In Place Calibration of the Aerodynamic and Propulsion Test Unit Air, Isobutane, and Liquid Oxygen System Venturi Tubes (invited)

Abstract

The Aerodynamic and Propulsion Test Unit (APTU) at the Arnold Engineering Development Complex (AEDC) has historically been used as a freejet test facility for missile scale systems. For propulsion system freejet tests, the mass-flow rate entering the engine has to be determined experimentally based on measurements made in the propulsion system flow path since a large fraction of the test medium exiting the freejet nozzle spills around the engine inlet. For the upcoming Medium Scale Critical Components (MSCC) test program, APTU will be used as a direct-connect test facility. All of the mass flow exiting the APTU direct-connect nozzle will flow directly through the propulsion system under test. This therefore requires both the precise metering of the flow rates and knowledge of the uncertainty of the mass-flow rates. This paper will discuss the calibration of the existing Hershel-type venturi tubes installed in APTU. The high-pressure air (HPA) system venturi tubes were calibrated in 2013 using a critical flow venturi test rig installed downstream of the Combustion Air Heater (CAH). The majority of the paper will be focused on describing the HPA system test program and the results. The liquid oxygen (LOX) venturi tubes will be calibrated in 2014 using a multiholed plate mounted on the exit of the CAH and the HPA system. The isobutane system venturi tubes will also be calibrated in 2014 using a Coriolis mass-flow meter installed upstream of the venturi tubes. The plans for the calibration of these two systems' venturi tubes will be described. A brief summary of the uncertainty analysis for the calculated venturi tube flow coefficient will conclude the paper. NomenclatureAEDC = Arnold Engineering Development Complex AFRL = Air Force Research Laboratory APTU = Aerodynamic and Propulsion Test Unit ASME = American Society of Mechanical Engineers A t = CFV throat cross sectional area, in. 2 , Eq. (5) CAH = Combustion Air Heater C f = venturi tube flow coefficient, CFV flow coefficient, Eqs. (1) and (5) CFV = critical flow venturi d = venturi throat diameter (inches), Eq. (1) °F = degrees Fahrenheit °R = degrees Rankin F a = venturi thermal expansion factor, Eq. (4) FCV = flow control valve ft = foot g c = gravitational constant 32.174 lb m *ft/lb f *sec 2 HPA = high-pressure air 2 Approved for public release; distribution unlimited. LOX = liquid oxygen LN 2 = liquid nitrogen MSCC = medium scale critical components M t = CFV throat Mach number, Eq. (5) NIST = National Institute of Standards and Testing P t = upstream total pressure (psia), Eq. (5) PDP = pressure drop plate psia = lb f /in. 2 absolute psid = lb f /in. 2 differential q m = mass-flow rate through the venturi tube R = gas constant for air (53.35 ft*lb m /lb f *°R) Re d = Reynolds number based on venturi tube throat diameter REFPROP= Reference Fluid Thermodynamic and Transport Properties T = current temperature T Ref = reference temperature T t = upstream total temperature (°R), Eq. (5) U = fluid velocity through the venturi tube throat VKF = Von Karman Facili...

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