A Reduced Order Model for Preliminary Design and Performance Prediction of Radial Turbopumps

2011 ◽  
Author(s):  
Luca d`Agostino ◽  
Angelo Pasini ◽  
Dario Valentini
Keyword(s):  
Performance Prediction ◽  
Reduced Order Model ◽  
Preliminary Design ◽  
Order Model ◽  
Reduced Order ◽  
And Performance

A Reduced-Order Model for the Preliminary Design of Small-Scale Radial Inflow Turbines

2021 ◽  
Author(s):  
Marco Manfredi ◽  
Marco Alberio ◽  
Marco Astolfi ◽  
Andrea Spinelli
Keyword(s):  
Heat Recovery ◽  
Internal Combustion Engines ◽  
Reduced Order Model ◽  
Pollutant Emissions ◽  
Small Scale ◽  
Preliminary Design ◽  
Order Model ◽  
Reduced Order ◽  
Wide Range ◽  
Loss Models

Abstract Power production from waste heat recovery represents an attractive and viable solution to contribute to the reduction of pollutant emissions generated by industrial plants and automotive sector. For transport applications, a promising technology can be identified in bottoming mini-organic Rankine cycles (ORCs), devoted to heat recovery from internal combustion engines (ICE). While commercial ORCs exploiting turbo-expanders in the power range of hundreds kW to several MW are a mature technology, well-established design guidelines are not yet available for turbines targeting small power outputs (below 50 kW). The present work develops a reduced-order model for the preliminary design of mini-ORC radial inflow turbines (RITs) for high-pressure ratio applications, suitable to be integrated in a comprehensive cycle optimization. An exhaustive review of existing loss models, whose development pattern is retraced up to the original approaches, is proposed. This investigation is finalized in a loss models effectiveness analysis performed by testing several correlations over six existing geometries. These test case turbines, operating with different fluids and covering a wide range of target expansion ratio, size, and gross power output, are then employed to carry out the validation procedure, whose results prove the robustness and prediction capability of the proposed reduced-order model.

Closed-loop control of unsteadiness over a rounded backward-facing step

2012 ◽  
Vol 703 ◽  
pp. 326-362 ◽  
Author(s):  
Alexandre Barbagallo ◽  
Gregory Dergham ◽  
Denis Sipp ◽  
Peter J. Schmid ◽  
Jean-Christophe Robinet
Keyword(s):  
Closed Loop ◽  
Random Noise ◽  
Reduced Order Model ◽  
Estimation Accuracy ◽  
Closed Loop Control ◽  
Backward Facing Step ◽  
Order Model ◽  
Loop Control ◽  
Reduced Order ◽  
And Performance

AbstractThe two-dimensional, incompressible flow over a rounded backward-facing step at Reynolds number $\mathit{Re}= 600$ is characterized by a detachment of the flow close to the step followed by a recirculation zone. Even though the flow is globally stable, perturbations are amplified as they are convected along the shear layer, and the presence of upstream random noise renders the flow unsteady, leading to a broadband spectrum of excited frequencies. This paper is aimed at suppressing this unsteadiness using a controller that converts a shear-stress measurement taken from a wall-mounted sensor into a control law that is supplied to an actuator. A comprehensive study of various components of closed-loop control design – covering sensor placement, choice and influence of the cost functional, accuracy of the reduced-order model, compensator stability and performance – shows that successful control of this flow requires a judicious balance between estimation speed and estimation accuracy, and between stability limits and performance requirements. The inherent amplification behaviour of the flow can be reduced by an order of magnitude if the above-mentioned constraints are observed. In particular, to achieve superior controller performance, the estimation sensor should be placed upstream near the actuator to ensure sufficient estimation speed. Also, if high-performance compensators are sought, a very accurate reduced-order model is required, especially for the dynamics between the actuator and the estimation sensor; otherwise, very minute errors even at low energies and high frequencies may render the large-scale compensated linearized simulation unstable. Finally, coupling the linear compensator to nonlinear simulations shows a gradual deterioration in control performance as the amplitude of the noise increases.

Reduced-Order Modeling of Extreme Speed Turbochargers

2021 ◽  
Author(s):  
David W. Fellows ◽  
Daniel J. Bodony ◽  
Ryan C. McGowan
Keyword(s):  
Fluid Dynamic ◽  
Lagrange Equation ◽  
Structural Response ◽  
Numerical Data ◽  
Forced Response ◽  
Reduced Order Model ◽  
Order Model ◽  
Structural Dynamic ◽  
Reduced Order ◽  
And Performance

Abstract In order to improve their efficiency and performance, aircraft intermittent combustion engines often incorporate turbochargers that are adapted from ground-based applications. These turbochargers experience conditions outside of their design operating envelope and are found to experience high-cycle fatigue brought on by aerodynamically-induced blade resonances. The onset of fluid-structural interactions, such as flutter and forced response, in turbochargers at these conditions has not been extensively studied. A reduced-order model of the aeroelastic response of the turbine is developed using the Euler-Lagrange equation informed by numerical data from uncoupled computational fluid dynamic (CFD) and computational structural dynamic (CSD) calculations. The structural response of the reduced-order model is derived from a method of assumed modes approach. The unsteady fluid response is described by a modified version of piston theory as a first step towards including inhomogeneous aerodynamic forcing. Details of the reduced order model are given. The capability of the reduced-order model to predict the presence of flutter from a subset of the uncoupled numerical simulation data is discussed.

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