Application of a Two-dimensional Unsteady Viscous Analysis Code to a Supersonic Throughflow Fan Stage

The Rai ROTOR1 code for two-dimensional, unsteady viscous flow analysis was applied to a supersonic throughflow fan stage design. The axial Mach number for this fan design increases from 2.0 at the inlet to 2.9 at the outlet. The Rai code uses overlapped O- and H-grids that are appropriately packed. The Rai code was run on a Cray XMP computer; then data postprocessing and graphics were performed to obtain detailed insight into the stage flow. The large rotor wakes uniformly traversed the rotor-stator interface and dispersed as they passed through the stator passage. Only weak blade shock losses were computerd, which supports the design goals. High viscous effects caused large blade wakes and a low fan efficiency. Rai code flow predictions were essentially steady for the rotor, and they compared well with Chima rotor viscous code predictions based on a C-grid of similar density

Supersonic through-flow fan design

The NASA Lewis Research Center has embarked on a program to experimentally prove the concept of a supersonic through-flow fan which is to maintain supersonic velocities throughout the compression system with only weak shock-wave flow losses. The detailed design of a supersonic through-flow fan and estimated off-design performance with the use of advanced computational codes are described. A multistage compressor facility is being modified for the newly designed supersonic through-flow fan and the major aspects of this modification are briefly described

Application of advanced computational codes in the design of an experiment for a supersonic throughflow fan rotor

Increased emphasis on sustained supersonic or hypersonic cruise has revived interest in the supersonic throughflow fan as a possible component in advanced propulsion systems. Use of a fan that can operate with a supersonic inlet axial Mach number is attractive from the standpoint of reducing the inlet losses incurred in diffusing the flow from a supersonic flight Mach number to a subsonic one at the fan face. The design of the experiment using advanced computational codes to calculate the components required is described. The rotor was designed using existing turbomachinery design and analysis codes modified to handle fully supersonic axial flow through the rotor. A two-dimensional axisymmetric throughflow design code plus a blade element code were used to generate fan rotor velocity diagrams and blade shapes. A quasi-three-dimensional, thin shear layer Navier-Stokes code was used to assess the performance of the fan rotor blade shapes. The final design was stacked and checked for three-dimensional effects using a three-dimensional Euler code interactively coupled with a two-dimensional boundary layer code. The nozzle design in the expansion region was analyzed with a three-dimensional parabolized viscous code which corroborated the results from the Euler code. A translating supersonic diffuser was designed using these same codes

Immune surveillance by rhinovirus-specific circulating CD4+ and CD8+ T lymphocytes.

It is difficult to experimentally infect volunteers with RV strains to which the subject demonstrates serological immunity. However, in RV challenges, viral clearance begins before de novo adaptive immune responses would develop. We speculated that adaptive immunity to RV reflects heterologous immunity by effector memory cells.DCs were generated from monocytes using GM-CSF and IL-4 and RV39 loading accomplished with a dose of ∼ 350 TCID50/10(5) cells. RV-induced maturation was established as modulation of MHC class II, CD80, CD83, and CD86. Circulating RV targeting CD4 and CD8 T cells were investigated as induction of RV-specific proliferation (CFSE-dilution).Maturation of DC by RV was confirmed as upregulation of MHC Class II (83.3 ± 5.0% to 87.8 ± 4.1%), CD80 (39.4 ± 7.2% to 47.6 ± 7.7%) and CD86 (78.4 ± 4.7% to 84.1 ± 3.4%). Both CD4 and CD8 memory T cells were recognized in the circulation of healthy subjects.RV drives DC maturation and results in their ability to present RV antigens to both T helper and cytotoxic lymphocytes. Both CD4 and CD8 cells capable of recognizing RV-associated antigens are present in the circulation of healthy subjects where they are presumably involved in immune surveillance and explain the rapid recruitment of an adaptive immune response during RV infection

Representative gating strategy used for DCs.

<p>After 5 days of culture, monocyte derived DCs were labeled with a dye to mark viable cells. Using flow cytometry, live cells were analyzed for expression of CD14 or CD11c and co-expression of HLA-DR. Cells that were CD14^low and CD11c/HLA-DR^high were further analyzed for cell surface markers. A representative histogram showing the change in CD80 expression following RV maturation is presented. </p

Analysis of DC maturation markers.

<p>Cell surface expression of DC activation markers was determined after incubation of cells with ∼350 TCID₅₀ (50 μg) of RV for 48 hrs. Data are presented as percent positive for each marker A) MHC Class II, B) CD80, C) CD86 and D) CD83. Individual data points show changes in surface expression from untreated and RV-treated DCs (n = 14). </p

Percent of CFSE^low CD4⁺ and CD8⁺ RV-specific T lymphocytes in healthy volunteers.

<p>CFSE-labeled CD3⁺ lymphocytes and RV-loaded DC were co-cultured as described for 7 days. Data display percent of CFSE^low T lymphocytes separately gated to analyze CD4⁺ and CD8⁺ populations after subtracting background proliferation induced by unloaded DC. </p

Proliferation and Cytokine Expression in Immune Surveillance.

<p>Proliferation and Cytokine Expression in Immune Surveillance.</p

Concentration (pg/ml) of Cytokines in Control and RV-Loaded DC-CD3⁺ T Lymphocyte Co-Cultures.

<p>*p<0.05</p><p>^†p<0.01</p><p>Concentration (pg/ml) of Cytokines in Control and RV-Loaded DC-CD3⁺ T Lymphocyte Co-Cultures.</p

Change in Cytokine Gene Expression in RV-Pulsed DC.

<p>*p<0.05</p><p>Change in Cytokine Gene Expression in RV-Pulsed DC.</p