Turbocharger Turbine Research Articles

Turbocharger turbine map scaling for virtual engine use

Emissions requirements, performance expectations, and expanding range of fuels for off-road engines are broadening engine air system requirements. As part of reducing engine development cost and risk, virtual engine simulation is used to select architecture and components capable of covering a broad range of requirements through low risk changes to the turbocharger turbine. A method is presented for predicting turbine performance changes due to turbine housing area change, the most effective of these low risk changes, from available turbine map data. The method, developed from a mean line model, learns four simplified geometry parameters, three loss coefficients, and two maximum efficiency rotor inlet incidence coefficients from a training turbine map data set, then predicts a scaled turbine map for changes to a simplified geometry parameter associated with housing area. Reduced mass flow RMS errors less than 4.3% and efficiency RMS errors less than 5.2% are expected when generating scaled turbine maps with this method, which is additional 2% error for flow and 3% error for efficiency over that expected when modeling actual turbine map data.

Influence of unsteady stage-interaction on loss generation in regulated two-stage radial turbines at pulsating conditions

Regulated multi-stage turbocharging is a key technology to achieve energy conservation and CO2 emission reduction in internal combustion engine with carbon-free fuel. The understanding of performance of the turbocharging system at the engine conditions is essential for the optimization of engine performance. This paper studies unsteady aerodynamic interaction in regulated two-stage turbocharger turbines at pulsating conditions produced by a heavy-duty diesel engine. Results show that the performance of high-pressure turbine (HPT) is highly sensitive to the unsteady stage-interaction, which is profoundly different from that of the low-pressure turbine (LPT). Specifically, when the bypass valve is opened, the cycle-average efficiency of the HPT declines significantly up to 10.8 % compared with that of closed valve. On the other hand, LPT is slightly influenced by the valve state, and the cycle-average efficiency drops by about 0.2 % when the valve is open. The entropy generation method is used to analyze the unsteady loss in HPT and LPT to unveil the mechanism of the unsteady interaction. Detailed flow analysis shows that the swirling flow result in the evident increase of entropy generation in the HPT and LPT volute. Meanwhile, tip leakage loss and incidence loss of HPT is enhanced by unsteady stage interaction.

Numerical Investigation of the Excitation Characteristics of Contaminated Nozzle Rings

The deposition of combustion residues in the nozzle ring (NR) of a turbocharger turbine stage changes the NR geometry significantly in a random manner. The resultant complex and highly asymmetric geometry induces low engine order (LEO) excitation, which may lead to resonance excitation of rotor blades and high cycle fatigue (HCF) failure. Therefore, a suitable prediction workflow is of great importance for the design and validation phases. The prediction of LEO excitation is, however, computationally expensive as high-fidelity, full annulus CFD models are required. Previous investigations showed that a steady-state computational model consisting of the volute, the NR, and a radial extension is suitable to reduce the computational costs massively and to qualitatively predict the level of LEO forced response. In the current paper, the aerodynamic excitation of 69 real contaminated NRs is analyzed using this simplified approach. The results obtained by the simplified simulation model are used to select 13 contaminated NR geometries, which are then simulated with a model of the entire turbine stage, including the rotor, in a transient time-marching manner to provide high-fidelity simulation results for the verification of the simplified approach. Furthermore, two contamination patterns are analyzed in a more detailed manner regarding their aerodynamic excitation. It is found that the simplified model can be used to identify and classify contamination patterns that lead to high blade vibration amplitudes. In cases where transient effects occurring in the rotor alter the harmonic pressure field significantly, the ability of the simplified approach to predict the LEO excitation is not sufficient.

Comparison between Computational Fluid Dynamics and Fluid-Structure Interaction Models of an Automotive Mixed Flow Turbocharger Turbine

Comparison between Computational Fluid Dynamics and Fluid-Structure Interaction Models of an Automotive Mixed Flow Turbocharger Turbine

An improved model for primary prediction of performance map for turbocharger radial turbine

In the contemporary landscape, possessing an intricate understanding of the performance characteristics of turbocharger radial turbine proves invaluable during engine development phases, to improve predictive capabilities of calculation codes and enhance the critical process of matching engines with turbochargers. This research deals with offering two precise yet straightforward analytical functions intended to generate comprehensive performance maps of turbocharger turbines. This is achieved through a refined adjustment of a preexisting analytical function, after introducing an inventive multiplication factor that aligns numerical calculations with experimental data to predict the turbine’s expansion ratio. Besides, a second analytical function forecasts the turbine’s thermo-mechanical efficiency by establishing a power balance equation between the turbine and supplied compressor map. The outcome of the developed model is compared with existing method on two distinct turbochargers, encompassing various rotational speeds. Additionally, a sensitive analysis aiming to detect the most important factors affecting our developed model while exploring it possible validity range for different thermodynamic parameters. The results indicate that the two functions yield reliable estimations of turbine performance, with maximum; root mean square error, R2, and mean absolute percentage error indices find around 9.47%, 0.993, and 9.03% for the turbine expansion ratio, and about 4.42%, 0.612, and 19.78% for efficiency prediction. This novel model enhances simulation accuracy while preserving user-friendliness and robustness based on the prerequisite of limited geometric and thermodynamic parameters at the turbocharger boundaries. Finally, the main advantages of the proposed model is its adaptability for the implementation in calculation codes, turbomachinery optimization strategies and assessments of the design and performance, addressing scenarios where the original turbine maps are rarely provided by turbocharger manufacturers.

Energy Evaluation of Synthesis Gas in a Turbocharger System Employing CFD Tools

Renewable energy sources derived from biomass, such as synthesis gases, represent an opportunity to take advantage of available waste resources and contribute to global energy rationing. This study developed an analysis with computational fluid dynamics (CFD) to estimate the energy behavior of synthesis gases through a turbocharger system. The synthesis gas used to drive the turbocharger turbine was extracted from the gasification of biomass from the Colombian Caribbean. The application of models for rigid body motion, as well as models of momentum, turbulence, energy, and conservation transport of species, suggest that the energy potential available by the turbine ranges from 0.4 kW to 5.2 kW of power generation, concerning mass flow rates entering the simulated system. The main findings of the study were temperature profiles, speed profiles, rotational speed variation, torque, and mechanical power generated in the turbocharger. It is emphasized that the synthesis gas studied presents a good behavior to generate energy through a turbine system of a turbocharger device.

Особенности комплексного расчета эжекционной системы охлаждения наддувочного воздуха в дизеле

The expediency of increasing the density of fresh charge at the inlet to the cylinder of a diesel engine with a gas turbine boost by using an ejection cooling system after the compressor to circulate cooling air through the cooler is substantiated. The urgency of improving the cooling systems of the charge air is noted in the direction of reducing the cost of power for operation and simplifying the design of their elements. The functional and design features of the elements of the charge air ejection cooling system are considered. The incompleteness of studying the functioning of the ejector at the outlet for intensive circulation of cooling air through the cooler matrix when placing the ejector after the turbocharger turbine is noted. The sequence of calculation of the system in the form of a block diagram is proposed, including a diesel engine, a compressor and a turbocharger turbine, a charge air cooler and an ejector in the exhaust system. The main factors characterizing the relationship between the functional and geometric parameters of the system elements are considered. The features of the complex calculation of the ejection cooling system for charge air in a diesel engine using mathematical modeling of processes in various elements of the system to find reserves and compromise solutions to reduce the cost of power for its operation and increase its efficiency are reflected. The results of the complex calculation of the ejection cooling system of the charge air using numerical modeling are presented graphically in the form of dependences of the parameters of its elements on the degree of pressure reduction in the turbocharger turbine. The analysis of the results of the complex calculation shows that the maximum values of the degree of cooling, charge air density and effective diesel power are achieved at different degrees of pressure reduction in the turbine or ejector. In this regard, it is concluded that it is advisable to choose the required values of the degrees of pressure reduction in the turbine or ejector on a compromise basis when designing an ejection cooling system for charge air.

Precipitation behavior of hexagonal carbides in a C containing intermetallic γ-TiAl based alloy

Intermetallic γ-TiAl based alloys are currently used as structural materials in high-temperature applications such as turbocharger wheels, valves and turbine blades. Adding C yields solid solution and precipitation hardening of the TiAl alloys, which raises their service temperature. Within this work, the effect of C on the TNM alloying system is analyzed by complementary differential scanning calorimetry measurements and selected heat treatments in conjunction with detailed electron microscopy analysis. This allowed the determination of the transition temperatures and revealed the precipitation onset of hexagonal Ti2AlC carbides between 1450 °C and 1475 °C. The precipitation kinetics of the carbides were further investigated by laser scanning confocal microscopy and revealed a preferred and steady growth in the length direction. Further, orientation relationships between the TiAl phases and the carbides from Blackburn and Burgers type could be determined by electron back-scatter diffraction. The results of this study provide a better understanding of the effect of C addition on the TNM alloy and thus enable further improvement of the alloying design process.

A Computationally Efficient Method for the Thermo-Structural Analysis of a Turbocharger Turbine Wheel Under Engine Transient Operation

Abstract The accurate evaluation of thermally-induced stresses is of particular importance for life-cycle analysis of modern turbochargers. Conjugated heat transfer (CHT), steady-state calculations represent the state-of-the-art, whose temperature distribution is usually imported into a structural solver as a thermal load for carrying out thermo-structural analyses. In the case of transient analyses, however, issues arise. Indeed, due to the different timescales of convective and conductive heat-transfer mechanisms, unsteady CHT simulations are burdened by high computational costs. Moreover, in the specific case of turbocharged engines, the timescales of engine load transients and turbocharger response may differ by a factor of up to 105. The present study proposes an approach for carrying out transient thermo-structural analyses of the solid domain only, characterized by a physical time in the order of 101 s, without the need for unsteady fluid flow calculations, which would imply the use of a solver time-step in the order of 10−5 s. In the proposed methodology, the effects of the fluid flow in the heat-transfer process are modeled by imposing adequate boundary conditions to wet surfaces of the solid domain with minimum computational effort. Indeed, by performing two steady-state CHT calculations and one steady-state computational fluid dynamics (CFD) calculation, time-dependent boundary conditions can be derived in terms of convective heat transfer coefficient and near-wall fluid temperature. The case study used for model development is a high-performance turbocharger turbine for automotive applications, responding to engine load transients of tenths of seconds. Initially, steady-state CFD and CHT models of the turbine stage are validated against experimental data. Then, transient analyses on the turbine wheel are carried out, and their results are imported as thermal loads into an unsteady structural solver, allowing for accurate transient thermo-structural analyses at sustainable computational cost.

Operation and Power Generation of a Disk-Shaped Pressure Gain Combustor

The objective of this experimental study is to evaluate the power generation capability of an ethylene–air disk-shaped pressure gain combustor (DPGC). The main content of this paper focuses on discussing the DPGC testing results, consisting of detonation wave dynamics, power generation, and accompanying combustion instabilities. The experiments can be grouped into two stages. In the first stage, the DPGC was tested under atmospheric back condition. Continuous detonation wave dynamics were evaluated among various testing conditions. Evolution of the detonation wave velocity with respect to changes in the equivalence ratio has been discussed. In the second stage of the experiments, the DPGC was tested with a turbocharger installed. Shaft power extracted by the turbocharger turbine from the DPGC exhaust was used as a metric for evaluating the DPGC power output. During the operation of the DPGC and turbocharger, low- and intermediate-frequency combustion instabilities were observed, which coexisted with the high-frequency component associated with the circumferentially propagating detonation wave. The experimental results suggest that the DPGC shows superiority in compactness relative to conventional combustion power systems. However, more improvements need to be made with regard to overall thermal efficiency in order to achieve the benefits from detonation combustion.

CFD Study of the Impacts of a Turbocharger’s Various Wastegate and Bypass Configurations on the Efficiency and the Flow Field of its Radial Turbine

Turbocharger systems enhance the engine power and efficiency, reduce its pollution, and downsize the engine volume. As the significance of exploiting turbochargers in gasoline engines is surging among automobile manufacturers, the necessity of improvement in the system components becomes more critical. This paper investigates the impacts of a turbocharger turbine bypass and wastegate geometry alterations on the performance and the flow field characteristics via numerical simulations. The numerical method verification and mesh independence study are performed for the original geometry. The simulation results of the altered geometries indicate that better alignment between the bypassed and the bulk flows leads to higher efficiency of the turbocharging system. In addition, the bent or elbow-shaped and protruded turbine walls immediately downstream of the wheel are found to be unfavorable. It is also uncovered that if the wastegate shape and the housing walls are designed in such a way that the effects of ensuing vortices are minimized, it improves the stage efficiency, which is desirable for two-stage turbochargers. Furthermore, a novel manufacturable design is proposed in this study, which increases the efficiency and useful power by 19.9% and 6.7%, respectively.

Variable nozzle turbocharger: gas-dynamic calculation, 3D modeling, CFD analysis, characteristics

Introduction (problem statement and relevance). The environmental requirements for vehicle engines becoming more stringent require development and introduction of high-performance turbo chargers. Transition from external to internal varying, namely to the variable nozzles of the turbine, is caused by the necessity to reduce the transient process time during operation of the engine and the vehicle itself.The purpose of the study is development and confi rmation of the methodology (general strategy) for designing and modernization of radial-axial turbines with variable nozzles.Methodology and research methods. The study used the combination of calculation models for the engine itself with preliminary verifi cation based on the results of tests on the engine test bench (AVL BOOST, CRUISE M), gas-dynamic calculation of the turbine stage with determination of geometric parameters of the blade ring, housing (volute) and blade drive mechanism, their geometric modeling (Siemens NX) followed by 3D models export, CFD simulation of the stage fl ow including taking into account the transfer element (with impeller rotation) and generation of the stage curves (AVL FIRE).Scientific novelty and results. Combination (synthesis) of calculation models of different levels makes it possible to determine geometric parameters of the turbocharger turbine with variable nozzles providing high effi ciency (performance factor) of the turbine stage with a simultaneous shift of the maximum torque mode of the engine itself to the area of lower crankshaft rotation rate (along the full-load curve).Practical signifi cance of the paper consists in reduction of the time of design and subsequent refi nement (experimental) works during creation and modernization of turbines with variable nozzles of small-sized turbochargers. The obtained values of relative geometric parameters can be used at the design stage

Numerical Analysis of the Effects of Grooved Stator Vanes in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow

The flow through the stator vanes of a variable geometry turbocharger turbine can reach supersonic conditions and generates a shock wave on the stator vanes, which has a potential impact on the flow loss as well as on unsteady aerodynamic interaction. The shock wave causes a sudden increase in pressure and can lead to boundary separation and strong excitation force, besides pressure fluctuation in the rotor blades. Thus, in this study, the flat surface of the vanes of a commercial variable geometry turbocharger turbine has been modified to analyze the effects of two grooved surfaces configuration using CFD simulations. The results reveal that the grooves change the turbine efficiency, especially at higher speed, where the increase in the efficiency is between 2% and 6% points. Additionally, the load fluctuation around the rotor leading edge can be reduced and minimize the factors that compromise the integrity of the turbine. Furthermore, the grooves reduce the supersonic pocket developed on the suction side of the vane and diminish the shock wake intensity. Evaluating the effectiveness of the available energy usage in the turbine, on the one hand, at lower speed, the fraction of energy at the inlet destinated to produce power does not change significantly with a grooved surface on the stator vanes. On the other hand, at higher speed and higher pressure ratio with 5 grooves occurs the most effective approach of the maximum energy.

Using Machine Learning for Loss Prediction in a Hybrid Meanline Modeling Method to Deliver Improved Radial Turbine Performance Prediction

Abstract Low fidelity modeling approaches remain attractive due to an unrivaled ability to predict full turbine performance maps quickly compared to high-fidelity approaches such as computational fluid dynamics (CFD), especially in the preliminary design process. As improvements in performance on a component level approach a point of diminishing returns, the ability to efficiently optimize the complete charging system for a given duty is a topic attracting significant research interest. In the case of turbocharging applications, existing engine and powertrain simulations require turbine maps to calculate the turbine performance, which are usually obtained from experimental testing. Unfortunately, the need for extrapolation is unavoidable because of the limited range of testing data available, leading to inaccuracies especially at off-design conditions. To enable intensive modeling and optimization of complete vehicle powertrains for different drive cycles, the current piece of work seeks to combine the advantages of machine learning techniques and physical meanline modeling to facilitate faster, more accurate predictions of complete turbocharger maps. This paper presents a novel methodology for turbocharger turbine rotor and nozzle performance prediction based on hybrid modeling. The turbine rotor and nozzle were parameterized to conduct CFD simulations for a wide variety of turbine geometries, which were used to form a database to train an artificial neural network (ANN). The predicted losses provided by the ANN were then utilized in the meanline code, substituting for the conventional empirical loss models. As well as removing the need for empirical loss models, modifications were undertaken to the meanline approach to further enhance modeling accuracy. First, in order to accurately characterize the stage mass flow capacity, the losses occurring in the nozzle and rotor were subdivided into those occurring before and after the throat. A second novel aspect is that the aerodynamic blockage level at the rotor throat was implemented as a variable rather than a constant value. By training the ANN to predict the variation of blockage with geometry and operating condition, a more accurate depiction of the changing secondary flow fields could be achieved. The capabilities of the hybrid meanline modeling method were evaluated on several unseen test cases. The resulting predictions of efficiency and mass flowrate demonstrated strong correlation with CFD results and experimental test results. The hybrid meanline modeling method therefore displays great potential in wide range radial turbine performance prediction with enhanced accuracy in comparison to traditional approaches.

Numerical Analysis of Two-Stage Turbine System for Multicylinder Engine under Pulse Flow Conditions with High Pressure-Ratio Turbine Rotor

Internal combustion engine (ICE) exhaust gases provide a high amount of energy which is partially lost to the environment. Such energy can be recovered with a turbocharger turbine or other after-treatment device. As the engine exhaust flow varies not only with the engine load but also with the opening and closing of the exhaust valves, a proper matching between the engine and the turbine should be established to maximize the recovery of waste energy. That is why a twin-scroll or dual turbocharging system is implemented, especially in multi-cylinder engines. Such systems require a very complex pipeline to eliminate the interference of the exhaust pulses between the adjacent cylinder ignitions. In this study, the two-stage, multi-channel turbine system was investigated for two different rotor geometries: the old, high-performance rotor A and the smaller but more modern rotor B, which was scaled to match rotor A. Both geometries were compared at three different turbine speeds and variable turbine geometry (VTG) vane positions. It was found that the two-stage turbine system with rotor B geometry provided an 8% higher total efficiency than rotor A due to the lower flow losses within the rotor passage.

Characterization and mechanism analysis of interaction between Inconel 713C superalloy and a novel crucible-shell “integrated” mold

A novel crucible-shell “integrated” mold for rapid preparation of supercharged turbines was quantitatively characterized, and the interaction mechanism between refractory and melt was systematically analyzed. The results show that Inconel 713C superalloy is not easy to react with aluminum silicate fiber crucible, and the interaction between them is physical penetration. At the same time, the slag balls in the crucible are easy to peel off into the alloy and form inclusions. The reaction between Inconel 713C superalloy and shell surface material (ZrSiO4) can be divided into Penetration, Stalling/dissolution, Reaction and Diffusion stages. The interface reaction layer is composed of Nb2O5, Al2O3, ZrO2, Cr2O3 and TiO2. The oxide elements produced by the reaction come from the alloy and ceramic shell. Compared with the traditional preparation of turbocharger turbine under discontinuous vacuum, the use of “integrated” mold to prepare turbine under continuous vacuum environment reduces the oxygen, nitrogen and hydrogen content of castings, and the purity of Inconel 713C superalloy is higher and the preparation time is faster, which is conducive to industrial production, which can shed new lights on choosing alternative refractory material for the rapid preparation of high-purity superalloys.

Thermodynamic analysis of power recovery of marine diesel engine under high exhaust backpressure by additional electrically driven compressor

Marine diesel engines can be exposed to high backpressure conditions, because various aftertreatment systems and waste heat recovery devices have been applied to reduce emissions and some exhaust outlets are below sea level. The engine performance deteriorates sharply under high backpressure. This paper aims to study power recovery method under high backpressure based on thermodynamic analysis. Firstly, thermodynamic model is established and validated by experimental data. Next, effects of turbocharger efficiency and turbine area on power recovery are studied. The results show that feasible turbine performance are limitations for power recovery. If energy of compressor can be increased without changing turbine area, limitations can be overcome. Thirdly, additional electrically driven compressor as a solution is proposed to recover engine power. A comparative study of different electrically driven compressor schemes is carried out. The most suitable scheme is the series scheme at low-pressure stage because operating points for original compressor and electrically driven compressor are within a reasonable range. Finally, research on power recovery is carried out on optimal electric compressor scheme. The results show that when backpressure is 0.65 bar, engine net power can be increased by 49.4% and exhaust temperature drops by about 77 K, which largely reduces turbine thermal load.

Aeromechanical Optimization of Scalloping in Mixed Flow Turbines

Abstract Scalloping of radial and mixed-flow turbocharger turbine rotors has been commonplace for many years as a means of inertia reduction and stress relief. The interest in turbine rotor inertia reduction is driven by transient loading requirements of turbocharged internal combustion engines, as this is a key factor in the time taken to meet transient engine torque requirements. Due to the high-density materials used in turbine rotors, any material removal from the turbine wheel has a significant impact on turbocharger inertia, and thus the transient response of the engine. It is well known that scalloping reduces not only inertia, but also efficiency. This study aimed to identify if it was possible to produce a new scallop design which reduced the scalloping efficiency penalty without increasing inertia or compromising mechanical constraints. This was carried out with the aim of developing design recommendations for scalloping where a complete minimization of inertia is not the design goal. A multipoint, multi-physics numerical optimization, with constraints on inertia and back disc stress, was carried out to determine what efficiency benefit could be realized by aerodynamically designing mixed-flow turbine scalloping. An efficiency benefit was identified across the entire turbocharger operating line, with increased benefit at low engine load, whilst not exceeding the design constraints. Scalloping losses for the baseline design were found to be greatest at low engine load, where the turbine experienced a low expansion ratio, mass flow, and speed. This explains why an aerodynamic redesign yields the greatest benefit under those operating conditions. These performance predictions were experimentally validated on the cold flow test rig at Queen's University Belfast, with good agreement between simulated and measured data. To conclude the study, a detailed loss audit was carried out to identify key loss generating flow structures and to understand how changes in geometry affected the formation and development of these flow structures throughout the passage. A large vortex which entered the passage from the scalloped region and interacted with the tip leakage vortex along the suction surface of the blade was identified as the main source of loss due to scalloping. The optimized design was found to better control the location of entry of this vortex into the blade passage, thus reducing the associated loss and facilitating a performance improvement. Geometric design guidelines were then proposed based on these findings.

Laser Powder Bed Fusion of Intermetallic Titanium Aluminide Alloys Using a Novel Process Chamber Heating System: A Study on Feasibility and Microstructural Optimization for Creep Performance

A laser powder bed fusion process operating at elevated temperatures is introduced capable of fabricating crack-free and dense intermetallic titanium aluminide alloy specimens as well as demonstrator components using a base plate heating up to 900 °C and a unique heating system of the uppermost powder bed layer up to 1200 °C. Two so-called 4th generation alloys, TNM and TNM+, were used for this study. The microstructure and its evolution during subsequent heat treatments were investigated and explained by employing scanning electron microscopy, hardness testing, X-ray diffraction, differential scanning calorimetry and thermodynamic equilibrium calculation. Selected specimens were subjected to creep tests at 750 °C. The microstructures after processing consist of extraordinarily fine lamellar γ-TiAl/α2-Ti3Al-colonies with globular γ and βo-TiAl grains for both the TNM and TNM+ alloy, exhibiting a microstructure gradient from the last consolidated powder layer down to the starting layer due to cellular reaction, which increases the amount of globular γ and βo at the boundaries of the γ/α2-colonies. During annealing in proximity to the γ-solvus temperature, banded microstructures might form, as the α-grain size is only partially controlled by heterogeneously distributed γ/β-phase, which stems from the process-related Al loss. Additionally, the occurrence of thermally-induced porosity is investigated. Optimizing the microstructure to a homogenized, almost fully lamellar microstructure, involved annealing in the β-single phase field region and led to improved creep properties. Finally, TNM demonstrator components with complex geometries, such as aero engine blades and turbocharger turbine wheels, are fabricated by employing the novel laser powder bed fusion process.

Research on exhaust energy distribution regulation for fuel economy improvement of turbocompound diesel engine

The stringent requirements for reducing CO2 emissions from internal combustion engines promote the development of waste heat recovery (WHR) technologies. Turbocompounding is a promising WHR technology offering fuel-saving potential along with low volume and weight requirements. Meanwhile, the exhaust energy distribution regulation plays a significant role in improving the engine fuel economy. In this study, the coupling influence and mechanism of the variable geometry turbocharger (VGT) turbine and power turbine (PT) regulation on the recovery power and engine performance were studied from novel perspective of exhaust energy distribution. And the cooperative control strategies of VGT rack position and PT speed under whole operating conditions were first proposed. It is concluded that the increase in the VGT rack position and the PT speed leads to a decrease in the proportion of exhaust energy distributed to the VGT turbine, which affects the intake and exhaust conditions, resulting in changes in PT power and net engine output power. In addition, as the engine speed increases under full load, the optimal VGT rack position and PT speed increase. Compared to the base engine, the equivalent brake specific fuel consumption can be reduced by 3.8% at the engine speed of 2200 r/min with the optimized control of the exhaust energy distribution for the turbocompounding. The control strategy of exhaust energy distribution is of great significance to explore the maximum potential of energy efficiency improvement of turbocompound diesel engines.