Past Projects

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A few snapshots from past projects can be seen above.




Past Projects


Inter-Turbine Burners for Improved Part-Power Performance of Turboshaft Engines

    The use of an inter-turbine burner for improving the part-power performance of small turboshaft engines was investigated. An inter-turbine burner is a second combustor placed between the gas generator exit and the power turbine to "reheat" the engine gas stream before it enters the power turbine. The inter-turbine burner is used to increase engine power at the maximum power setting permitting the core engine to be run closer to its design condition at part-power settings. Cycle analysis shows significant improvement in specific horsepower with an accompanying increase in specific fuel consumption at the full power condition. The part-power specific fuel consumption improves significantly at power levels below half of the maximum power. This improved specific fuel consumption at part-power settings will reduce fuel consumption during the cruise/loiter segments of the UAV mission. Thus there is a net benefit to time-on- station, provided that the cruise/loiter segment is long compared to the take-off and climb segments. The increased specific horsepower of a turboshaft engine with an inter-turbine burner results in a lighter engine for the same maximum power. The commercial application of the proposed ITB engine technology is a new class of cycles for industrial, marine, and aircraft gas turbine engines.

Precompressor Cooling with Water and Oxidizer for Small Access to Space Vehicles

    A study was undertaken to investigate the use of pulse detonation (PD) technology in a relatively near term (~2020 timeframe) engine system for a subsonic commercial aircraft applications. The effort concentrates on an analysis of concepts utilizing PD combustion for a regional jet commercial aircraft engine application. A first order systems analysis of the PD application is presented along with an estimate of installed performance. Conceptual engine design figures of merit include operational costs, engine weight, configuration variations, and, in general, the overall benefits of using PD over current propulsion systems. This study effort addresses the current and projected flight qualification requirements that must be met by future commercial aircraft, particularly environmental compatibility. In the analysis of the application of PD technology to regional aircraft, an engine designated as the RJ7 is used as the baseline engine for this study. The RJ7 is at the current state of regional jet engine technology and its performance and costs are well characterized. The engine concept evaluation criteria include specific fuel consumption, weight, mechanical simplicity (manufacturability and maintainability), installation benefits/penalties to the airframe, and environmental compatibility.

Axial Vorticity Flame Stabilization System for Ramburner Applications

    The objective of the proposed Phase I project was to design, fabricate, assemble and characterize an axial-vorticity flame stabilization system for application to ramjet burners. This effort was successfully completed as planned. By using various combinations of axial-vorticity flameholders and swirl vanes APRI performed tests in which the local flow angle over the step was varied from 15 to 40 degrees in 5-degree increments. The flame stabilization limits were characterized as a function of flow velocity and equivalence ratio. The results demonstrated that as this local flow angle decreased, the range of conditions under which flameholding was achieved decreased. Thus, for a given stoichiometry and mass flow rate, as the local flow angle over the step is decreased, the flow velocity in the separated flow region downstream of the step increases until no flame can be stabilized. Acoustic analysis and acoustic pressure measurements were also made. The results were that no large-amplitude pressure oscillations were observed under any flow conditions.

A Designed-to-Cost Turbojet for Target Drone Applications

    The Navy seeks low cost 160 pound thrust target drone turbojet engines at a cost of $10,000 per engine. This $10,000 per engine price objective was set based on the observation that aviation hobbyists can purchase commercially available turbojet engines for $5000 or less. These hobby engines typically produce less than 50 pounds of thrust and rely on simple designs based on automotive turbocharger components and technology. Inherent to these hobby engine designs is a low overall engine pressure ratio and low turbine inlet temperature. These two features permit the design of an engine with a relatively simple compressor and an uncooled turbine, which may be executed using the inexpensive cast component technology used in automotive turbochargers. Using Navy mission and design requirements, Advanced Projects Research, Incorporated (APRI) has designed an axial flow turbojet engine using simple cast components for the compressor and turbine parts. Formed metal and simple machined parts are used for the bulk of the remainder of the system. To execute the design, fabrication, and eventual production of the proposed engine APRI has worked with manufacturers of automotive turbocharger and supercharger components and manufacturers of hobby turbojet engine components. The feasibility of a low-cost 160 pund thrust axial flow turbo jet engine was demonstrated through design and manufacturing engineering.


Inquiries concerning any of APRI's past projects should be directed to Dr. Thomas Sobota at


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