Condensation in Radial Turbines—Part I: Mathematical Modeling

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Sebastian Schuster ◽  
Dieter Brillert ◽  
Friedrich-Karl Benra
Keyword(s):  
Waste Heat ◽  
Saturation Temperature ◽  
Steam Temperature ◽  
Radial Turbine ◽  
Liquid Film Flow ◽  
Quantitative Analyses ◽  
Computational Fluid Dynamics Cfd ◽  
Droplet Liquid ◽  
Radial Turbines ◽  
Turbine Impeller

In this two-part paper, the investigation of condensation in the impeller of radial turbines is discussed. In Paper I, a solution strategy for the investigation of condensation in radial turbines using computational fluid dynamics (CFD) methods is presented. In Paper II, the investigation methodology is applied to a radial turbine type series that is used for waste heat recovery. First, the basic CFD approach for the calculation of the gas-droplet-liquid-film flow is introduced. Thereafter, the equations connecting the subparts are explained and a validation of the models is performed. Finally, in Paper I, condensation phenomena for a selected radial turbine impeller are discussed on a qualitative basis. Paper II continues with a detailed quantitative analyses. The aim of Paper I is to explain the models that are necessary to study condensation in radial turbines and to validate the implementation against available experiments conducted on isolated effects. This study aims to develop a procedure that is applicable for investigation of condensation in radial turbines. Furthermore, the main processes occurring in a radial turbine once the steam temperature is below the saturation temperature are explained and analyzed.

Condensation in Radial Turbines—Part II: Application of the Mathematical Model to a Radial Turbine Series

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Sebastian Schuster ◽  
Dieter Brillert ◽  
Friedrich-Karl Benra
Keyword(s):  
Waste Heat ◽  
Liquid Films ◽  
Condensation Process ◽  
Droplet Deposition ◽  
Impeller Blade ◽  
Radial Turbine ◽  
Condensing Flows ◽  
The Mathematical Model ◽  
Radial Turbines ◽  
Turbine Impeller

In the second part of this two part paper, the condensation process and the movement of the liquid phase near the impeller blades of a radial turbine are studied. The investigation methodology presented in part 1 is applied to a radial turbine type series used for waste heat recovery. First, the subcooling necessary for the beginning of the condensation process is examined and a relationship between the location of maximum subcooling and the onset of droplet deposition at the surfaces of the turbine impeller is determined. Thereafter, the movement of liquid films on the impeller blades is analysed and characterized. Correlations determining the movement of droplets originating from liquid film atomization on the edge of the impeller blade along the casing are derived. Finally, conclusions are drawn depicting the most important findings of condensing flows in radial turbines.

The Feasibility of Using an Air Turbine to Drive an Afterburner Fuel Pump

2003 ◽  
Author(s):  
N. E. Backus ◽  
K. W. Ramsden ◽  
M. K. Yates ◽  
P. Laskaridis ◽  
P. Pilidis
Keyword(s):  
Mass Flow ◽  
Engine Speed ◽  
Performance Data ◽  
Fuel Pump ◽  
Radial Turbine ◽  
Air Turbine ◽  
Fixed Proportion ◽  
Mass Flows ◽  
Electric Engine ◽  
Radial Turbines

Current fighter engine designs extract power to drive the afterburner fuel pump through the use of a gearbox. The presence of the gearbox only allows the fuel pump to operate at a fixed proportion of engine speed. In addition the fuel pump is continually rotating, although not pumping fuel, even when the afterburner is not engaged. This article investigates the feasibility of using an air turbine to drive the afterburner fuel pump in preparation for supporting an all-electric engine. Utilising performance data for a typical modern military engine, 1-dimensional design techniques were used to design several radial turbines to power the afterburner fuel pump. A choice of an axial or a radial air turbine is possible. Both were reviewed and it was determined that a radial turbine is optimum based on manufacturability and (theoretical) efficiency. Several design iterations were completed to determine the estimated weight and size based on various air off-take locations, mass flows, and rotational speeds. These iterations showed that increasing mass flow allows for lower rotational speeds and/or smaller diameter rotors, but with a corresponding increases in thrust penalties.

Modeling of Buoyancy-Driven Natural Ventilation in Workshop: Optimization of Distance between Heat Source and Ground

2012 ◽  
Vol 170-173 ◽  
pp. 2579-2582 ◽  
Author(s):  
Ya Xin Su ◽  
A Long Su ◽  
Xin Wan
Keyword(s):  
Heat Source ◽  
Indoor Air ◽  
Energy Cost ◽  
Lower Energy ◽  
Natural Ventilation ◽  
Waste Heat ◽  
Heat Sources ◽  
Hot Air ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

Natural ventilation is suitable for application to workshops with heat sources to keep good indoor air quality at lower energy cost. In this paper, the authors numerically investigated the buoyancy-driven natural ventilation in a workshop with heat source based on computational fluid dynamics (CFD) method. The effect of the distance between heat source and ground on the air flow and temperature distribution was examined. Results showed that the average air temperature at operation zone could be effectively reduced when the distance between heat source and ground increased. The temperature field in the upper zone of the workshop was improved by diminishing the hot air zone near the ceiling and the waste heat directly going into the operation zone decreased when the distance between heat source and ground increased.

scholarly journals Optimization of Radial Impulse Turbine for Oscillating Water Column Wave Renewable Energy

2019 ◽  
Vol 8 (12) ◽  
pp. 5699-5703
Keyword(s):  
Water Column ◽  
Oscillating Water Column ◽  
Peak Efficiency ◽  
Impulse Turbine ◽  
Trapped Air ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Radial Turbine ◽  
Wide Range ◽  
Computational Fluid Dynamics Cfd

An oscillating water column (OWC) extracts the power of waves by trapping air above a water column. This trapped air is compressed and decompressed by the wave action flow inside a turbine power to the mechanical power during process, and it is important as the turbines are expected to operate in oscillating and reversing flows over a wide range of conditions. The objectives of this study are to determine and analyze the type of radial impulse turbine of OWC and to optimize the performance of a radial impulse turbine for OWC by using Computational Fluid Dynamics (CFD). This requires a comprehensive investigation on turbine configuration, turbine efficiency, OWC integration, and turbine operation with respect to climate condition. The outcome of this study to settle the main drawbacks of radial turbine namely lower peak efficiency and damping on OWC can be considered. Later, these problems will be further study to identify the behavior of the airflow through the machine, sources of energy loss, and impact of different parameters on the turbine performance.

Investigation on the Degree of Reaction in Twin Scroll Radial Turbines at Different Operating Conditions for Turbocharging Applications

2019 ◽  
Author(s):  
Carlo Cravero ◽  
Davide De Domenico ◽  
Andrea Ottonello
Keyword(s):  
High Performance ◽  
Mean Value ◽  
Operating Conditions ◽  
Axial Thrust ◽  
Degree Of Reaction ◽  
Radial Turbine ◽  
Wide Range ◽  
Partial Admission ◽  
Rotor Losses ◽  
Radial Turbines

Abstract Frequently in turbocharging radial turbine studies, some assumptions have to be done in order to make 1D matching calculations as easy as possible and to develop simulation approaches that can be useful for different purposes, like axial thrust prediction. One of these assumptions concerns the degree of reaction, which is often considered constant and equal to the value 0.5. In standard radial turbines design the velocity triangles are set by the target to keep a mean degree of reaction of 50%, in order to obtain low rotor losses and to minimize the exit swirl to get lower losses in the exhaust diffuser. From the experience gained on radial turbines operating in a wide range of conditions, it is evident that: the degree of reaction presents large variations along a given isospeed (especially at low rotational speed) and the mean value is far from 0.5 (particularly true in high performance applications). In the present work a method for the representation of the degree of reaction for radial turbine is suggested. The approach has been developed onto a twin scroll radial turbine for turbocharging, considering a large dataset of operating conditions (at both equal and partial admission). The discussion and the method suggested are based on a rich database from experimental data and numerical simulations developed by the authors on the 3D configuration of the turbines under investigation.

scholarly journals Radial Turbine Thermo-Mechanical Stress Optimization by Multidisciplinary Discrete Adjoint Method

2020 ◽  
Vol 5 (4) ◽  
pp. 30
Author(s):  
Alberto Racca ◽  
Tom Verstraete ◽  
Lorenzo Casalino
Keyword(s):  
Thermal Stresses ◽  
Efficient Computation ◽  
Radial Turbine ◽  
Discrete Adjoint ◽  
Design Variables ◽  
Back Plate ◽  
Stress Optimization ◽  
Computationally Intensive ◽  
The Cost ◽  
Turbine Impeller

This paper addresses the problem of the design optimization of turbomachinery components under thermo-mechanical constraints, with focus on a radial turbine impeller for turbocharger applications. Typically, turbine components operate at high temperatures and are exposed to important thermal gradients, leading to thermal stresses. Dealing with such structural requirements necessitates the optimization algorithms to operate a coupling between fluid and structural solvers that is computationally intensive. To reduce the cost during the optimization, a novel multiphysics gradient-based approach is developed in this work, integrating a Conjugate Heat Transfer procedure by means of a partitioned coupling technique. The discrete adjoint framework allows for the efficient computation of the gradients of the thermo-mechanical constraint with respect to a large number of design variables. The contribution of the thermal strains to the sensitivities of the cost function extends the multidisciplinary outlook of the optimization and the accuracy of its predictions, with the aim of reducing the empirical safety factors applied to the design process. Finally, a turbine impeller is analyzed in a demanding operative condition and the gradient information results in a perturbation of the grid coordinates, reducing the stresses at the rotor back-plate, as a demonstration of the suitability of the presented method.

scholarly journals A Robust Adiabatic Model for a Quasi-Steady Prediction of Far-Off Non-Measured Performance in Vaneless Twin-Entry or Dual-Volute Radial Turbines

2020 ◽  
Vol 10 (6) ◽  
pp. 1955
Author(s):  
José Ramón Serrano ◽  
Francisco J. Arnau ◽  
Luis Miguel García-Cuevas ◽  
Vishnu Samala
Keyword(s):  
Mass Flow ◽  
Performance Parameters ◽  
Flow Conditions ◽  
Fitting Procedure ◽  
Radial Turbine ◽  
Novel Approach ◽  
Proposed Model ◽  
Double Entry ◽  
Radial Turbines ◽  
Fitting Parameters

The current investigation describes in detail a mass flow oriented model for extrapolation of reduced mass flow and adiabatic efficiency of double entry radial inflow turbines under any unequal and partial flow admission conditions. The model is based on a novel approach, which proposes assimilating double entry turbines to two variable geometry turbines (VGTs) using the mass flow ratio ( MFR ) between the two entries as the discriminating parameter. With such an innovative approach, the model can extrapolate performance parameters to non-measured MFR s, blade-to-jet speed ratios, and reduced speeds. Therefore, the model can be used in a quasi-steady method for predicting double entry turbines performance instantaneously. The model was validated against a dataset from two different double entry turbine types: a twin-entry symmetrical turbine and a dual-volute asymmetrical turbine. Both were tested under steady flow conditions. The proposed model showed accurate results and a coherent set of fitting parameters with physical meaning, as discussed in this paper. The obtained parameters showed very similar figures for the aforementioned turbine types, which allows concluding that they are an adequate set of values for initializing the fitting procedure of any type of double entry radial turbine.

Design and Analysis of Radial Turbine for Turbocharger Application

2017 ◽  
Author(s):  
Bharathan Raghavan Desikan ◽  
David John Rajendran ◽  
Sharad Kapil ◽  
Seepana Venkata Ramana Murty ◽  
Deshkulkarni Kishore Prasad
Keyword(s):  
Kinetic Energy ◽  
Internal Combustion Engines ◽  
Low Cost ◽  
Navier Stokes ◽  
Combustion Engines ◽  
Customer Requirements ◽  
Turbine Wheel ◽  
Radial Turbine ◽  
Ansys Cfx ◽  
Radial Turbines

Turbochargers are used in internal combustion engines to increase their volumetric efficiency and power. Turbochargers consist of a centrifugal compressor driven by a radial turbine. Radial turbines convert the excess kinetic energy in the exhaust gases to power. Vane less radial turbine consists of a volute and a turbine wheel. It is preferred because of its low cost, robustness and good off-design performance. In this study, a radial turbine wheel and volute are designed to meet the power and efficiency requirements. A number of trials are carried out, and the design, which gives the necessary performance and meets the customer requirements, is chosen. The design is analyzed using a validated 3D Navier-Stokes (NS) solver, viz. ANSYS-CFX software at both design and off-design conditions and turbine characteristics are generated.

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