Local Swirl Chamber Heat Transfer and Flow Structure at Different Reynolds Numbers

Abstract

Local flow behavior and heat transfer results are presented from two swirl chambers, which model passages used to cool the leading edges of turbine blades in gas turbine engines. Flow results are obtained in an isothermal swirl chamber. Surface Nusselt number distributions are measured in a second swirl chamber (with a constant wall heat flux boundary condition) using infrared thermography in conjunction with thermocouples, energy balances, and in situ calibration procedures. In both cases, Reynolds numbers Re based on inlet duct characteristics range from 6000 to about 20,000. Bulk helical flow is produced in each chamber by two inlets, which are tangent to the swirl chamber circumference. Important changes to local and globally averaged surface Nusselt numbers, instantaneous flow structure from flow visualizations, and distributions of static pressure, total pressure, and circumferential velocity are observed throughout the swirl chambers as the Reynolds number increases. Of particular importance are increases of local surface Nusselt numbers (as well as ones globally averaged over the entire swirl chamber surface) with increasing Reynolds number. These are tied to increased advection, as well as important changes to vortex characteristics near the concave surfaces of the swirl chambers. Higher Re also give larger axial components of velocity, and increased turning of the flow from each inlet, which gives Go¨rtler vortex pair trajectories greater skewness as they are advected downstream of each inlet. [S0889-504X(00)00502-X]

Experimental Approach on a Swirl Flow and Heat Transfer Coefficient Using a 3-D Stereo-PIV and Liquid Crystals

“…The oil particles are provided by seeder (LAVision) for velocity measurements. Acrylic also works well for infrared imaging because its surface emissivity ranges from 0.60 to 0.65 [9]. Particle images are taken using two high resolution cameras and processed by DaVis software as shown in Fig.…”

“…All three Re numbers (nominal and ±50%) are presented at Re = 7,000, 14,000, and 21,000 and flow rate measurements were plotted for all velocity profiles involving the TLC experiment. The definition of the swirl number is the ratio of the flux of angular momentum and the flux of axial momentum per Moon, et al [1] and Hedlund, et al [9]. Fig.…”

“…To maximize the understanding of the physical mechanism and to optimize the internal cooling design, a considerable number of studies have been conducted during the past 30 years by Moon et al [1], Glezer et al [2], and Ligrani et al [3] adding to the first proposed design by Kreith et al [4]. In the early studies, experiments dealt with producing a swirl in a tube flow and found the augmentation surface heat transfer rates relative to non-swirl flows [1]- [8][13]- [16]. Early research included tangential jets from wall slots to generate large scale swirl in internal tube flow.…”

CFD Simulation of Turbulent Air Flow in Diffuser and it's Effect on Fluid Properties

“…The swirling flow can also be influenced by the air inlet geometry [5]. Hedlund et al [6][7] reviewed a variety of devices and geometries to produce swirl in internal flows. They studied another swirl chamber which employed tangential jets from wall slots or ducts to produce large scale swirling in internal tube flows.…”

Effect of Rotation on the Cyclone Cooling Method Mass Transfer Measurements

“…investigated the flow field in a swirl chamber with tangential injection and found that the reason for the rise in heat transfer is the radial pressure gradient and the high turbulence. There are much more proceedings dealing with this topic, for example Glezer et al [1996] and Hedlund et al [2000] but there is only one known where swirling flow was investigated in a rotating system. This is Glezer et al [1998].…”