High-speed Crossflow Research Articles

Transverse Supersonic Controlled Swirling Jet in a Supersonic Cross Stream

The spreading rate and mixing of a transverse jet in high-speed crossflow were modified using a swirling injector with a central control jet. The controlled supersonic swirling injector (CSSI) could be used to affect mixing both in the core and the shear layer of the jet. Rayleigh/Mie scattering from flowfield ice crystals and planar laser-induced fluorescence of the NO molecules were used to characterize penetration and mixing of the CSSI for six different cases. Instantaneous images were used to study the dynamical structures in the jet, whereas ensemble images provided information regarding the jet trajectory. Standard deviation images revealed information about the large-scale mixing/entrainment. Probability density functions were used to evaluate the probability and location of freestream, mixed, and jet fluid. They were also used to track the centerline and jet boundary on a dynamic scale. Side- (streamwise)-view images showed that the injector was capable of providing high penetration when compared to circular and swirling baseline injectors. An increase of 16% in mixing area was observed with the optimal case as compared with the other control cases. End- (spanwise)-view images show a maximum of 78 % increase in total area contained within the jet boundary for the optimal case when compared to the circular injector. Higher spanwise extent of the jet boundary was also observed with controlled cases, which could provide higher interfacial area for better mixing between the jet and the cross stream when compared to their baseline counterparts.

Jet Interaction with a Primary Jet and an Array of Smaller Jets

A combined experimental-numerical study of the jet interaction flowfield associated with sonic injection of a gas into a turbulent, high-speed crossflow (M=4.0) was conducted with an innovative configuration for jet-thruster applications. This configuration consists of a sonic primary jet, flanked by arrays of smaller secondary sonic injectors that interact with the flowfield created by the primary jet. The mass flow from the small secondary jets ranged from 0.5-1% of that from the primary jet. Pressure sensitive paint was used to measure the pressure field acting on the surface. Forces and moments acting on the flat plate were quantified by integration of the pressure field. Schlieren photographs were used to analyze the main flow features generated by the jet interaction. The numerical solution used the Reynolds-averaged Navier-Stokes equations and Wilcox's κ-ω turbulence model

2008 高速斜行気流による水噴霧の微粒化 : 液柱の不安定と分裂特性

2008 高速斜行気流による水噴霧の微粒化 : 液柱の不安定と分裂特性

Evaluation of Bundled Tube Vibration due to Cross-Flow by Statistical Correlation of Random Fluid Force.

For heat exchangers with a small-pitch tube bundle, it is important to evaluate the vibration of the tube due to strong turbulence of fairly high-speed cross-flow. In this study, statistical quantities of fluid force were obtained experimentally to numerically evaluate the turbulent-flow-induced vibration. A tube bundle of 0.0254-meter-diameter and 0.032-meter-pitch tubes was installed in an experimental test section. Specifically, local fluid force acting on a tube was measured using 0.013-meter-wide force sensors installed along the axial direction of the measured tube, and the correlation length was deduced from the fluid forces of the two adjacent sensors. Vibration levels evaluated analytically using the fluid force correlation were compared with the levels obtained from several experiments. The analytical results agreed well with the experimental vibration levels.

Effects of viscosity and surface tension on a jet plume in supersonic crossflow

L injection into a high-speed crossflow has been considered in a number of aerospace systems. Recent developments in engine design and new hybrid fuels with large viscosity and surface tension ranges and the lack of data relating the behavior of the jet to physical properties were the motivating forces behind this study. In a crossflow the jet is deformed and bent downstream by the main flow. Several types of waves appear on the windward edge leading to breakup. Some are capillary disturbances and waves caused by turbulence, and some are aerodynamically induced waves which are primarily responsible for the decomposition of the jet. The viscosity and surface tension of the injectant have a direct effect on the spray plume, both internally and at the surface.

An Analysis of High-Speed Cross Flow Turbines

An Analysis of High-Speed Cross Flow Turbines