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Intermeshing counter-rotating twin screw extruders play an important role in polymer processing, especially for the extrusion of profiles and pipe, largely from polyvinyl chloride. There has been little effort on flow modeling of these machines and most of this has involved representing the machine as a “leaky” positive displacement pump and estimating leakages. In recent years, M.H. Hong and the authors have developed more general methods of simulation of flow in this machine and both applied and experimentally verified it for a few designs. Here we extend these efforts to a broader range of screw designs, especially with deeper screw channels where transverse shearing induced by the flights is important. Calculations are done for isothermal power law fluids. The results are compared with experiment. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers

By coupling counter--rotating coupled nonlinear oscillators, we observe a ``mixed'' synchronization between the different dynamical variables of the same system. The phenomenon of amplitude death is also observed. Results for coupled systems with co--rotating coupled oscillators are also presented for a detailed comparison. Results for Landau-Stuart and Rossler oscillators are presented., Chaos, Solitons & Fractals (2010) -- In Press

The article “Simulation of Counter-Rotating Vortex Pairs on a Triangular-Flapped Wing with Flap-Tip Free Vortex Modeling”, written by Woo-Ram Kang, Se Hwan Park and Duck-Joo Lee, was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 08 September 2018 with open access.

In these last years a growing interest has been devoted to counter-rotating propellers especially for pod/stern drive applications for pleasure boats. In this context DINAV has been interested in the framework of an industrial R&D project to develop design/analysis computer codes for such kind of propulsors which is based on a modern lifting-line/lifting surface design method [1–4]. The present work is devoted to the comparison between the foregoing numerical design/analysis tools and the results of the cavitation tunnel tests. The validation study has been performed on a set counter rotating propellers designed to be installed on a commercial pod drive system.. Despite some uncertainty intrinsically connected to the nature of the test, results are very well in agreement with design points, allowing to validate the theoretical codes developed so far and to obtain semi-empirical correction factors for future application.

The paper reviews new experimental technologies for the development of advanced fans with high bypass ratios. Most of those developments are carried out in a highly specialized acoustic test facility available at the Central Institute of Aviation Motors (CIAM) in Moscow. The C-3A facility is equipped with an anechoic chamber specifically designed for acoustic, aerodynamic, and mechanical investigations of counter rotating fan models.

The initial conditions for electron trajectories at the exit from the tunnelling barrier are often used in strong field models, for example to bridge the first and the second steps of the three-step model celebrated in this issue. Since the analytical R-matrix theory does not rely on the three-step model or the concept of the tunnelling barrier in coordinate space, obtaining the initial conditions for electron trajectories at the barrier exit is, strictly speaking, not necessary to calculate standard observables. Not necessary, but possible—especially when motivated by the occasion of this issue. The opportunity to evaluate such initial conditions emerges as a corollary of analysing sub-barrier kinematics, which includes the interplay of laser and Coulomb fields on the sub-cycle scale (see the companion paper I). We apply our results to discuss the difference in such initial conditions for co- and counter-rotating electrons liberated during strong field ionisation. We derive quantum orbits and classical trajectories describing ionization dynamics of co- and counter-rotating electrons in long-range potentials.

A composite model has been developed to simulate the extrusion process for intermeshing counter-rotating twin-screw extruders. An experimentally based melting model, solids conveying model, and new improved metering model, were combined to develop this formulation. The procedure for global design of a flood feed intermeshing counter-rotating twin screw extruder is presented. Illustrative calculations are made for polyvinyl chloride and high density polyethylene in this type of machines with different screw designs. Computations are made for axial variation of the fill factor, pressure, temperature and melting profiles. Simulations were found to match with experimental results well. The model was also applied to scale-up.

To cope with the warming global environments, the authors had proposed the counter-rotating type hydroelectric unit, which is composed of the tandem runners and the peculiar generator with double rotational armatures. This unit can be supplied to various water circumstances, for instance, the traditional large hydropower, the mini/micro hydropower, and the tidal power. The fundamental performances and the flow conditions around the runners have been investigated and the design materials for the runners have been presented. Continuously, this paper discusses the performances at the on-cam operation, in the large tidal power station. The model unit was operated while keeping the relative rotational speed constant nT = 900 min −1 , namely 60 Hz, irrespective of the hydropower circumstances. The output and the hydraulic efficiency are affected by the blade setting angles of the front and the rear runners. Resultantly, both optimum angles giving the maximum output and/or the maximum efficiency are presented at the various discharges/heads.

This study aims to analyze aerodynamic characteristics of a counter-rotating wind turbine. For this purpose, three kinds of rotor configurations which are 2-bladed single, 4-bladed single and counter-rotating rotor were compared by using a numerical method. The numerical method used here was based on vortex lattice method and was validated with measurements of the NREL phase-VI rotor. Through numerical calculations of induction factors and power coefficients for each rotor configuration, the aerodynamic feasibility of a counter-rotating wind turbine was considered.

This paper illustrates the linear stability and the nonlinear evolution of two opposite-signed quasi-geostrophic vortices. We investigate the influence of the volume ratio between the two vortices as well as the influence of their vertical offset. Instability is always found for sufficiently close vortices. A convenient measure of the separation distance between the two vortices at their margin of stability is the horizontal gap between their two outermost edges. When the vortex volume ratio is very close to unity, the critical gap at the margin of stability tends to increase with the vertical offset. However, for volume ratios greater than 1.1, it decreases with the vertical offset. This is due to differences in the magnitude of the tilt angle of the vortices. The nonlinear evolution of unstable equilibria tends to be destructive, often breaking one vortex or both vortices into smaller vortices.

An experimental investigation has been performed to study the unsteady pressure fluctuation of rotor tip region in high pressure stage of a vaneless counter-rotating turbine. The experiment is carried out on a blow-down short duration turbine facility. The investigation indicates that the blow-down short duration turbine facility is capable of substituting continuous turbine facilities in most turbine testing. Through this experimental investigation, a distinct blade-to-blade variation is observed. The results indicate that the combined effects of vane wake, tip leakage flow, complicated wave systems and rotor wake induce the remarkable blade-to-blade variations. The results also show that the unsteady effect is intensified along the flow direction.

Direct numerical simulation has been performed to study flow interactions in multiple jets in cross-flow. Configurations considered are twin jets side-by-side and triple jets in tandem. Computations are carried out at the jet to cross-flow velocity ratio of 2.5 and the Reynolds number 225 based on the free-stream quantities and the jet width D . For twin jets, results show that in the vicinity of jet exits, the merging of two counter rotating vortex pairs (CRVP) is strongly dependent on the gap of two jets. Downstream in the far-field, a large single CRVP dominates. The simulation is in qualitatively good agreement with the experimental findings by other researchers. For triple jets, more complicated flow structures are revealed, in which a total of three vortex pairs has been identified, but none of them is dominating. The observations of complex flow structure could assistant relevant industrial applications.

The counter-rotating axial flow fan shows that the complex flow characteristics with three-dimensional, viscous, and unsteady flow fields. For the understanding of the entire core flow in counter-rotating axial flow fan, it is necessary to investigate the three-dimensional unsteady flow field between the rotors. This information is also essential for the improvement of the aerodynamic characteristics, the reduction of the aerodynamic noise level and vibration characteristics of the counter-rotating axial flow fan. The purpose of this study is, therefore, to present the periodic characteristics of the blade passage flow, the wake and the tip vortex, which are utilized for the blade design data for the improvement of the aerodynamic characteristics, the reduction of the aerodynamic noise level and vibration characteristics of the counter-rotating axial flow fan. In this paper, the three-dimensional unsteady flow by the rotor-rotor interaction of the CRF were investigated at the design point(peak efficiency operating point). Unsteady flow fields in the CRF are measured at the cross-sectional planes of the upstream, between and downstream of each rotor using the 45° inclined hot-wire probe. The stationary hot-wire technique used the 45° inclined hot-wire probe, which rotates successively with 120 degrees increments about its own axis. And, the sampling data of unsteady flow fields were phase-locked averaged to remove the random components.

Experimental studies were carried out to characterize the screw pumping behavior of various screw elements for a closely intermeshing counter-rotating twin screw extruder. The pumping capacity of the screw elements was compared to earlier flow simulations by some the authors of this type of twin screw extruder.

We have made a study of the development of phase morphology of an immiscible blend(75/25)(polypropylene–polyamide-6) for different types of continuous mixers including (i) Buss Kneader, (ii and iii) modular intermeshing corotating and counter-rotating twin screw extruders, and (iv) NEX-T Kobelco Continuous Mixer. Comparisons are made using different screw configurations for each machine. Generally, in comparison of the different machines, the intermeshing counter-rotating twin screw extruder produced the finest dispersed morphology. Using a droplet breakup kinetic model, we interpreted the blend dispersed phase droplet breakdown rate and coalescence rate. In comparison with our earlier study of the continuous mixing of agglomerates of CaCO3 particles the polymer droplet breakup rate was smaller than that of the particle agglomerates and the coalescence rates of droplets were many times greater than the particle reagglomerates rates. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Counter rotating turbine offers advantages on weight, volume, efficiency, and maneuverability relative to the conventional turbine because of its special architecture. Nowadays, it has been a worldwide research emphasis and has been used widely in the aeronautic field, while its application in the astronautic field is seldom investigated. Researches of counter rotating turbine for rocket turbopump are reviewed in this paper. A primary analysis of a vaneless counter rotating-turbine configuration with rotors of different diameters and rotational speeds is presented. This unconventional configuration meets the requirements of turbopump and may benefit the performance and reliability of rocket engines.

Measurement of total aerodynamic loads acting on airplane’s high speed CRORs, is one of the tasks of experimental aerodynamics. A special plant for this task solving was developed in TsAGI. One of the main challenges in the way of solving this problem is to develop a six-component rotating shaft balance (RSB) for the front and rear airscrews of CROR. The substantial stage of the balance development is the choice of the design. A promising design for the RSB was developed. It is a system of 12 non-prismatic beams, which is transmitting loads from the airscrews throughout a rim to a support. The rim connected to an airscrews hub and support rigidly connected to the shaft of VVP. Calculations have shown that this design has several advantages compared to known designs of eight beams.

This article presents a multi-objective optimization to improve the hydrodynamic performance of a counter-rotating type pump-turbine operated in pump and turbine modes. The hub and tip blade angles of impellers/runners with four blades, which were extracted through a sensitivity test, were optimized using a hybrid multi-objective genetic algorithm with a surrogate model based on Latin hypercube sampling. Three-dimensional steady incompressible Reynolds-averaged Navier–Stokes equations with the shear stress transport turbulence model were discretized via finite volume approximations and solved on a hexahedral grid to analyze the flow in the pump-turbine domain. For the major hydrodynamic performance parameters, the pump and turbine efficiencies were selected as the objective functions. Global Pareto-optimal solutions were searched using the response surface approximation surrogate model with the non-dominated sorting genetic algorithm, which is a multi-objective genetic algorithm. The trade-off between the two objective functions was determined and described with regard to the Pareto-optimal solutions. As a result, the pump and turbine efficiencies for the arbitrarily selected optimum designs in the Pareto-optimal solutions were increased as compared with the reference design.

Insulating particles or drops suspended in carrier liquids may start to rotate with a constant frequency when subjected to a uniform DC electric field. This is known as the Quincke rotation electro-hydrodynamic instability. A single isolated rotating particle exhibit no translational motion at low Reynolds number, however interacting rotating particles may move relative to one another. Here we present a simple system consisting of two interacting and deformable Quincke rotating particle covered drops, i.e. deformable Pickering drops. The drops attract one another and spontaneously form a counter-rotating pair that exhibits electro-hydrodynamic driven propulsion at low Reynolds number flow. © EDP Sciences and Springer 2016. The final publication is available at https://link.springer.com/article/10.1140%2Fepjst%2Fe2016-60090-2. This is the authors' accepted and refereed manuscript to the article.

A composite model of solids conveying, melting and melt flow in a closely intermeshing counter-rotating twin-screw extruder of modular design has been developed. This is based on combining melt conveying models with new melting and solids conveying models. Computations are made for axial fill factor, pressure, temperature and melting profiles. The results are compared with experiment.

The steady state performance of the counter rotating floating ring Journal bearing is analyzed with isothermal finite bearing theory. The effect of different parameters affecting the performance of the bearing (namely speed ratio, clearance ratio and radii ratio), have been investigated. The load carrying capacity of the bearing increasing with decreasing the radii ratio (R2/R1) of the ring and clearance ratio (c1/c2), in the other hand, the coefficient of friction increases with increasing the clearance and radii ratios, while decreases with incre4asing the bearing to journal speed ratio (γ). It is shown during this work that different operating conditions are greatly enhanced the performance of such bearings.

Contra-rotating axial compressor/fan (CRAC) is a promising technology to meet the future goals aircraft industry. Massive time accurate simulations are performed to investigate rotating stall in CRAC containing two counter-rotating rotors. Particularly, the back pressure increasing with a very small step to avoid missing flow field transition from stability to instability. Due to the canceling of the stator, the instability of downstream rotor is more stronger. The present studies mostly focus on the downstream rotor. The tip leakage flow field is analyzed in detail under near stall condition, which indicates that a secondary leakage flow plays an important role in the unsteadiness of CRAC's unsteady flow field. The frequency analysis in the tip clearance of downstream rotor under multiple near stall conditions captured the transition of the second harmonic frequency which can be used as stall inception signal. Moreover, the rotating stall onset process in real CRAC is simulated on the numerical stall.

The relative Ma number from rotor outlet is often quite large in high pressure turbine, especially in vaneless counter rotating turbine. Therefore, it is necessary that appropriate blades are adopted for high Ma working circumstances. In this paper, 13 design parameters are firstly chosen through analysis of the key factors that affecting the high Ma turbine performance. Then the non-uniform rational B spline method is employed to parameterize the model of turbine blade, and made the dynamic parameters of key geometric parameters associate. Furthermore, a parametric modeling method is developed for high Ma turbine cascade. Later, the method is applied to design a big bend angle and high Ma turbine blade used for a counter rotating turbine of VCE. Simulations are carried out to verify the modeling and the results prove that design demands under both working patterns can be satisfied, which implies that the blades modelling method developed in this paper is appropriate for high Ma turbine blades.Copyright © 2015 by ASME

A numerical study of turbulent flow through 3×3 multi swirler arrangement has been performed using the realizable k-e turbulence model on a grid with about 19 million points. All co and alternate co/counter swirler configurations comprised of radial-radial swirler with counter rotating vanes are analyzed. The offset distances of swirler exit from the base wall of confinement of 0.02D and 0.31D are considered where D is the diameter of swirler exit. For both arrangements, a strong jet is issued as the flow exits individual swirl cup. Recirculation is observed at the walls and between each swirl cup along with the formation of central toroidal recirculation zone (CTRZ) at each individual swirler. It is observed that all co swirling arrangement has a stronger more compact individual CTRZ. On the other hand alternate co and counter arrangement produces more swirler-to-swirler interactions. When the offset between swirler exit and base wall of confinement is increased to 0.31D, longer but more compact CTRZ are formed at each swirler cup. The velocity gradient for 0.31D offset case is also higher than that of 0.02D. These differences in the flow field indicate better combustion performance, fuel breakup and flame anchoring for the higher offset case.Copyright © 2015 by ASME

We find that the classical one-dimensional XY model, with angular-momentum-conserving Langevin dynamics, mimics the non-Newtonian flow regimes characteristic of soft matter when subjected to counterrotating boundaries. An elaborate steady-state phase diagram has continuous and first-order transitions between states of uniform flow, shear-banding, solid-fluid coexistence and slip planes. Results of numerical studies and a concise mean-field constitutive relation offer a paradigm for diverse nonequilibrium complex fluids. � 2015 American Physical Society.

An efficiency model at design performance for counter-rotating turbines is developed and validated. Based on the efficiency equations, an off-design performance model for counter-rotating turbines is developed. Combined with a thermodynamic model for a solar chimney system and a solar radiation model, annual energy output of solar chimney systems is determined. Two counter-rotating turbines, one with inlet guide vanes, the other without, are compared to a single-runner system. The design and off-design performances are weighed against in three different solar chimney plant sizes. It is shown that the counter-rotating turbines without guide vanes have lower design efficiency and a higher off-design performance than a single-runner turbine. Based on the output torque versus power for various turbine layouts, advantageous operational conditions of counter-rotating turbines are demonstrated.

The coherent effects including counter-rotating coupling on spontaneous emission are presented for a microwave driven V-type three-level atom. Novel coherent effects are realized: (i) There is an infinite series of spectral lines, which are separated by the microwave frequency, independent of the separation of the excited states, no matter whether the microwave transition is resonant or not. This is in sharp contrast to the case of the weak coupling, where the spectral interval is mainly determined by the separation of the excited states. (ii) Selective appearance and inhibition of the spectral lines are obtained simply by varying the microwave Rabi frequency. (iii) Spectral lines have a twofold structure. The physical mechanisms are analysed by employing the dressed states representation.

This paper describes a technique for measuring the pressure distribution of fluids flowing through a deformable nip of rolls counter-rotating at high speed. The technique is based on the use of a high sensitivity piezoelectric transducer mounted on the rigid roll of a laboratory film coater developed for the hydrodynamic characterization of roll coating flows. The pressure data are continuously recorded in a PC through a data acquisition card having a high-speed recording capacity, so that the experiments can be performed in conditions quite similar to those encountered in the coating industry. The pressure distribution of Newtonian fluids with different roll speeds and applied load between the rolls are reported and discussed. The results obtained are in good agreement with the data reported in the literature.

When integrals in the standard Tremaine-Weinberg method are evaluated for the case of a realistic model of a doubly barred galaxy, their modifications introduced by the second rotating pattern are in accord with what can be derived from a simple extension of that method, based on separation of tracer's density. This extension yields a qualitative argument that discriminates between prograde and retrograde inner bars. However, the estimate of the value of inner bar's pattern speed requires further assumptions. When this extension of the Tremaine-Weinberg method is applied to the recent observation of the doubly barred galaxy NGC 2950, it indicates that the inner bar there is counter-rotating, possibly with the pattern speed of -140 +/- 50 km/s/arcsec. The occurrence of counter-rotating inner bars can constrain theories of galaxy formation.

We report high spatial resolution VLA observations of the low-mass star-forming region IRAS 16293-2422 using four molecular probes: ethyl cyanide (CH$_3$CH$_2$CN), methyl formate (CH$_3$OCHO), formic acid (HCOOH), and the ground vibrational state of silicon monoxide (SiO). Ethyl cyanide emiss ion has a spatial scale of $\sim20''$ and encompasses binary cores A and B as determined by continuum emission peaks. Surrounded by formic acid emission, methyl formate emission has a spatial scale of $\sim6''$and is confined to core B. SiO emission shows two velocity components with spatial scales less than 2$''$ that map $\sim2''$ northeast of the A and B symmetry axis. The redshifted SiO is $\sim2''$ northwest of blueshifted SiO along a position angle of $\sim135^o$ which is approximately parallel to the A and B symmetry axis. We interpret the spatial position offset in red and blueshifted SiO emission as due to rotation of a protostellar accretion disk and we derive $\sim$1.4 M$_{\odot}$ interior to the SiO emission. In the same vicinity, Mundy et al. (1986) also concluded rotation of a nearly edge-on disk from OVRO observations of much stronger and ubiquitous $^{13}$CO emission but the direction of rotation is opposite to the SiO emission findings. Taken together, SiO and $^{13}$CO data suggest evidence for a counter-rotating disk. Moreover, archival BIMA array $^{12}$CO data show an inverse P Cygni profile with the strongest absorption in close proximity to the SiO emission, indicating unambiguous material infall toward the counter-rotating protostellar disk at a new source location within the IRAS 16293-2422 complex. The details of these observations and our interpretations are discussed., Comment: 18 pages, 5 figures, accepted for publication in the Astrophysical Journal

Our ultrasound in-line monitoring studies revealed that dispersion or dissipation melting mechanism played a dominant role during melting of unplasticized polyvinyl chloride (uPVC) in an intermeshing counter-rotating twin-screw extruder. It is found that calendering effect between two screws contributes to the melting of PVC particles, and results in dispersion or dissipation melting. Thus, in this paper, a dispersed melting model in calender gaps is considered to predict polymer melting length in terms of numbers of calender gaps. Effects of screw geometries (channel depth, calender gap clearance) and processing conditions including screw speed and leakage flow on melting length are discussed for particle-filled fluid models. The calculated results are compared with experimental observations by both “screw pulling out” method and ultrasound in-line monitoring method. Ultrasound in-line monitoring provides a solution to overcome the time delay occurred in screw-pulling out method.

An 'incipient' spreading centre east of (and orthogonal to) the East Pacific Rise at 2 degrees 40' N has been identified as forming a portion of the northern boundary of the Galapagos microplate. This spreading centre was described as a slowly diverging, westward propagating rift, tapering towards the East Pacific Rise. Here we present evidence that the 'incipient rift' has also rifted towards the east and opens anticlockwise about a pivot at its eastern end. The 'incipient rift' then bounds a second microplate, north of the clockwise-rotating Galapagos microplate. The Galapagos triple junction region, in the eastern equatorial Pacific Ocean, thus consists of two counter-rotating microplates partly separated by the Hess Deep rift. Our kinematic solution for microplate motion relative to the major plates indicates that the two counter-rotating microplates may be treated as rigid blocks driven by drag on the microplates' edges3.

A series of experiments was carried out using a counter-rotating flume that is housed in a computer-controlled cold room. A digital image process system (DIPS) was used to observe frazil ice processes. In particular, the effects of air temperature and flow velocity on the supercooling and frazil ice processes were examined. The super cooling process was found to be strongly related to air temperature and water depth, but only weakly related to water velocity. The water velocity has a strong influence on frazil evolution, frazil size, and number of the particles, however. The measured frazil size distribution by volume was found to be reasonably well approximated by a log-normal distribution. Frazil growth continues in number and size during supercooling and appears to reach a stable state at the end of the principal period of supercooling. All characteristic parameters of the supercooling processes and frazil size distribution were found to be related to the Reynolds number, an index of the intensity of flow turbulence. This information can be used in the development of models of frazil ice dynamics.Key words: supercooling, frazil ice, distribution, flow velocity, air temperature, turbulence.

We have investigated the generation of spiral waves in a Couette–Taylor system between counter rotating cylinders and found that for small supercriticality, the competition of spirals propagating in opposite directions along the axis of cylinders results in a formation of a localized source. Measuring the group velocity as a function of the amplitude, we have determined that these spirals have anomalous dispersion, in the sense that the phase and group velocity of each have opposite signs. The coupled complex Ginzburg–Landau equations offer a good theoretical framework to explain these results.

The three-dimensional linear instability of axisymmetric flow between exactly counter-rotating disks is studied numerically. The dynamics are governed by two parameters, the Reynolds number . Axisymmetric instabilities are also calculated; these may be stationary or Hopf bifurcations. Their thresholds are always higher than those of non-axisymmetric modes.

A current density pattern of a polycyclic π-system can be obtained as a superposition of all circuit currents, i.e., currents induced formally in all possible cyclic paths in the π system. Most circuits in coronene are diatropic (4n+2)-membered ones. In fact, all (4n+2)- and 4n-membered circuits are diatropic and paratropic, respectively. This is why this hydrocarbon sustains counter-rotating rim (diatropic) and hub (paratropic) currents when it is placed in a magnetic field. Thus, rim and hub currents in coronene are indivisible parts of many circuit currents. In contrast, the coronene tetracation/tetraanion sustains conrotatory diatropic rim and hub currents.

Response surface methodology has been used to predict the optimal processing parameters, viz. barrel temperature and screw speed, for devulcanization of natural rubber based waste rubber powder in a counter rotating twin screw extruder. Central composite rotatable design for two variables at five levels was chosen as the experimental design. The results obtained after measuring the responses were fitted as a two variable second order equation and the corresponding contour plots were plotted and analyzed. Optimum properties were predicted at 219 °C temperature and 20 rpm screw speed, which were also confirmed experimentally.

Previous experimental studies of melting of pellets in an intermeshing counter-rotating twin-screw extruder have shown that melting is initiated both between the screws and at the barrel. Models are developed for melting in both those regions. The melting between the screws is initiated by frictional work on the pellets by the calendering stresses between the screws. The melting action at the barrel is induced by a barrel temperature higher than the melting point and propagated by viscous dissipation heating of the melt film produced.

In the mid seventies a new propulsor for aircraft was designed and investigated - the so-called PROPFAN. With regard to the total pressure increase, it ranges between a conventional propeller and a turbofan with very high bypass ratio. This new propulsion system promised a reduction in fuel consumption of 15 to 25% compared to engines at that time.

A series of systematic wind tunnel tests of a given stratospheric airship counter-rotating propeller have been conducted in this paper. The basic aerodynamic performance of the stratospheric airship counter-rotating propeller has been explored. In addition, different from conventional propellers, the effect of low Reynolds number has been illustrated. Compared with single-rotating propellers, the interference between front and rear propeller has also been discussed. The experimental results indicate that low Reynolds number would strongly reduce the efficiency of counter-rotating propellers. Due to the interference between a pair of propellers, the performance of front propeller gets slightly worse, whereas the performance of rear propeller turns much better. A significant improvement of efficiency of overall CRP would be gained. By comparison with other configuration of propeller propulsion system, it indicates the counter-rotating propeller would be a wise option applied on stratospheric airships.