...Stephen T. McClain; B. Keith Hodge; Jeffrey P. Bons The discrete-element model for flows over rough surfaces considers the heat transferred from a rough surface to be the sum of the heat convected from the flat surface and the heat convected from the individual roughness elements to the fluid...

...Stephen T. McClain; Jason M. Brown The discrete-element model for flows over rough surfaces was recently modified to predict drag and heat transfer for flow over randomly rough surfaces. However, the current form of the discrete-element model requires a blockage fraction and a roughness-element...

...Hugh M. McIlroy, Jr.; Ralph S. Budwig Results are presented of extensive boundary layer measurements taken over a flat, smooth plate model of the front one-third of a turbine blade and over the model with an embedded strip of realistic rough surface. The turbine blade model also included elevated...

... they enhance heat transfer significantly. Furthermore, rough surfaces reduce nonuniformity of surface temperature. Reducing nonuniformity can increase part life by reducing thermal gradients and thermal-induced stresses. The additional pressure drop due to the surface roughness is negligible when compared...

... transfer rough surfaces turbulence external flows Introduction of roughness by ribs in flow passages is a popular method of enhancing heat transfer in the cooling passages, e.g., of turbine blades and combustors. The heat transfer and fluid flow in ribbed ducts have been extensively studied both...

... roughness but overpredict St for real roughness. These findings expose limitations in the traditional equivalent sandgrain roughness model and the common use of ordered arrays of roughness elements to simulate real roughness surfaces. The elevated freestream turbulence levels produce augmentation ratios...

... turbines cooling film flow rough surfaces coatings heat transfer friction Roughness Spallation Turbine Modern land-based turbine airfoils operate in severe environments with high temperatures and near critical stresses. Highly turbulent combustor exit flows, with significant thermal...

... cooling jets heat transfer rough surfaces Various methods have been developed over the years to keep the airfoil temperatures below critical levels. A main objective in turbine blade cooling design is to achieve maximum heat transfer coefficients while minimizing the coolant flow rate. One...

... in use in multistage compressors. compressors boundary layer turbulence aerodynamics cascade systems rough surfaces flow control gas turbines 08 May 2000 01 February 2000 Contributed by the International Gas Turbine Institute and presented at the 45th International Gas...

.... Manuscript received by the International Gas Turbine Institute February 2000. Paper No. 2000-GT-222. Review Chair: D. Ballal. 08 May 2000 01 February 2000 gas turbines cooling heat transfer convection rough surfaces jets flow measurement Various methods have been developed...

... infrared spectra temperature measurement Mach number turbulence rough surfaces It is important to understand the effects of surface roughness on turbine blade heat transfer. Surface roughness is expected to increase blade surface heat transfer. Whether blade temperature increases, depends...

... Turbine and Aeroengine Congress and Exhibition, Munich, Germany, May 8–11, 2000. Manuscript received by the International Gas Turbine Institute February 2000. Paper No. 2000-GT-230. Review Chair: D. Ballal. 08 May 2000 01 February 2000 gas turbines heat transfer rough surfaces...

... received by the International Gas Turbine Institute February 2000. Paper No. 2000-GT-461. Review Chair: D. Ballal. 08 May 2000 01 February 2000 centrifuges rotational flow rough surfaces boundary layers shear flow flow separation pressure control Centrifugal Blower Vaneless...

.... The wavelet analysis suggested that transition over rough surfaces may be in bypass mode because the disturbances were shown to be amplified in a broad spectral band. [S0889-504X(00)00302-0] Surface roughness was shown to have several effects on the structure of transitional boundary layer flow: 1...

... was reduced as air speed increased. Details on the development of this correction are documented in Pinson 23 . 3 Comparison of heat transfer data obtained for different roughness conditions at free-stream velocities of 4.6, 8.6, and 16.1 m/s The heat transfer results of four rough surface...

... fluid dynamics turbulence rough surfaces gas turbines The demand for improvements in the efficiency and power output of gas turbines has led engine designers continuously to seek to raise operating temperatures. In order to preserve the structural integrity of rotating blades, elaborate...