Facilities

1. Computational

The Computational Combustion Laboratory (CCL) at the School of Aerospace Engineering has many processing capabilities.

The current facility includes:

  • 900-core Linux cluster (2.66 GHz dual-cores Intel Woodcrest, 1 TB RAM, 12 TB disk space)
  • 480-core Linux cluster (2.6 GHz quad-core Intel, 1 TB RAM, 4 TB disk space)
  • 3456-core Linux cluster (16 TB RAM, 2.6 GHz Intel Sandy Bridge and Ivy Bridge cores, 150 TB DDN disk space)
  • Dual 20-core Intel with 4x60 core Intel Xeon Phi (280 cores total)
  • Intel Knight Landing (KNL) 64-core workstation
  • 25+ multi-core workstations and large data servers

CCL also has access to many large-scale computing facilities in Federal Laboratories in NASA , Department of Energy and Department of Defense where most of the large-scale simulations are conducted .

2. Experimental

2.1 Supersonic Facilities

    2.1.1 Non-reacting Mixing Facility
    • Rectangular Nozzles: Mach 1.75, 2.5, 3.5
    • Air Mass Flow Rate: 3 – 11.8 kg/s
    • Stagnation Pressure: 0.4 – 1,400 kPa (Absolute)
    • Stagnation Temperature: 290 – 800 K
    • Nozzle Cross-Section: 80 mm X 80 mm
    • Test Section Cross-Section: 80 mm X 105.4 mm X 235 mm
    • Free-Stream Unit Re: 42x106 –102x106 m-1

    This facility is a conventional supersonic blow down wind tunnel with a preheated inflow from an indirect, gas fired heat exchanger. At the nominal stagnation pressure of 0.66 MPa (Re/m = 66.6 x 106), the facility can be operated continuously for approximately 10 minutes, with about 3 such operations per day. The tunnel is in a modular form thus providing great flexibility. The supersonic nozzle is designed to produce shock-free supersonic jet with uniform turbulence level in the cross-section. To permit optical access, the sidewalls of the test section are fitted with optical grade quartz windows that span the entire height of the test section and 235 mm long. In addition, the tunnel floor and ceiling have 3 circular sockets (Ø 70 mm), which can be used for optical access, wall pressure distribution or Pitot probe
    measurements. Each plug can have pressure taps arranged on a cross pattern (17 tap holes along the axial and transverse directions). With three plugs installed, wall pressure measurements can be obtained at 51 stream wise locations. Pressure distributions normal to the flow can be measured using a probe mounted on a motorized traverse with a resolution of 0.025 mm.

    In the current set up, supersonic air enters the test section through an 80 x 80 mm cross-sectional area duct before it flows over a 25.4 mm high, backward facing step. The test section pressure for current tests is 400kPa and unless mentioned the secondary jet exit pressure is designed to match this pressure. To simulate fuel injection, a sonic jet of helium (and sometimes nitrogen or carbon di-oxide) can be injected below a splitter plate. A ramp is installed downstream of the backward-facing step to reduce the influence of streamline curvature and make the mixing layer horizontal. The stagnation pressure and temperature of the helium are measured before the flow enters the sonic injector.

    To obtain the different convective compressibility conditions, the secondary stream can be supplied from either pressurized gases stored in tanks or heated air.
    Three-component LDV, Stereo PIV and high resolution Schlieren systems are available and can be used in this system.

    2.1.2 Reacting Facility

    • Rectangular Nozzles: Mach 1.25, 1.75, 2.5
    • Air Mass Flow Rate: 3 – 11.8 kg/s
    • Stagnation Pressure: 0.4 – 1,400 kPa (Absolute)
    • Stagnation Temperature: 290 – 800 K
    • Nozzle Cross-Section: 50 mm X 50 mm
    • Test Section Cross-Section: 50 mm X 50 mm X 750 mm

    The supersonic combustion facility is connected to the Combustion Laboratory blow down system. A 101.6 mm diameter pipe connects the stagnation tank to the wall outlet, it is thermally insulated with 63.5 mm thick glass wool coating and an infrared reflecting stainless steel shell. The air flow-rate is controlled through an upstream pressure regulator and the flow-rate is inferred from the stagnation pressure. The settling tank is a 0.6 m × 2.8 m cylinder in which low velocities are achieved (order of Mach 0.001). The components downstream of the settling tank have a modular square construction. Components are inter-changeable and re-configurable. The fuel and PIV seed particles are injected into the injection module and mix/homogenize in the homogenizer module. Here, three wire meshes provide uniformity and background turbulence elimination. Following the homogenizer is the turbulence generator section where one of several turbulence generation devices create nearly isotropic turbulence of varying intensity. Next, the converging module reduces the area by a factor of 9.3:1 followed by the converging-diverging nozzle. The test section is attached to the rear end of the C-D nozzle.

    The primary injection system is rated for 13,789 kPag and fuel is delivered through an array of 1.5 mm holes. The fuel injection array is located far upstream of the test section and oriented in a counter-flowing arrangement to enhance mixing and guarantee uniform fueling of the test section. The injection array is choked so that the fuel flow rate can be controlled by setting the fuel’s upstream pressure. The flow rate is metered through two techniques: (a) an upstream sub-critical orifice and (b) an isentropic flow calculations at injection location. The two measures offer redundancy in the fuel flow rate measurement and help identify leaks in upstream piping or clogs at the injection point.

    2.2 Subsonic Reacting Facilities

    • Test Section Mach Number(s): 0.1, 0.2-0.6
    • Air Mass Flow Rate: 3 – 11.8 kg/s
    • Stagnation Pressure: 0.4 – 1,400 kPa (Absolute)
    • Stagnation Temperature: 290 – 800 K
    • Nozzle Cross-Section: 50 mm X 50 mm
    • Test Section Cross-Section: 50 mm X 50 mm X 750 mm

    The subsonic compressible facility is connected to the building’s blow down system. There are two changeable test sections. A 76.2 mm diameter pipe connects the stagnation tank to the wall outlet. The air flow rate is controlled through the use of an upstream manual valve and the flowrate is metered via an upstream sub-critical orifice. The settling tank is a 0.9 m × 2.8 m cylinder in which low velocities are achieved (order of Mach 0.001). The components downstream of the settling tank have a modular square construction. Components are inter-changeable and reconfigurable. The fuel and PIV seed particles are injected into the injection module and mix/homogenize in the homogenizer module. Here, three wire meshes provide uniformity and background turbulence elimination. Following the homogenizer is the turbulence generator section where one of several turbulence generation devices create nearly isotropic turbulence of varying intensity.

    Two test sections are available depending on the necessary Mach number: (a) The straight duct is a 146 mm x 146 mm test section for low Mach number studies (M < 0.1) and is used to study incompressible isotropic turbulence decay and incompressible flame-turbulence interactions, (b) the converging test section can be attached to the rear end of a 9.3:1 contraction and has a 50 mm x 50 mm test section. This test section can achieve subsonic flow in a Mach number 0.2-0.6 range depending on the flow rate.

    Both test sections are made of 6061 aluminum steel plate. The converging test section has a 412.8 mm homogenizer section after the turbulence generator and prior to the converging module. This homogenizer allows the generated turbulence to achieve spatial homogeneity prior to entering the convergence. The converging test section is approximately 870 mm long with full optical access along the length. The straight duct test section features two diverging side walls to correct for frictional acceleration of the mean velocity. The straight duct test section is 1374.8 mm long and attaches directly to the turbulence generator. There is optical access along 750 mm of the straight test section to allow full side and top-on optical access to the test section.

    The primary injection system is rated for 206.8 kPaG and fuel is delivered through an injection array located far upstream of the test section. The fuel injectors are oriented in a counter flowing arrangement to enhance mixing and guarantee uniform fueling of the test section. The array uses sub-critical injection of fuel due to the low pressure capability. The flow rate is controlled by a manual value upstream of the injection locations. The flow rate is metered through an upstream sub-critical orifice.

    2.3 Diagnostics

    2.3.1 Pressure and Temperature Measurements

    Pressure is measured in the stagnation chamber, at the fuel injector and at the subcritical orifices. The pressure transducers are in the range: 0-209, 0-689, 0-2068, 101-689 and 101-1723 kPa. All pressure transducers have an accuracy of 0.25% of their full span. Temperature is measured in the settling tank and in the fuel line. The thermocouples are all K-type.

    2.3.1 Optical Measurements

    Two side windows and one top-down windows (plus one bottom window for the converging test section) allow flow visualization techniques to be carried over a 750 mm long region. Current optical diagnostics include:

    • High resolution Schlieren
    • OH-PLIF, CH-PLIF
    • CH2O PLIF (simultaneous with OH PLIF)
    • 3-component LDV
    • PIV and Stereo-PIV