sustainable solutions
_ Make continuous use of latest know-how in science, engineering
_ Eliminate thinking barriers, specialization. Cross-link lessons from nature
_ Practice meshed thinking for best practices in AF-design. Cover aeromechanics, heat transfer, mechanical strength, materials, controls

Fig.1 shows basics of current aero-designs for AFs: The mathematical smooth-flow condition (KUTTA, 1902), leads to sharp trailing edges (TE). Details of the TE-geometry are crucial for AF-performance. Fig.1 also indicates an inner-co-oled gas turbine vane as an example for hot, blunt TE airfoils. Typical for coola-bility is a thick TE with tangentially exiting cooling air (KUTTA, vE , _ = 0).

2. Objectives for solution, potential users
Focus is on TE-design, due to its key role for best AF-performance. A whole systems approach and integral thinking are concentrated on the near-TE flow, depicted in Fig.2. Real flow shows an unsteady roll-up of a trailing edge vortex (TEV), a largely non-smooth flow condition and a nonsymmetric wake. It consists of the primary, strong TEV and a weak UV. Both vortices alternately shed with a characteristic frequency fVS, which depends on the Reynolds-number ReR (AF-chord R).

The intermittent suction mechanism (S from TEV) leads to a mean, approximate satisfaction of the KUTTA-condition. The TEV-induced bound vortex around the AF is equivalent to the mean circulation _. The bound vortex generates the transverse lift force FL (Fig.1). The following general objectives for compre-hensive, long term solutions are based on the above mechanisms:
_ Concentrate on the near-TE flow. Find means to raise the turning capability of the AF, without separation
_ Use unsteady flow mechanics, beneficial natural shedding vortex control
_ Save fuel /energy /material with ecologically responsible concepts

Considering potential users, the following specific objectives are tracking critical needs. They are anticipatory in two areas of engineering applications:
1) HOT, blunt TE, inner-cooled AFs / Gas turbines, jet-engines etc.:
_ Raise Vane /blade cascade efficiencies, AF-design-life
_ Reduce Fuel consumption /CO2 - production, Emissions (NOx , CO), Noise, Overall machine life-cycle-costs
_ Provide combustion dynamics margin
_ Optimize air consumption /cooling /aerodynamics /combustion /mechanics
_ Prevent hot streaks, hot gas mix-in, local overheating, spallation of coating

2) COLD, solid AFs / Aircraft wings, turbomachines etc.:
_ Raise fuel efficiency for both cruise flight and take-off /landing
_ Reduce emissions, CO2 - production, Noise /vibrations
_ Improve stall margin, safety

The new design solutions will attract many customers and benefit mankind. Potential customers are makers /users of the following machines /components:
_ Subsonic /transsonic fixed /rotary aircraft wings
_ Wind turbines /Blowers
_ Hydroturbines /Pumps
_ Propellers, Drives for ships
_ Steam-, gas turbines /Turbocompressors /Jet-engines

3. Work strategy, solutions
An integral approach leads to new concepts, and the following seven steps characterize the comprehensive, anticipatory work strategy, which is in com-pliance with nature`s underlying principles:
1) Get inspired from swimmers, flyers in nature
2) Step back from current thinking /designs. Open for new observations
3) Apply nature to engineering. Understand mechanisms
4) Combine known fluid mechanics with latest research
5) Use verified results from the unsteady "Finite Vortex Model" (R.Liebe, 2002)
6) Find AF- designs with maximum turning capability, without flow separation
7) Verify, quantify the new concept numerically /experimentally

Fig.3 shows spade- /spike- structures plus hairy sensors at the TE of dragonflies` wings. It typically shows, how nature rigorously manages vortices in viscous, low ReR - flows, allowing for non-smooth, 3D, unsteady flow around the TE.

Fig.4, 5 indicate new AF-designs along the steps 2) to 6) for higher Reynolds-numbers. Solutions are shown, which trigger the primary TEV-roll-up and amplify it towards an unsymmetric wake with higher suction on the SS (TEV >> UV). Streamlines and the saddle point SP undergo natural, high-frequency oscillations. The new designs arrive at a lower mean SP-position, flow turning rises by __.

Tiny changes at the TE, with little energy input are now shown to function as an "Oscillating Fluid Edge" (OFE), being "in resonance with nature". The solution does very well represent an unsteady pendant to R.B.Fuller`s Trimtab. In addi-tion, small geometric changes and devices at the right position are shown to ef-fectively cause a global rise of AF-performance. This also follows the very well known credo of R.B.Fuller: "Doing the most with the least".

Differing designs for high Reynolds-number flows result for both areas of ap-plication:
1) HOT, blunt TE, inner-cooled AFs:

Fig.4 shows for the hot, hollow, air-cooled gas turbine vane of Fig.1, how the exiting coolant itself is used to raise the cascade power /efficiency via TEV-amplification with higher turning of the mean flow:
1.1 Strengthen the tiny TEV by a non-tangential _ = 15° to 25°, high velocity of the exiting coolant vE ≈ vL , avoiding secondary shear-layers /hot streaks
1.2 Additional TEV- strengthening by a periodic suction and blowing, super-imposed to vE (PSB: ± mOS , net zero flow ). The PSB, being characterized by the excitation frequency fOS /mean intensity vE, RMS
1.3 Strengthen the TEV also by a diverging-trailing-edge design (DTE), Fig.5 B. Alternatively use a "Jet-DTE"- design, Fig.5 A

Other improvements:
_ Better AF-cooling via upstream coolant unsteadiness
_ More uniform TE-cooling via a double-exit design
_ Use fluidic- or valve- systems with low-energy-inputs for PSB-generation

2) COLD, sharp TE, solid AFs:
Fig.5 shows TE-designs for cold, solid AF applications (aircraft etc.). Again TEV-strengthening is reached by activating the wake-vortices, not by avoiding them. The outlined concept follows
2.1 Employ a "Jet-DTE"- design, Fig.5 A, using a ReR - dependent feeder-flow mB at # with _ ca. 50°. The PSB is superimposed, so that m = mB ± mOS with vE ≈ vL (alternative: DTE, Fig.5 B)
2.2 Use a closed control circuit for optimum PSB (see hairy sensors in Fig.3): Membrane sensors at * (in Fig.5 A, B) pick-up the natural shedding frequency fVS and intensity. They control the PSB for optimum fOS ≈ fVS and vE, RMS . This closed loop of an "adaptive wing profile" can follow ReR

Other improvements:
_ Reduced wake-instabilities /vibrations /noise via slits, fences, damping protrusions, inclined TE-cut-offs
_ Adaptation to current ReR (cruise, take-off /landing) by using a variable VDTE for an "adaptive wing" with variable _, Fig.5 C

The solutions Fig.4, 5 use the "Oscillating Fluid Edge" to manage the natural vortices beneficially. A known message of R.B.Fuller is modified, and it fits here well: "Don`t fight vortices, use them". These OFE-designs are good, unsteady examples for R.B.Fuller`s static trimtab-principle.

First verifications of the OFE-proposals indicate, that roughly a 20% higher performance is achievable.

4. Results, verification, implementation
The verification phase has been started with an internationally respected expert for computational fluid dynamics (CFD) from the Technical University of Berlin (TUB) /Germany: Prof. Frank Thiele currently runs CFD analyses for single AF /cascades. Latest steady /unsteady Navier-Stokes (RANS) results for a heavy duty gas turbine indicate (Fig.4,6 ):
_ A reference cascade including detailed near-TE-flow was successfully simulated (100% load, ReR ca. 106, _ = 0, code "ELAN")
_ Adding a DTE-design (doubled _), a non-tangential coolant exit (_ = 20°) raised the turning capability by __ = +1.3°
_ Additional PSB excitation (fOS ca.20 KHz) is expected to produce a total of +20 % rise of the cascade efficiency
_ All objectives are achievable

Fig.6 shows velocities /streamlines for the cascade /DTE (_ = 15°). Rigorous numerical testing continues.
Fig.6 also shows the overall strategy for verification, financing and successful implementation of the solution. A comprehensive project has been started "Performance improvements from new designs for trailing edges of engineering airfoils". The program is achievable in 4 to 5 years, the stepwise procedure A) to F) minimizes risk. Work is performed within the author`s engineering consulting business "turbo-improve-consult", with the website:

www.turbo-improve-consult.de

Next development steps A) to C) are planned with the partners TUB, DLR. Parallel activities aim at getting strategic partners from turbomachine and aircraft industry for spontaneous cooperation and financial support of D), E), Fig.6. Currently 13 companies are contacted in Europe, USA and Japan. The final preferred state, step F) is to achieve a broad acceptance and introduction of the new OFE-designs.