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Previous studies have shown that using blowing slots can reduce the effects of the rotor downwash on the main wing of a tilt-rotor aircraft, particularly the V-22 Osprey. The current study investigates the placement and air velocity of the leading edge blowing slot for optimization of the download reduction. The realizable turbulent kinetic energy - rate of dissipation (rke) numerical model available in Fluent 6.2.12 was used to model the flow involved under the rotors and the subsequent downwash around the main wing. It was found that the leading edge blowing slot is most beneficial when it is placed just upwind of the separation point without blowing slots. In the current investigation the optimal configuration is found between 0 percent and 1 percent of the chord length.

The Rand Cam engine is a novel design which avoids the use of pistons in favor of a cavity of varying size and shape. A set of vanes protrudes from a rotor into a circular trough in a stator. The vanes seal to the walls and base of the trough, which is of varying depth, and progress around the trough with rotation of the rotor. These vanes therefore pass through the rotor and are constrained to move parallel to the rotational axis. Intake and exhaust processes occur through ports in the stator wall which are revealed by the passing vanes. Advantages of the basic design include an absence of valves, reduction in reciprocating masses, presence of an integral flywheel in the rotor and strong fluid movement akin a swirl induced by the relative velocity between the rotor and stator.

The Rand-Cam engine is a positive displacement machine, operating on a four stroke cycle, which consists of a rotor with multiple axial vanes forming combustion chambers as the rotor and vanes rotate in a cam shaped housing. The cam housing, consisting of two “half-housings” or stators, contains a toroidal trough of varying depth machined into each stator. The two stators are phased so that the shallowest point on one trough corresponds to the deepest on the other. A set of six vanes, able to move axially through machined holes in the rotor, traverses the troughs creating six captured zones per side. These zones vary in volume with rotor rotation. Since each trough has two deep sections and two shallow sections with ramps in between, full four stroke operation is obtained between each pair of vanes in each trough, corresponding to twelve power “strokes” per revolution.

Analysis of two types of bearings has been performed for the rotor shaft of the Rand Cam™ engine. Rolling element bearings and a combination of journal and thrust bearings for selected engine configurations have been considered. The engine configurations consist of four, five, six, seven, and eight vanes. The bearing geometry and orientation was also addressed. This analysis is crucial due to the potentially large axial loading on the bearings and the need for the bearing arrangement to be compact and reliable. An emphasis was placed on the combination of fluctuating axial and radial loads and the resulting effect upon the bearings. Tapered roller bearings were found to be effective. However, a combination of journal and thrust bearings is a more compact bearing arrangement for this application. The eight vane configuration is the most desirable configuration based upon the bearing analysis.

The commercially available RNG k-e turbulence model with enhanced wall treatment found in Fluent 6.1 was used to solve the flow over a V-22 Osprey wing equipped with blowing slots. The solutions were then compared to experimental data. Good correlation between the computational and experimental data was found. Download on the wing from the rotors while the aircraft is operating in vertical take-off and landing mode was found to be reduced by the blowing slots.

Predicting the aerodynamic forces in the wake of an object can be difficult using theoretical and computational methods. This is particularly true for airframes that have multiple engines and whose flight envelope involves the use of large control surfaces. One such aircraft is the C-130 which adds the further complication of a rear cargo door and ramp. Modeling the wake near the rear of this aircraft can be difficult and inaccurate unless validated against actual flight data. For this study a simple test apparatus, developed by the authors, was used to measure the velocity profile in the wake area of the rear cargo door of such an aircraft. The test apparatus contained 32 pressure ports, one of these ports was assigned to a static pressure probe. All pressures were referenced to an additional static pressure measured at the edge of the cargo ramp. The remaining, 31 pressure probes were distributed regularly between three vertical rake assemblies.