Effects of Turning Angle and Turning Internal Radius on Channel Impingement Cooling for a Novel Internal Cooling Structure

Abstract

Recently, a novel internal cooling structure, namely multi-channel wall, has been put forward to enable higher overall cooling effectiveness with less coolant and pressure loss. Our previous work has proved the advantages of the design relative to conventional impingement cooling and swirl cooling. Channel impingement cooling structure, which is utilized at the turning region of the leading edge, is the critical factor to realize the high cooling performance of the design. Hence, the turning angle and turning internal radius of the cooling channel are two key parameters, and this paper focuses on the effects of these two parameters on the flow and heat transfer characteristics of the channel impingement cooling structure. Nine simplified single-channel models with different turning angles (45°, 60°, and 75°) and radiuses (0.6 mm, 0.9 mm, and 1.2 mm) were adopted to conduct the study, and the jet Reynolds number ranges from 10,000 to 40,000. The results show that the turning angle and turning internal radius affect the jet form significantly for the same mechanism. Small turning angle means large impingement, which leads to stream-wise counter-rotational vortices and high turbulence intensity, but increasing turning internal radius transfers the jet form from impingement jet to laminar layer attaching the target surface with low heat transfer. The turning internal radius has stronger effect than turning angle. With higher jet Reynolds number, both the heat transfer and total pressure loss increase dramatically, and the effects of geometrical parameters are clearer.

Computational and experimental evaluation of heat transfer intensity in channels of complex configuration for gas flow with different levels of turbulence

“…Analysis of articles by other authors has shown that the influence of the gas-dynamic characteristics of flows (in particular, the turbulence intensity) on the heat transfer level is of great importance in the nuclear industry when cooling nuclear reactors [5,6]. Heat transfer intensification by controlling the flow gas dynamics is widely used in the field of turbine engineering [7][8][9]. Gramespacher et al [7] investigates the effect of surface roughness on the turbulence intensity of flows and, accordingly, on the heat transfer level.…”

“…Gramespacher et al [7] investigates the effect of surface roughness on the turbulence intensity of flows and, accordingly, on the heat transfer level. He et al [8] propose to improve heat transfer in order to increase the efficiency of cooling of turbine parts and assemblies, based on numerical simulation. The turbulence level of flows is of great importance for the heat exchange intensity in various heat exchangers [10][11][12].…”