Presenting unified treatments of current aspects of experimental fluid mechanics at a level useful to graduate students, researchers, and practicing engineers, this series serves the research community by consolidating widespread and often scattered knowledge. The books and monographs are equally suitable for learning and reference, and relevant topics are experimental techniques whose mastery requires a knowledge that can conveniently be contained in a book, as well as topics in fluid dynamics where understanding is based largely, though not necessarily exclusively, upon experiments. Thus, the books may contain up to one-third theory, and each one is a complete, integrated discourse, as opposed to a group of essays on selected sub-topics, with an editor or principal author responsible for unifying the conceptual content.

The identification of laminar-turbulent boundary layer transition on wind tunnel models provides essential data for modem wing design. However, simulating true flight Reynolds numbers with scaled models requires the use of cryogenic wind tunnels. Transition detection in 'war" wind tunnels can be realized using commercially available IR cameras. In parallel, the temperature sensitive paint (TSP) technique is well established as an additional tool. In cryogenic testing IR i m g n g becomes more difficult because of the reduction in radiated energy and the shift to longer wavelengths. Therefore, the TSP technique has become a promising alternative here. However, applying temperature sensitive paint in a large-scale cryogenic wind tunnel like the EuropeanTransonic Wind tunnel (ETW) needs specific modification of existing TSP formulations. Cooperative tests in the ETW therefore were performed by DLR and NAL (Japan). In these measurements, NAL's paint and DLR's mobile PSP/TSP system for data acquisition and evaluati~n'.~.' were used. Some efforts were m d e to adapt the system to specific conditions given at the ETW wind tunnel. So for the first time it was successfully realized to perform a TSP luminescent paint test at cryogenic temperatures in a commercial wind tunnel. Nomenclature Re =Reynolds number Ma =Machnumber p,, T AT 6T a =angle ofattack CL =lift coefficient x*,y*,z* =wing coordinates S = half wing span of model rl =normalized spanwise coordinate (y*/s) x/c =normalized chordwise coordinate = stagnationpressure/temperature in tunnel =total a m u n t of temperature change = temperature difference on wing THE CRYOGENIC WIND TUNNELThe European Transonic Wind tunnel (ETW) sited in Cologne, Germny, i s an industrial cryogenic pressurized facility. It provides the capability for achieving full scale flight Reynolds numbers of transport aircrafi by testing at pressures between 125 and 450 !@a and at temperatures between 110 and 310 K, using nitrogen as the test gas. The tunnel started operation in 1994, and, after a phase of commissioning and evaluation, it is available for productive testing since 19964. Aerodvnarrdc CircuitThe ETW has a closed aerodynamic circuit contained inside an intemally insulated pressure shell. The two stage, fixed blade compressor are driven by a 50 MW synchronous motor. To achieve the desired low tem perahues of the test gas, liquid nitrogen is injected continuously into the tunnel upstream of the compressor. The corresponding gaseous nitrogen exhaust upstream of the stilling chamber is contmlled by valves for the accurate maintenance of tunnel pressure. From the settling chamber equipped with a honeycomb and anti-turbulence screens, the flow enters the test section via a flexible nozzle of contraction ratio 1 : 12 (&I). Figure 1: Aerodynamic circuit of the ETW wind tunnel. LN2: liquid nitrogen, GN2: gaseous nitrogen. 0-7803-8 149-1/03/$17.0002003 IEEE 77The test section has slots in the top and bottom wall for full span model tests and slotted side walls for half model tests. Mach number...

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The tangential momentum accommodation coefficient (TMAC) was investigated experimentally from the mass flow rate through a single microtube under the slip flow and the early part of the transition regime. The measurements were carried out by the constant-volume method under the mean Knudsen number smaller than 0.3, which is based on the mean pressure of the inlet and the outlet of the microtube, to apply the second-order slip boundary condition. To measure TMACs on various materials, quite large microtube was employed, which require the reduction in leakage. TMAC was obtained from the slip coefficient determined by the relation of the mass flow rate to the mean Knudsen number. The obtained mass flow rate was well explained by the theoretical equation. TMACs of deactivated-fused silica with argon, nitrogen, and oxygen were measured, showing the tangential momentum was not accommodated completely to the surface, and the values showed good agreement with previous studies. From the comparison between microtubes with different inner diameter, it is showed that TMAC is determined mainly by gas species and surface material.