This paper deals mainly with the development of a high-speed wind tunnel for the testing of turbine or compressor blade cascades under two-dimensional air flow at velocities up to that of sound. It includes a brief resume of the early history of the technique, and goes on to enumerate the variables which must be brought under the operator's control. Reference is made to methods of presentation of results, including the use of optical systems for demonstration of shock phenomena. Finally, the control system evolved for operating the high-speed tunnel is described, and some notes are added on the protection of the operators from fatigue induced by monotony and noise.
The general problem of erosion of turbine blading under wet steam operating conditions is reviewed and remedial methods available to the design engineer are considered. Of these, direct attack on the source of erosion, steam-borne water drops, is most attractive and is examined in some detail.Five stages may be distinguished in the process culminating in erosion. They are: formation of droplets, their deposition on diaphragm blading, subsequent detachment, acceleration towards the moving blades and final impact with them.The possibilities of interrupting this process at any stage are discussed and the paper primarily deals with the experimental investigation of these possibilities for the three intermediate stages using a full sized cascade of hollow last stage diaphragm blades. This enabled various configurations of extraction slots to be investigated as well as the effects of energizing the blade wakes and heating the bladcs. The construction and operation of the cascade and associated instrumentation are discussed and results are presented in terms of blading efficiencies for the various processes.
eds., Immunology of Parasitic Infections, 848 pp., 2nd ed. Blackwell Scientific Publications, Oxford, 1982. $99.50 (U.S.).The present book is a revised and rewritten edition of the 1976 edition but follows the same general format. The book is concerned primarily with immunology of human parasitic diseases, however, the use of experimental animals is discussed as are some of the important zoonoses such as giardiasis, toxoplasmosis, babesiosis, and some of the helminthiases. Other parasites that are of primary interest to veterinarians such as ascarids, cestodes and Fasciola spp also are included.Thirty-two authors have contributed to the book, which is divided into three sections. The first contains six chapters concerned with the immune response to parasitic infections.Of special interest to pathologists is the chapter by K.S. Warren on Mechanisms of Immunopathology in Parasitic Infections. Although only 22 pages are included in the chapter, an adequate assessment of the problem is made. Much of the information on immunopathology is about leishmaniasis and schistosomiasis.The second section of the book deals with immunity, immunopathology and immunodiagnosis of parasitic infections of man and domestic animals. In the 596 pages of this section of the book, I76 are devoted to trypanosomiasis and schistosomiasis-which are currently fertile fields for immunoparasitologic research. Specific sections on immunopathology are in the chapters on African and American trypanosomiasis, leishmaniasis, malaria, babesiosis, schistosomiasis, filariasis, trichinelliasis and cestodiasis.The section on the immune response to nematodes is brief considering the large number of species of nematodes. Only two pages contain information on arrested development with just 3% pages on visceral and ocular toxocariasis.The third section of the book contains information on life cycles and ecology of parasites. The information presented is brief but provides a review of the present knowledge of major groups and individual parasites. The last part ofthis section asks "What can the immunologist do to help control helminthic disease?" Vector control and chemotherapy have done little to control parasitic diseases on a global basis. Parasitic diseases still affect a major portion of the world population. The editors note that in the eight years between the first and second editions of the book, some diseases such as malaria have increased-so has the field of immunoparasitology.
A twin-exhaust steam turbine of 60-MW output was used for a field study of a method of wet steam erosion control which had been examined previously under laboratory conditions. The last stage of one exhaust was modified so that measured quantities of steam and water could be extracted, or steam injected through slots in the trailing edges of the diaphragm blades. Variations in erosion rates of the last-stage moving blades in both exhausts were compared by recording continuously the changes in emissivity of radio-active labels attached to sample blades. An introscope was used to study flow conditions during the experiment, and after some five months' operation the set was opened up for inspection, which confirmed the estimates that water extraction reduced erosion by a factor of 5.
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