my $value = "aa\nbb\n\n\n\n";
$value =~ s/\n/\r\n/g;
my @lines = split(/\n/,$value);
my $tmp;
foreach $tmp (@lines){
	$tmp =~ s/\r//g;
	print "'$tmp'<br>";
}

こんな感じ\rの部分はなんでも良い