The effect of freestream turbulence on film cooling adiabatic effectiveness. ASME Turbo Expo,

ABSTRACT The film-cooling performance of a flat plate in the presence of low and high freestream turbulence is investigated using thermochromic liquid crystal thermography. Fullsurface distributions of the convective heat transfer coefficient are determined for three blowing rates on a model with three straight holes spaced three diameters apart. An increase in heat transfer coefficient due to mass injection is clearly observed in the images and is quantitatively determined for both the low and high freestream turbulence cases. The increase in heat transfer coefficient is greater than in previously published research, possibly due to the use of different, more representative thermal boundary conditions upstream of the injection location. These boundary conditions, along with high resolution images, may account for the appearance of "fork tine" patterns of high heat transfer due to the presence of these vortices, not previously seen. Although the driving potential for heat transfer is less, it is observed that in some instances film cooling may cause an increase in overall heat transfer due to the increase in heat transfer coefficient

2001-GT-0164 MEASUREMENTS IN A TURBINE CASCADE FLOW UNDER ULTRA LOW REYNOLDS NUMBER CONDITIONS

ABSTRACT With the new generation of gas turbine engines, low Reynolds number flows have become increasingly important. Designers must properly account for transition from laminar to turbulent flow and separation of the flow from the suction surface, which is strongly dependent upon transition. Of interest to industry are Reynolds numbers based upon suction surface length and flow exit velocity below 150,000 and as low as 25,000. In this paper, the extreme low end of this Reynolds number range is documented by way of pressure distributions, loss coefficients and identification of separation zones. Reynolds numbers of 25,000 and 50,000 and with 1% and 8-9% turbulence intensity of the approach flow (Free Stream Turbulence Intensity, FSTI) were investigated. At 25,000 Reynolds number and low FSTI, the suction surface displayed a strong and steady separation region. Raising the turbulence intensity resulted in a very unsteady separation region of nearly the same size on the suction surface. Vortex generators were added to the suction surface, but they appeared to do very little at this Reynolds number. At the higher Reynolds number of 50,000, the low-FSTI case was strongly separated on the downstream portion of the suction surface. The separation zone was eliminated when the turbulence level was increased to 8-9%. Vortex generators were added to the suction surface of the low-FSTI case. In this instance, the vortices were able to provide the mixing needed to reestablish flow attachment. This paper shows that massive separation at very low Reynolds numbers (25,000) is persistent, in spite of elevated FSTI and added vortices. However, at a higher Reynolds number, there is opportunity for flow reattachment either with elevated freestream turbulence or with added vortices. This may be the first documentation of flow behavior at such low Reynolds numbers. Though undesirable to operate under these conditions, it is important to know what to expect and how performance may be improved if such conditions are unavoidable

Novel Inhibitors of InhA Efficiently Kill Mycobacterium tuberculosis under Aerobic and Anaerobic Conditions▿

Drug resistance in Mycobacterium tuberculosis has become a serious global health threat, which is now complicated by the emergence of extensively drug-resistant strains. New drugs that are active against drug-resistant tuberculosis (TB) are needed. We chose to search for new inhibitors of the enoyl-acyl carrier protein (ACP) reductase InhA, the target of the first-line TB drug isoniazid (also known as isonicotinoic acid hydrazide [INH]). A subset of a chemical library, composed of 300 compounds inhibiting Plasmodium falciparum enoyl reductase, was tested against M. tuberculosis. Four compounds were found to inhibit M. tuberculosis growth with MICs ranging from 1 μM to 10 μM. Testing of these compounds against M. tuberculosis in vitro revealed that only two compounds (CD39 and CD117) were bactericidal against drug-susceptible and drug-resistant M. tuberculosis. These two compounds were also bactericidal against M. tuberculosis incubated under anaerobic conditions. Furthermore, CD39 and CD117 exhibited increased bactericidal activity when used in combination with INH or rifampin, but CD39 was shown to be toxic to eukaryotic cells. The compounds inhibit InhA as well the fatty acid synthase type I, and CD117 was found to also inhibit tuberculostearic acid synthesis. This study provides the TB drug development community with two chemical scaffolds that are suitable for structure-activity relationship study to improve on their cytotoxicities and bactericidal activities in vitro and in vivo