Application of CFD to explain stall behavior of the SSME flowmeter

Ascoli, Edward P.; Clever, W. C.; Hadid, A. H.; Lynch, E. D.; Stewart, Maurice Bruce; Lee, K.

doi:10.2514/6.1999-2458

Cited by 1 publication

(2 citation statements)

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“…Unsteady 2-D CFD analysis by A. Hadid [6], and pseudo-unsteady 3-D CFD analysis by E. Ascoli et.al. [5] have shown that when the blade passes the strong wakes in the flow pattern generated behind the hexagonal flow straightener cells, momentary stall-like flow features are produced on the blade which slow down the rotor. Both CFD studies suggest that the occurrence of these successive stalls may produce effects high frequency oscillation of the rotor speed.…”

Section: Engine Fuel Flow (Gpm)mentioning

confidence: 99%

“…In order to solve the dynamic simulations in which equation (1) is Using the flow field behind the flow straightener Ca(R,a, 8(t)) as generated by the 3-D CFD calculation in Reference [5], and using generic CoIC L coefficients [8] for the rotor airfoils, the rotor torque using equation (2) can be calculated immediately and used to numerically advance equation (1) in time. Using this simplified procedure, the rotor response to a small and sudden change in the flow rate has been calculated.…”

Section: Quasi-steady Operation Of the Ssme Fuel Flowmetermentioning

confidence: 99%

See 1 more Smart Citation

The Effect of Acoustic Disturbances on the Operation of the Space Shuttle Main Engine Fuel Flowmeter

Marcu

Szabo²,

Dorney

et al. 2007

43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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The Space Shuttle Main Engine (SSME) uses a turbine fuel flowmeter (FFM) in its Low Pressure Fuel Duct (LPFD) to measure liquid hydrogen flowrates during engine operation. The flowmeter is required to provide accurate and robust measurements of flow rates ranging from 10000 to 18000 GPM in an environment contaminated by duct vibration and duct internal acoustic disturbances. Errors exceeding 0.5% can have a significant impact on engine operation and mission completion. The accuracy of each sensor is monitored during hot-fire engine tests on the ground. Flow meters which do not meet requirements are not flown. Among other parameters, the device is screened for a specific behavior in which a small shift in the flow rate reading is registered during a period in which the actual fuel flow as measured by afacility meter does not change.Such behavior has been observed over the years for specific builds of the FFM and must be avoided or limited in magnitude in flight. Various analyses of the recorded data have been made prior to this report in an effort to understand the cause of the phenomenon; however, no conclusive cause for the shift in the instrument behavior has been found.The present report proposes an explanation of the phenomenon based on interactions between acoustic pressure disturbances in the duct and the wakes produced by the FFM flow straightener. Physical insight into the effects of acoustic plane wave disturbances was obtained using a simple analytical model. Based on that model, a series of threedimensional unsteady viscous flow computational fluid dynamics (CFD) simulations were performed using the MSFC PHANTOM turbomachinery code. The code was customized to allow the FFM rotor speed to change at every time step according to the instantaneous fluid forces on the rotor, that, in tum, are affected by acoustic plane pressure waves propagating through the device.The results of the simulations show the variation in the rotation rate of the flowmeter due to the interaction of the flow straightener wakes and the upstream propagating acoustic waves. A detailed analysis of the acoustic disturbance effects is presented along with an assessment of the impact on measurement accuracy.

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Section: Engine Fuel Flow (Gpm)mentioning

confidence: 99%

Section: Quasi-steady Operation Of the Ssme Fuel Flowmetermentioning

confidence: 99%