Managed, advanced technology research programs in gas turbine systems, organic Rankine cycles, and other thermal systems, mechanical systems, and advanced software applications. Invented several thermal systems and devices and received one US patent. Managed and conducted research in expert systems and applications for military problems. Managed cost, business, and technical proposal development (several million dollars), and execution of projects and programs. Managed Straight Stack algorithm and software development on a $10m US Air Force program for aircraft engine (gas turbine) overhaul.
a.Straight Stack Algorithm and Software Development Program for Air Force
Program managers at Mechanical Technology Incorporated (MTI), Latham, NY, identified some problems with the US Air Force gas turbine engine maintenance at Oklahoma and San Antonio Air Logistics Centers. The overhaul of turbine engines was a manual process and resulted in a slow turn around of jet engines. When the overhauled engines were finally assembled and tested, they often failed on the engine balancing test stand. The failed assemblies were recycled to the disassembly and reassembly shops. This testing and reassembly cycle was repeated several times contributing to long overhaul times and excessive costs.
Here is a brief explanation of the technical problem. The compressors of the gas turbine engines under investigation typically had sixteen disks, which were assembled together by means of long bolts that passed through sixteen sets of bolt-holes in each rotor. When they were remanufactured, each disk has a small eccentricity and a small skew. Of course, an ideal rotor will have no eccentricity and is parallel (no skew) on both faces. Therefore, a practical assembly of a compressor was never a true cylinder but had a curved profile for the final rotor. When such a rotor was spun at the high speeds typical for gas turbines, the eccentricities caused severe vibrations. In cases where the effects of the eccentricities and skews accumulated in a positive fashion, the resulting vibrations were intolerable and occasionally destroyed the rotor assembly. Dynamic analysis of the rotor revealed permissible profiles of eccentricity. The assembly process was designed to take advantage of these permissible limits by aligning the bolt-holes on each rotor with its neighbors.
Simple mathematical calculation shows that there are sixteen to the power fifteen combinations of compressor assemblies possible. Therefore, a manual assembly and testing process is not practical. So MTI engineers proposed a computer modeling of the assembly. But even on a computer, the combinations were so numerous that brute-force search within a realistic time limit was impractical. I developed a novel method, called the stacking algorithm to address the problem.
I started with measuring and characterizing the rotors by means of a laser coordinate measurement machine (LCMM). From the coordinate measurements, eccentricity and skew for each rotor were obtained. I developed the stacking algorithm by combining the “branch and bound” technique used in operations research and search techniques common in artificial intelligence (AI). I led a group of programmers in elegant computer storage techniques to handle the combinations as the search for a solution progressed. I recognized that in most practical situations, the solution space was large. Finding any single solution was sufficient. There was no need to discover all possible solutions. In most practical cases, my opportunistic method provided a solution, as verified by simulation programs. I prescribed physical time limits on the computer to terminate a search. The stacking algorithm and computer system worked exceptionally well. This is an example of an affordable engineering solution to a military problem utilizing techniques available in the academic and industrial research communities.
