Rotorcraft Aeroelastic Testing in the Langley Transonic Dynamics Tunnel

Yeager, William T.; Mirick, Paul H.; Hamouda, M‐Nabil H.; Wilbur, Matthew L.; Singleton, Jeffrey D.; Wilkie, W. Keats

doi:10.4050/jahs.38.3.73

Cited by 2 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Model similitude to a full-scale vehicle requires that wind-tunnel flow conditions and model structural characteristics satisfy various relationships. 1,5,[17][18][19][20] Some facilities study the aeroelastic and buffet phenomena of a wind tunnel model and tunnel support system without relation to a flight vehicle. 21 An important distinction for TDT is that the aeroelastic and buffet phenomena discussed in this document refer to events experienced by a flight vehicle and the corresponding ability of a wind tunnel model to simulate those events.…”

Section: A Typical Aeroelastic Scaling Parametersmentioning

confidence: 99%

“…(6) for conditions where gas thermodynamic scaling can be neglected (Refs. 1,5,[17][18][19][20]. The application and importance of these parameters will be discussed in the following sections.…”

Section: A Typical Aeroelastic Scaling Parametersmentioning

confidence: 99%

“…Rotorcraft tests are considered a separate class of test since Froude number, in addition to other dynamic parameters, also plays a critical role relating the amount of blade deflection for a given aerodynamic load and rotor speed. 1,19,20 Rigid buffet tests, conducted with an essentially rigid model, are classified here as a special case of aerodynamic performance tests. Since neither the deflection nor dynamics of the vehicle are simulated in rigid buffet tests, they are not aeroelastic in nature.…”

Section: B Scaling Parameter Importance For Different Classes Of Winmentioning

confidence: 99%

“…It has generally been accepted that simultaneously matching Froude number and Mach number is not typically possible, whereas matching mass ratio, stiffness, and reduced frequency is mandatory. 1,19,20 Ref. 20 recommends matching Mach number for rotorcraft performance tests and matching Froude number for rotorcraft stability tests.…”

Section: ) Experimental Example Of Dynamic Scaling Importance For Flmentioning

confidence: 99%

“…Early in the history of TDT, a rotorcraft performance test was conducted comparing the sub-scale heavy gas data acquired in TDT § with full-scale air data acquired in the NASA Full-scale Aerodynamic Complex (NFAC) for an AH-1G rotor. 1,19,24 The TDT test studied variations in Reynolds number and dynamic scaling. Due to the use of heavy gas in TDT, the dynamically-scaled model was able to simultaneously match Mach number and Froude number in addition to elastic scaling, mass ratio and reduced frequency.…”

Section: ) Experimental Example Of Dynamic Scaling Importance For Flmentioning

confidence: 99%

See 4 more Smart Citations

Unique Testing Capabilities of the NASA Langley Transonic Dynamics Tunnel, an Exercise in Aeroelastic Scaling

Ivanco

2013

AIAA Ground Testing Conference

View full text Add to dashboard Cite

The NASA Langley Research Center Transonic Dynamics Tunnel (TDT) is well known for its aeroelastic testing capabilities. Its large size, transonic speed range, variable pressure capability, and use of either air or R-134a heavy gas as a test medium enable unparalleled manipulation of flow-and-structure-dependent scaling quantities. This paper will present select scaling quantities that are important for the proper characterization of any dynamic phenomenon and many static aeroelastic phenomena. An analytical demonstration is presented comparing the unique ability of TDT to match these scaling quantities by comparison to other leading facilities with other test mediums. Complementary to aeroelastic testing, the TDT is well-suited for high risk testing and for those tests that require unusual model mount or support systems. Examples are presented. In addition to its unique aeroelastic testing capabilities, flow quality and Reynolds number capability are briefly discussed. Finally, the ability of the TDT to support future NASA research thrusts and likely vehicle designs is presented.* Research Aerospace Engineer, Aeroelasticity Branch, Mail Stop 340, AIAA Senior Member. https://ntrs.nasa.gov/search.jsp?R=20140000340 2020-07-16T13:47:06+00:00Z HE NASA Langley Research Center (LaRC) Transonic Dynamics Tunnel (TDT) has been operational since 1960 investigating a wide range of aeroelastic and non-aeroelastic phenomena. 1-4 A dedicated aeroelastic test facility, the TDT is a large, variable pressure, transonic wind tunnel that can use either air or heavy gas (R-134a) as a test medium. Unlike typical wind tunnel testing which focuses upon modeling the aerodynamics experienced by a flight vehicle, the study of aeroelasticity requires modeling of the structural response of the flight vehicle when exposed to representative aerodynamics. The coupling between fluid and structural interaction can be described by a series of non-dimensional scaling parameters. Fluid and structural-response coupling tends to increase in sensitivity as the sonic condition is approached since the lift-curve-slope steepens as a function of Mach number and slight structural perturbations have an increasing aerodynamic effect. 5 As a result, many vehicles experience a "transonicdip" in the stability boundary with the lowest stability margins existing at high subsonic Mach numbers. 5,6 High subsonic Mach numbers are where most transport aircraft cruise, where high performance aircraft pass through, where launch vehicles experience the highest unsteady buffet loads during ascent, 7 and are also where computational fluid dynamics (CFD) codes have the greatest difficulty in modeling flow physics; especially unsteady flow physics. 8 Therefore, experimental data in the transonic speed range is of particular importance. Typically regarded as the world's premier aeroelastic test facility, [9][10][11][12][13] TDT fulfills a unique niche in the wind tunnel infrastructure as a result of its unparalleled ability to manipulate fluid-structure scaling parameters. T...

show abstract

Section: A Typical Aeroelastic Scaling Parametersmentioning

confidence: 99%

Section: A Typical Aeroelastic Scaling Parametersmentioning

confidence: 99%

Section: B Scaling Parameter Importance For Different Classes Of Winmentioning

confidence: 99%

Section: ) Experimental Example Of Dynamic Scaling Importance For Flmentioning

confidence: 99%

Section: ) Experimental Example Of Dynamic Scaling Importance For Flmentioning

confidence: 99%

See 3 more Smart Citations

Unique Testing Capabilities of the NASA Langley Transonic Dynamics Tunnel, an Exercise in Aeroelastic Scaling

Ivanco

2013

AIAA Ground Testing Conference

View full text Add to dashboard Cite

show abstract

Vibratory Loads Reduction Testing of the NASA/Army/MIT Active Twist Rotor

Wilbur¹,

Mirick²,

Yeager³

et al. 2002

j am helicopter soc

Self Cite

102

106

View full text Add to dashboard Cite

Recent studies have indicated that controlled strain-induced hlade twisting can he attained nsingpiezoelectric Active Fiber Composite technology, and that such advancement may provide a mechanism for reduced rotorcraft vibrations and increased rotor performance. To validate these findings experimentally, a cooperative effort between the NASA Langley Research Center, the Army Research Lahoratory, and the MIT Active Materials and Structures Lahoratory has been developed. As a result of this collaboration a four-bladed, aeroelastically scaled, active-twist model rotor has been designed and fabricated for testing in the heavy gas test medium of the NASA Langley 'lkansonic Dynamics Thnnel. Initial wind tunnel testing has been conducted to assess the impact of active hlade twist on both fixed-and rotating-system vihratory loads in forward flight. The active twist control was found to have a pronounced effect on all system loads and was shown to offer generally reductions in fixed-system loads of 60% to 95%, depending upon flight condition, with 1.

show abstract

Rotorcraft Aeroelastic Testing in the Langley Transonic Dynamics Tunnel

Cited by 2 publications

References 0 publications

Unique Testing Capabilities of the NASA Langley Transonic Dynamics Tunnel, an Exercise in Aeroelastic Scaling

Unique Testing Capabilities of the NASA Langley Transonic Dynamics Tunnel, an Exercise in Aeroelastic Scaling

Vibratory Loads Reduction Testing of the NASA/Army/MIT Active Twist Rotor

Contact Info

Product

Resources

About