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By BERNARD LEWIS

Professor Lindvall, The Combustion Inst i tute is happy to have the privilege of holding this Symposium on Combustion at the California Inst i tute of Technology. Yours is an institution that is known and revered all over the world. I have heard many in this country and abroad ex- press their pleasure at the prospect of being here. I t is particularly appropriate that the Eighth International Symposium on Combustion be held at Caltech. For one thing, the subject of the chemistry and physical chemistry of combus- tion of liquid and solid propellants was about due for discussion; and I know of no more fitting place to hold such discussions than at this institution where for so many years your able faculty and students have addressed themselves, successfully, to this vital area. I would hasten to add that dis- cussion of these problems at The Combustion Inst i tute symposia is not overdue. The various workers in the field have made important recent progress in their studies of the mechanism and chemical kinetics of the burning process of pro- pellants and I think they are ready to air their views and exchange thoughts. I expect the dis- cussions will be animated and productive of new ideas. Combustion scientists have a unique oppor- tunity, even an obligation, to demonstrate the power of basic research to help guide the intelli- gent development of useful and efficient propul- sion devices.

Professor Lindvall, I should be happy if you would convey to President DuBridge the grati- tude of all members of The Combustion Inst i tute for the gracious hospitality extended to all of us by him, and, through him, by the California Inst i tute of Technology. I hope that the fruits of these discussions will be worthy of his expression of confidence in the scientific and engineering aims of The Combustion Inst i tute in a field that is so vital to what is transpiring in this and many other countries.

I am sorry that the Honorary Chairman of this Symposium could not be with us today, owing to other important commitments in Europe. I am sure Professor yon Kgrmgn will be with us in spirit; we send him our heartfelt felicitations. There has just been held under his leadership

another of the always interesting and important Technical Meetings of the AGARD Combustion and Propulsion Panel, this time on "Advanced Propulsion Techniques" under the able direction of Professor Penner. I feel a particular kinship to the AGARD Symposia, most of whose Combus- tion Conferences I have been privileged to attend. Throughout the years AGARD and The Com- bustion Inst i tute have cooperated with each other with lasting benefits. I t is to be hoped that the precedent set in holding an AGARD Sym- posium just prior to a Combustion Inst i tute Sym- posium will be continued. These symposia are generating an awareness of the problems in com- bustion that still face us and they are responsible for the generation of new knowledge, far more than meets the eye, that is needed to build the skills for development and design work.

Our thanks are due the Pasadena City College for making available this auditorium for some of the more general meetings.

The Western States Division of The Combus- tion Insti tute has cooperated with the local com- mittees at Caltech to make this symposium a success. Many of the members of that division have given of their time and effort. I particularly wish to mention William Bennet and Gilbert Bahn of The Marquardt Corporation, Bob Levine of North American Aviation, and Wesley Rigg of the Office of Naval Research. We extend special thanks to Dr. McCloskey and the four local committees for the efficient handling of the many details on arrangements, both business and social.

To members and visitors from other countries we extend, as always, our warmest greetings. The Combustion Inst i tute is truly an international scientific society and the sections in the various member countries (16, I believe with an additional nation pending) play an important part in mak- ing these symposia a success technically. The participation in the presentations and discussions of combustion scientists from other countries assures us that we are exposed to a cross-section of the world's combustion research and thinking.

I welcome all members of The Combustion Insti tute and visitors from this country. Many of you have come almost as far as some of our

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foreign members. I hope that you will derive benefit from the discussions and that you will find the long travel well compensated, both in pleasure and learning.

To Professor Penner we owe a deep debt of gratitude. I t is he who is largely responsible, as Chairman of the Papers Subcommittee, for the scope of the subjects covered. Those who have held this position before know that, although the Papers Subcommittee has international member- ship, ult imately the real burdens fall on the chair- man who, because of limitations of time and distance, bears the brunt of the work and respon- sibility. Professor Penner has given unstintingly of his time and strength and the results are excel- lent. I move that we show our appreciation by giving him a round of applause.

Finally, I would like you all to know that these symposia of The Combustion inst i tute have been possible only through the financial assistance of the Air Force Office of Scientific Research, The Office of Naval Research and The Office of Ord- nance Research, whose grants have defrayed expenses of organization, and travel of many visitors from abroad. The publication of the pro- eeedings of the symposia have been made possible by grants from some seventy industrial com- panies. They can justly be proud of their accom- plishment in the series of tomes that form "the bible" of combustion research earned out all over the world during and since the war.

The agenda of this meeting covers a wide range of topics. The terms "basic" and "applied" as employed to characterize the end object of an investigation are frequently misleading since they tend to imply that the conceptual procedures, employed in an investigation more or less directly related to an end object, arc different from those employed when the investigation is primarily motivated by curiosity into the nature of under- lying phenomena. Without any desire to label the topics in this manner, I would note that those to be discussed in the ensuing sessions cover the entire range, from those attempting detailed descriptions of quite idealized situations to those concerned with the study of the combustion process in practically important systems.

With respect to the lat ter category, it is par- tieularty appropriate that we concern ourselves at this meeting with problems arising out of the development of propulsion devices. The Pacific Coast has become the most important center of this country for this work, and large numbers of the combustion scientists resident here are en-

gaged in the design of combustion systems for rocket engines, in the accumulation of data perti- nent to such design, and in the study of special features of the combustion process, an under- standing of which is required for satisfactory operation.

For the first time at one of these combustion symposia, consideration will be given to the com- bustion of solid propellants. Rockets employing solid propellants have been developed or are under development for missions of all types, ranging from small tactical rockets to large vehicles for intercontinental or space travel. Composite propellants, based on the oxidizer ammonium perchlorate, have been extensively studied. We shall hear some of the work on the decomposition and deflagration of pure am- monium perchlorate and ammonium perchlorate propellants.

Erosive burning of actual propellant grains as a consequence of high gas velocities results in deviations from the behavior predicted by the simple laws for burning rate. This phenomenon is difficult to describe and to control. An adequate description is required in propellant grain design studies and control is required for operational re- liability. The presentation to us of some recent work in this field will be received with much interest.

In the field of combustion problems associated with the operation of solid fueled rockets, we shall also consider questions of combustion stabil- i ty in such systems. In addition to several con- tr ibuted papers in this field, the opinions of a number of experts will be heard in an informal round-table discussion on acoustic instability, a discussion that will, I trust, be a vigorous and productive one and one that will stimulate addi- tional work leading to solution of this vexing problem.

Studies of the combustion of liquid propellants and of the combustion process in liquid-fueled rockets continue to be vigorously prosecuted. In these systems, where cognizance must be taken of atomization, evaporation, and mixing and where efficiency and reliability depend on all of these steps, a host of problems exists demanding experi- mental ingenuity of a high order. The programs of this and preceding symposia demonstrate the extent to which our understanding of these sys- tems has increased, and the degree to which we are able to control them has improved.

From this brief summary it is apparent that the agenda of this meeting takes proper recognition

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of the large amount of activity in this area de- voted to propulsion-connected problems of com- bustion. I t also points up the fact that the great expansion of combustion research and develop- ment that we have experienced in the last fifteen years has, to a very considerable extent, been in response to the demands of an expanding pro- pulsion industry. I t is not at all surprising that this should be so. The design requirements of air- borne propulsion units, with the required high heat release rates and the restrictions on weight, size, and geometry, pose problems of a severity that are not encountered in stat ionary combus- tion systems. Additionally, it may be noted that the airborne propulsion industry is a new industry with a fantastic rate of obsolescence, so that the combustion engineer is not confronted with a large capital investment in existing equipment.

I t is, I think, opportune to suggest that there exists a very considerable opportunity to apply the recent improvements in combustion tech- nology to the more traditional applications. Such applications will be over a relatively long term, as obsolescence of old equipment and expansion of existing facilities permit the design of new com- bustion systems.

When one considers that area of combustion research that is not strictly connected with an end application, it has become almost traditional to divide the area under the labels, "laminar flames," "turbulent flames" and "detonation." All of these areas are well represented in the agenda of this meeting.

I t has been apparent that substantial progress in the detailed description of the laminar flame is dependent on the ability to describe the details of the flame reaction. I t is interesting to note that manyof the contributed papers at this symposium are devoted to the elucidation of flame kinetics and that this emphasis is supported by a number of other papers dealing more directly with chemi- cal kinetics and allied topics.

The production of ions by flames has received less study than the importance of the subject warrants. The ionic concentration is greater than that predicted for equilibrium and must result ul t imately from the non-equilibrium distribution of energy in the flame front. Studies of ions in flames will thus yield information on the very fun- damental question of the constitution and state of species in the flame front. At this meeting, we shall engage for the first time in a full scale dis- cussion of this intriguing subject.

We have noted the recent development of

interest in the details of the transformation from deflagration to detonation in explosive gas mix- tures, in droplet suspensions, and in solids. I t seems to me that this topic is particularly deserv- ing of study, since from one point of view the deflagration-detonation transition can be re- garded as an instance of flame instability. Study of the transition, under well defined conditions, should illuminate the ~hole problem of combus- tion instabili ty in other systems.

I have commented, briefly and incompletely, on some of the topics to engage our attention during the balance of this week. The program is comprehensive and well organized, it will appeal to the special interest of nearly everyone and it should provoke a lively and profitable interchange of ideas between those who work in different areas and in different countries.

Progress in any branch of science is achieved by the efforts of a number of workers employing a diversity of techniques and addressing them- selves to a wide variety of problems. The indi- vidual scientist may be confronted with a design problem of iramediate urgency or he may have the opportunity of investigating some idealized system motivated only by his own curiosity. Generally his activities fall somewhere in between these two extremes. To each problem, he should bring the resources of available background in- formation and to each he should apply the in- vestigative techniques and method of solution appropriate both to the circumstances and to the problem at hand.

It is a matter for some concern that theoretical or fundamental combustion research has not made very many positive design contributions to systems of engineering importance. Combustor design is carried out with a rationale based pri- marily on experience in combustor design; basic research is carried out on the multitudinous aspects of idealized systems, and the twain do not meet very often. There is a need for new concepts, new models, and new definitions of problems for fundamental investigations. The application of present fundamental information and the defini- tion of new fundamental problems for investiga- tion both depend upon effective communication between those whose concern is with engineering applications and those engaged in the less utili- tarian types of work. I t is in the provision of an avenue for such communication that these sym- posia of The Combustion Inst i tute offer their most significant service.