Flight-test base pressure measurements in turbulent flow

Bulmer, Bruce M.

doi:10.2514/3.7292

Cited by 11 publications

(4 citation statements)

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“…During in-flight tests, a spark shadowgraph of a nine-degree half-angle cone with sharp nose at a freestream Mach number of 4.81 revealed many detailed features of the flow in the shock layer, the boundary layer, and the base region [4]. Mach number dependence of base pressure were experimentally investigated by Merz et al [5] at subsonic speeds, Chow [6] at transonic speeds, and Bulmer [7] and Zarin [8] at supersonic and hypersonic speeds. These experimental investigations demonstrated that the base pressure coefficient is relatively constant at freestream Mach numbers between 0.0 and 0.8, but begins to fall rapidly as the flow approaches sonic speed.…”

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confidence: 98%

Time-Series and Time-Averaged Characteristics of Subsonic to Supersonic Base Flows

Kawai

Fujii

2007

AIAA Journal

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Physics of cylindrical base flows ranging from subsonic to supersonic speeds at zero angle of attack are computationally investigated. Time-series and time-averaged investigations of base flows show distinctive characteristics at subsonic, transonic, and supersonic regimes. Normalized time-averaged base pressure decreases proportionally with respect to increasing freestream dynamic pressure in the subsonic regime of M 1 < 0:8. The base pressure begins to fall rapidly in the transonic regime and then settles down and decreases gradually toward an asymptotic value at M 1 > 1:5. Normalized base pressure fluctuations sharply increase at transonic speeds, whereas they decrease with increasing freestream Mach number at subsonic and supersonic speeds. Appearance of unsteady local shock waves change the characteristics of base pressure distinctively at the transonic speeds. Spectra of the base pressure show one clear peak at subsonic speeds (related to the shear layer dynamics), two clear peaks at transonic speeds (related to the shear layer dynamics and its subharmonic), and three major peaks at supersonic speeds (related to the shear layer dynamics, its subharmonic, and an additional mechanism). Instability of the free shear layers has dominant influence on the overall base flowfield over a wide range of Mach numbers ranging from subsonic to supersonic speeds. However, at supersonic speeds, an additional mechanism of instability within the recirculating region is possibly at work and has dominant influence on the flowfield. The dominant mechanisms significantly cause the strong Mach number dependence of the high-pressure region which is strongly related to the base pressure. The spectrum analysis suggests that the substantial base pressure fluctuations are caused by the pulsing of the flow inside the recirculating region. Nomenclature a = sonic speed C K = Yoshizawa model coefficientfrom closest wall to blending position d wall = distance from closest wall M = local Mach number Pr t = turbulent Prandtl number p = local static pressure q = local dynamic pressure q j = heat flux vector R = cylinder base radius Re = Reynolds number S ij = strain rate tensor Sr = Strouhal number T = temperature u = axial velocityx, y, z = Cartesian coordinates x j = coordinate vector = ratio of specific heats filter = filter length scale t = integration time x, y, z = step size of the grid in x, y, z directions ij = Kronecker delta t = turbulent eddy viscosity = kinematic eddy viscosity = density = blending function Superscripts LES = quantity in large-eddy simulation formulation RANS = quantity in Reynolds-averaged Navier-Stokes formulation = dimensional quantity = spatial-filtered or ensemble-averaged quantitỹ = Favre-filtered or Favre-averaged quantity = wall unit quantity Subscripts 1 = freestream quantity

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confidence: 98%

Time-Series and Time-Averaged Characteristics of Subsonic to Supersonic Base Flows

Kawai

Fujii

2007

AIAA Journal

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“…The coefficient of molecular viscosity is evaluated in the flow solver employing Sutherland's formula. The flow is assumed to be laminar, which is consistent with experimental results of Cassanto [37] and Bulmer [42].…”

Section: Numerical Algorithm 51 Governing Fluid Equationsmentioning

confidence: 55%

“…The base pressure measurements on a 9° semi-cone angle at Mach range of 3.50-9.20 have been carried out by Zarin [41]. Flight-test base pressure measurements were conducted by Bulmer [42] for Mach number range of 0.5-15. The shapes of the Viking, Mars Path Finder (MPF), Mars Exploration Rovers (MER), Phoenix, Mars Science Laboratory (MSL), Mu-Science Engineering Satellite (MUSES-C) are similar to the Apollo capsule [43].…”

Section: Review Of the Base Pressure Datamentioning

confidence: 99%

Numerical Simulation of Base Pressure and Drag of Space Reentry Capsules at High Speed

Mehta¹

2019

Hypersonic Vehicles - Past, Present and Future Developments

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The numerical simulations over several reentry vehicles are carried out by solving time-dependent compressible laminar axisymmetric Navier-Stokes equations for Mach 1.2-6.0. The fluid dynamics equations are discretized in spatial coordinates using integral formulation in conjunction with a finite volume method which reduce to semi-discretized ordinary differential equations. A local time-step is used to achieve steady-state solution. The numerical computation is carried out on a single-block structured computational grid. The flowfield features over the reentry vehicle such as formation of a bow shock wave ahead of the fore-body, expansion fan on the shoulder, and recirculation zone in the base region are well captured in the numerical simulations. Lower pressure acting on the base of the reentry capsule acts as base drag. The base drag coefficient based on maximum cross-section of the reentry capsule must satisfy inequality. The base drag coefficient is a function of several geometrical parameters of the fore-body and back-shell of reentry capsule, boundary layer, formation of free-shear layer in the wake region and freestream Mach number. The purpose of this chapter is to numerically evaluate and tabulate the base pressure and the base drag coefficients of various reentry space capsules at zero angle of incidence.Keywords: aerodynamic, base drag, CFD, high speed flow, viscous flow, reentry vehicle, shock wave Present and Future Developments Numerical Simulation of Base Pressure and Drag of Space Reentry Capsules at High Speed DOI: http://dx.doi.org/10.5772/intechopen.83651 the axisymmetric laminar compressible Navier-Stokes equations on a single-block structured grid, i.e., the number of grid points in the radial direction in each zone of the computational region is same. Surface pressure variations over the vehicles are computed which reveal a systematic understanding of the flow features over the capsule at high speeds. It also reveals the effect of geometrical parameters on aerodynamic base drag coefficient. The unsteady flow characteristics of the OREX and the Beagle-2 are analyzed in Ref. [28].

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“…For values of C 1 above 0.98 (M 1 > 15), one could account for the curvature of the correlation curve (dashed line).•Is it possible to scale base pressures for cones in such a way as to correlate them with the cylinder data? Because the flight test data for 0c = 9°( Bulmer 1976) form the most complete set of turbulent, hypersonic base pressure data available, they were used for the initial part of this phase. Bulmer's data for two different trajectories are plotted inFig.…”

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A review and development of correlations for base pressure and base heating in supersonic flow

Lamb

Oberkampf

1993

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A comprehensive review of experimental base pressure and base heating data related to supersonic and hypersonic flight vehicles has been completed. Particular attention was paid to free-flight data as well as wind tunnel data for models without rear sting support. Using theoretically based correlation parameters, a series of internally consistent, empirical prediction equations has been developed for planar and axisymmetric geometries (wedges cones, and cylinders). These equations encompass the speed range from low supersonic to hypersonic flow and laminar and turbulent forebody boundary layers. A wide°r ange of cone and wedge angles and cone bluntness ratios was included in the data base used to develop the correlations. The present investigation also included preliminary studies of the effect of angle of attack and specific-heat ' ratio of the gas. 3 OlSTRIBUTION OF TH!_"DOCUMENTl,SUNLIMITED Acknowledgment The authors thank Mary McWherter Walker of the Computational Fluid Dynamics Department at Sandia National Laboratories for computing the inviscid and parabolized Navier-Stokes solutions used in this study. The authors also thank David Kuntz and Vincent Amatucci of the Thermophysics Department at Sandia for reviewing this report and making a number of valuable suggestions.

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Flight-test base pressure measurements in turbulent flow

Cited by 11 publications

References 7 publications

Time-Series and Time-Averaged Characteristics of Subsonic to Supersonic Base Flows

Time-Series and Time-Averaged Characteristics of Subsonic to Supersonic Base Flows

Numerical Simulation of Base Pressure and Drag of Space Reentry Capsules at High Speed

A review and development of correlations for base pressure and base heating in supersonic flow

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