Rolls-Royce Holdings

About: Rolls-Royce Holdings is a company organization based out in Derby, United Kingdom. It is known for research contribution in the topics: Turbine & Gas compressor. The organization has 4027 authors who have published 6305 publications receiving 80517 citations. The organization is also known as: Rolls-Royce Holdings plc.

Nonlinear acceleration of coupled fluid–structure transient thermal problems by Anderson mixing

Abstract: SUMMARY Conjugate heat-transfer problems are typically solved using partitioned methods where fluid and solid subdomains are evaluated separately by dedicated solvers coupled through a common boundary. Strongly coupled schemes for transient analysis require fluid and solid problems to be solved many times each time step until convergence to a steady state. In many practical situations, a fairly simple and frequently employed fixed-point iteration process is rather ineffective; it leads to a large number of iterations per time step and consequently to long simulation times. In this article, Anderson mixing is proposed as a fixed-point convergence acceleration technique to reduce computational cost of thermal coupled fluid–solid problems. A number of other recently published methods with applications to similar fluid–structure interaction problems are also reviewed and analyzed. Numerical experiments are presented to illustrate relative performance of these methods on a test problem of rotating pre-swirl cavity air flow interacting with a turbine disk. It is observed that performance of Anderson mixing method is superior to that of other algorithms in terms of total iteration counts. Additional computational savings are demonstrated by reusing information from previously solved time steps. Copyright © All rights reserved 2012 Rolls-Royce plc.

Development of a test planning methodology for performing experimental model validation of bolted flanges

Abstract: This work presents a strategy for testing and validating structures connected together with bolted joints, which are the most common components in mechanical structures. Considering the great number of coupled mechanical structures and research studies on this subject, the authors focused this research work on bolted flanges of aircraft engine casings. In fact, the coupling of engine casings is generally obtained by a large number of joints which assure the correct sealing at the flanges’ interfaces. From a finite element (FE) modelling perspective, joints are often modelled by either rigid connections or springs, otherwise incurring a very expensive computational time. This modelling approach is not a problem when dealing with low amplitude levels of vibrations. For higher levels of vibrations, joints and flanges cannot be considered rigidly connected and that exerted flexibility at the joints’ area can determine nonlinear dynamic behaviour. This work aims to study the dynamic behaviour of bolted flanges by using modal testing performed under controlled response amplitude. Two test structures, (1) a simple bolted flange test case and (2) a sector of a Rolls-Royce aero-engine casing, are tested under high level of vibrations. Both test structures are modelled by FE method, and nonlinear elements are used for modelling the flanges’ interfaces so as to perform prediction of nonlinear responses. These predictions are eventually correlated with the measured data.

Thermal stability of Ti–46Al–5Nb–1W alloy

Abstract: The TiAl-based alloy Ti–46Al–5Nb–1W has been exposed at the temperature of 700 °C for up to 5000 h in air. The decomposition processes of all major phases in this alloy: γ, α 2, β and ω, have been investigated in detail by transmission electron microscopy and have been correlated with tensile properties. It is found that considerable amounts of β phase are retained in the as-cast ingot condition and these readily decompose into the ω phase. As the exposure in air proceeds, along with the coarsening of ω particles, a reverse transformation from ω to β can occur at 700 °C. During exposure, α 2 lamellae begin to decompose significantly after 3000 and 5000 h exposures. Some break up into small sized α 2 +γ grains through a ‘perpendicular decomposition’ mode, whilst γ lamellae remains essentially unchanged. Up to 5000-h exposure times do not produce any significant changes in proof stress and tensile strength in this alloy. A marginal decrease in tensile ductility measured at room temperature is, however, suggested.

Component with internal damping

Abstract: A component such as a blade for use in a gas turbine engine comprises a body 2 formed from outer panels 8, 10 defining an internal cavity 12 . A damping element 14 is provided in the cavity 12 and is secured at one end between the panels 8, 10 at one end of the body 2 , for example adjacent the root of the blade. Damping material fills the cavity 12 and so extends between the damping element 14 and the panels 8, 10 . Vibration induced in the blade causes relative movement between the body 2 of the blade and the damping element 14 , causing energy loss in the damping material which damps the vibration. The components 8, 10, 14 may be secured by a diffusion bonding process.

Air intakes for gas turbine engines

Abstract: An inlet particle separator for a gas tubine engine, comprises, (a) an annular air inlet duct, (b) downstream of the inlet duct an annular obturating member having a continuous surface, the menber arranged to bifurcate the inlet duct into annular compressor and scavenge ducts, the compressor duct leading downstream to an engine compressor stage, the scavenge duct being located radially inwardly of the compresor duct and directed upstream thereof, and arranged to scavenge solid matter from the air flow through the inlet duct. The inlet duct is provided with an annular constriction at its downstream end extending radially inwards from a radially outer wall of the inlet duct. The inlet duct is angled so as to direct incoming air against the obturating member, the arrangement of the obturating member, the inlet duct, and the constriction being such as to prevent line-of-sight viewing of the compressor duct from the inlet duct and to deflect solid matter colliding with the walls of the inlet duct into the scavenge duct.