Compound Turbine Turbocharger

Compound Turbine Turbocharger1 Designed by Jacob Sykora

The current generations of centrifugal turbochargers are severely limited in the amount of boost pressure they can produce. This is due to their reliance on a single exhaust turbine and compressor rotor, which raises issues with the balance required between turbine size and backpressure. Axial compressors and compound generator turbines have no such issue; they can efficiently compress air and extract energy, respectively.

An axial compressor (like those in a jet engine) can reach very large pressure ratios by compressing the air over multiple stages of blade rings. Similarly, an exhaust turbine generator (like those in power plants) efficiently extracts energy from hot expanding gas.

The compound turbine turbocharger combines standard centrifugal turbocharger technology with compound turbine technology, allowing for high exhaust energy extraction and greater compression while minimizing backpressure.

This system is part of a larger design project the “Sykora-Ramsey Multi-Cycle Engine.”

Copywrite © 2023 Jacob Sykora and Leo Ramsey.

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The exhaust flows through a compound turbine that starts with a standard centrifugal turbine. From there it flows through a set of stationary (fixed) curved buckets, which reverse the jet against a set of moving blades. This reversal and reimpact can occur several times before the exhaust escapes, allowing the system to extract more exhaust energy with each subsequent set.

The intake air flows through a compressor turbine comprising multiple sets of moving rotors that accelerate the

Exhaust turbine blades Image Source: Wikipedia “compounding steam turbines”

air and press it against static stators. These stators reverse and compress the jet of intake air before finally feeding it into a standard centrifugal turbocharger compressor. The rotors and stators are flat on their angle for effective compression. The final set of stator blades can be oriented to direct airflow axially to avoid the need to redesign the centrifugal compressor to handle a swirling inlet flow.

(Bruffell 853) The turbocharger’s bearing assembly is the standard system and should be adjusted for extending mass on either side. (Bruffell 853) Compressor turbine blades This turbocharging system is as scalable as current turbocharger technology and would provide a significant increase in Diesel engine compression.

Similar concepts have been proposed like the Axial-Radial Turbocharger described in Vol. 99, Section 3: JOURNAL OF ENGINES, Part 1 (1990), which added a single axial fan to the compressor. Another concept the Two-shaft turbocharger, which is detailed in the patent of the same name (US7571607B2), uses axial fans to compound both the intake and exhaust sides but mounts them on a separated internal shaft.

In comparison to these earlier designs, this turbocharger has significantly less complexity than the two-shaft turbocharger, while the axial radial turbocharger is limited to only one axial fan on the compressor side. The axial radial turbocharger was not adopted when it was proposed in 1990, however,

given the push for higher efficiency and lower emissions, compound turbochargers stand to be an important development.

References: •

Bruffell, W. K., et al. “Axial-Radial Turbocharger for Automotive Applications.” SAE Transactions, vol. 99, 1990, pp. 849–57. JSTOR, http://www.jstor.org/stable/44548546.

Accessed 26 Oct. 2023.

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Vrbas, Gary D. Two-Shaft Turbocharger. 11 Aug. 2009.

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Salisbury, J. Kenneth. Kent’s Mechanical Engineers’ Manual. Twelfth ed., John Wiley, and Sons Inc.