A SUPPLEMENT TO THE MECHANICAL ENGINEERING MAGAZINE

AS THE TURBINE TURNS... By Dr. Lee S. Langston, Professor Emeritus of Mechanical Engineering, University of Connecticut

at the U.S. Naval Research Laboratory [3], Detonation Gas Turbines the U.S. Air Force Research Laboratory [4], the University of Texas at Arlington [5] and

During the early days of gas turbine development in the 1930’s, getting here at the University of Connecticut [6]. Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/135/12/50/6358502/me-2013-dec4.pdf by guest on 29 September 2021 combustors to work efficiently took a lot of ingenuity and effort. The RDE concept for a detonation Both inventors of the aviation gas turbine - Hans von Ohain in Germany and Frank combustor consists of a concentric Whittle in England - first resorted to hydrogen fuel with its more forgiving high flame circular-tube annulus, where a premixed speed, before they solved liquid fuel combustion problems. The first industrial gas fuel/air mixture is injected axially at the turbine, Brown Boveri’s 1939 Neuchatel Switzerland 4 MW unit, had a single, very annulus entrance. Once initiated, a large and long combustor, reflective of the nascent state of liquid fuel combustion detonation propagates at supersonic technology at the time [1]. speeds circumferentially around the annulus, moving downstream in an By contrast, modern gas turbine combustors are now compact, robust, tolerant of a axial direction with at first rapidly rising wide variety of fuels, and provide the highest combustion intensities (rate of energy pressures and then falling, as the swirling 3 released per unit volume, as high as 75,000 Btu/s ft ). They heat gas path flow in a flow approaches the exit of the annulus. near constant pressure process, to thermodynamically approximate the “energy in” Challenges in the design included high isobaric part of a . heat transfer loads to the annular surfaces Figure 1 and decelerating the exiting flow to b) Detonation gas turbine subsonic velocities, while minimizing with an RDE combustor. aerodynamic losses. A possible application of RDE to a gas turbine is shown in Fig. 1, taken from Nordeen [6]. Figure 1a) is a sketch of a conventional twin-spool gas turbine with various stations labeled. Figure 1b) is the sketch of an equivalent where the entire high pressure spool and conventional combustor have been replaced with an RDE combustor. Conceptually, the pressure rise of the high a) Conventional twin-spool gas turbine. compressor in 1a) is brought about by Currently, all flame processes in gas turbines fall within the combustion category the supersonic shock system in the RDE of deflagration [2]. This is the term describing subsonic combustion propagating combustor in Fig. 1b). The Fig. 1a) high through heat transfer. In a typical gas turbine combustor this subsonic heat addition turbine is also eliminated, since there is no leads to near constant pressure process in the gas path flow. high compressor to be driven. Thus, the RDE design in Fig. 1b) has one less spool, In contrast to deflagration, detonation combustion involves a supersonic flow, resulting in less weight and a shorter with the chemical reaction front accelerating, driving a shock wave system in its engine. advancement. Detonations, usually associated with explosives and explosions, produce very high pressures and high velocities. Thus, if harnessed in a gas turbine Figure 2, taken from Schwer and Kailasanath combustor, detonation could reduce the need for some expensive compressor and [3], is a pressure P (normalized by ambient turbine hardware, lighten engine weight and possibly increase gas turbine power pressure Pref) volume v (normalized by output. specific volumeref v ) diagram for an ideal fluid particle moving through each of the In recent years there have been growing research activities to utilize detonation gas turbines in Fig. 1. Positions on each to combust fuel/air mixtures in gas turbine combustors. In the 1990s detonation Pv curve are indicated by corresponding based power concepts began with pulse detonation (PDEs), and have now station numbers in Fig. 1. moved into the continuous detonation mode, termed rotating detonation engines (RDEs). Currently, RDE experimental and computational activities are taking place ...Continued on p. 54

GLOBAL GAS TURBINE NEWS DECEMBER 2013 50 A SUPPLEMENT TO THE MECHANICAL ENGINEERING MAGAZINE A SUPPLEMENT TO THE MECHANICAL ENGINEERING MAGAZINE

As the Turbine Turns... continued from page 50 A VIEW FROM THE CHAIR By Karen Thole, Chair, ASME IGTI Board The ASME International Gas Turbine Institute is continuing to as the Local Liaison Committee Chair. And, expand its international reach throughout the year to new thanks to the many others who chaired Figure 3 sessions, reviewed papers, presented markets through symposiums, courses, and conferences. papers, exhibited, and sponsored. We also

To inform you on what we have done in 2013 beyond Turbo Expo, ASME IGTI held the appreciate our student session assistants Experimental RDE second Organic (ORC) Conference in the Netherlands and The Turbine and the Student Advisory Committee for Exhaust Plume. Blade Tip Symposium and Course Week in Germany. These were two exciting and engaging the students in San Antonio. Of Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/135/12/50/6358502/me-2013-dec4.pdf by guest on 29 September 2021 successful international events organized by ASME IGTI staff and volunteers. In addition, course, the valued ASME IGTI staff pulled Photo courtesy of we will be holding the second annual Gas Turbine India Conference this December, everything together as they always do. Air Force Research which has expanded into a two day conference due to growth in participants and I also want to make you aware that the Laboratory. presentations. newly approved editor for the ASME This expansion of the ASME International Gas Turbine Institute’s activities arrives at a Journal of Turbomachinery is Ron Bunker. good time in terms of re-structuring ASME’s Knowledge and Community sector and Ron is replacing Dave Wisler, who has Institutes. I spoke of this re-organization in my last note so this is only to say that it’s given excellent service to our community continuing to progress. I’ve been working closely with our sister institute, the Internationalfor many years in being the Editor for Petroleum Technology Institute (IPTI), on the re-structuring and to better understand Journal of Turbomachinery. References how we might use some of their best practices. ASME IGTI will have opportunities in the Finally, I want to end by wishing each of near future to closely collaborate with colleagues who have similar interests and even you a happy and safe holiday season. In 1.Langston, Lee S., 2010, “Visiting the further expand the markets we serve. reflecting on this past year in my current Museum of the World’s First Gas Turbine role as chair of the ASME IGTI Board, Power plant”, Global Gas Turbine News, As an update on our prized Turbo Expo, we have hit another record in terms of the Comparison of Brayton and detonation cycles, with different operating April, p. 3. number of abstracts submitted for 2014. A total of 2,147 abstracts were submitted, which it has been my pleasure to serve our Figure 2 pressure ratios, from Schwer and Kailasanath [3]. represents a 16.5% growth from 2013. If we compare the 2014 abstract submissions to community and so I would like to take time 2. Lefebvre, Arthur H., 1983, Gas Turbine v the 2012 submissions, also held in Europe, there was an 8% growth. There continues to thank you for allowing me to do so. The two-spool gas turbine in Fig. 1a) is represented as the Brayton cycle with an Combustion, McGraw-Hill, p. 33. to be significant interest and research being conducted to improve turbomachinery operating compressor pressure ratio of 10, between positions 2.0 and 3.0. 3. Schwer, D.A., and Kailasanath, K., 2011, efficiencies through collaborations between industry, government agencies, and “Rotating Detonation-Wave Engines”, 2011 Karen Thole The single spool RDE gas turbine of Fig. 1b) is represented by a detonation cycle which academia. With the successful 2013 Turbo Expo in San Antonio, it’s not too surprising NRL Review, pp. 90-94. Board Chair accounts for the supersonic features of the heat addition, starting at station 2.5’. This is that there is a strong continued interest from the community to participate in 2014. Why at the exit of the low pressure compressor (LPC) which has an operating compressor 4. Tellefsen, Jonathan R., King, Paul I., Schauer, was it successful? It was because of the persistent efforts of the volunteers including pressure ratio of 2. (The shape of the detonation cycle is similar to that of a constant Frederick R., and Hoke, John L., 2012, Bernhard Winkelmann who was the Executive Conference Chair; Seung Jin Song who v o l u m e h e a t a d d i t i o n H u m p h r e y c y c l e [ 7 ] . ) T h e e x i t o f t h e R D E c o m b u s t o r i s a t s t a t i o n 4 . 5 ’. “Analysis of an RDE with Convergent Nozzle was the Conference Chair; Tim Lieuwen who was the Technical Program Chair; Howard in Preparation for Turbine Integration”, Hodson, Philip Andrew and Geoff Sheard as the Review Chairs; and Harold Simmons As many of us learned in our thermo courses, the area enclosed by a cycle on a Pv American Institute of Aeronautics and diagram is a measure of the work out of the device, for quasi-static processes. In Astronautics, paper AIAA 2012-0773, pp. 1-11. Fig. 2, the detonation cycle area exceeds that of the Brayton cycle. The exceeding CONFERENCE UPDATE This past October, the ASME International Gas area has been labeled as additional work by Schwer and Kailasanath, providing the 5. Braum, Eric M., Lu, Frank K., Wilson, promise of an increased output for a RDE gas turbine. Donald R., and Camberos, Jose A., 2013, Turbine Institute had the opportunity to host “Airbreathing Rotating Detonation Wave two separate conferences in Europe. Continued research and development by the RDE technical community is needed Engine Cycle Analysis”, Aerospace Science to see if the promise of improved performance and downsized turbomachinery and Technology, Vol. 27, pp. 201-208. The ASME 2013 Turbine Blade Tip Symposium and Course for a detonation cycle is real. However, any skeptics should remember the Week was held in Hamburg, Germany from September travail and tribulation (alluded to at our beginning here) early gas turbine 6. Nordeen, Craig A., 2013 “Thermodynamics of a Rotating Detonation Engine”, Ph.D. 30 to October 3. The event addressed the current state of developers experienced to perfect the deflagration combustors of today. v Thesis, University of Connecticut. the art in the design, analysis, and improvement of turbine blade tips. The two-day course of lectures preceded the 7. Heiser, William H., and Pratt, David T., 2002 ASME IGTI is the society “ Analysis of Pulse technical symposium to provide background, state-of- for turbine professionals like you! Detonation Engines”, Journal of Propulsion the-art design, and operability issues surrounding the and Power, Vol. 18, No. 1, pp. 68-76. topic. The two-day symposium hosted over 75 attendees Visit us on the Web! and built upon the lecture series with current proposed or enacted solutions, studies to gain insight to the physics, Lee Langston is former ed- and an industry panel session for open discussion. itor of the ASME Journal of Engineering for Gas Turbines ...Continued on p. 53 go.asme.org/IGTI and Power and has served ASME INTERNATIONAL GAS TURBINE INSTITUTE Phone: +1-404-847-0072 on the ASME IGTI Board as Fax: +1-404-847-0151 both Chair and Treasurer. Email: [email protected] GLOBAL GAS TURBINE NEWS DECEMBER 2013 48 GLOBAL GAS TURBINE NEWS DECEMBER 2013 54