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The use of numerical control offers a method of reducing cost and assuring a more uniform product. Areas of economic consideration that are directly connected to numerical control include parts selection, machine load, second-source development, tooling, quantity, schedule, engineering product design, and program verification.

Preplanning, efficient programming, adequate maintenance technicians, and effective shop loading are the key areas in maintaining maximum utilization of numerically controlled machine tools. In order for management to know whether these groups are performing, a recording system which shows up time and down time is required. If a manual system is undesirable, there are several other types of monitors on the market.

A numerical analysis is conducted to investigate the performance degradation of iced airfoils in terms of meteorological parameters. Reference ice accretion shapes are taken from NASA's icing wind tunnel test results. Ice accretion shape and aerodynamic performance of the airfoil are numerically calculated under the same conditions as those used in the tests, and response surface equations are generated based on the results. The response surface models are applied to the conditions specified in Federal Aviation Regulations, appendix C of part 25, and the changes in aerodynamic coefficients are investigated. The areas of most significant lift and drag performance degradation overlap. The lift coefficient plunges more than 50% under temperatures greater than −10°C and LWC greater than 2g/m3. Under the same conditions, the drag performance greatly decreases as well. On the other hand, the moment coefficient greatly decreases under temperatures of less than −40°C and greater MVD.

The importance of the variation of relative humidity across turbomachinery engine components for in-flight icing is shown by numerical analysis. A species transport equation for vapor has been added to the existing CFD methodology for the simulation of ice growth and water flow on engine components that are subject to ice crystal icing. This entire system couples several partial differential equations that consider heat and mass transfer between droplets, crystals and air, adding the cooling of the air due to particle evaporation to the icing simulation, increasing the accuracy of the evaporative heat fluxes on wetted walls. Three validation cases are presented for the new methodology: the first one compares with the numerical results of droplets traveling inside an icing tunnel with an existing evaporation model proposed by the National Research Council of Canada (NRC).

Ice accretions on aircraft flight surfaces can degrade lift, increase drag, and reduce controllability. Anti-icing systems can remove or prevent ice growth. To predict the ice shrinkage or accretion using models such as LEWICE, the convective heat transfer behavior at the ice surface must be quantified. The work here is focused on understanding the convective heat transfer for several laser-scanned ice shapes by using commercial computational fluid dynamics (CFD) heat transfer simulations. The leading edge ice shape from a NACA 0012 airfoil and its geometrically unwrapped simplification are studied. Limitations encountered with a semi-automated unstructured mesh generation tool are presented. Thin boundary layer mesh thicknesses (i.e. much thinner than the flow’s viscous or thermal boundary layers) are found to be necessary in order to capture the surface curvature features and preserve good mesh quality near the geometric surface.

The study of aerodynamic forces in hypersonic environments is important to ensure the safety and proper functioning of aerospace vehicles. These forces vary with the angle of attack (AOA) and there exists an optimum angle of attack where the ratio of the lift to drag force is maximum. In this paper, computational analysis has been performed on a blunt cone model to study the aerodynamic characteristics when hypersonic flow is allowed to pass through the model. The flow has a Mach number of 8.44 and the angle of attack is varied from 0º to 20º. The commercial CFD solver ANSYS FLUENT is used for the computational analysis and the mesh is generated using the ICEM CFD module of ANSYS. Air is selected as the working fluid. The simulation is carried out for a time duration of 1.2 ms where it reaches a steady state and the lift and drag forces and coefficients are estimated. The pressure, temperature, and velocity contours at different angles of attack are also observed.

In this study we examined numerically the electrostatic spray transfer processes in the rotary bell spray applicator, which is this case implemented in a full 3D representation. Instead of an experimental approach [Stevenin et al., 2015, Fluids Eng., 137 (11)], here an algorithm implemented and developed for this simulation includes airflow, spray dynamics, tracking of paint droplets and an electrostatic modularized solver to present atomization and in-flight spray phenomena for the spray forming procedure. The algorithm is implemented using the OpenFOAM package. The shaping airflow is simulated via an unsteady 3D compressible Navier-Stokes method. Solver for particle trajectory was developed to illustrate the process of spray transport and also the interaction of airflow and particle that is solved by momentum coupling.

In a jet engine, ice accreted on a fan rotor can be shed from the blade surface due to centrifugal force, and the shed ice can damage compressor components. This phenomenon, which is referred to as ice shedding, threatens safe flight. However, there have been few studies on ice shedding because ice has numerous unknown physical parameters. Although existing icing models can simulate ice growth, these models do not have the capability to reproduce ice shedding. As such, in a previous study, we developed an icing model that takes into account both ice growth and ice shedding. In the present study, we apply the proposed icing model to a jet engine fan in order to investigate the effect of ice growth and shedding on the flow field. The computational targets of the present study are the engine fan and the fan exit guide vane (FEGV); thus, we simultaneously deal with the rotor-stator interaction problem.

This work presents the anti-icing simulation results from a pressure sensing probe. This study used various turbulence models to understand their influence in surface temperature prediction. A fully turbulence model and a transition turbulence model are considered in this work. Both dry air and icing conditions are considered for this study. The results show that at low Angle of Attack (AOA) both turbulence model results compared well and at higher AOA the results deviated. Overall, as AOA increases, the k-ꞷ SST model predicted the surface temperature colder than the Transition SST model result.

The purpose of this study is to investigate the effects of the size and location of wind fences on the rotor performance to avoid as well as quantify any adverse effects of outside wind on the measurement accuracy. To this end, firstly, a novel actuator disk method is developed which couples open source CFD code named OpenFOAM with blade element method and rotor flapping equations. Secondly, the parametric studies are conducted with respect to wind fence configurations which contain fence radius, inlet/outlet duct size and location etc. For quantitative evaluation of rotor performance variation according to inlet/outlet duct size, the mass flow and momentum rate on the ducts are. The rotor performance variation depending on the wind fence configuration is examined and consequently parametric study cases are classified according as calculated rotor thrust coefficient. Moreover, it is explained the difference of flow field in wind fence by demonstrating the pressure coefficient.

Streamwise vortices can be observed to interact in a number of real world scenarios. Vortex generators operating in boundary layers, as well as aircraft flying in formation can produce vortex interactions with multiple streamwise vortices in close proximity to each other. The tracking of these vortex paths as well as the location and nature of their breakdown is critical to determining how the structures can be used to aid flow control, and how large scale turbulence develops from them. Six configurations of two NACA0012 vanes were evaluated computationally to observe the interactions of a pre-existing vortex with a vortex generated downstream. Co and counter-rotating configurations at three different lateral spacings were used to vary vortex position and impingement on the rear vane.

A computational study of separated flows over a NACA 0012 airfoil at transitional Reynolds numbers is performed. The transitional nature of the flowfield is incorporated into the computations through γ-Reθ transition model based on local variables. Fully turbulent and transitional computations are performed for steady airfoil flowfields and computed results are compared against experiments. The γ-Reθ transition model, in association with Menter’s SST turbulence model is used for the transitional solutions while, SST turbulence model alone is used for the fully turbulent solutions. Both steady and unsteady compressible flow analysis for transition onset prediction and flow separation characterization has been performed. Effects of free stream flow conditions on flow transition are examined.

The aim of this paper is to present a numerical analysis of high-speed flows over a missile geometry. The N1G missile has been selected for our study, which is subjected to a high-speed flow at Mach 4 over a range of Angle of attack (AoA) from 0° to 6°. The analysis has been conducted for a 3-dimensional missile model using ANSYS environment. The study contemplates to provide new insights into the missile aerodynamic performance which includes the coefficient of lift (CL) , coefficient of drag (CD) and coefficient of moment (CM) using computational fluid dynamics (CFD). As there is a lack of availability of data for missile geometry, such as free stream conditions and/or the experimental data for a given Mach number, this paper intends to provide a detailed analysis at Mach 4. As the technology is advancing, there is a need for high-speed weapons (missiles) with a good aerodynamic performance, which intern will benefit in reduction of fuel consumption.

The numerical simulation of ice melting process on an iced helicopter rotor blade is presented. The ice melting model uses an enthalpy-porosity formulation, and treats the liquid-solid mushy zone as a porous zone with porosity equal to the liquid fraction. The ice shape on the blade section is obtained by the icing code with a dynamic mesh module. Both of the temperature change and the ice-melting process on the rotor blade section surface are analyzed. The phenomenon of ice melting is analyzed through the change of temperature and liquid fraction on the abrasion/ice interface. The liquid fraction change as with time on the abrasion/ice surface is observed, which describes the ice-melting process well. The numerical results show that the ice melting process can be simulated effectively by the melting model. The de-icing process can be monitored by observing the change of the liquid fraction of the area around the abrasion/ice interface.

NASA Glenn Research Center’s Propulsion Systems Laboratory (PSL) allows ice-crystal ice accretion tests on jet engines. This pressurized wind tunnel facility allows engines to be operated at flight altitudes and temperatures. Steady state and unsteady computational fluid dynamics simulations were performed for the PSL geometry, including the spray bars with their supports, and the converging duct section. These simulation results help to characterize the performance of the tunnel and are important for understanding the flow and particle behavior leading up to the engine test section. The results indicate complex flow structures, with vortex shedding and non-uniform flow features. Flow separation is observed in several regions. Several flow features and vortices are seen to persist to the duct exit plane where the fan section of a jet engine would be mounted for testing.

Numerical investigation of airflow at a transonic speed over the wing of the NASA high-lift Common Research Model (CRM) with and without a conformal vortex generator (CVG), placed on the airfoil suction side has been performed. The objective of the investigation was to assess the impact of CVG on the wing’s lift to drag (L/D) ratio and tip vortices. The wing has aspect and taper ratios of respectively 9, and 0.275, and a leading-edge sweep angle of 37.24 degrees. The root and tip chords were respectively 11.81m and 2.73 m with an approximate mean chord of 6.62 m. The angle of attack was 2.5 degrees. The CVG was distorted V-shaped with a base distance of approximately 4.8 cm, a depth of 8.8 cm, and a tip-to root angle of approximately 30.20. The CVG is on both sides of the tape pointing in opposite directions. The tape is 2 mm thick, 83 cm wide, spanning the entire length of the wing surface.

Hybrid (bolted/bonded) joining is becoming one of the innovative joining processes for light weight structures in the transport industry, especially in the aerospace industry where weight reduction and high joining requirements are permanent challenges. Combining the adhesive bonding with the mechanical joining -riveting for instance- can lead to an enhancement of the properties of the joint compared to the wide established riveting, as a result of a synergistic load bearing interaction between the fastener and the adhesive bondline. The influence of the rivet installation process on a hybrid joint regarding the joint stress state, the change of the bondline thickness as well as its effects on the joint performance and load transfer are some of the factors that drive the users to a better understanding of the hybrid joining process.

The automotive underbody diffuser is an expansion device which works by speeding up the air flowing underneath a vehicle. This reduces the pressure below the vehicle thereby increasing downforce. When designed properly, it can lead to a massive gain in downforce and even a reduction in drag. However, a majority of the research and development is restricted to motorsport teams and supercar manufacturers and is highly secretive. Most of the publicly available research has been done for very simple shapes (bluff bodies) to study the effects of ground clearance and rake angle. Very little research has been done for complex geometries with vanes, flaps and vortex generators. This paper aims to investigate the effects of the addition of vanes/strakes and flaps, their location as well as angle, on diffuser performance. Computational Fluid Dynamics simulations have been carried out using three dimensional, steady state RANS equations with the k-ε turbulence model on STAR CCM+ V9.06.

This paper describes the application of a finite volume procedure for a fluid network to predict thermofluid transients during chilldown of cryogenic transfer lines. The conservation equations of mass, momentum, and energy and the equation of state for real fluids are solved in a fluid network consisting of nodes and branches. The numerical procedure is capable of modeling phase change and heat transfer between solid and fluid. This paper also presents the numerical solution of pressure surges during rapid valve opening without heat transfer. The numerical predictions of the chilldown process have been compared with experimental data.

The use of a magnetic field applied to a gaseous conducting boundary layer flow as been proposed as a mean to control boundary layer losses. The solution of the Navier-Stokes equations together with the induction equation for the magnetic field was numerically obtained using a Finite Volume code. The effects of the magnetic field are introduced into the momentum equations by means of a Lorentz force source term. Further, several turbulence models were modified in order to include the magnetic field perturbation. The computation of the transitional flow on a flat plate was made for several values of the magnetic field, and a relaminarization of the flow was obtained for sufficient high values of the magnetic field. The code was also applied for the computation of the flow around an airfoil as an example application of an high speed high-altitude UAV.