Tidal effects on intra-continental earthquake initiation in the Tibetan Plateau and its adjacent areas

To investigate the tidal effects on intra-continental earthquake initiation in the Tibetan Plateau and its surrounding areas,we selected over 1,500 focal mechanism solutions of inland earthquakes(epicenter locates at least 100 km to the coastlines)from Global Centroid Moment Tensor(GCMT)project and analyzed the values of tidal normal and shear stress as well as tidal Coulomb failure stress.For Coulomb failure stress calculation,we used Coulomb 3.40 software.We find that:(1)p-values of tidal stress change suggests a high tidal correlation of earthquake imitations with tidal normal stress change;(2)when tidal normal stress reached the local maximum values of compression and when tidal shear stress were closed to the positive peaks,earthquakes generated more frequently;(3)particular seismogenic environments such as strong continental plate interactions and the existence of fluids or rheologic substance possibly raise the tidal correlations and(4)higher sensitivity of earthquake initiation to earth tide presents along with higher seismicity,suggesting the rate of rain energy accumulation somehow has a dominating effect on the tidal correlation of earthquake initiation.

Experimental investigations of the spray structure and interactions between sectors of a double-swirl low-emission combustor

In this paper,the spray characteristics of a double-swirl low-emission combustor are analyzed by using Particle Imaging Velocimetry(PIV)and Planar Laser Induced Fluorescence(PLIF)technologies in an optical three-sector combustor test rig.Interactions between sectors and the influence of main stage swirl intensity on spray structure are explained.The results illustrate that the swirl intensity has great effect on the flow field and spray structure.The spray cone angle is bigger when the swirl number is 0.7,0.9 than that when the swirl number is 0.5.The fuel distribution zone is larger and the distribution is more uniform when the swirl number is 0.5.The fuel concentration in the center area of the center plane of side sector(Plane 5)is larger than that of the center plane of middle sector(Plane 1).The spray cone angle in Plane 5 is larger than that in Plane 1.The width of spray cone becomes larger with the increase of Fuel-Air Ratio(FAR),whereas the spray cone angle under different fuel-air ratios are absolutely the same.The results of the mechanism of spray organization in this study can be used to support the design of new low-emission combustor.

Lean blowout characteristics of spray flame in a multi-swirl staged combustor under different fuel decreasing rates

Lean Blow Out(LBO)poses a significant safety hazard when occurring in aero-engines.Understanding the lower stability limits of gas turbine combustors and the characteristics of spray flame close to LBO are imperative for safe operation.The objective of this work is to evaluate the effects of fuel decreasing rates and pressure drops of the injector on LBO performances in a multiswirl staged combustor equipped with an airblast injector.A set of hardware and control system was developed to realize a user-defined fuel supply law.High-speed imaging was applied to record complete LBO processes under the conditions of linear fuel reduction and stable airflow.Partical Image Velocimetry(PIV)and Planar Mie(PMie)scattering were used to acquire the flow fields and spray fields under non-reacting conditions.Experimental results have shown that LBO limits extend to leaner conditions as the pressure drop of the injector increases.With an increase of the fuel decreasing rate,the exhaust temperature before flame extinction increases,and the LBO Fuel-to-Air-Ratio(FAR)decreases.The time evolution of the integral CH*intensity conforms to a linear function during the LBO process.Proper Orthogonal Decomposition(POD)was used to analyze the dynamic characteristics of lean-burn flames.Under different fuel decreasing rates and pressure drops of the injector,flames close to LBO present similar modal spatial distributions,alternately appearing axial,radial,high-order axial,and high-order radial oscillations.