Showing papers on "Turbofan published in 2017"
TL;DR: In this paper, the authors describe a numerical reproduction of the 22-in source diagnostic test fan rig of the NASA Glenn Research Center and perform numerical flow simulations for three different rotor configurations.
Abstract: The present work describes a numerical reproduction of the 22-in source diagnostic test fan rig of the NASA Glenn Research Center. Numerical flow simulations are performed for three different rotor...
123 citations
TL;DR: In this article, a measurement campaign has been performed on a Snecma/NPO Saturn SaM146-1S17 turbofan, where radial and angular profiles of particulate matter (PM) properties in the engine exhaust hot flow were measured.
50 citations
10 Jul 2017
TL;DR: In this paper, the design process for the control system of an advanced geared turbofan engine is described and applied to a simulation that is representative of a 30,000 lbf thrust class concept engine with two main spools, ultra-high bypass ratio, and variable area fan nozzle.
Abstract: This paper describes the design process for the control system of an advanced geared turbofan engine. This process is applied to a simulation that is representative of a 30,000 lbf thrust class concept engine with two main spools, ultra-high bypass ratio, and a variable area fan nozzle. Control system requirements constrain the non-linear engine model as it operates throughout its flight envelope of sea level to 40,000 ft and from 0 to 0.8 Mach. The control architecture selected for this project was developed from literature and reflects a configuration that utilizes a proportional integral controller integrated with sets of limiters that enable the engine to operate safely throughout its flight envelope. Simulation results show the overall system meets performance requirements without exceeding system operational limits.
45 citations
TL;DR: In this article, a new lifecycle real-time model to describe turbofan engine dynamic behavior called Adaptive Linear Parameter Varying Model (ALPVM) is proposed, and the issues of engine/model mismatch compensation and performance degradation adaptation are focused on.
39 citations
10 Jul 2017
TL;DR: In this paper, the authors proposed electric drive specific power, electric drive efficiency, and electrical propulsion fraction as the key performance parameters for a partially turboelectric aircraft power system and investigated their impact on the overall aircraft performance.
Abstract: The purpose of this paper is to propose electric drive specific power, electric drive efficiency, and electrical propulsion fraction as the key performance parameters for a partially turboelectric aircraft power system and to investigate their impact on the overall aircraft performance. Breguet range equations for a base conventional turbofan aircraft and a partially turboelectric aircraft are found. The benefits and costs that may result from the partially turboelectric system are enumerated. A break even analysis is conducted to find the minimum allowable electric drive specific power and efficiency, for a given electrical propulsion fraction, that can preserve the range, fuel weight, operating empty weight, and payload weight of the conventional aircraft. Current and future power system performance is compared to the required performance to determine the potential benefit.
27 citations
TL;DR: An adaptive model predictive controller with a new scheduling scheme for turbofan engines is proposed, which can transfer engine from one working state to the others within the flight envelope, which provides an effective approach for the design of the adaptive controllers.
Abstract: An adaptive model predictive controller with a new scheduling scheme for turbofan engines is proposed, which can transfer engine from one working state to the others within the flight envelope. First, the flight envelope is divided into several sections according to the engine inlet parameters, and the nominal points in each section are determined, respectively. Then, considering the requirements of the turbofan engines, a constrained linear model predictive control algorithm is improved, and a series of constrained predictive controllers are designed based on the linear models at different nominal points. Furthermore, a novel scheduling scheme with two layers is constructed, where the first layer is the flight envelope scheduling layer that introduces fuzzy membership degree logic to distribute the weights of all nominal predictive controllers, and the second layer is the power scheduling layer by adopting a linear interpolation method. Simulation results show that the proposed scheduling scheme can coordinate these two layers to realize the steady-state and transition-state control of the turbofan engines at off-nominal points within the envelope, which provides an effective approach for the design of the adaptive controllers.
25 citations
TL;DR: In this article, the authors determined particulate matter (PM) emissions in the exhaust plumes from two gas turbine aircraft engines: a CF34-3A1 turbofan engine and a TPE331-6-252B turboprop engine.
25 citations
TL;DR: In this article, structural and unstructured grids were generated to perform Reynolds Averaged Navier-Stokes computations aimed at analyzing the baseline flow without control and determining relevant location and settings for active flow control systems.
23 citations
TL;DR: This paper presents a full one-dimensional core and fan flowpath turbofan optimization model, based on first principles, and meant to be used during aircraft conceptual design optimization, formulated as a signomial program.
Abstract: This paper presents a full one-dimensional core and fan flowpath turbofan optimization model, based on first principles, and meant to be used during aircraft conceptual design optimization. The mod...
20 citations
TL;DR: In this paper, the performance of a low-bypass ratio turbofan engine with variable guide vanes (VGVs) and bleed air was evaluated with a 0D/1D modeling approach.
19 citations
01 Jan 2017
TL;DR: In this article, the authors propose a set of theoretical models to predict, during the conceptual design phase, the sound emitted by the fan stage of an aero-engine, covering a range of discipilnes that span between aerodynamics and acoustics.
Abstract: This thesis proposes a set of theoretical models to predict, during the conceptual design Phase, the sound emitted by the fan stage of an aero-engine. The models are analytical or semi-analytical, and cover a range of discipilnes that span between aerodynamics and acoustics. Various fan architectures, such as the conventional ducted turbofan, the ducted contra-rotating fan and the contra-rotating open Rotors, are addressed on a common basis.
This thesis presents the theoretical fundament of the fan noise prediction program PropNoise.
TL;DR: In this article, a high pressure turbine blade in a military turbofan engine was investigated to determine the root cause of failure, and the authors found that the loss of coating and the presence of heavily oxidized intergranular fracture features including substrate material aging and airfoil curling in the trailing edge of a representative blade indicate that the coating is not providing adequate oxidation protection.
Abstract: Abstract Failure of a high pressure (HP) turbine blade in a military turbofan engine is investigated to determine the root cause of failure. Forensic and metallurgical investigations are carried out on the affected blades. The loss of coating and the presence of heavily oxidized intergranular fracture features including substrate material aging and airfoil curling in the trailing edge of a representative blade indicate that the coating is not providing adequate oxidation protection and the blade material substrate is not suitable for the application at hand. Coating spallation followed by substrate oxidation and aging leading to intergranular cracking and localized trailing edge curling is the root cause of the blade failure. The remaining portion of the blade fracture surface showed ductile overload features in the final failure. The damage observed in downstream components is due to secondary effects.
TL;DR: In this paper, a means for aircraft propulsion using electroaerodynamic thrust has been proposed, potentially enabling near-silent and solid-state flight, and the authors have experimentally quantified electroaerodymyric energy.
Abstract: Electroaerodynamic thrust has been proposed as a means for aircraft propulsion, potentially enabling near-silent and solid-state flight. Studies to date have experimentally quantified electroaerody...
28 May 2017
TL;DR: A real-time optimization control method to enhance engine thrust response and enlarge its maximum thrust during emergent flight is proposed, and the on-board engine predictive model is devised by a multi-input multi-output recursive reduced least squares support vector regression method.
Abstract: A real-time optimization control method is proposed to enhance engine thrust response and enlarge its maximum thrust during emergent flight This real-time optimization control is model based, and
TL;DR: In the past decade, aircraft fuel burn has been continually decreased, mainly by improving thermal and propulsion efficiencies with consequent decrement in specific fuel consumption as discussed by the authors, mainly by reducing fuel consumption of aircraft.
20 Sep 2017
TL;DR: In this article, the effect of the air-inlet distortion on the fan-tip region is investigated and the authors show that the effect is mainly concentrated in the fan tip region, leading to a strong variation of fan-blade unsteady loading.
Abstract: New ultra high bypass ratio architectures may significantly affect the fan tonal noise of future aircraft engines. Indeed, such a noise source is supposed to be dominated by the interaction of fan-blade wakes with outlet guide vanes. However, shorter nacelles in these engines are expected to trigger an important air-inlet distortion that can be responsible for new acoustic sources on the fan blades. Full annulus simulations based on the unsteady Reynolds-averaged Navier–Stokes equations are presently used to study this effect. Simulation results show that the air-inlet distortion has a main effect in the fan-tip region, leading to a strong variation of the fan-blade unsteady loading. It also significantly modifies the shape of the fan-blade wakes and, consequently, the unsteady loading of the outlet guide vanes. Acoustic predictions based on the extension of Goldstein’s analogy to an annular duct in a uniform axial flow are presented and show that the fan sources notably contribute to the fan tonal noise. The air-inlet distortion is responsible for an increase of the noise radiated by both the fan and the outlet guide vane sources, leading to a global noise penalty of up to three decibels.
TL;DR: In this paper, the flow details from a vane-based distortion generator were analized for non-uniform flow ingestion by turbofan engines, and the results showed that the resulting flow details can account for nonuniform flows ingested by engines.
Abstract: Engine/airframe integration in advanced aircraft concepts must account for nonuniform flows ingested by turbofan engines. In this work, flow details from a vane-based distortion generator were anal...
01 Feb 2017
TL;DR: In this article, a split-flow method for the streamline solver, alternative to the publicly available analysis-oriented method, is implemented and initially compared with two-dimensional axisymmetric computational fluid dynamics on two representative geometries for high and low bypass ratios.
Abstract: The two-dimensional through-flow modeling of turbomachinery is still one of the most powerful tools available to the turbomachinery industry for aerodynamic design, analysis, and post-processing of test data due to its robustness and speed. Although variety of aspects of such a modeling approach are discussed in the publicly available literature for compressors and turbines, not much emphasis is placed on combined modeling of the fan and the downstream splitter of turbofan engines. The current article addresses this void by presenting a streamline curvature through-flow methodology that is suitable for inverse design for such a problem. A new split-flow method for the streamline solver, alternative to the publicly available analysis-oriented method, is implemented and initially compared with two-dimensional axisymmetric computational fluid dynamics on two representative geometries for high and low bypass ratios. The empirical models for incidence, deviation, loss, and end-wall blockage are compiled from t...
05 Jun 2017
TL;DR: This paper discusses characteristic multi-disciplinary issues related to quiet short take-off and landing for civil transport aircraft with a typical short to medium range mission and a range of technology projects that aim at significant noise reductions and at the generation of e�cffient and flexible high lift.
Abstract: This paper discusses characteristic multi-disciplinary issues related to quiet short take-off and landing for civil transport aircraft with a typical short to medium range mission. The work reported here is focussing on the noise aspects and is embedded in the collaborative research centre CRC880 in Braunschweig, Germany. This long term aircraft Research initiative focusses on a new transport aircraft segment for operation on airports with shorter
runway length in commercial air transport. This calls for a community-friendly aircraft designed for operations much closer to the home of its passengers than today. This Scenario sets challenging, seemingly contradictory aircraft technology requirements, namely those for extreme lift augmentation at low noise. The Research Centre CRC880 has therefore devised a range of technology projects that aim at significant noise reductions and at the generation of e�cffient and flexible high lift. The research also addresses
flight Dynamics of aircraft at takeoff and landing. It is envisaged that in general significant noise reduction -compared to a reference turbofan driven aircraft of year 2000 technology- necessarily requires component noise
reduction in combination with a low noise a/c concept. Results are presented from all the acoustics related projects of CRC880 which cover the aeroacoustic simulation of the source noise reduction by flow permeable materials, the characterization, development, manufacturing and operation of (porous) materials especially tailored to aeroacoustics, new UHBR
turbofan arrangements for minimum exterior noise due to acoustic shielding as well as the
prediction of jet noise vibration excitation of cabin noise by UHBR engines compared to conventional turbofans at cruise.
17 Aug 2017
TL;DR: In this article, a pulse detonation combustion (PDC) model integrated within Chalmers University's s gas turbine simulation tool GESTPA N is proposed to support the development of novel aircraft engine architectures exploiting the synergies between intercooling, aftercooling and PDC.
Abstract: This paper proposes a pulse detonation combustion (PDC) model integrated within Chalmers University' s gas turbine simulation tool GESTPA N (GEneral Stationary and Transient Propulsion ANalsysis). The model will support the development of novel aircraft engine architectures exploiting the synergies between intercooling, aftercooling and PDC. The proposed engine architectures are based on a reference high bypass ratio geared-turbofan engine model with performance levels estimated to be available by year 2050. Parametric studies have been carried out for each proposed advanced architecture, providing engine cycle mid-cruise design point parameters. Design sensitivity studies related to intercooling technology in combination with a PDC are further explored for a number of heat-exchanger design effectiveness values and associated pressure loss levels. The acquired results suggest that the incorporation of PDC technology within a conventional core has the potential to significantly improve engine thermal efficiency. Incorporating intercooling improves the cycle performance for any pre-combustion OPR above 10 and contributes to an increase in specific power over the entire range of OPR. Finally, the results demonstrate that aftercooling the high pressure compressor delivery air further improves core specific power, but cancels out any SFC and thermal efficiency benefits arising from pulse detonation.
TL;DR: In this paper, the authors presented a diffusion blade profiles for designing a fan rotor with an ultra-low rotating speed, which is characterized by large cambers and convergent blade passages in their rear parts.
Dissertation•
06 Jul 2017
TL;DR: In this paper, the effects of inlet distortion on aerodynamic properties of a UHBR engine were investigated using full-annulus simulations of the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations.
Abstract: Fuel consumption and noise reduction trigger the evolution of aircraft engines towards Ultra High Bypass Ratio (UHBR) architectures. Their short air inlet design and the reduction of their interstage length lead to an increased circumferential inhomogeneity of the flow close to the fan. This inhomogeneity, called distortion, may have an impact on the tonal noise radiated from the fan module. Usually, such a noise source is supposed to be dominated by the interaction of fan-blade wakes with Outlet Guide Vanes (OGVs). At transonic tip speeds, the noise generated by the shocks and the steady loading on the blades also appears to be significant. The increased distortion may be responsible for new acoustic sources while interacting with the fan blades and the present work aims at evaluating their contribution. The effects of distortion on the other noise mechanisms are also investigated. The work is based on full-annulus simulations of the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations. A whole fan module including the inlet duct, the fan and the Inlet and Outlet Guide Vanes (IGVs/OGVs) is studied. The OGV row is typical of current engine architecture with an integrated pylon and two different air inlet ducts are compared in order to isolate the effects of inlet distortion. The first one is axisymmetric and does not produce any distortion while the other one is asymmetric and produces a level of distortion typical of the ones expected in UHBR engines. A description and a quantification of the distortion that is caused by both the potential effect of the OGVs and the inlet asymmetry are proposed. The effects of the distortion on aerodynamics are highlighted with significant modifications of the fanblade wakes, the shocks and the unsteady loading on the blades and on the vanes. Both direct and hybrid acoustic predictions are provided and highlight the contribution of the fan-blade sources to the upstream noise. The downstream noise is still dominated by the OGV sources but it is shown to be significantly impacted by the inlet distortion via the modification of the impinging wakes.
TL;DR: In this article, a novel Hammerstein-Wiener representation of engine models is introduced, and a nonlinear generalized minimum variance type of optimal control law is derived, the feature of the proposed approach is that it does not require the inversion operation that usually upsets those nonlinear control techniques.
Abstract: Acceleration control of turbofan engines is conventionally designed through either schedule-based or acceleration-based approach. With the widespread acceptance of model-based design in aviation industry, it becomes necessary to investigate the issues associated with model-based design for acceleration control. In this paper, the challenges for implementing model-based acceleration control are explained; a novel Hammerstein-Wiener representation of engine models is introduced; based on the Hammerstein-Wiener model, a nonlinear generalized minimum variance type of optimal control law is derived; the feature of the proposed approach is that it does not require the inversion operation that usually upsets those nonlinear control techniques. The effectiveness of the proposed control design method is validated through a detailed numerical study.
26 Jun 2017
TL;DR: In this paper, the authors applied a computational tool for the flow analysis of the turbine engine that has been tested with ice crystal ingestion in the Propulsion Systems Laboratory (PSL) at NASA Glenn Research Center.
Abstract: The main focus of this study is to apply a computational tool for the flow analysis of the turbine engine that has been tested with ice crystal ingestion in the Propulsion Systems Laboratory (PSL) at NASA Glenn Research Center. The PSL has been used to test a highly instrumented Honeywell ALF502R-5A (LF11) turbofan engine at simulated altitude operating conditions. Test data analysis with an engine cycle code and a compressor flow code was conducted to determine the values of key icing parameters, that can indicate the risk of ice accretion, which can lead to engine rollback (un-commanded loss of engine thrust). The full engine aerothermodynamic performance was modeled with the Honeywell Customer Deck specifically created for the ALF502R-5A engine. The mean-line compressor flow analysis code, which includes a code that models the state of the ice crystal, was used to model the air flow through the fan-core and low pressure compressor. The results of the compressor flow analyses included calculations of the ice-water flow rate to air flow rate ratio (IWAR), the local static wet bulb temperature, and the particle melt ratio throughout the flow field. It was found that the assumed particle size had a large effect on the particle melt ratio, and on the local wet bulb temperature. In this study the particle size was varied parametrically to produce a non-zero calculated melt ratio in the exit guide vane (EGV) region of the low pressure compressor (LPC) for the data points that experienced a growth of blockage there, and a subsequent engine called rollback (CRB). At data points where the engine experienced a CRB having the lowest wet bulb temperature of 492 degrees Rankine at the EGV trailing edge, the smallest particle size that produced a non-zero melt ratio (between 3 percent - 4 percent) was on the order of 1 micron. This value of melt ratio was utilized as the target for all other subsequent data points analyzed, while the particle size was varied from 1 micron - 9.5 microns to achieve the target melt ratio. For data points that did not experience a CRB which had static wet bulb temperatures in the EGV region below 492 degrees Rankine, a non-zero melt ratio could not be achieved even with a 1 micron ice particle size. The highest value of static wet bulb temperature for data points that experienced engine CRB was 498 degrees Rankine with a particle size of 9.5 microns. Based on this study of the LF11 engine test data, the range of static wet bulb temperature at the EGV exit for engine CRB was in the narrow range of 492 degrees Rankine - 498 degrees Rankine , while the minimum value of IWAR was 0.002. The rate of blockage growth due to ice accretion and boundary layer growth was estimated by scaling from a known blockage growth rate that was determined in a previous study. These results obtained from the LF11 engine analysis formed the basis of a unique “icing wedge.”
10 Jul 2017
TL;DR: In this paper, a control system designed specifically for issues associated with shape memory alloy (SMA)-actuated VAFN is described and a dynamic analysis of the geared turbofan with the SMA actuators is performed.
Abstract: Aggressive design goals have been set for future aero-propulsion systems with regards to fuel economy, noise, and emissions. To meet these challenging goals, advanced propulsion concepts are being explored and current operating margins are being re-evaluated to find additional concessions that can be made. One advanced propulsion concept being evaluated is a geared turbofan with a variable area fan nozzle (VAFN), developed by NASA. This engine features a small core, a fan driven by the low pressure turbine through a reduction gearbox, and a shape memory alloy (SMA)-actuated VAFN. The VAFN is designed to allow both a small exit area for efficient operation at cruise, while being able to open wider at high power conditions to reduce backpressure on the fan and ensure a safe level of stall margin is maintained. The VAFN is actuated via a SMA-based system instead of a conventional system to decrease overall weight of the system, however, SMA-based actuators respond relatively slowly, which introduces dynamic issues that are investigated in this work. This paper describes both a control system designed specifically for issues associated with SMAs, and dynamic analysis of the geared turbofan VAFN with the SMA actuators. Also, some future recommendations are provided for this type of propulsion system.
17 Aug 2017
TL;DR: It is shown that airframe noise makes a significant contribution to the total noise of an airplane with open-rotor engines at landing.
Abstract: Community noise of a hypothetical medium-range airplane equipped with open-rotor engines is assessed by numerical modeling of the aeroacoustic characteristics of an isolated open rotor with the simplest blade geometry. Various open-rotor configurations are considered at constant thrust, and the lowest-noise configuration is selected. A two-engine medium-range airplane at known thrust of bypass turbofan engines at different segments of the takeoff–landing trajectory is considered, after the replacement of those engines by the open-rotor engines. It is established that a medium-range airplane with two open-rotor engines meets the requirements of Chapter 4 of the ICAO standard with a significant margin. It is shown that airframe noise makes a significant contribution to the total noise of an airplane with open-rotor engines at landing.