Rolls-Royce Motor Cars

About: Rolls-Royce Motor Cars is a based out in . It is known for research contribution in the topics: Turbine & Gas compressor. The organization has 3845 authors who have published 4934 publications receiving 58973 citations. The organization is also known as: Rolls-Royce Motor Cars Limited.

Nickel diffusion braze alloy and method for repair of superalloys

Abstract: A braze alloy powder mixture that includes a low-melt powder composition and a high-melt powder composition. The low-melt powder composition is made of one or more low-melt powders and includes 50-70 % Ni, 8-20 % Cr, 8-15 % Ta, 4-10 % Co, 2-7 % Al, and up to 2.25 % B. The high-melt powder composition is made of one or more high-melt powders and includes 50-70 % Ni, 2-10 % Cr, 2-10 % Ta, 5-15 % Co, 2-10 % Al, 2-10 % W, and up to about 3 % each of Re, Mo and Hf. Up to about 1 % Ti, W, Mo, Re, Nb, Hf, Pd, Pt, Ir, Ru, C, Si, and/or Zr may be included in the low-melt powder, while the high-melt powder may include up to about 1 % each of Ti, Nb, C, B, Si, and Zr.

Ignition Delay Time and Laminar Flame Speed Calculations for Natural Gas/Hydrogen Blends at Elevated Pressures

Abstract: Applications of natural gas and hydrogen co-firing have received increased attention in the gas turbine market, which aims at higher flexibility due to concerns over the availability of fuels. While much work has been done in the development of a fuels database and corresponding chemical kinetics mechanism for natural gas mixtures, there are nonetheless few if any data for mixtures with high levels of hydrogen at conditions of interest to gas turbines. The focus of the present paper is on gas turbine engines with primary and secondary reaction zones as represented in the Alstom and Rolls Royce product portfolio. The present effort includes a parametric study, a gas turbine model study, and turbulent flame speed predictions. Using a highly optimized chemical kinetics mechanism, ignition delay times and laminar burning velocities were calculated for fuels from pure methane to pure hydrogen and with natural gas/hydrogen mixtures. A wide range of engine-relevant conditions were studied: pressures from 1 to 30 atm, flame temperatures from 1600 to 2200 K, primary combustor inlet temperature from 300 to 900 K, and secondary combustor inlet temperatures from 900 to 1400 K. Hydrogen addition was found to increase the reactivity of hydrocarbon fuels at all conditions by increasing the laminar flame speed and decreasing the ignition delay time. Predictions of turbulent flame speeds from the laminar flame speeds show that hydrogen addition affects the reactivity more when turbulence is considered. This combined effort of industrial and university partners brings together the know-how of applied, as well as experimental and theoretical disciplines.

Relative importance of open rotor tone and broadband noise sources

Abstract: A study is made of the noise levels and spectral characteristics of three contra-rotating propeller rigs: rig 140 tested in 1989, rig 145 build 1 tested in 2008, and rig 145 build 2 tested in 2010. We use tone deletion techniques, applied to the inflow microphone data, to show the relative importance of propeller broadband noise to propeller tones with increasing frequency and, in particular, that by the time we reach only moderate frequencies, the one third octave spectra become dominated by the broadband noise components. We also show that the broadband noise continues to be important as blade speed and rig thrust are varied and that these spectral characteristics are present on both modern and older contra-rotating propeller designs – even those with a profusion of tones and strong tone protusion. We also show how the tone and broadband noise levels have reduced with more recent, and aeroacoustically improved, blade designs

Effect of methane-dimethyl ether fuel blends on flame stability, laminar flame speed, and Markstein length

Abstract: Binary fuel blends provide challenges to chemical kinetics models not seen by testing only pure fuels, allowing them to be proven over a wider range of inputs. The effect of adding dimethyl ether (DME) to methane (CH 4 ) on the laminar flame speed, Markstein length, and Lewis number was studied experimentally and numerically over a range of initial pressures from 1 to 10 atm, with the volumetric ratios of the fuel blends ranging from 60% CH 4 /40% DME to 80% CH 4 /20% DME. This data set includes high-pressure results that have never been published before. The experimental results were compared to an improved kinetics model, an ongoing effort spanning the past few years. Model results are in very good agreement with the experimental data. For the 80/20 blend of CH 4 /DME, the Lewis number remained close to unity as the equivalence ratio increased, in comparison to the large decrease in Lewis number for pure DME as equivalence ratio is increased. This small change in Lewis number, with the value remaining near unity, resulted in the 80/20 blend of CH 4 /DME remaining stable throughout the entire range of 5-atm experiments, while all other pure fuels and blends exhibited instabilities at initial pressures equal to or greater than 5 atm. In addition, the Markstein lengths were greatly affected by the blending of the fuels. A small amount of DME addition caused the Markstein lengths to change by a large value. Finally, a rigorous uncertainty analysis was performed on the experimental data, giving the error with respect to the true value rather than the standard deviation of repeated experiments.