In order to study the effect of axial spacing on behaviors of aerodynamic performance and aerodynamic noises in a contra-rotating fan, the steady/unsteady Reynolds-averaged Navier-Stokes equations are solved by the numerical method in conjunction with a SST turbulence model, and the effects of axial spacing on performance and aerodynamic characteristics are investigated. Furthermore, BEM is adopted to compute the radiation noise of the contra-rotating fan caused by unsteady pressure fluctuations. The results show that axial spacing is an important factor which can affect the aerodynamic performance of contra-rotating fan. As a whole, the effect of axial spacing on the blade loading of Rotor 2 is significantly greater than that of Rotor 1. For Rotor 2, the smaller axial spacing leads to the large secondary flow loss, and the larger axial spacing leads to the strong mixing loss. With the increase of axial spacing, the radiation noise at the characteristic frequency decreases, but showed different changing degrees. With consideration of the aerodynamic performance and aerodynamic noises of the contra-rotating fan, the optimal comprehensive performance appears at the axial spacing of 0.5 chord.
Purpose
The obtained simulation structures could reflect the appearances and the features of the fabrics. The purpose of this paper is to promote a lot for design and manufacturing of weft-knitted lace fabrics (WKLF).
Design/methodology/approach
The advantages of WKLF compared with warp-knitted ones were displayed. The formation mechanism of the WKLF was analyzed with employing the mechanics principles. Spring-mass model was proposed in this paper to achieve the simulation of the fabrics. End mass points and intermediate mass points were involved in the model. The displacement of end mass points was considered the dominance and the foundation to settle the positions of all the mass points.
Findings
A novel jacquard lace style fabric with pattern-background effect knitted on circular knitting machine were put forward, which were different from the traditional lace fabrics manufactured on the warp knitting machines.
Originality/value
First, as the manufacturing equipment, circular knitting machine costs much less than warp knitting machine; second, the elastic performance along weft direction of WKLF is more excellent than that of warp-knitted ones. Third, the excellent extensibility gives nice comfort; furthermore, long floating threads do not exist on the WKLF surface, so that the snag will be avoided.
Because thermowells are prone to fatigue damage in petroleum cracking gas pipelines, in this paper, the LES method is used to simulate the flow around thermowells through two-way thermal-fluid-solid coupling, the internal causes of thermowell damage are explored, and measures for improving the thermowell safety are proposed. According to this study, when high-speed, high-temperature gas passes the thermocouple bushing, the main factors affecting the structural safety of the thermocouple bushing are the alternating stress caused by the vortex falling off, the thermal stress cycle due to the temperature gradient, and the pressure gradient impacted by the gas. Furthermore, this paper proposes improving the thermowell safety by installing the interference devices and optimizing the installation angle. The improvement measures were studied by conducting a two-way thermal fluid-structure coupling simulation. The results of this study show that after installing the interference device and optimizing the installation angle the displacement deformation of the thermowell and the equivalent stress is reduced by 57.2% and 72.1%, respectively, which indicates the safety improvement of the thermowell structure and the effectiveness of the method. The research contents of this paper can provide guidance for the installation and use of thermocouple bushing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.