Dennis Cooper

Impinging jet studies for turbulence model assessment—I. Flow-field experiments

Abstract The paper reports an extensive set of measurements of a turbulent jet impinging orthogonally onto a large plane surface. Two Reynolds numbers have been considered, 2.3 × 10 4 and 7 × 10 4 while the height of the jet discharge above the plate ranges from two to ten diameters, with particular attention focused on two and six diameters. The experiment has been designed so that it provides hydrodynamic data for conditions the same as those for which Baughn and Shimizu [ ASME J. Heal Transfer 111, 1096 (1989)] have recently reported Nusselt number data (at Re = 23 000). In both experiments, before discharge, the air passed along a smooth pipe sufficiently long to give fully developed flow at the exit plane of the jet—a feature that is helpful in using the data for turbulence-model evaluation. Hot-wire measurements have been made with pipes of nominally one-inch (26 mm) and four inches (101.6 mm) diameter. Data are reported of the mean velocity profile in the vicinity of the plate surface and also of the three Reynolds-stress components lying in the x-r plane. Computational results reported in a companion paper [ Inl. J. Heal Mass Transfer 36, 2685–2697 (1993)] indicate a good degree of internal consistency between the mean and turbulent field data in that models predicting the mean flow poorly (or well) also predict the turbulence data poorly (well).

A methodology for online wear debris morphology and composition analysis

Online or inline detection of basic debris features, i.e. size, quantity, size distribution, shape, and compositions simultaneously with real time diagnostics is one of the possible ways to perform wear debris analysis with high reliability. At present many techniques and sensors are available that can perform near real time detection and diagnostics for debris quantitative features. But to perform real time detection and diagnostics for features like shape and composition still requires a reliable technical concept. In this article a new technique for online wear debris shape and composition analysis is described. The developed technique is a combination of hardware and software based on imaging technology for shape and composition detection. Rule-based algorithms are used to perform near real time debris analysis diagnostics. An experimental study is also presented that shows the possible potential of the developed technique on real applications.

Instrument for the measurement of heat flux from a surface with uniform temperature

An instrument for the measurement of heat flux from a surface with a nearly uniform temperature is described. This instrument contains a thin‐film electrical resistance heater embedded in a copper cone which is thermally isolated from the surrounding walls. A differential thermocouple between the copper cone and the wall is nulled such that the electrical power becomes a direct measure of the surface heat flux. The advantage of this design over earlier sensors is its modular characteristic and its ability to be flush mounted in an external surface or mounted in the wall of a duct. It has been used to measure the local time‐average heat transfer coefficient inside a circular duct. The time constant in this application was 43 s. For these measurements an uncertainty analysis is presented which shows that this instrument has an uncertainty of ±3.6% for a convective heat flux of 342 W/sq m. The major source of uncertainty was the surface area.

Development of Flowfield and Surface Heat-transfer Measurement and Visualisation Techniques for Internal Rotating Cooling Flows in Gas Turbine Blades

This paper reviews the authors experimental investigations of heat and fluid flow through rotating cooling passages, relevant to the internal cooling of gas turbine blades. The main experimental facility used is a rotating water flow table. While sacri