Aeroacoustic design of the Prop Fan

Metzger, F. B.; Rohrbach, C.

doi:10.2514/6.1979-610

Cited by 13 publications

(8 citation statements)

References 1 publication

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“…Another possible reason might be that the heat transfer performance in the fully developed region is different from that for the whole length duct if entrance effects are important. Reference [13] reported that although for some rib arrangements, the heat transfer coef®cient decreased to a steady level as the¯ow developed to the fully developed region, the heat transfer did not decrease in the downstream region but continued to increase throughout the entire length for other periodic rib arrangements.…”

Section: Wall Averaged Nusselt Numbermentioning

confidence: 95%

Heat transfer distribution in rectangular ducts with V-shaped ribs

Gao

Sundén

2001

Heat and Mass Transfer

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Heat transfer distributions are presented for a rectangular duct with two opposite wide walls arranged with V-shaped ribs pointing upstream or downstream relative to the main¯ow direction. The rectangular duct has an aspect ratio of 1/8. The parallel V-shaped circular ribs are arranged staggered on the two wide walls. The rib height-to-hydraulic diameter ratio is 0.06, with an attack angle of 60°. The pitch-to-height ratio equals 10. The tested Reynolds numbers range from 1000 to 6000. The test surface is sprayed with black paint and then liquid crystal, and a steady state method is adopted to obtain the temperature distribution between adjacent ribs. The secondary¯ow caused by the angled ribs creates different spanwise variation of the heat transfer coef®cient on the rib-roughened wall for different V-rib orientations. Interaction between heat transfer and secondary¯ow is analyzed. In the streamwise direction, the temperature distribution shows a sawtooth behavior between a pair of adjacent ribs. Local Nusselt numbers are presented between a pair of adjacent ribs, and based on these the average Nusselt numbers are calculated to investigate the augmentation of heat transfer by the presence of the V-shaped ribs. IntroductionPeriodic ribs are frequently employed in heat exchangers to enhance the heat transfer process. The heat transfer distribution and enhancement caused by parallel ribs has been investigated [1]. V-shaped ribs originated from the concept that angled ribs can act as longitudinal vortex generator and provide heat transfer augmentation. It is then assumed that V-shaped ribs can principally double the high heat transfer region and provide even higher heat transfer coef®cients (see, e.g., [2]). Because the¯ow ®eld is disturbed by the presence of the ribs and the orientation of the V-shaped ribs will induce different types of secondarȳ ow, and the local heat transfer distributions are also different.Han et al. used thermocouples to investigate the heat transfer of a square duct with 45 and 60°V-shaped ribs, and the ribs could point in the main¯ow direction or in the opposite direction [3]. The ribbed walls were in-line and the Reynolds number covered the range of 15 000± 90 000. The V-shaped ribs directed opposite to the main ow provided the highest heat transfer enhancement. Taslim et al. employed liquid crystal thermography to study the heat transfer enhancement caused by V-shaped ribs on two opposite walls of a square duct [2]. The 45°angled ribs were arranged with a ®xed pitch-to-height ratio of 10. In the whole Reynolds number range of 5000±30 000, for the blockage ratio (e/D h ) of 0.083, it was revealed that V-shaped ribs pointing downstream produced the highest heat transfer enhancement. These results contradict those of [3]. In another investigation, Ekkad and Han measured the heat transfer of a two-pass square duct with 60°V-ribs using liquid crystal thermography. The Reynolds numbers were from 6000 to 60 000 [4]. The Nusselt number ratio distributions for the ®rst pass with V-ribs pointing in...

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Section: Wall Averaged Nusselt Numbermentioning

confidence: 95%

Heat transfer distribution in rectangular ducts with V-shaped ribs

Gao

Sundén

2001

Heat and Mass Transfer

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“…However, such a calculation will require the definition of the baseline propeller blade geometry, which may not be available to the engine or aircraft designer. Even if the baseline geometry is available, the calculated ideal efficiency map will only be valid if the scaled propeller design keeps the same number of blades (the ideal efficiency being a function of the number of blades [24]). Scaling for a different number of blades will require a database of ideal efficiency maps; each one for a different number of blades, as done by Borst [8].…”

Section: Ideal Efficiency Estimationmentioning

confidence: 99%

“…13 as a function of the averageC L predicted by Eq. (24). This time, all the data collapse into a linear function between the average lift coefficient of Eq.…”

Section: Estimation Of Blade Activity Factormentioning

confidence: 99%

“…(24) for the calculation of the AF will be illustrated using a simplified example. Let us consider the reference propeller of Table 2, which has eight blades, an AF of 150, and is designed to satisfy the C T requirements on two operating points.…”

Section: Estimation Of Blade Activity Factormentioning

confidence: 99%

“…Using Eq. (24), an average lift coefficient can be calculated for each one of the design points. From these design points, the one giving the maximum lift coefficient (usually the takeoff point) will be the one sizing the reference propeller activity factor.…”

Section: Estimation Of Blade Activity Factormentioning

confidence: 99%

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Novel Propeller Map Scaling Method

Giannakakis

Goulos

Laskaridis

et al. 2016

Journal of Propulsion and Power

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This paper presents a novel method of scaling a baseline propeller map η prop fJ;C P ;M in order to obtain the performance of a propeller with different design characteristics. The developed method employs a Goldstein/ Theodorsen model to calculate the ideal efficiency and a simple approach to estimate the propeller activity factor. The proposed scaling technique enables the use of a single propeller map for propellers with different design flight conditions, diameters, number of blades, activity factors, tip speeds, or power, provided that the blade sweep and airfoil distributions remain constant.

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Weakly nonlinear acoustic and shock-wave theory of the noise of advanced high-speed turbopropellers

Tam

Salikuddin²

1986

J. Fluid Mech.

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An acoustic and shock-wave theory of the noise generated by advanced turbo-propellers operating at supersonic tip helical velocity and high-subsonic cruise Mach number is developed. The theory includes the thickness and loading noise of the highly swept propeller blades. When operating at their design conditions these propellers radiate extremely intense sound waves. Because of the weakly nonlinear propagation effects these high-intensity acoustic disturbances steepen up quickly to form shock waves. In the present theory advantage is taken of the fact that in the blade fixed-rotating-coordinate system the acoustic and shock-wave fields are time independent. The problem is formulated in this coordinate system as a boundary-value problem. Weakly nonlinear propagation effects are incorporated into the solution following Whitham's nonlinearization procedure (Whitham 1974). The change in the disturbance-propagation velocity due to fluid-particle motion as well as the change in the speed of sound resulting from compression and rarefaction are all taken into account. It is found that the equal-area rule of Whitham's shock-fitting method is also applicable to the present problem. This method permits easy construction of the three-dimensional shock surfaces associated with the acoustic disturbances of these high-speed turbopropellers. Numerical results of the present theory are compared with the measurements of the JETSTAr flight experiment and the United Technology Research Center low-cruise Mach number open-wind-tunnel data. Very favourable overall agreements are found. The comparisons indicate clearly that, when these supersonic turbopropellers are operated at their high subsonic design-cruise Mach number, weakly nonlinear propagation effects must be included in the theory if an accurate prediction of the waveform of the sound wave incident on the design aircraft fuselage is to be obtained. This is especially true for noise radiated in the upstream or forward directions. In the forward directions the effective propagation velocity of the acoustic disturbances is greatly reduced by the convection velocity of the ambient flow. This allows more time for the cumulative nonlinear propagation effects to exert their influence, leading to severe distortion of the waveform and the formation of shock waves.

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Aeroacoustic design of the Prop Fan

Cited by 13 publications

References 1 publication

Heat transfer distribution in rectangular ducts with V-shaped ribs

Heat transfer distribution in rectangular ducts with V-shaped ribs

Novel Propeller Map Scaling Method

Weakly nonlinear acoustic and shock-wave theory of the noise of advanced high-speed turbopropellers

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