Nozzle test case details

Guidelines/Instructions for Participation in PAW03: Nozzle Test Cases

1. Objectives: The main objective the third Propulsion Aerodynamics Workshop (PAW03) is to assess the accuracy of existing computer codes and modeling techniques in simulating the steady-state aerodynamics of complex nozzle exhaust flows. The degree of success of these simulations will be judged against measured nozzle performance data, and flow field surveys of static and total pressure in regions of interest. Participants are also encouraged to expand beyond RANS with different turbulence models and start to examine URANS, DES, and LES, as well as time-dependent modeling.

2. Two nozzle geometries are provided as test cases:

I. Dual Separate Flow Reference Nozzle (DSFR): (2D axi-symmetric & 3D with Pylon and flow splitters provided). This configuration is carried over from PAW02. New participants may go through 2D Axi-symmetric geometry analysis (optional) while participants from PAW02 may use 3D geometry with optional refined mesh, innovative schemes, grid topology, optimization methods to best match test results provided by ASE FluiDyne. 

  • Experienced participants may well provide recommendations to advance state-of- the-art CFD best practices. 
  • An optional 2D study is available that explores the effects of a third stream on the 2D axisymmetric DSFR geometry in forward flight. See description in Section 3. 

II. Dual Mixed Flow Reference Nozzle (DMFR): (2-D Axi-symmetric & 3-D half model (180) with rakes and flow splitters provided). Three levels of mesh – coarse, medium and fine structured mesh will be provided.




3. Specifics for Dual Separate Flow Reference Nozzle (DSFR):

I. General:

  • DSFR hardware built and tested at ASE FluiDyne is a 3-D complex configuration which includes a pylon, bifurcations, struts, and instrumentation rakes. This configuration was used previously, as test case for PAW02. New workshop participants may complete CFD analysis requested previously; however, new participants are requested to update and use refined and innovative mesh and solution options to match test data and provide results.
  • There is a 3rd stream configuration (axi-symmetric) for the test case
  • As before, CFD solvers should use ideal gas equations and properties with γ(air) = 1.4 and R=53.35 ft/lbf/lb.R, g =32.174 ft/s2 (or equivalent if other units). Likewise, ideal flows and thrusts will also use ideal gas equations/properties. 
  • Thrust and discharge coefficients for 3-D case will be similar in definition but actual thrust and mass flows will require inclusion of pylon and splitter surfaces. The total thrust coefficient, Ct, for DSFR combines the two stream and is defined as Total Thrust Coefficient, Ct or Cfg = F(actual) / {F(ideal, fan) + F(ideal,core)}

II. Test Cases:

  • There are seven cases to be run on a constant extraction ratio, ER = 1.2 (ER = Ptfan/Ptcore). 
  • There are seven fan to ambient pressure ratio conditions to run Ptfan/Pamb = 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6. 
  • As a minimum requirement, four cases should be run for validation against test data over choked and un-choked conditions.

III. Free Stream Boundaries: 

All cases should be run static (or nearly static if participants CFD code is unable to run M=0). In addition, all cases should use the following values for free stream ambient pressure and temperature:

  • Pamb = 14.24 psi
  • Tamb = 520.0 deg R

IV. Fan Stream Inflow Boundary:

  • All cases will be run with the same uniform fan stream total temperature, Ttfan = 530.0 deg R.
  • Fan total pressure will be set according to the fan nozzle pressure ratio defined for the case, e.g. Ptfan/Pamb = 1.4 (case 1). Note: Fan Total Pressure, Ptfan = (Ptfan/Pamb) * Pamb
  • Turbulence Intensity = 5% and ratio of turbulent to molecular viscosity = 1.0 for all cases (some turbulence models use turbulent length scale, then set it to give a turbulent to molecular viscosity ratio of approximately 1.0).
V. Core Stream Inflow Boundary:
  • All cases will be run with the same uniform core stream total temperature, Ttcore = 530.0
  • deg R.
  • Core total pressure will be set according to the fan nozzle pressure ratio defined for the case and ER = 1.2. Note: Core Total Pressure, Ptcore = Ptfan / ER.
  • Turbulence Intensity = 5% and ratio of turbulent to molecular viscosity = 1.0 for all cases (some turbulence models use turbulent length scale, then set it to give a turbulent to molecular viscosity ratio of approximately 1.0).
VI. Third Stream Optimization Study (Optional): 
Perform a thrust optimization study on the 2D axi-symmetric DSFR geometry with a tertiary stream (see figure below). For a set flow conditions maximize the vent thrust as a function of vent location, X (i.e. determine vent thrust as difference between thrust of nozzle with vent and without vent).
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Paw Aiaa,
Jul 11, 2016, 12:54 PM
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Paw Aiaa,
Jun 20, 2016, 5:23 PM