504 Matching Results

Search Results

Advanced search parameters have been applied.

A low-speed experimental investigation of the effect of a sandpaper type of roughness on boundary-layer transition

Description: From Summary: "An investigation was made in the Langley low-turbulence pressure tunnel to determine the effect of size and location of a sandpaper type of roughness on the Reynolds number for transition. Transition was observed by means of a hot-wire anemometer located at various chordwise stations for each position of the roughness. These observations indicated that when the roughness is sufficiently submerged in the boundary layer to provide a substantially linear variation of boundary-layer velocity with distance from the surface up to the top of the roughness, turbulent "spots" begin to appear immediately behind the roughness when the Reynolds number based on the velocity at the top of the roughness height exceeds a value of approximately 600. At Reynolds numbers even slightly below the critical value (value for transition), the sandpaper type of roughness introduced no measurable disturbances into the laminar layer downstream of the roughness. The extent of the roughness area does not appear to have an important effect on the critical value of the roughness Reynolds number."
Date: August 15, 1956
Creator: von Doenhoff, Albert E. & Horton, Elmer A.
Partner: UNT Libraries Government Documents Department

A low-speed experimental investigation of the effect of a sandpaper type of roughness on boundary-layer transition

Description: Report presenting an investigation in the low-turbulence pressure tunnel to determine the effect of size and location of a sandpaper type of roughness on the Reynolds number for transition. Transition was observed by means of a hot-wire anemometer at various chordwise stations for each position of roughness.
Date: October 1956
Creator: von Doenhoff, Albert E. & Horton, Elmer A.
Partner: UNT Libraries Government Documents Department

Effects of fabrication-type roughness on turbulent skin friction at supersonic speeds

Description: Report presenting an investigation of the effects of fabrication-type surface roughness on turbulent skin-friction drag at supersonic speeds. It was found that fabrication of the thin-skin constructions could be done sufficiently well in practice so as to cause no increase in drag over the smooth body; however, the juncture-type roughnesses produced significant increases in drag as compared with the smooth body. Results indicated that increasing the unit Reynolds number has a detrimental effect and increased the Mach number has a powerful alleviating effect on drag due to surface roughness.
Date: July 1958
Creator: Czarnecki, K. R.; Sevier, John R., Jr. & Carmel, Melvin M.
Partner: UNT Libraries Government Documents Department

Investigation of effects of distributed surface roughness on a turbulent boundary layer over a body of revolution at a Mach number of 2.01

Description: Report presenting an investigation of the effects of distributed surface roughness, consisting of lathe-tool marks, on the skin friction of a turbulent boundary layer over a body of revolution at Mach number 2.01. The investigation was made on three ogive-cylinders at zero angle of attack over a surface-roughness range from 23 to 480 microinches root mean square. Results indicated that the effects of distributed surface roughness on a turbulent boundary layer at Mach number 2.01 are generally similar to those found at Mach number 1.61 and at subsonic speeds.
Date: February 1958
Creator: Sevier, John R., Jr. & Czarnecki, K. R.
Partner: UNT Libraries Government Documents Department

A pressure-distribution investigation of a fineness-ratio-12.2 parabolic body of revolution (NACA RM-10) at M = 1.59 and angles of attack up to 36 degrees

Description: Report presenting a pressure-distribution investigation of a parabolic body of revolution with a fineness ratio of 12.2, which was performed in the 4- by 4-foot supersonic tunnel at Mach number 1.59 and Reynolds number 3.6 x 10(sub 6), based on body length, for a range of angles of attack. Results regarding basic pressures, aerodynamic coefficients, asymmetrical pressures, comparison of experimental and theoretical pressures, artificial roughness, section coefficients, and body coefficients are provided.
Date: October 30, 1952
Creator: Cooper, Morton; Gapcynski, John P. & Hasel, Lowell E.
Partner: UNT Libraries Government Documents Department

Boundary-layer transition at Mach 3.12 with and without single roughness elements

Description: Report presenting temperatures on the external surface of a straight hollow cylinder aligned parallel to the air stream. Results regarding the recovery-factor distribution without roughness, transition without roughness, transition caused by roughness, and analysis of roughness results are provided.
Date: December 1954
Creator: Brinich, Paul F.
Partner: UNT Libraries Government Documents Department

Recovery temperatures and heat transfer near two-dimensional roughness elements at Mach 3.1

Description: Report presenting an investigation to determine the effect of single and multiple two-dimensional roughness elements on the temperature distribution, pressure distribution, and heat transfer at Mach 3.1. Results regarding recovery temperatures and heat transfer are provided.
Date: February 1958
Creator: Brinich, Paul F.
Partner: UNT Libraries Government Documents Department

Effects of surface roughness and extreme cooling on boundary-layer transition for 15 degrees cone-cylinder in free flight at Mach numbers to 7.6

Description: Report presenting an investigation of three cone-cylinder bodies to obtain boundary-layer-transition data at very low ratios of wall to local stream temperature. Surface finishes at several levels of roughness height were tested. Results regarding the smooth body and rough bodies are provided.
Date: March 5, 1958
Creator: Rabb, Leonard & Krasnican, Milan J.
Partner: UNT Libraries Government Documents Department

Experimental investigation of the problem of surface roughness

Description: Based on the universal laws of turbulent velocity distribution at rough and smooth walls, there is in the present work presented a method that allows surface roughness tests and in particular, measurements on the roughness of ship surfaces to be carried out in a much simpler manner. The types of roughness investigated were in the form of flat, rough plates installed in a square-section rectangular channel, the other three walls always being smooth. Twenty-one plates of various roughness were investigated, the roughness elements being the following: spheres of diameter 0.41 and 0.21, respectively, spherical segments, cones, and "short" and "long" angles.
Date: April 1937
Creator: Schlichting, H.
Partner: UNT Libraries Government Documents Department

The effect of surface roughness on the performance of a 23 degree conical diffuser at subsonic Mach numbers

Description: Report of an investigation to determine the effect of surface roughness on the performance of a 23 degree conical diffusers with 2:1 ratio of exit to inlet area and a constant-area tail pipe. Information about the pressure survey results, including total-pressure-loss coefficient, diffuser effectiveness, and boundary-layer profiles is provided.
Date: January 16, 1952
Creator: Persh, Jerome
Partner: UNT Libraries Government Documents Department

Investigation of distributed surface roughness on a body of revolution at a Mach number of 1.61

Description: Report presenting an investigation of the effects of distributed surface roughness, consisting of lathe-tool marks, on the skin-friction drag of a body of revolution at Mach number 1.61. Tests were conducted on ogive-cylinders at zero angle of attack over a range of roughness and Reynolds number. The results indicate that the effects of surface roughness are generally similar to those found at subsonic speeds.
Date: June 1954
Creator: Czarnecki, K. R.; Robinson, Ross B. & Hilton, John H., Jr.
Partner: UNT Libraries Government Documents Department

Some measurements and power spectra of runway roughness

Description: "Measurements of actual runway roughness obtained by a profile-survey method (engineer's level) are presented. Data were obtained from a survey of a relatively rough runway and a smooth runway. The results of this study are presented as roughness profiles of the runways surveyed and in the form of power spectra" (p. 1).
Date: November 1954
Creator: Walls, James H.; Houbolt, John C. & Press, Harry
Partner: UNT Libraries Government Documents Department

Investigation of Extreme Leading-Edge Roughness on Thick Low-Drag Airfoils to Indicate Those Critical to Separation

Description: Bulletin presenting a study of several airfoils, including a conventional NACA 23021 and some low-drag airfoils for which the thickness had been increased, as smooth airfoils and after the application of a standard roughness. The results show some of the airfoils to be critical to separation resulting from such flow disturbances.
Date: June 1942
Creator: Davidson, Milton
Partner: UNT Libraries Government Documents Department

Measurements and Power Spectra of Runway Roughness at Airports in Countries of the North Atlantic Treaty Organization

Description: "Measurements of runway roughness obtained by a profile-survey method are presented. A variety of runway lengths or sections and degrees of roughness were measured. The results are presented as elevation profiles of the runways surveyed and in the form of power spectra" (p. 1).
Date: July 1958
Creator: Thompson, Wilbur E.
Partner: UNT Libraries Government Documents Department

The Effects of Roughness at High Reynolds Numbers on the Lift and Drag Characteristics of Three Thick Airfoils

Description: "In connection with studies of airfoils applicable to large high-speed aircraft, the effects of roughness on three 22-percent-thick airfoils were investigated. The tests were made over a range of Reynolds number from about 6 to 26 x 10(exp 6) for the airfoils smooth and with roughness strips applied to the surfaces. The results indicated that for the roughened models the scale effect was generally favorable" (p. 1).
Date: August 1944
Creator: Abbott, Frank T., Jr. & Turner, Harold R., Jr.
Partner: UNT Libraries Government Documents Department

Effects of Reynolds Number and Leading-Edge Roughness on Lift and Drag Characteristics of the NACA 653-418, a=1.0 Airfoil Section

Description: Bulletin presenting tests made in the two-dimensional low-turbulence tunnel of an airfoil section with roughness in the form of carborundum grains applied to the leading edge. Marked reductions in maximum lift coefficient were found to be caused by the roughness throughout the test range of Reynolds number.
Date: November 1945
Creator: Quinn, John H., Jr.
Partner: UNT Libraries Government Documents Department

A Flight Investigation of the Effect of Surface Roughness on Wing Profile Drag With Transition Fixed

Description: Report presenting a flight investigation made on a wing section of a P-47D airplane to determine the effect of roughness on wing profile drag with transition fixed far forward. Surveys of the wake were made for two surface conditions with transition fixed by a thread at 5 percent chord back of the leading edge on the upper and lower surfaces. Below the Mach number at which shock occurred, variations in Mach number of as much as 0.16 appeared to have no appreciable effect on the section profile-drag coefficients of either the smooth or roughened surfaces with transition fixed.
Date: September 1944
Creator: Zalovcik, John A. & Wood, Clotaire
Partner: UNT Libraries Government Documents Department

Effect of Surface Roughness Over the Downstream Region of a 23 Degree Conical Diffuser

Description: Note presenting an experimental investigation conducted to determine the effects of varying extents of surface roughness over the downstream region of a 23 degree conical diffuser with an inlet-boundary-layer thickness of the order of 5 percent of the inlet diameter. The air flows used in the investigation cover an inlet Mach number range from about 0.10 to 0.40. The results indicate that the flow in the roughened diffuser was steady and reproducible for all conditions.
Date: January 1954
Creator: Persh, Jerome & Bailey, Bruce M.
Partner: UNT Libraries Government Documents Department

Assessing out-of-band flare effects at the wafer level for EUV lithography

Description: To accurately estimate the flare contribution from the out-of-band (OOB), the integration of a DUV source into the SEMATECH Berkeley 0.3-NA Micro-field Exposure tool is proposed, enabling precisely controlled exposures along with the EUV patterning of resists in vacuum. First measurements evaluating the impact of bandwidth selected exposures with a table-top set-up and subsequent EUV patterning show significant impact on line-edge roughness and process performance. We outline a simulation-based method for computing the effective flare from resist sensitive wavelengths as a function of mask pattern types and sizes. This simulation method is benchmarked against measured OOB flare measurements and the results obtained are in agreement.
Date: January 25, 2010
Creator: George, Simi; Naulleau, Patrick; Kemp, Charles; Denham, Paul & Rekawa, Senajith
Partner: UNT Libraries Government Documents Department

Mask roughness and its implications for LER at the 22- and 16-nm nodes

Description: Line-edge roughness (LER) remains the most significant challenge facing the development of extreme ultraviolet (EUV) resist. The mask, however, has been found to be a significant contributor to image-plane LER. This has long been expected based on modeling and has more recently been demonstrated experimentally. Problems arise from both mask-absorber LER as well as mask multilayer roughness leading to random phase variations in the reflected beam and consequently speckle. Understanding the implications this has on mask requirements for the 22-nm half pitch node and below is crucial. Modeling results indicate a replicated surface roughness (RSR) specification of 50 pm and a ruthenium capping layer roughness specification of 440 pm. Moreover, modeling indicates that it is crucial to achieve the current ITRS specifications for mask absorber LER which is significantly smaller than current capabilities.
Date: February 16, 2010
Creator: Naulleau, Patrick; George, Simi A. & McClinton, Brittany M.
Partner: UNT Libraries Government Documents Department

Simplified models for mask roughness induced LER

Description: The ITRS requires < 1.2nm line-edge roughness (LER) for the 22nm half-pitch node. Currently, we can consistently achieve only about 3nm LER. Further progress requires understanding the principle causes of LER. Much work has already been done on how both the resist and LER on the mask effect the final printed LER. What is poorly understood, however, is the extent to which system-level effects such as mask surface roughness, illumination conditions, and defocus couple to speckle at the image plane, and factor into LER limits. Presently, mask-roughness induced LER is studied via full 2D aerial image modeling and subsequent analysis of the resulting image. This method is time consuming and cumbersome. It is, therefore, the goal of this research to develop a useful 'rule-of-thumb' analytic model for mask roughness induced LER to expedite learning and understanding.
Date: February 21, 2011
Creator: McClinton, Brittany & Naulleau, Patrick
Partner: UNT Libraries Government Documents Department

Flight measurements of the effects of surface condition on the supersonic drag of fin-stabilized parabolic bodies of revolution

Description: Report presenting testing of rocket-powered models at supersonic speeds to determine some of the surface conditions on the zero-lift drag of fin-stabilized parabolic bodies of revolution. Two types of models and three types of surface roughness were tested. Results regarding mean-drag coefficients, side-pressure coefficients, and total-drag coefficients are provided.
Date: May 2, 1952
Creator: Jackson, H. Herbert
Partner: UNT Libraries Government Documents Department

Investigation of boundary-layer transition on 10 degree cone in langley 4- by 4-foot supersonic pressure tunnel at Mach numbers of 1.41, 1.61, and 2.01

Description: Report presenting an investigation to determine the transition Reynolds numbers on a 10 degree cone in the 4- by 4-foot supersonic pressure tunnel at three Mach numbers and a range of Reynolds numbers. Results regarding a smooth cone and a cone with roughness are provided.
Date: May 1956
Creator: Sinclair, Archibald R. & Czarnecki, K. R.
Partner: UNT Libraries Government Documents Department