The Hypersonic International Flight Research Experimentation (HIFiRE) program is a hypersonic flight test program executed by the Air Force Research Laboratory (AFRL) andAustralian Defence Science and Technology Organisation (DSTO). HIFiRE flight one flew in March 2010. Principle goals of this flight were to measure hypersonic boundary-layer transition and shock boundary layer interactions in flight. The flight successfully gathered pressure, temperature and heat transfer measurements during ascent and reentry. HIFiRE-1 has provided transition measurements suitable for calibrating N-factor prediction methods for flight, and has produced some insight into the structure of the transition front on a cone at angle of attack. Pressure and heat transfer measurements in the shock-boundary-layer interaction were obtained. Preliminary analysis of the shock boundary layer interaction shows intermittent pressure fluctuations qualitatively similar to those measured in wind tunnel experiments. A large amount of data was obtained on the flight, and significant data reduction efforts continue. Nomenclature Symbolsamplitude at lower neutral bound, dimensionless C h = heat transfer coefficient (Stanton number), , dimensionless C p = specific heat, J/kg K f = frequency, Hz h = altitude, m H = specific enthalpy, J/kg k = thermal conductivity, W/mK L = reference length from stagnation point to flare / cylinder corner, 1.6013 m full scale M = freestream (upstream of vehicle shock) Mach number N = ln[A(f)/A 1 (f)], dimensionless p = pressure, kPa = fluctuating pressure (instantaneous departure from local mean), kPa p = pressure zero-shift at t=60 seconds, kPa = heat transfer rate, W/m 2 Re = freestream unit Reynolds number per meter,  ∞ U ∞ / ∞ s = streamwise surface arc length from stagnation point, m t = time after liftoff, seconds T = temperature, K U = magnitude of the velocity vector, m/s v = velocity component normal to missile x-axis, m/s x = distance from stagnation point along vehicle centerline, m y = vertical (pitch-plane) coordinate, or depth below model wetted surface m 2  = thermal diffusivity, k/C p , m 2 /s  = wind-fixed angular coordinate around vehicle circumference, =0 on windward stagnation line, degrees (Figure 11)  = body-fixed angular coordinate around vehicle circumference,  = 0 on primary instrumentation ray, degrees (Figure 11)  = density, kg/m 3  = viscosity, N s / m 2 Subscripts 0 = stagnation conditions 1 = lower neutral bound m = measured in flight e = evaluated at boundary-layer edge tr = transition location w = evaluated at model wall x = evaluated at distance x from stagnation point ∞ = freestream conditions, upstream of model bow shockAcronyms AFRL Air Force Research Laboratory AoA angle of attack AOSG Aerospace Operational Support Group, Royal Australian Air Force ARC Ames Research Center AVD Air Vehicles Division BC boundary condition BEA best estimated atmosphere BET best estimated trajectory BLT boundary-layer transition

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This paper has three main objectives. First, it aims to show that basic general conservation principles for viscous flow can be formulated in terms of diffusion and convection. Secondly, it aims to show that three scalar conservation principles suffice to provide a method for characterizing swirling axisymmetric flows in terms of axial and boundary production of the conserved quantities. Thirdly, it aims to exemplify these two objectives by giving a complete specification of the axial causes for swirl-free conically similar flow in otherwise free space.This series of papers, overall, is concerned with the analysis and characterization of swirling conically similar flows in terms of the singularities that generate the conserved quantities. In conically similar flows there is no natural lengthscale, and the sole parameters governing the flow are provided by the strengths of the singularities that cause the flow. These are required to have the same dimensions as a power of the kinematic viscosity v. The axisymmetric flow generated by uniform production of swirl angular momentum per unit mass along a half-axis at a constant rate provides a simple example.In conically similar flow the three conservation principles for axisymmetric flow provide a sixth-order non-autonomous system of two ordinary differential equations governing the flow. Here, in Part 1, these equations are derived for the general case of swirling flow, and are shown to reduce to a fourth-order system when swirl is absent. The two scalar conservation principles describing swirl-free flow are used to classify the basic axial causes for this system.Part 2 analyses these basic exact one-parameter swirl-free families of solutions, and Part 3 extends the analysis to the remaining one-parameter family of swirling flows associated with uniform swirl angular-momentum production on a half-axis. Each of the families is characterized by a single independent cause, and two of them provide new non-trivial solutions of the Navier–Stokes equations. The effects of nonlinear coupling of these basic one-parameter causes and of conically similar distributions over conical boundaries will be examined in later papers.

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In Part 1 of this series conservation principles for ring circulation and kinematic swirl angular momentum were developed for general axisymmetric incompressible viscous flow. These principles were then used to classify the four independent axial causes of swirl-free conically similar viscous flow. Part 2 provided a detailed analysis of the one-parameter swirl-free flows that are generated by each one of the axial singularities acting alone. The present paper extends, to swirling flow, the description of the axial singularities that drive axisymmetric viscous flow. In the special case of conically similar viscous flow, two independent half-line sources of swirl angular momentum suffice to complete the set of axial singularities that can generate such swirling flows. The individual strengths of the six independent axial causes provide a complete characterization of all conically similar viscous flows that can be generated in this way. This Part 3 completes the task of analysing in detail the independent one-parameter flows generated by axial causes by studying the flow caused by uniform production of kinematic swirl angular momentum on a half-axis. This flow demonstrates how swirl may induce an axial half-plane flow. For large swirl circulation strengths, swirl angular momentum diffuses and convects so as to fill slightly more than half the space with an almost constant density of swirl angular momentum. A well-developed internal boundary layer, in the form of an outward radial jet, then separates this region from one in which the flow is almost irrotational. The jet entrains two impinging convection fields. The angular location of the jet is determined by relating the axial component of moment of whirl produced at the origin to the strength of the swirling circulation singularity on the axis.