Blade Cant

Canting of the blade is done for mechanical reasons only. At high blade loadings, the blade is canted forward to partially counterbalance hydrodynamic and centrifugal bending forces also, canting produces a double curvature, which makes the blade stiffer and stronger. The backward or forward sweep of the leading edge is obtained by a face cut on the inducer blading such that forward canting of the blade results in a sweepback of the leading edge and a backward cant angle results in a...

Axial Retention Axial Preload

The axial preload at assembly shall be adequate to withstand maximum hydrodynamic forces including dynamic forces, thermal contraction, centrifugal contractions including Poisson's contractions, and unbalance. Dynamic forces cannot be known in advance they may be estimated to be 30 percent of the steady hydrodynamic forces. Thermal contractions should be calculated on the basis of a slow chilldown period and should include the effects of differential expansion or contraction due to differences...

Fluid Thermodynamic Effects

Rocket Engine Turbopump Blades

For an ideal fluid, which is as approximated by cold water, hydrocarbon and amine fuels, and other low-vapor-pressure fluids, the limitation on suction performance is always leading-edge cavitation in the inducer. With certain fluids there is observed a thermodynamic suppression head TSH that acts to decrease the critical NPSH requirements of the inducer refs. 1, 6-25 . Among the fluids known to exhibit this effect are liquid hydrogen, liquid oxygen, storable oxidizers such as N2O4, and hot...

Glossary

A inducer inlet flow area, ft2 tt 4 D2 d2 An meridional cross-sectional area of a mathematical expression, eq. 42 defined in eq. 42b b mathematical expression, eq. 42 defined in eq. 42a b exponent in eq. 48 approx. value 0.5 Cp pressure coefficient, eq. 61 defined in eq. 60 constant of integration, eqs. 38 and 41 defined in eq. 43 c absolute fluid velocity, ft sec c radial clearance, ft eqs. 54 and 55 Cij specific heat of liquid, Btu lb- R cm. max maximum obtainable meridional fluid D inducer...

Introduction

The inducer is the axial inlet portion of the turbopump rotor whose function is to raise the inlet head by an amount sufficient to preclude cavitation in the following stage. The inducer may be an integral part of the pump rotor or it may be mounted separately on the pump shaft upstream of the impeller. The principal objective in the design of an inducer is the attainment of high suction performance, but the achievement of maximum performance is limited by structural design considerations. The...

State Of The

Rocket Engine Turbo Pump

Inducers are classified according to head-rise capability and also according to the shape of the meridional flow path. They are divided by head-rise capability into low head head coefficent f lt 0.15 1 and high head f gt 0.15 . The head-rise capability is a function of blade geometry i.e., flat-plate, modified-helix, or vortex type . The low-head inducer blading is either flat-plate or flat-plate plus modified-helix, depending on hub-tip contours and value. The high-head inducer blading is a...

Inlet Tip Diameter and Contour Tip Diameter

The inlet tip diameter shall be derived from mathematical consideration of optimum flow conditions for maximum suction performance. The inlet tip diameter should be obtained mathematically from the relationship between suction specific speed Ss, blade tip cavitation number K, and flow coefficient lt t gt as follows A When the suction performance is specified in terms of Q, n, and NPSH, the blades must operate at the highest possible value Kd of the cavitation number K. For an inducer with a...

References

A Performance Investigation of an Eight-Inch Hubless Pump Inducer in Water and Liquid Nitrogen. NASA TN D-3807, 1967. 2. Brumfield, R. G. Optimum Design for Resistance to Cavitation in Centrifugal Pumps. P-10 Propulsion Memorandum, U. S. Naval Ordnance Test Station, Feb. 1948. 3. Ross, C. C. and Banerian, G. Some Aspects of High-Suction Specific Speed Pump Inducers. Trans. ASME, vol. 78, Nov. 1956, pp. 1715-1721. 4. Stripling, L. B. Cavitation in Turbopumps...