Tail Cone Research Articles

Process exploration for scale melting and solidifying of municipal solid waste incineration (MSWI) fly ash by horizontal cyclone melting furnace

This study used the horizontal tubular heating furnace to explore the melting potential of circulating fluidized bed (CFB) incinerator fly ash and mechanical grate furnace (MGF) incinerator fly ash. The horizontal cyclone melting furnace was then built to explore further the feasibility of scale melting of MSWI fly ash. The melting characteristic temperature, amorphous content, and heavy metal leaching concentration characterized the melting potential and solidification effect of MSWI fly ash. The experimental results show that the amorphous content of CFB fly ash after melting is up to 92.37%, and the volatilization rate of heavy metals Zn, Pb, and Ni does not exceed 30%. MGF fly ash exhibits the “sintering into shells” phenomenon during heating, and the leaching concentrations of heavy metals Pb in the sintered products still exceed the standard limits. In addition, the volatilization rates of heavy metals Cu, Zn, Cd, Pb, Cr, and Ni in Slag II are above 50%, and the volatilization rate of Cr reaches 85%. So, slag’s amorphous content also affects heavy metals’ volatilization rate. The MSWI fly ash melting characteristic temperature decreases with the decrease of alkalinity value. When the alkalinity value drops to 0.6, the melting characteristic temperature reaches its lowest value. Mixing 80% CFB fly ash or 50% MGF bottom ash into MGF fly ash can significantly enhance the melting potential to reduce hazardous waste. When using the horizontal cyclone melting furnace to process MSWI fly ash on a large scale, MSWI fly ash achieves an excellent melting effect with an amorphous content of over 93% at the positions of the furnace middle section, inner tail cone, slag discharge outlet, and flue gas outlet. The fly ash particles are in motion in the melting furnace, so the particle size distribution affects the melting effect of MSWI fly ash.

Analysis of Jet Blast Distance of a Refined Engine Nozzle Model for Departing Aircraft

To evaluate the influence distance and evolution law of the jet blast under the full thrust state of the aircraft engine, we constructed a refined single-engine nozzle model in this study. Using a specific B737-800 engine as an illustrative example, this model takes into account both the internal combustion of the engine and the shearing effect of the tail cone on the airflow; based on a structured grid, the grid and far-field independence of the numerical solution were verified. The numerical simulation results obtained via the Fluent software were compared with the data outlined in the Boeing aircraft characteristics manual for a thorough analysis. Our results indicated that the calculated jet influence distance from the refined nozzle model aligns more closely with the data in the aircraft characteristics manual, albeit with superior accuracy compared to the simplified nozzle model employed in previous studies. The findings of this study can serve as a valuable reference for computing jet influence distances across various aircraft types and engine models, providing data support for the study of safety intervals for aircraft crossing the runway behind the takeoff point.

Effects of distortion on a BLI fan

Abstract The BLI (boundary layer ingestion) concept for propulsion seeks to improve the energy efficiency of aircraft propulsion. This is achieved by accelerating low momentum flow ingested from boundary layers and wakes developed over the fuselage through the fan. A major challenge that needs to be overcome to realise the benefits is that the fan needs to work efficiently in distorted flow. Understanding the effects of distortion on the aerodynamic performance and the distortion transfer through the fan is therefore essential to future designs. A BLI fan, designed at reduced scale, is used for analytic modelling and experiments in a rig designed for this purpose. The test rig replicates BLI conditions for a fan installed at the aircraft tail cone. An unsteady model that includes all blades and vanes of the fan, as well as the nacelle and the by-pass duct of the test rig is used for CFD (computational fluid dynamics) simulations. Test results are used to confirm that the CFD model is representative of the aerodynamics of the fan. The tests are conducted using varying fan operating conditions but also tests with an added distortion screen. Analysis results are then used to investigate the effects of distortion on the fan efficiency, as well as on the overall efficiency. The fan efficiency is found to be moderately decreased depending on the level of and extent of inlet circumferential distortion. In terms of overall energy efficiency, a net improvement over a similar fan in clean inlet flow is found.

Numerical Modeling to Investigate the Aerodynamics of a Boundary-Layer Ingested Transonic Fan

Boundary-layer ingested engines have the potential to offer significantly reduced fuel burn, but the fan stage must be designed to run efficiently with a distorted inflow. It must also be able to withstand unsteady aerodynamic loads resulting from a complex nonuniform flowfield. This paper applies different numerical methods for an improved understanding of the aerodynamic interaction between a transonic fan and inlet distortion. A single-stage transonic tail cone thruster fan was designed using both in-house and commercial tools operating in an inlet distortion flowfield. This paper demonstrates that the relevant metrics required to compute the aerodynamic performance of a fan stage in distorted conditions can be reasonably modeled with a few harmonics using the nonlinear harmonic method in a fraction of time in comparison to a full annulus time marching solution. The nonlinear harmonic method also reduces the computational domain, and hence reduces the solution runtime by an order of magnitude. However, it fails to accurately resolve the wake and potential field transfer across the blade rows due to a limited number of harmonics being applied. A detailed aerodynamic description of the unsteady inflow distortion, the interacting blade-row mechanisms, the flow redistribution upstream of the rotor, the distortion transfer across the different blade rows, and the corresponding aerodynamic losses can be analyzed accurately using only a full annulus time-marching method.

Development of Tail and Nose Cone for Underwater Vertical Profiler Using Fused Deposition Modelling Technology

Unmanned underwater vehicle (UUV) research is currently a prominent and quite well-known topic for researchers from various engineering disciplines. A wide number of applications for 3D printing technologies have been explored, including robotics, automotive components, food, healthcare, space, marine, etc. This paper introduces the implementation of additive manufacturing technology (3D printing) into marine applications. The use of various 3D printing processes to create complex, cost-effective profiles have recently gained popularity to test the durability of newly designed products. The subsequent sections will explain the development of 3D printed nose and tail cones for the Underwater vehicles which will be used for underwater exploration. The development process is divided into the design of nose and tail cones using Solidworks, a 3D design software, flow analysis for the estimation and reduction of drag, operational depth of 3D printed parts using FEA software ANSYS, and prototyping using fused deposition modelling technology. The developed tail and nose cone were implemented into the vertical profiler and tested at the NITK swimming pool and successfully profiled the vertical column of the pool.

Research on Drag Reduction Mechanism of Supersonic Ship Tail-shaped Projectile Based on Computer-aided Simulation

<p>In order to quantitatively study the influence of the shape of the stern on the resistance of the projectile, the computer-aided fluid dynamics method was used to numerically analyze the shape of the stern model with different mach numbers under the condition of supersonic speed, by analyzing and comparing the pressure coefficient distribution of the stern flow field, the stern surface and the bottom of the projectile ship. The results showed that the tail resistance of the projectile increases linearly with the increase of the tail cone angle; the bottom resistance of the projectile is affected by the area of the bottom of the projectile (shrinkage ratio) and the tail cone angle, and increases linearly with the increase of the shrinkage ratio; The overall drag coefficient of the projectile is related to the bottom resistance and the tail resistance. When the tail length is fixed, there is a tail cone angle that minimizes the drag coefficient, and its size is related to the flight speed of the projectile. When the flight speed of the arrow increases to 3Ma, the optimal solution of the tail cone angle reaches a stable value and its value is about 9.8°, which has a certain reference value for the design of the aerodynamic shape of the high Mach number arrow.</p> <p> </p>

Boundary-Layer Ingestion Benefit for the STARC-ABL Concept

Boundary-layer ingestion (BLI) offers the potential for significant fuel burn reduction by exploiting tightly coupled aeropropulsive effects. NASA’s Single-aisle Turboelectric Aircraft with Aft Boundary-Layer propulsion (STARC-ABL) concept employs BLI on an electrically powered tail cone thruster to take advantage of the technology on what is otherwise a conventional airframe. Despite the traditional airframe of this concept, aeropropulsive integration is critical to the BLI propulsor’s performance. Therefore, it is vital to employ tightly coupled aeropropulsive models to design BLI systems. In this work, 3-D RANS simulations are used to model the aerodynamics, and 1-D thermodynamic cycle analyses are used to model the propulsion system. The two models are tightly coupled using NASA’s OpenMDAO framework, enabling efficient design optimization through gradient-based optimization with analytic derivatives. Using this coupled aeropropulsive framework, 18 computational fluid dynamics (CFD)-based aeropropulsive design optimizations are performed to study the power requirements of the BLI configuration and a reference podded configuration where the electric fan ingests freestream air. This study provides the first set of CFD-based performance data for the STARC-ABL concept across the design space of BLI fan size and pressure ratio. The results quantify the power savings through BLI compared to a traditional propulsion system.

A review of the bird impact process and validation of the SPH impact model for aircraft structures

The aim of this paper is to study the phenomenon of bird strike during each phase of the impact and to present a numerical model for its prediction in order to develop the best practices to make a structural component resistant to bird strike. To this end, the Smooth Particle Hydrodynamics (SPH) bird model is developed and validated based on experiments by Barber and Wilbeck and two papers by Guida et al. The experiments considered the impact of small birds on rigid flat panels. Guida et al. developed a 8 lb bird model to predict the impact on a deformable small leading-edge bay and on a full-scale leading edge. The hydrodynamic theory is applied to determine the shock pressure, the shock equation of state, the stagnation pressure and the steady-state equation for water with different porosities. Subsequently, the bird structure is analyzed for different bird geometries and target models. This analysis allowed to design critical components of an aircraft structure, such as the leading edge of the C27J aircraft tail cone in compliance with current aviation airworthiness requirements.

Evaluation of a Regional Aircraft with Boundary Layer Ingestion and Electric-Fan Propulsor

This paper presents a conceptual study of a regional aircraft with a turboelectric propulsion system and boundary-layer ingestion. The aircraft has an additional electric propulsor installed at the aircraft tail cone, which is driven by generators installed on both underwing engines, aiming to ingest the fuselage boundary layer and improve the aircraft overall performance. The proposed configuration is an aircraft reengining of the reference aircraft platform, the Embraer 175-E1, targeting minimizing airframe modifications. Parametric variations of the thrust split ratio as well as the electric fan pressure ratio were performed in order to create a design space of possible solutions for the proposed concept and also to provide insights of the aircraft key variables trends. From that, a feasible and optimized configuration in terms of efficiency was selected and compared to the reference aircraft. As the main conclusion, it was determined that the studied propulsion system has the potential to provide specific air range benefits in the order of 4 to 7%, which may not be enough to justify a new development.

Harmonic Forcing from Distortion in a Boundary Layer Ingesting Fan

Integrating a fan with a boundary layer ingestion (BLI) configuration into an aircraft fuselage can improve propulsion efficiency by utilizing the lower momentum airflow in the boundary layer developed due to the surface drag of the fuselage. As a consequence, velocity and total pressure variations distort the flow field entering the fan in both the circumferential and radial directions. Such variations can negatively affect fan aerodynamics and give rise to vibration issues. A fan configuration to benefit from BLI needs to allow for distortion without large penalties. Full annulus unsteady computational fluid dynamics (CFD) with all blades and vanes is used to evaluate the effects on aerodynamic loading and forcing on a fan designed to be mounted on an adapted rear fuselage of a Fokker 100 aircraft, i.e., a tail cone thruster. The distortion pattern used as a boundary condition on the fan is taken from a CFD analysis of the whole aircraft with a simplified model of the installed fan. Detailed simulations of the fan are conducted to better understand the relation between ingested distortion and the harmonic forcing. The results suggest that the normalized harmonic forcing spectrum is primarily correlated to the circumferential variation of inlet total pressure. In this study, the evaluated harmonic forces correlate with the total pressure variation at the inlet for the first 12 engine orders, with some exceptions where the response is very low. At higher harmonics, the distortion content as well as the response become very low, with amplitudes in the order of magnitude lower than the principal disturbances. The change in harmonic forcing resulting from raising the working line, thus, increasing the incidence on the fan rotor, increases the forcing moderately. The distortion transfers through the fan resulting in a non-axisymmetric aerodynamic loading of the outlet guide vane (OGV) that has a clear effect on the aerodynamics. The time average aerodynamic load and also the harmonic forcing of the OGV vary strongly around the circumference. In particular, this is the case for some of the vanes at higher back pressure, most likely due to an interaction with separations starting to occur on vanes operating in unfavorable conditions.

Performance analysis of turbo-electric propulsion system with fuselage boundary layer ingestion

A propulsion system analysis of an aircraft concept featuring a fuselage tail cone integrated turbo-electrically powered fan is presented. The aircraft has two underwing podded geared turbofan engines and an aft-fuselage mounted boundary layer ingesting fan. The fuselage fan is driven by an electric motor that is powered by power offtake from the main power plants under the wing. A long-range tube-and-wing aircraft with a year 2050 entry into service is used as a reference. A coupled multidisciplinary method for system level assessment of the turbo-electric boundary-layer ingesting propulsion system is presented. A correlation-based method is used to predict fuselage drag and a series of optimizations are carried out for a range of fuselage fan diameters. The optimal level of ingested drag is 30%-57% of the total fuselage drag, resulting in a net reduction in mission fuel burn of 0.6%-3.6% depending on technology assumptions. Further analysis reveals that installation effects, mainly increased mass, offset some of the gains of boundary layer ingestion for the smallest fuselage fan sizes. For larger fan sizes, it is instead the losses in the electric machinery together with the lower efficiency of the fuselage fan, compared to the main engine fan, that compensate for the gains from boundary layer ingestion. However, the by far strongest effect for determining the optimal level of ingested drag is that it is very difficult to obtain a net benefit from ingesting the half of the total fuselage drag contained in the outer part of the boundary layer. The benefit is outweighed by losses in the electric transmission system, installation effects and efficiency deficits of having an aft-mounted fan instead of larger size under-wing main engines. This is true also under the assumption of radical technology such as superconducting electric machinery. It is concluded that the studied aircraft architecture, despite having a high theoretical potential, faces a large difficulty in beneficially ingesting the significant amount of the fuselage drag contained in the outer part of the boundary layer. This severely limits its potential to substantially reduce the fuel burn compared to a conventional twin-engine tube-and-wing aircraft in the year 2050 timeframe.

Production process monitoring and post-production strain measurement on a full-size carbon-fibre composite aircraft tail cone assembly using embedded optical fibre sensors

Multiplexed optical fibre sensors were embedded into a carbon-fibre-reinforced-preform during the industrial production of a full-sized, one-piece tail cone assembly for a regional jet aircraft. Optical fibre Fresnel sensors monitored both the infusion of the resin, via measurement of the refractive index-dependent attenuation in the reflected light signal, and the degree of cure of the resin, via measurement of the chemical cure reaction-dependent change in refractive index. The resin cure was also monitored by optical fibre Bragg gratings (FBGs) fabricated in high linearly birefringent optical fibre, which measured through-thickness strain development, while FBGs in standard single mode optical fibre measured longitudinal strain development. The magnitudes and profiles of the transverse and longitudinal strains developed during the curing process were consistent across different locations on the tail cone. Typical transverse and longitudinal strains, related to cure reaction-induced shrinkage, were −1500 ± 17 μϵ and −500 ± 5 μϵ, respectively. Post-production, the same embedded FBG sensors were used subsequently to monitor structural strains when the tail cone was subjected to vacuum pressure loading. The longitudinal strains measured using the embedded FBG sensors were generally in good agreement with the longitudinal strains measured by the surface-bonded resistance foil strain gauge (RFSG) sensors, both qualitatively and quantitatively. The in-plane transverse and circumferential strains, oriented collinearly, were measured by the embedded FBGs and appropriately oriented surface-bonded RFSG sensors, respectively, and were, qualitatively, in good agreement.

A TAIL CONE VERSION OF THE HALPERN–LÄUCHLI THEOREM AT A LARGE CARDINAL

AbstractThe classical Halpern–Läuchli theorem states that for any finite coloring of a finite product of finitely branching perfect trees of height ω, there exist strong subtrees sharing the same level set such that tuples in the product of the strong subtrees consisting of elements lying on the same level get the same color. Relative to large cardinals, we establish the consistency of a tail cone version of the Halpern–Läuchli theorem at a large cardinal (see Theorem 3.1), which, roughly speaking, deals with many colorings simultaneously and diagonally. Among other applications, we generalize a polarized partition relation on rational numbers due to Laver and Galvin to one on linear orders of larger saturation.

Autonomous flight performance improvement of the morphing aerial robot by aerodynamic shape redesign

In this article, autonomous flight performance of an unmanned aerial robot is advanced by benefiting aerodynamic nose and tail cone shapes redesign both experimentally and computationally. For this intention, aerodynamic performance criteria (i.e. maximum fineness) of a scaled model of our autonomous aerial robot called as Zanka-II produced in Erciyes University Faculty of Aeronautics and Astronautics Model Aircraft Laboratory is first observed in sub-sonic Wind Tunnel. Results obtained in this wind tunnel are validated using a computational fluid dynamics (CFD) software (i.e. Ansys). Therefore, nose and tail cone of fuselage are improved in order to maximize maximum fineness of the autonomous aerial robot. A novel scaled model using optimum data is then produced and placed in Wind Tunnel in order to validate Ansys results with experimental results. By using geometrical data of ultimate aerodynamically optimized aerial robot, better autonomous flight performance is achieved in both simulation environment (i.e. Matlab and Simulink) and real time flights.

Reactive acoustic liner design

Acoustic treatment to reduce fan noise levels in a wind tunnel circuit consists of fibrous materials such as fibreglass or rockwool. Open cell foam materials are also used as acoustic treatments. The acoustic treatments are conventionally applied at fan tail cone regions, tunnel walls along fan diffuser section, cross-legs, test section diffuser, and nozzle contraction areas. However, conventional treatments are not possible in cryogenic wind tunnels, since bulk absorber materials with required resistivity, when operating at cryogenic temperatures, are not available. One possible solution is to design reactive silencers tuned to dominant frequencies. One such approach was used as noise control technique so as to satisfy test section noise specifications. The sound power spectrum of the compressor at different speeds were evaluated. The estimated test section sound pressure levels showed noise reduction at two dominant frequencies were required. The acoustic treatment, therefore, resulted in a double layer reactive design tuned to the two dominant frequencies. The design process will be highlighted in the presentation. The final treatment details will also be presented.Acoustic treatment to reduce fan noise levels in a wind tunnel circuit consists of fibrous materials such as fibreglass or rockwool. Open cell foam materials are also used as acoustic treatments. The acoustic treatments are conventionally applied at fan tail cone regions, tunnel walls along fan diffuser section, cross-legs, test section diffuser, and nozzle contraction areas. However, conventional treatments are not possible in cryogenic wind tunnels, since bulk absorber materials with required resistivity, when operating at cryogenic temperatures, are not available. One possible solution is to design reactive silencers tuned to dominant frequencies. One such approach was used as noise control technique so as to satisfy test section noise specifications. The sound power spectrum of the compressor at different speeds were evaluated. The estimated test section sound pressure levels showed noise reduction at two dominant frequencies were required. The acoustic treatment, therefore, resulted in a double layer...

Flow Characteristics of Double Serpentine Convergent Nozzle With Different Inlet Configuration

Serpentine nozzles have been used in stealth fighters to increase their survivability. For real turbofan aero-engines, the existence of the double ducts (bypass and core flow), the tail cone, the struts, the lobed mixers, and the swirl flows from the engine turbine, could lead to complex flow features of serpentine nozzle. The aim of this paper is to ascertain the effect of different inlet configurations on the flow characteristics of a double serpentine convergent nozzle. The detailed flow features of the double serpentine convergent nozzle including/excluding the tail cone and the struts are investigated. The effects of inlet swirl angles and strut setting angles on the flow field and performance of the serpentine nozzle are also computed. The results show that the vortices, which inherently exist at the corners, are not affected by the existence of the bypass, the tail cone, and the struts. The existence of the tail cone and the struts leads to differences in the high-vorticity regions of the core flow. The static temperature contours are dependent on the distributions of the x-streamwise vorticity around the core flow. The high static temperature region is decreased with the increase of the inlet swirl angle and the setting angle of the struts. The performance loss of the serpentine nozzle is mostly caused by its inherent losses such as the friction loss and the shock loss. The performance of the serpentine nozzle is decreased as the inlet swirl angle and the setting angle of the struts increase.

Modeling Boundary Layer Ingestion Using a Coupled Aeropropulsive Analysis

The single-aisle turboelectric aircraft with an aft boundary layer propulsor aircraft concept is estimated to reduce fuel burn by 12% through a turboelectric propulsion system with an electrically driven boundary layer ingestion propulsor mounted on the fuselage tail cone. This motivates a more detailed study of the boundary layer ingestion propulsor design, which requires considering the fully coupled airframe propulsion integration problem. However, boundary layer ingestion studies thus far have accounted only for the aerodynamic effects on the propulsion system, or vice versa, but have not considered the two-way coupling. This work presents a new approach for building fully coupled aeropropulsive models of boundary layer ingestion propulsion systems. A one-dimensional thermodynamic cycle analysis is coupled to a Reynolds-averaged Navier–Stokes simulation. This aeropropulsive model is used to assess how the propulsor design affects the overall performance for a simplified model of the single-aisle turboelectric aircraft with an aft boundary-layer propulsor. The results indicate that both propulsion and aerodynamic effects contribute equally toward the overall performance and that the fully coupled model yields substantially different results compared to the uncoupled model. Although boundary layer ingestion offers substantial fuel burn savings, it introduces propulsion-dependent aerodynamic effects that need to be accounted for.

Optimization approach for identification of dynamic parameters of localized joints of aircraft assembled structures

Ground Vibration Test (GVT) is a crucial step in the design process of a new aircraft. The test involves the analysis of different load configurations that helps to understand the real structural behaviour, to certificate some extreme load cases and also to validate and improve the Finite Element (FE) model used in the design. The validation of the FE model is done by making a comparison between Frequency Response Functions (FRF) from the GVT and the FE model at some response points. Ideally, numerical and experimental results should be in agreement. This is certainly true in the case of single components but in the case of assemblies it is common that numerical and experimental results show discrepancies, especially in the case of dynamic analysis. These differences increase as the number of components in the assembly grows, because connections are usually not represented sufficiently well in the FE model. The components of these assembled structures are usually connected at a small number of points, and they can be seen as local sources of stiffness and damping. In the FE model these joints can be represented as lumped spring/damper elements in a simplified way. In this paper a formulation of the dynamic equilibrium equation employing a decoupled approach for the joint mechanical properties of an assembly is presented. Later, an optimization process based on this formulation that involves the joint properties as design variables has been developed in order to identify the joint parameters that improve the adjustment between numerical and experimental FRF in the case of harmonic excitations. The approach has been applied to a FE model that represents the connection between a segment of fuselage and the tail cone and to a real aircraft system where experimental data is available. The results achieved with this procedure are very efficient and promising.

Preliminary sizing correlations for the rear-end of transport aircraft

Purpose – The purpose of this study of which this work is only the first part, is the development of conceptual design tools to perform an optimized design of the rear fuselage and tail surfaces. The development of a new and extensive database of transport aircraft and an analysis of certain general, rear fuselage and horizontal stabilizer parameters of the aircraft are presented in this paper. Design/methodology/approach – In addition to the development of a comprehensive high accurate database, linear and non-linear correlations between different parameters of the aircraft have been established. Data were analyzed using comparison criteria between aircraft database based on the mission, the number of engines installed or arrangement of the tail surfaces. Findings – It has been possible to obtain very relevant, linear and non-linear correlations for critical design parameters to optimize the design of the rear fuselage and horizontal tail. Research limitations/implications – In the case of the tail cone,...

Equivariant deformations of algebraic varieties with an action of an algebraic torus of complexity 1

Let $X$ be a 3-dimensional affine variety with a faithful action of a 2-dimensional torus $T$. Then the space of first order infinitesimal deformations $T^1(X)$ is graded by the characters of $T$, and the zeroth graded component $T^1(X)_0$ consists of all equivariant first order (infinitesimal) deformations. Suppose that using the construction of such varieties from [1], one can obtain $X$ from a proper polyhedral divisor $\mathscr D$ on $\mathbb P^1$ such that the tail cone of (any of) the used polyhedra is pointed and full-dimensional, and all vertices of all polyhedra are lattice points. Then we compute $\dim T^1(X)_0$ and find a formally versal equivariant deformation of $X$. We also establish a connection between our formula for $\dim T^1(X)_0$ and known formulas for the dimensions of the graded components of $T^1$ of toric varieties.