Combustion of hydrogen injected into a supersonic airstream (the SHIP computer program)

The mathematical and physical basis of the SHIP computer program which embodies a finite-difference, implicit numerical procedure for the computation of hydrogen injected into a supersonic airstream at an angle ranging from normal to parallel to the airstream main flow direction is described. The physical hypotheses built into the program include: a two-equation turbulence model, and a chemical equilibrium model for the hydrogen-oxygen reaction. Typical results for equilibrium combustion are presented and exhibit qualitatively plausible behavior. The computer time required for a given case is approximately 1 minute on a CDC 7600 machine. A discussion of the assumption of parabolic flow in the injection region is given which suggests that improvement in calculation in this region could be obtained by use of the partially parabolic procedure of Pratap and Spalding. It is concluded that the technique described herein provides the basis for an efficient and reliable means for predicting the effects of hydrogen injection into supersonic airstreams and of its subsequent combustion

Prediction of hydrodynamics and chemistry of confined turbulent methane-air frames in a two concentric tube combustor

A formulation of the governing partial differential equations for fluid flow and reacting chemical species in a two-concentric-tube combustor is presented. A numerical procedure for the solution of the governing differential equations is described and models for chemical-equilibrium and chemical-kinetics calculations are presented. The chemical-equilibrium model is used to characterize the hydrocarbon reactions. The chemical-kinetics model is used to predict the concentrations of the oxides of nitrogen. The combustor considered consists of two coaxial ducts. Concentric streams of gaseous fuel and air enter the inlet duct at one end; the flow then reverses and flows out through the outer duct. Two sample cases with specified inlet and boundary conditions are considered and the results are discussed

A high-lift optimization methodology for the design of leading and trailing edges on morphing wings

Data Availability Statement - The experimental data presented in Figure 10 and Figure 11 are available in Reference [2] “Axelson, J.A.; Stevens, G.L. Investigation of a Slat in Several Different Positions on a NACA 64A010 Airfoil for a Wide Range of Subsonic Mach Numbers. Technical Note 3129; Ames Aeronautical Laboratory: Moffett Field, CA, USA, March 1954.”Morphing offers an attractive alternative compared to conventional hinged, multi-element high lift devices. In the present work, morphed shapes of a NACA 64A010 airfoil are optimized for maximum lift characteristics. Deformed shapes of the leading and trailing edge are represented through Bezier curves derived from locally defined control points. The optimization process employs the fast Foil2w in-house viscous-inviscid interaction solver for the calculation of aerodynamic characteristics. Transitional flow results indicate that combined leading and trailing edge morphing may increase maximum lift in the order of 100%. A 60–80% increase is achieved when morphing is applied to leading edge only—the so-called droop nose—while a 45% increase is obtained with trailing edge morphing. Out of the stochastic optimization algorithms tested, the Genetic Algorithm, the Evolution Strategies, and the Particle Swarm Optimizer, the latter performs best. It produces the designs of maximum lift increase with the lowest computational cost. For the optimum morphed designs, verification simulations using the high fidelity MaPFlow CFD solver ensure that the high lift requirements set by the optimization process are met. Although the deformed droop nose increases drag, the aerodynamic performance is improved ensuring the overall effectiveness of the airfoil design during take-off and landing

Mathematical Modelling of Single- and Two-Phase Flow Problems in the Process Industries

Many key issuesin design for the process industries are related to the behaviour of fluids in turbulent flow, often involving more than one phase, chemical reaction or heat transfer. Computational-Fluid-Dynamics (CFD) techniques have great potential for analysing these processes and can be of great help to the designer, by reducing the need to resort to cut and try : approaches to the design of complex equipment. The paper presents the fundamental principles of CFD within the context of the so-called finite-domain technique. The procedure can handle one-, two-, and three-dimensional distributions of the variables in space, steady or transient processes, multi-phase processes, and effects such as turbulence, compressibility of phases, buoyancy, phase-change, chemical reactions, gravity stratification, etc. Demonstrations are made of the application of the procedure to the numerical computation of some process industry situations, such as those occurring in adsorbers/regenerators, combustors, cement kilns, and heat - exchangers. It is concluded that :- The finite - domain versions of the differential equations are soluble, with modest computer costs;- The solutions are always physically plausible; and,- There is a need for extensive evaluation and validation of CFD physical and chemical sub-models, particularly those concerning turbulence, chemical kinetics and interphase-transport processes

ENVIRONMENTAL REGULATIONS AND STANDARD SETTING – Effluent Limits for Discharges- A. Karavanas, M.N. Christolis and N.C. Markatos EFFLUENT LIMITS FOR DISCHARGES

permitting, Environmental or permit or discharge conditions