Recent Radial Turbine Research at the NASA Lewis Research Center

Rohlik, H. E.; Kofskey, M. G.

doi:10.1115/72-gt-42

Cited by 7 publications

(2 citation statements)

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“…As is usually adopted for radial inward turbines, the inlet blade angle β 4g was considered to be 90 • in this application. Concerning instead the inlet absolute flow angle α 4 , in the best efficiency condition, it is substantially a function of the specific speed n s , as shown in [34]. The data reported in [34] have been employed to obtain a numerical correlation [19] used to obtain a first attempt value of the inlet absolute flow angle α 4 , which is successively updated on the basis of the results:…”

Section: Rotor Designmentioning

confidence: 99%

Hybrid Propulsion Efficiency Increment through Exhaust Energy Recovery—Part 1: Radial Turbine Modelling and Design

et al. 2023

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The efficiency of Hybrid Electric Vehicles (HEVs) may be substantially increased if the energy of the exhaust gases, which do not complete the expansion inside the cylinder of the internal combustion engine, is efficiently recovered by means of a properly designed turbogenerator and employed for vehicle propulsion; previous studies, carried out by the same authors of this work, showed a potential hybrid vehicle fuel efficiency increment up to 15% by employing a 20 kW turbine on a 100 HP rated power thermal unit. The innovative thermal unit here proposed is composed of a supercharged engine endowed with a properly designed turbogenerator, which comprises two fundamental elements: an exhaust gas turbine expressly designed and optimized for the application, and a suitable electric generator necessary to convert the recovered energy into electric energy, which can be stored in the on-board energy storage system of the vehicle. In these two parts, the realistic efficiency of the innovative thermal unit for hybrid vehicle is evaluated and compared to a traditional turbocharged engine. In Part 1, the authors present a model for the prediction of the efficiency of a dedicated radial turbine, based on a simple but effective mean-line approach; the same paper also reports a design algorithm, which, owing to some assumptions and approximations, allows a fast determination of the proper turbine geometry for a given design operating condition. It is worth pointing out that, being optimized for quasi-steady power production, the exhaust gas turbine considered is quite different from the ones commonly employed for turbocharging application; for this reason, and in consideration of the required power size, such a turbine is not available on the market, nor has its development been previously carried out in the scientific literature. In the Part 2 paper, a radial turbine geometry is defined for the thermal unit previously calculated, employing the design algorithm described in Part 1; the realistic energetic advantage that could be achieved by the implementation of the turbogenerator on a hybrid propulsion system is evaluated through the performance prediction model under the different operating conditions of the thermal unit. As an overall result, it was estimated that, compared to a reference traditional turbocharged engine, the turbocompound system could gain vehicle efficiency improvement between 3.1% and 17.9%, depending on the output power level, while an average efficiency increment of 10.9% was determined for the whole operating range.

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Section: Rotor Designmentioning

confidence: 99%

Hybrid Propulsion Efficiency Increment through Exhaust Energy Recovery—Part 1: Radial Turbine Modelling and Design

et al. 2023

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“…In this work, three types of nozzle losses were considered: the passage loss, the trailing edge loss, and the post-expansion loss. Among the few available nozzle passage loss formulations, those by Rodgers [46] and Rohlik [67] appear to be the most reliable in the literature [68]. The formulation by Rodgers [46] was preferred since it directly relates the loss to geometry and flow parameters without resorting to the use of the boundary layer parameters, which are less straightforward to estimate.…”

Section: Empirical Models For Losses and Flow Deviationmentioning

confidence: 99%

A methodology for the preliminary design and performance prediction of high-pressure ratio radial-inflow turbines

Meroni

Robertson

Martinez-Botas

et al. 2018

Energy

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The Role of Dense Gas Dynamics on Organic Rankine Cycle Turbine Performance

Wheeler

Ong²

2013

Journal of Engineering for Gas Turbines and Power

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In this paper, we investigate the real gas flows which occur within organic Rankine cycle (ORC) turbines. A new method for the design of nozzles operating with dense gases is discussed, and applied to the case of a high pressure ratio turbine vane. A Navier–Stokes method, which uses equations of states for a variety of working fluids typical of ORC turbines, is then applied to the turbine vanes to determine the vane performance. The results suggest that the choice of working fluid has a significant influence on the turbine efficiency.

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Recent Radial Turbine Research at the NASA Lewis Research Center

Cited by 7 publications

References 0 publications

Hybrid Propulsion Efficiency Increment through Exhaust Energy Recovery—Part 1: Radial Turbine Modelling and Design

Hybrid Propulsion Efficiency Increment through Exhaust Energy Recovery—Part 1: Radial Turbine Modelling and Design

A methodology for the preliminary design and performance prediction of high-pressure ratio radial-inflow turbines

The Role of Dense Gas Dynamics on Organic Rankine Cycle Turbine Performance

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