Aerothermal Dynamic Characteristics of Array Micro Ribs in Channel Flow

Abstract

With the rising complexity of internal cooling structures in gas turbine blades, the limited cooling air volume and pressure head provided by the compressor have become significant constraints to further enhancements in the overall efficiency of gas turbines. To address this, micro-turbulators have been proposed as a viable solution in recent research. The rib turbulators, as a typical internal cooling structure, have inherent limitations in heat transfer measurements. In this study, a segmented lumped parameter method was employed to experimentally analyze the aerothermal dynamic characteristics of micro ribs under varying rib heights and Reynolds numbers in channel flow. It was found that heat transfer performance closely correlates with both rib height and the height of the incoming boundary layer. Under certain conditions of dimensionless height and dimensionless number, optimal heat transfer enhancement near the micro-rib was observed, leading to an approximately 30% increase in the overall thermal performance (OTP) compared to the results from research into traditional 90° ribs. Numerical results based on the Reynolds stress model (RSM) suggest that this improvement is primarily due to the increased turbulence intensity in the near-wall region (y+ = 20–55) of the boundary layer caused by the micro ribs. This study presents a new characteristic parameter e+/Re that offers improved representation of the heat transfer performance of micro ribs, and reveals that when this parameter is around 40, micro ribs can provide high heat transfer with low pressure loss, thereby improving the overall efficiency. These results underscore the potential applicability of micro ribs in advancing the efficiency of gas turbines and other related fields.