Numerical Optimization, Characterization, and Experimental Investigation of Additively Manufactured Communicating Microchannels

Abstract

The degree of complexity in internal cooling designs is tied to the capabilities of the manufacturing process. Additive manufacturing (AM) grants designers increased freedom while offering adequate reproducibility of microsized, unconventional features that can be used to cool the skin of gas turbine components. One such desirable feature can be sourced from nature; a common characteristic of natural transport systems is a network of communicating channels. In an effort to create an engineered design that utilizes the benefits of those natural systems, the current study presents wavy microchannels that were connected using branches. Two different wavelength baseline configurations were designed; then each was numerically optimized using a commercial adjoint-based method. Three objective functions were posed to (1) minimize pressure loss, (2) maximize heat transfer, and (3) maximize the ratio of heat transfer to pressure loss. All baseline and optimized microchannels were manufactured using laser powder bed fusion (L-PBF) for experimental investigation; pressure loss and heat transfer data were collected over a range of Reynolds numbers. The AM process reproduced the desired optimized geometries faithfully. Surface roughness, however, strongly influenced the experimental results; successful replication of the intended flow and heat transfer performance was tied to the optimized design intent. Even still, certain test coupons yielded performances that correlated well with the simulation results.

CFD of roughness effects on laminar heat transfer applied to additive manufactured minichannels

“…PBF technologies permit superior flexibility to fabricate complex functional channels for thermal management systems [7,16], including mini-and micro-channels [17][18][19]. Many researchers have employed this capacity to create cooling channels with enhanced thermal performance features such as waviness [20], interconnectivity [21], permeability [22], internal pin fins [23], and longitudinal vortex generators [24].…”

Engineering and Economic Aspects of Additive Manufacturing in Energy Related Industries

“…Kirsch et al [44] used AM to make micro-scale design optimizations for efficient heat removal. At the micro-scale, the surface finish plays a significant role in the heat transfer and pressure loss of any cooling design They observed that additively manufactured cooling channels have shown the surface roughness increases both heat transfer and pressure loss to similar levels as highly engineered turbine cooling schemes.…”