increasing J. K(My)1 is the most 
sensitive to J, and (py), is the 
least sensitive to J. Bxcept for the 
Fy component, these data do not 
closely follow the trends indicated by 
Wereldsma (12). For the longitudinal 
wakes behind the screen, the slopes 
of «(pF m) with increasing J are less 
negative than in inclined flow. The 
relative slopes among the four 
components are generally the same for 
each propeller-wake combination, except 
for some cases at greater than design J. 
Figure 7 compares the variations 
of (px)1 with J obtained in the 
present experiment in inclined flow with 
variations obtained in previous exper- 
iments in which the unsteady blade loads 
were determined over a range of J in 
inclined flow (13,14,15,16). Each of 
these sets of experimental results show 
that (py), decreases substantially 
with increasing J. 
Figure 8 compares the variation 
in k(Fx)1 with J obtained in the 
present experiment behind the wake 
screen with the blade frequency K(Fx)n 
obtained in previous experiments in 
MEYNE and NOLTE 
BEDNARZIK 
BLAUROCK 
RAESTAD 
Current, P4402 
Current, P4661 
Current, P4661 
Current, P4710 
Current, P4710 
K(Ex)1/*(Fx)1, REF 
JIREF 
Fig. 7 — Comparison of First Harmonic Blade 
Loading Coefficients in Tangential Wakes 
which the unsteady bearing forces were 
measured in longitudinal wakes produced 
by screens in a closed-jet water tunnel 
(17,18,19). The results in References 
17, 18, and 19 are for the blade fre- 
quency component of ‘py, whereas in 
the present investigation the shaft 
frequency component of Kkpy was 
measured. However, the mechanism for 
generating the unsteady blade loading in 
axial flow appears to be independent of 
the harmonic of shaft rotation. Each of 
the three previous sets of experiments 
shows that k(px)n decreases with 
increasing J to some minimum value near 
design J, and then increases with 
further increase in J. Figure 8 
illustrates that variations of k(py)1 
with J obtained in the present 
experiment generally follow the trend of 
the data in References 17, 18 and 19. 
In general, “(Px)n is somewhat less 
sensitive to in longitudinal wake 
patterns than it is in tangential wake 
patterns. 
REFERENCE PROPELLER | FIGURE 
BOSWELL and MILLER 
NELKA 
VALENTINE and KADER 
Current 
Current 
Current 
Current 
Current 
K(Ex)n/*(Ex)n, REF 
0.9 
pees | 
0.4 06 08 1.0 1.2 1.4 16 
JSREF 
Fig. 8 — Comparison of Various Experimental Blade 
Loading Coefficients in Longitudinal Wakes 
