A study of the flow and heat transfer in a stationary model of a two-pass internal coolant passage is presented, which focuses on the flow characteristic effects on the wall heat transfer distribution. Results are given in the upstream fully developed region. Heat transfer measurements were made with a transient technique using thermochromic liquid crystal technique to measure a surface temperature. The technique allows full surface heat transfer coefficient measurements on all the walls. Flow measurements were made with a stereoscopic digital PIV system, which measures all three-velocity components simultaneously. The coolant passage model consists of two square ducts, each having a 20 hydraulic diameter length. The ducts are connected by a sharp 180° bend with a rectangular outer wall. 45° ribs are mounted in a staggered arrangement on the bottom and top walls of both legs. The height of the ribs is equal to 0.1 hydraulic diameters. They are spaced 10 rib heights apart. The flow and heat transfer measurements were obtained at one flow condition with an inlet flow Reynolds number, based on the hydraulic diameter, of 50,000. The paper presents detailed measurement results of the flow characteristics and of the heat transfer distribution in the upstream straight leg of the passage and describes how the main and secondary flows influence the heat transfer distribution in the fully developed regions of the channel.

A study of flow in two stationary models of two-pass internal coolant passages is presented, which focuses on the flow characteristics in the 180-deg bend region, and downstream of the bend, where the flow is redeveloping. A stereoscopic digital PIV system measured all three velocity components simultaneously to obtain mean velocity, and turbulence quantities of the flow field. The coolant passage model consisted of two square passages, each having a 20 hydraulic diameter length, separated by a rounded-tip web of 0.2 passage widths, and connected by a sharp 180-deg bend with a rectangular outer wall. Ribs were mounted on the bottom and top walls of both legs, with a staggered arrangement, and at 45 deg to the flow. The rib height and spacing were 0.1 and 1.0 passage heights, respectively. The measurements were obtained for a flow condition, with a Reynolds number of 50,000. The geometries are similar in both sections except for one, which is equipped with extraction holes to simulate holes for film cooling. Two series of holes are placed solely in the bottom wall, four holes are located in the bend, and 12 in the downstream leg. The global extraction through the holes was set to 50% of the inlet massflow. This paper presents new measurements of the flow in the straight legs, as well as in the bend of the passage equipped with holes, detailed comparison of the flow upstream, inside and downstream of the bend region between both configurations, and the effects of extraction inside the cooling channels.

A study of the flow and heat transfer in a stationary model of a two-pass internal coolant passage is presented, which focuses on the flow characteristic effects on the wall heat transfer distribution. Results are given in the upstream fully developed region. Heat transfer measurements were made with a transient technique using thermochromic liquid crystal technique to measure a surface temperature. The technique allows full surface heat transfer coefficient measurements on all the walls. Flow measurements were made with a stereoscopic digital PIV system, which measures all three-velocity components simultaneously. The coolant passage model consists of two square ducts, each having a 20 hydraulic diameter length. The ducts are connected by a sharp 180 deg bend with a rectangular outer wall. 45 deg ribs are mounted in a staggered arrangement on the bottom and top walls of both legs. The height of the ribs is equal to 0.1 hydraulic diameters. They are spaced 10 rib heights apart. The flow and heat transfer measurements were obtained at one flow condition with an inlet flow Reynolds number, based on the hydraulic diameter, of 50,000. The paper presents detailed measurement results of the flow characteristics and of the heat transfer distribution in the upstream straight leg of the passage and describes how the main and secondary flows influence the heat transfer distribution in the fully developed regions of the channel.

A study of flow in a stationary model of a two-pass internal coolant passage is presented which focuses on the flow characteristics in the 180-deg bend region and downstream of the bend, where the flow is redeveloping. A stereoscopic digital PIV system measured all three velocity-components simultaneously to obtain mean-velocity and turbulence quantities of the flow field. The coolant passage model consisted of two square passages, each having a 20 hydraulic diameter length, separated by a web of 0.2 passage widths and connected by a sharp 180 deg bend with a rectangular outer wall. Ribs were mounted on the bottom and top walls of both legs with a staggered arrangement and at 45 deg to the flow. The rib height and spacing were 0.1 and 1.0 passage heights, respectively. The measurements were obtained for a flow condition with a Reynolds number of 50,000. The geometry is similar in the straight sections to a previous configuration but has ribs extending into the bend region. The paper presents new measurements of the flow in the straight legs of the passage, comparison of the flow in the bend region with a previous configuration and details of the flow recovery from the bend in the second leg.

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