosion damage was investigated. Through this study, we numerically clarified that the distribution of erosion is influenced by the location where the particles impinge at the second time, the suppression of erosion damage by lean is not very effective, the aerodynamic performance of the compound lean (CL) vane is the best because the secondary flow is suppressed, and the CL vane reduces the increment of total pressure loss due to erosion.

Keywords: Aircraft Engines, Aerodynamic and Design of Compressors, Thermal Management of Structures
Abstract: Icing in jet engines is one of the phenomena which poses a serious risk to an aircraft in the flight. Introduction of anti-icing devices such as bleed air and electrical heat is being promoted at stationary parts as measures against icing inside the engine. However, it is structurally difficult to introduce an anti-icing device to rotating parts including fan blades. Therefore, it is necessary to develop passive anti-icing technology for fan blade. In our previous study, icing simulation on the swept fan blade was performed. The swept shape was expected to raise the temperature on the blade surface due to the increase in flow rate. The results confirmed the anti-icing effect of the swept blade. However, in the previous study, the design parameters related to sweep were fixed, and systematic investigation of design parameters and anti-icing effect was absent. In this research, to improve the anti-icing effect on the swept blade, the authors consider six kinds of sweep blades with different design parameters and perform icing simulations on the base blade and the swept blades. The anti-icing effect and aerodynamic performance are evaluated. The swept blade shape is determined by morphing the stacking line of the base blade. The moving direction is the chord direction, and amount of the movement is calculated from four design parameters: the spanwise position of sweep start, the spanwise position of sweep end, sweep direction, and sweep angle. Icing simulation is performed using UPACS, a solver developed by JAXA. The simulation consists of flow field computation, droplet trajectory computation, thermodynamic computation, and grid regeneration. The flow field is assumed to be a three-dimensional compressible turbulent field, and the turbulence model is the Spalart-Allmaras model. The droplet is tracked by the Lagrangian method. The external forces acting on the droplet are drag, centrifugal, and Coriolis forces. For the thermodynamic model, Extended Messinger model is adopted. The computational domain is for one rotor blade considering the periodicity. The simulation results, the anti-icing effect is confirmed only when the sweep direction is backward. The larger sweep angle and the wider swept region contribute to anti-icing and reduction of aerodynamic efficiency deterioration. However, for the case which the spanwise position of sweep end is 35% or more, these tendencies attenuate. It suggests that an optimum range exists in the sweep region for preventing the icing and achieving the high aerodynamic efficiency.